Code review comment: `restArgs.get(restArgs.size() - 1)`  I think we can extract this or related logic to a variable. This is used multiple times. This will simplify the code increasing readability. L5083, L5088, L5098, L5115 (condition)

Code under review:
public void visit(BLangFunction funcNode) {
        SymbolEnv funcEnv = SymbolEnv.createFunctionEnv(funcNode, funcNode.symbol.scope, env);
        if (!funcNode.interfaceFunction) {
            addReturnIfNotPresent(funcNode);
        }

        
        funcNode.originalFuncSymbol = funcNode.symbol;
        funcNode.symbol = ASTBuilderUtil.duplicateInvokableSymbol(funcNode.symbol);
        funcNode.requiredParams = rewrite(funcNode.requiredParams, funcEnv);
        funcNode.restParam = rewrite(funcNode.restParam, funcEnv);
        funcNode.workers = rewrite(funcNode.workers, funcEnv);

        if (funcNode.returnTypeNode != null && funcNode.returnTypeNode.getKind() != null) {
            funcNode.returnTypeNode = rewrite(funcNode.returnTypeNode, funcEnv);
        }

        List<BLangAnnotationAttachment> participantAnnotation
                = funcNode.annAttachments.stream()
                .filter(a -> Transactions.isTransactionsAnnotation(a.pkgAlias.value,
                                                                   a.annotationName.value))
                .collect(Collectors.toList());
        funcNode.body = rewrite(funcNode.body, funcEnv);
        funcNode.annAttachments.forEach(attachment -> rewrite(attachment, env));
        if (funcNode.returnTypeNode != null) {
            funcNode.returnTypeAnnAttachments.forEach(attachment -> rewrite(attachment, env));
        }

        if (participantAnnotation.isEmpty()) {
            
            result = funcNode;
            return;
        }

        
        
        
        
        
        result = desugarParticipantFunction(funcNode, participantAnnotation);
    }

    private BLangFunction desugarParticipantFunction(BLangFunction funcNode,
                                                     List<BLangAnnotationAttachment> participantAnnotation) {
        BLangAnnotationAttachment annotation = participantAnnotation.get(0);
        BLangBlockFunctionBody onCommitBody = null;
        BLangBlockFunctionBody onAbortBody = null;
        funcNode.requiredParams.forEach(bLangSimpleVariable -> bLangSimpleVariable.symbol.closure = true);
        
        if (funcNode.receiver != null) {
            funcNode.receiver.symbol.closure = true;
        }
        BType trxReturnType = BUnionType.create(null, symTable.errorType, symTable.anyType);
        BLangType trxReturnNode = ASTBuilderUtil.createTypeNode(trxReturnType);
        
        BLangLambdaFunction commitFunc = createLambdaFunction(funcNode.pos, "$anonOnCommitFunc$",
                                                              ASTBuilderUtil.createTypeNode(symTable.nilType));
        BLangLambdaFunction abortFunc = createLambdaFunction(funcNode.pos, "$anonOnAbortFunc$",
                                                             ASTBuilderUtil.createTypeNode(symTable.nilType));

        BLangSimpleVariable onCommitTrxVar = ASTBuilderUtil
                .createVariable(funcNode.pos, "$trxId$0", symTable.stringType, null,
                                new BVarSymbol(0, names.fromString("$trxId$0"), this.env.scope.owner.pkgID,
                                               symTable.stringType, commitFunc.function.symbol));
        BLangSimpleVariable onAbortTrxVar = ASTBuilderUtil
                .createVariable(funcNode.pos, "$trxId$0", symTable.stringType, null,
                                new BVarSymbol(0, names.fromString("$trxId$0"), this.env.scope.owner.pkgID,
                                               symTable.stringType, abortFunc.function.symbol));

        BLangSimpleVarRef trxIdOnCommitRef = ASTBuilderUtil.createVariableRef(funcNode.pos, onCommitTrxVar.symbol);

        BLangSimpleVarRef trxIdOnAbortRef = ASTBuilderUtil.createVariableRef(funcNode.pos, onAbortTrxVar.symbol);

        for (Map.Entry<String, BLangExpression> entry :
                getKeyValuePairs((BLangStatementExpression) annotation.expr).entrySet()) {
            switch (entry.getKey()) {
                case Transactions.TRX_ONCOMMIT_FUNC:
                    BInvokableSymbol commitSym = (BInvokableSymbol) ((BLangSimpleVarRef) entry.getValue()).symbol;
                    BLangInvocation onCommit = ASTBuilderUtil
                            .createInvocationExprMethod(funcNode.pos, commitSym, Lists.of(trxIdOnCommitRef),
                                                        Collections.emptyList(), symResolver);
                    BLangStatement onCommitStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onCommit);
                    onCommitBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos, Lists.of(onCommitStmt));
                    break;
                case Transactions.TRX_ONABORT_FUNC:
                    BInvokableSymbol abortSym = (BInvokableSymbol) ((BLangSimpleVarRef) entry.getValue()).symbol;
                    BLangInvocation onAbort = ASTBuilderUtil
                            .createInvocationExprMethod(funcNode.pos, abortSym, Lists.of(trxIdOnAbortRef),
                                                        Collections.emptyList(), symResolver);
                    BLangStatement onAbortStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onAbort);
                    onAbortBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos, Lists.of(onAbortStmt));
                    break;
            }
        }

        if (onCommitBody == null) {
            onCommitBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos);
            BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onCommitBody);
            returnStmt.expr = ASTBuilderUtil.createLiteral(funcNode.pos, symTable.nilType, Names.NIL_VALUE);

        }
        if (onAbortBody == null) {
            onAbortBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos);
            BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onAbortBody);
            returnStmt.expr = ASTBuilderUtil.createLiteral(funcNode.pos, symTable.nilType, Names.NIL_VALUE);
        }

        commitFunc.function.body = onCommitBody;
        commitFunc.function.requiredParams.add(onCommitTrxVar);
        commitFunc.type = new BInvokableType(Lists.of(onCommitTrxVar.symbol.type),
                                             commitFunc.function.symbol.type.getReturnType(), null);
        commitFunc.function.symbol.type = commitFunc.type;
        commitFunc.function.symbol.params = Lists.of(onCommitTrxVar.symbol);

        abortFunc.function.body = onAbortBody;
        abortFunc.function.requiredParams.add(onAbortTrxVar);
        abortFunc.type = new BInvokableType(Lists.of(onAbortTrxVar.symbol.type),
                                            abortFunc.function.symbol.type.getReturnType(), null);
        abortFunc.function.symbol.type = abortFunc.type;
        abortFunc.function.symbol.params = Lists.of(onAbortTrxVar.symbol);

        BSymbol trxModSym = env.enclPkg.imports
                .stream()
                .filter(importPackage -> importPackage.symbol.
                        pkgID.toString().equals(Names.TRANSACTION_ORG.value + Names.ORG_NAME_SEPARATOR.value
                                                        + Names.TRANSACTION_PACKAGE.value))
                .findAny().get().symbol;
        
        BInvokableSymbol invokableSymbol =
                (BInvokableSymbol) symResolver.lookupSymbolInMainSpace(symTable.pkgEnvMap.get(trxModSym),
                        getParticipantFunctionName(funcNode));
        BLangLiteral transactionBlockId = ASTBuilderUtil.createLiteral(funcNode.pos, symTable.stringType,
                getTransactionBlockId());

        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        BLangLambdaFunction trxMainWrapperFunc = createLambdaFunction(funcNode.pos, "$anonTrxWrapperFunc$",
                                                                      Collections.emptyList(),
                                                                      funcNode.returnTypeNode,
                                                                      funcNode.body);

        for (BLangSimpleVariable var : funcNode.requiredParams) {
            trxMainWrapperFunc.function.closureVarSymbols.add(new ClosureVarSymbol(var.symbol, var.pos));
        }

        BLangBlockFunctionBody trxMainBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos);
        BLangLambdaFunction trxMainFunc
                = createLambdaFunction(funcNode.pos, "$anonTrxParticipantFunc$", Collections.emptyList(),
                                       trxReturnNode, trxMainBody);
        trxMainWrapperFunc.capturedClosureEnv = trxMainFunc.function.clonedEnv;
        commitFunc.capturedClosureEnv = env.createClone();
        abortFunc.capturedClosureEnv = env.createClone();
        BVarSymbol wrapperSym = new BVarSymbol(0, names.fromString("$wrapper$1"), this.env.scope.owner.pkgID,
                                               trxMainWrapperFunc.type, trxMainFunc.function.symbol);
        BLangSimpleVariable wrapperFuncVar = ASTBuilderUtil.createVariable(funcNode.pos, "$wrapper$1",
                                                                           trxMainWrapperFunc.type, trxMainWrapperFunc,
                                                                           wrapperSym);

        BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(funcNode.pos, trxMainBody);
        variableDef.var = wrapperFuncVar;

        BLangSimpleVarRef wrapperVarRef = rewrite(ASTBuilderUtil.createVariableRef(variableDef.pos, 
                                                                         wrapperFuncVar.symbol), env);
        BLangInvocation wrapperInvocation = new BFunctionPointerInvocation(trxMainWrapperFunc.pos, wrapperVarRef, 
                                                                           wrapperFuncVar.symbol, 
                                                                           trxMainWrapperFunc.function.symbol.retType);
        BLangReturn wrapperReturn = ASTBuilderUtil.createReturnStmt(funcNode.pos, addConversionExprIfRequired
                (wrapperInvocation, trxReturnNode.type));

        trxMainWrapperFunc.function.receiver = funcNode.receiver;
        trxMainFunc.function.receiver = funcNode.receiver;
        trxMainBody.stmts.add(wrapperReturn);
        rewrite(trxMainFunc.function, env);

        List<BLangExpression> requiredArgs = Lists.of(transactionBlockId, trxMainFunc, commitFunc, abortFunc);
        BLangInvocation participantInvocation
                = ASTBuilderUtil.createInvocationExprMethod(funcNode.pos, invokableSymbol, requiredArgs,
                                                            Collections.emptyList(), symResolver);
        participantInvocation.type = ((BInvokableType) invokableSymbol.type).retType;
        BLangStatement stmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, addConversionExprIfRequired
                (participantInvocation, funcNode.symbol.retType));
        funcNode.body = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos, Lists.of(rewrite(stmt, env)));
        
        return funcNode;
    }

    private Name getParticipantFunctionName(BLangFunction function) {
        if (Symbols.isFlagOn((function).symbol.flags, Flags.RESOURCE)) {
            return TRX_REMOTE_PARTICIPANT_BEGIN_FUNCTION;
        }
        return TRX_LOCAL_PARTICIPANT_BEGIN_FUNCTION;
    }

    @Override
    public void visit(BLangResource resourceNode) {
    }

    public void visit(BLangAnnotation annotationNode) {
        annotationNode.annAttachments.forEach(attachment ->  rewrite(attachment, env));
    }

    public void visit(BLangAnnotationAttachment annAttachmentNode) {
        annAttachmentNode.expr = rewrite(annAttachmentNode.expr, env);
        result = annAttachmentNode;
    }

    @Override
    public void visit(BLangSimpleVariable varNode) {
        if (((varNode.symbol.owner.tag & SymTag.INVOKABLE) != SymTag.INVOKABLE)
                && (varNode.symbol.owner.tag & SymTag.LET) != SymTag.LET) {
            varNode.expr = null;
            result = varNode;
            return;
        }

        if (varNode.typeNode != null && varNode.typeNode.getKind() != null) {
            varNode.typeNode = rewrite(varNode.typeNode, env);
        }

        
        BLangExpression bLangExpression = rewriteExpr(varNode.expr);
        if (bLangExpression != null) {
            bLangExpression = addConversionExprIfRequired(bLangExpression, varNode.type);
        }
        varNode.expr = bLangExpression;

        varNode.annAttachments.forEach(attachment -> rewrite(attachment, env));

        result = varNode;
    }

    @Override
    public void visit(BLangLetExpression letExpression) {
        SymbolEnv prevEnv = this.env;
        this.env = letExpression.env;
        BLangExpression expr = letExpression.expr;
        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(letExpression.pos);
        for (BLangLetVariable letVariable : letExpression.letVarDeclarations) {
            BLangNode node  = rewrite((BLangNode) letVariable.definitionNode, env);
            if (node.getKind() == NodeKind.BLOCK) {
                blockStmt.stmts.addAll(((BLangBlockStmt) node).stmts);
            } else {
                blockStmt.addStatement((BLangSimpleVariableDef) node);
            }
        }
        BLangSimpleVariableDef tempVarDef = createVarDef(String.format("$let_var_%d_$", letCount++),
                expr.type, expr, expr.pos);
        BLangSimpleVarRef tempVarRef = ASTBuilderUtil.createVariableRef(expr.pos, tempVarDef.var.symbol);
        blockStmt.addStatement(tempVarDef);
        BLangStatementExpression stmtExpr = ASTBuilderUtil.createStatementExpression(blockStmt, tempVarRef);
        stmtExpr.type = expr.type;
        result = rewrite(stmtExpr, env);
        this.env = prevEnv;
    }

    @Override
    public void visit(BLangTupleVariable varNode) {
        result = varNode;
    }

    @Override
    public void visit(BLangRecordVariable varNode) {
        result = varNode;
    }

    @Override
    public void visit(BLangErrorVariable varNode) {
        result = varNode;
    }

    

    @Override
    public void visit(BLangBlockStmt block) {
        SymbolEnv blockEnv = SymbolEnv.createBlockEnv(block, env);
        block.stmts = rewriteStmt(block.stmts, blockEnv);
        result = block;
    }

    @Override
    public void visit(BLangSimpleVariableDef varDefNode) {
        varDefNode.var = rewrite(varDefNode.var, env);
        result = varDefNode;
    }

    @Override
    public void visit(BLangTupleVariableDef varDefNode) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        varDefNode.var = rewrite(varDefNode.var, env);
        BLangTupleVariable tupleVariable = varDefNode.var;

        
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(varDefNode.pos);

        
        BType runTimeType = new BArrayType(symTable.anyType);

        
        String name = "tuple";
        final BLangSimpleVariable tuple = ASTBuilderUtil.createVariable(varDefNode.pos, name, runTimeType, null,
                new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, runTimeType,
                        this.env.scope.owner));
        tuple.expr = tupleVariable.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(varDefNode.pos, blockStmt);
        variableDef.var = tuple;

        
        createVarDefStmts(tupleVariable, blockStmt, tuple.symbol, null);
        createRestFieldVarDefStmts(tupleVariable, blockStmt, tuple.symbol);

        
        result = rewrite(blockStmt, env);
    }

    private void createRestFieldVarDefStmts(BLangTupleVariable parentTupleVariable, BLangBlockStmt blockStmt,
                                            BVarSymbol tupleVarSymbol) {
        final BLangSimpleVariable arrayVar = (BLangSimpleVariable) parentTupleVariable.restVariable;
        boolean isTupleType = parentTupleVariable.type.tag == TypeTags.TUPLE;
        DiagnosticPos pos = blockStmt.pos;
        if (arrayVar != null) {
            
            BLangArrayLiteral arrayExpr = createArrayLiteralExprNode();
            arrayExpr.type = arrayVar.type;
            arrayVar.expr = arrayExpr;
            BLangSimpleVariableDef arrayVarDef = ASTBuilderUtil.createVariableDefStmt(arrayVar.pos, blockStmt);
            arrayVarDef.var = arrayVar;

            
            
            
            BLangExpression tupleExpr = parentTupleVariable.expr;
            BLangSimpleVarRef arrayVarRef = ASTBuilderUtil.createVariableRef(pos, arrayVar.symbol);

            BLangLiteral startIndexLiteral = (BLangLiteral) TreeBuilder.createLiteralExpression();
            startIndexLiteral.value = (long) (isTupleType ? ((BTupleType) parentTupleVariable.type).tupleTypes.size()
                    : parentTupleVariable.memberVariables.size());
            startIndexLiteral.type = symTable.intType;
            BLangInvocation lengthInvocation = createLengthInvocation(pos, tupleExpr);
            BLangInvocation intRangeInvocation = replaceWithIntRange(pos, startIndexLiteral,
                    getModifiedIntRangeEndExpr(lengthInvocation));

            BLangForeach foreach = (BLangForeach) TreeBuilder.createForeachNode();
            foreach.pos = pos;
            foreach.collection = intRangeInvocation;
            types.setForeachTypedBindingPatternType(foreach);

            final BLangSimpleVariable foreachVariable = ASTBuilderUtil.createVariable(pos,
                    "$foreach$i", foreach.varType);
            foreachVariable.symbol = new BVarSymbol(0, names.fromIdNode(foreachVariable.name),
                    this.env.scope.owner.pkgID, foreachVariable.type, this.env.scope.owner);
            BLangSimpleVarRef foreachVarRef = ASTBuilderUtil.createVariableRef(pos, foreachVariable.symbol);
            foreach.variableDefinitionNode = ASTBuilderUtil.createVariableDef(pos, foreachVariable);
            foreach.isDeclaredWithVar = true;
            BLangBlockStmt foreachBody = ASTBuilderUtil.createBlockStmt(pos);

            
            BLangIndexBasedAccess indexAccessExpr = ASTBuilderUtil.createIndexAccessExpr(arrayVarRef,
                    createLengthInvocation(pos, arrayVarRef));
            indexAccessExpr.type = (isTupleType ? ((BTupleType) parentTupleVariable.type).restType : symTable.anyType);
            createSimpleVarRefAssignmentStmt(indexAccessExpr, foreachBody, foreachVarRef, tupleVarSymbol, null);
            foreach.body = foreachBody;
            blockStmt.addStatement(foreach);
        }
    }

    @Override
    public void visit(BLangRecordVariableDef varDefNode) {

        BLangRecordVariable varNode = varDefNode.var;

        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(varDefNode.pos);

        BType runTimeType = new BMapType(TypeTags.MAP, symTable.anyType, null);

        final BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(varDefNode.pos, "$map$0", runTimeType,
                null, new BVarSymbol(0, names.fromString("$map$0"), this.env.scope.owner.pkgID,
                        runTimeType, this.env.scope.owner));
        mapVariable.expr = varDefNode.var.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(varDefNode.pos, blockStmt);
        variableDef.var = mapVariable;

        createVarDefStmts(varNode, blockStmt, mapVariable.symbol, null);

        result = rewrite(blockStmt, env);
    }

    @Override
    public void visit(BLangErrorVariableDef varDefNode) {
        BLangErrorVariable errorVariable = varDefNode.errorVariable;

        
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(varDefNode.pos);

        
        BVarSymbol errorVarSymbol = new BVarSymbol(0, names.fromString("$error$"),
                this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner);
        final BLangSimpleVariable error = ASTBuilderUtil.createVariable(varDefNode.pos, errorVarSymbol.name.value,
                symTable.errorType, null, errorVarSymbol);
        error.expr = errorVariable.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(varDefNode.pos, blockStmt);
        variableDef.var = error;

        
        createVarDefStmts(errorVariable, blockStmt, error.symbol, null);

        
        result = rewrite(blockStmt, env);
    }

    /**
     * This method iterate through each member of the tupleVar and create the relevant var def statements. This method
     * does the check for node kind of each member and call the related var def creation method.
     *
     * Example:
     * ((string, float) int)) ((a, b), c)) = (tuple)
     *
     * (a, b) is again a tuple, so it is a recursive var def creation.
     *
     * c is a simple var, so a simple var def will be created.
     *
     */
    private void createVarDefStmts(BLangTupleVariable parentTupleVariable, BLangBlockStmt parentBlockStmt,
                                   BVarSymbol tupleVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {

        final List<BLangVariable> memberVars = parentTupleVariable.memberVariables;
        for (int index = 0; index < memberVars.size(); index++) {
            BLangVariable variable = memberVars.get(index);
            BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(variable.pos, symTable.intType, (long) index);

            if (NodeKind.VARIABLE == variable.getKind()) { 
                createSimpleVarDefStmt((BLangSimpleVariable) variable, parentBlockStmt, indexExpr, tupleVarSymbol,
                        parentIndexAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.TUPLE_VARIABLE) { 
                BLangTupleVariable tupleVariable = (BLangTupleVariable) variable;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVariable.pos,
                        new BArrayType(symTable.anyType), tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangTupleVariable) variable, parentBlockStmt, tupleVarSymbol, arrayAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.RECORD_VARIABLE) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, symTable.mapType, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangRecordVariable) variable, parentBlockStmt, tupleVarSymbol, arrayAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.ERROR_VARIABLE) {

                BType accessedElemType = symTable.errorType;
                if (tupleVarSymbol.type.tag == TypeTags.ARRAY) {
                    BArrayType arrayType = (BArrayType) tupleVarSymbol.type;
                    accessedElemType = arrayType.eType;
                }
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, accessedElemType, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangErrorVariable) variable, parentBlockStmt, tupleVarSymbol, arrayAccessExpr);
            }
        }
    }

    /**
     * Overloaded method to handle record variables.
     * This method iterate through each member of the recordVar and create the relevant var def statements. This method
     * does the check for node kind of each member and call the related var def creation method.
     *
     * Example:
     * type Foo record {
     *     string name;
     *     (int, string) age;
     *     Address address;
     * };
     *
     * Foo {name: a, age: (b, c), address: d} = {record literal}
     *
     *  a is a simple var, so a simple var def will be created.
     *
     * (b, c) is a tuple, so it is a recursive var def creation.
     *
     * d is a record, so it is a recursive var def creation.
     *
     */
    private void createVarDefStmts(BLangRecordVariable parentRecordVariable, BLangBlockStmt parentBlockStmt,
                                   BVarSymbol recordVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {

        List<BLangRecordVariableKeyValue> variableList = parentRecordVariable.variableList;
        for (BLangRecordVariableKeyValue recordFieldKeyValue : variableList) {
            BLangVariable variable = recordFieldKeyValue.valueBindingPattern;
            BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(variable.pos, symTable.stringType,
                    recordFieldKeyValue.key.value);

            if (recordFieldKeyValue.valueBindingPattern.getKind() == NodeKind.VARIABLE) {
                createSimpleVarDefStmt((BLangSimpleVariable) recordFieldKeyValue.valueBindingPattern, parentBlockStmt,
                        indexExpr, recordVarSymbol, parentIndexAccessExpr);
                continue;
            }

            if (recordFieldKeyValue.valueBindingPattern.getKind() == NodeKind.TUPLE_VARIABLE) {
                BLangTupleVariable tupleVariable = (BLangTupleVariable) recordFieldKeyValue.valueBindingPattern;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVariable.pos,
                        new BArrayType(symTable.anyType), recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangTupleVariable) recordFieldKeyValue.valueBindingPattern,
                        parentBlockStmt, recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (recordFieldKeyValue.valueBindingPattern.getKind() == NodeKind.RECORD_VARIABLE) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentRecordVariable.pos, symTable.mapType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangRecordVariable) recordFieldKeyValue.valueBindingPattern, parentBlockStmt,
                        recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.ERROR_VARIABLE) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentRecordVariable.pos, variable.type, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangErrorVariable) variable, parentBlockStmt, recordVarSymbol, arrayAccessExpr);
            }
        }

        if (parentRecordVariable.restParam != null) {
            
            
            

            DiagnosticPos pos = parentBlockStmt.pos;
            BMapType restParamType = (BMapType) ((BLangVariable) parentRecordVariable.restParam).type;
            BLangSimpleVarRef variableReference;

            if (parentIndexAccessExpr != null) {
                BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(pos, "$map$1",
                        parentIndexAccessExpr.type, null, new BVarSymbol(0, names.fromString("$map$1"),
                                this.env.scope.owner.pkgID, parentIndexAccessExpr.type, this.env.scope.owner));
                mapVariable.expr = parentIndexAccessExpr;
                BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(pos, parentBlockStmt);
                variableDef.var = mapVariable;

                variableReference = ASTBuilderUtil.createVariableRef(pos, mapVariable.symbol);
            } else {
                variableReference = ASTBuilderUtil.createVariableRef(pos,
                        ((BLangSimpleVariableDef) parentBlockStmt.stmts.get(0)).var.symbol);
            }

            List<String> keysToRemove = parentRecordVariable.variableList.stream()
                    .map(var -> var.getKey().getValue())
                    .collect(Collectors.toList());

            BLangSimpleVariable filteredDetail = generateRestFilter(variableReference, pos,
                    keysToRemove, restParamType, parentBlockStmt);

            BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol);

            
            BLangSimpleVariable restParam = (BLangSimpleVariable) parentRecordVariable.restParam;
            BLangSimpleVariableDef restParamVarDef = ASTBuilderUtil.createVariableDefStmt(pos,
                    parentBlockStmt);
            restParamVarDef.var = restParam;
            restParamVarDef.var.type = restParamType;
            restParam.expr = varRef;
        }
    }

    /**
     * This method will create the relevant var def statements for reason and details of the error variable.
     * The var def statements are created by creating the reason() and detail() builtin methods.
     */
    private void createVarDefStmts(BLangErrorVariable parentErrorVariable, BLangBlockStmt parentBlockStmt,
                                   BVarSymbol errorVariableSymbol, BLangIndexBasedAccess parentIndexBasedAccess) {

        BVarSymbol convertedErrorVarSymbol;
        if (parentIndexBasedAccess != null) {
            BType prevType = parentIndexBasedAccess.type;
            parentIndexBasedAccess.type = symTable.anyType;
            BLangSimpleVariableDef errorVarDef = createVarDef("$error$" + errorCount++,
                    symTable.errorType,
                    addConversionExprIfRequired(parentIndexBasedAccess, symTable.errorType),
                    parentErrorVariable.pos);
            parentIndexBasedAccess.type = prevType;
            parentBlockStmt.addStatement(errorVarDef);
            convertedErrorVarSymbol = errorVarDef.var.symbol;
        } else {
            convertedErrorVarSymbol = errorVariableSymbol;
        }

        parentErrorVariable.reason.expr = generateErrorReasonBuiltinFunction(parentErrorVariable.reason.pos,
                parentErrorVariable.reason.type, convertedErrorVarSymbol, null);

        if (names.fromIdNode((parentErrorVariable.reason).name) == Names.IGNORE) {
            parentErrorVariable.reason = null;
        } else {
            BLangSimpleVariableDef reasonVariableDef =
                    ASTBuilderUtil.createVariableDefStmt(parentErrorVariable.reason.pos, parentBlockStmt);
            reasonVariableDef.var = parentErrorVariable.reason;
        }

        if ((parentErrorVariable.detail == null || parentErrorVariable.detail.isEmpty())
            && parentErrorVariable.restDetail == null) {
            return;
        }

        BType detailMapType;
        BType detailType = ((BErrorType) parentErrorVariable.type).detailType;
        if (detailType.tag == TypeTags.MAP) {
            detailMapType = detailType;
        } else {
            detailMapType = symTable.detailType;
        }

        parentErrorVariable.detailExpr = generateErrorDetailBuiltinFunction(
                parentErrorVariable.pos,
                convertedErrorVarSymbol, null);

        BLangSimpleVariableDef detailTempVarDef = createVarDef("$error$detail",
                parentErrorVariable.detailExpr.type, parentErrorVariable.detailExpr, parentErrorVariable.pos);
        detailTempVarDef.type = parentErrorVariable.detailExpr.type;
        parentBlockStmt.addStatement(detailTempVarDef);
        this.env.scope.define(names.fromIdNode(detailTempVarDef.var.name), detailTempVarDef.var.symbol);

        for (BLangErrorVariable.BLangErrorDetailEntry detailEntry : parentErrorVariable.detail) {
            BLangExpression detailEntryVar = createErrorDetailVar(detailEntry, detailTempVarDef.var.symbol);

            
            createAndAddBoundVariableDef(parentBlockStmt, detailEntry, detailEntryVar);

        }
        if (parentErrorVariable.restDetail != null && !parentErrorVariable.restDetail.name.value.equals(IGNORE.value)) {
            DiagnosticPos pos = parentErrorVariable.restDetail.pos;
            BLangSimpleVarRef detailVarRef = ASTBuilderUtil.createVariableRef(
                    pos, detailTempVarDef.var.symbol);
            List<String> keysToRemove = parentErrorVariable.detail.stream()
                    .map(detail -> detail.key.getValue())
                    .collect(Collectors.toList());

            BLangSimpleVariable filteredDetail = generateRestFilter(detailVarRef, parentErrorVariable.pos, keysToRemove,
                    parentErrorVariable.restDetail.type, parentBlockStmt);
            BLangSimpleVariableDef variableDefStmt = ASTBuilderUtil.createVariableDefStmt(pos, parentBlockStmt);
            variableDefStmt.var = ASTBuilderUtil.createVariable(pos,
                    parentErrorVariable.restDetail.name.value,
                    filteredDetail.type,
                    ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol),
                    parentErrorVariable.restDetail.symbol);
            BLangAssignment assignmentStmt = ASTBuilderUtil.createAssignmentStmt(pos,
                    ASTBuilderUtil.createVariableRef(pos, parentErrorVariable.restDetail.symbol),
                    ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol));
            parentBlockStmt.addStatement(assignmentStmt);
        }
        rewrite(parentBlockStmt, env);
    }

    private BLangSimpleVariableDef forceCastIfApplicable(BVarSymbol errorVarySymbol, DiagnosticPos pos,
                                                         BType targetType) {
        BVarSymbol errorVarSym = new BVarSymbol(Flags.PUBLIC, names.fromString("$cast$temp$"),
                this.env.enclPkg.packageID, targetType, this.env.scope.owner);
        BLangSimpleVarRef variableRef = ASTBuilderUtil.createVariableRef(pos, errorVarySymbol);

        BLangExpression expr;
        if (targetType.tag == TypeTags.RECORD) {
            expr = variableRef;
        } else {
            expr = addConversionExprIfRequired(variableRef, targetType);
        }
        BLangSimpleVariable errorVar = ASTBuilderUtil.createVariable(pos, errorVarSym.name.value, targetType, expr,
                errorVarSym);
        return ASTBuilderUtil.createVariableDef(pos, errorVar);
    }

    private BLangSimpleVariable generateRestFilter(BLangSimpleVarRef mapVarRef, DiagnosticPos pos,
                                                   List<String> keysToRemove, BType targetType,
                                                   BLangBlockStmt parentBlockStmt) {
        
        
        
        
        

        BLangExpression typeCastExpr = addConversionExprIfRequired(mapVarRef, targetType);

        int restNum = annonVarCount++;
        String name = "$map$ref$" + restNum;
        BLangSimpleVariable mapVariable = defVariable(pos, targetType, parentBlockStmt, typeCastExpr, name);

        BLangInvocation entriesInvocation = generateMapEntriesInvocation(
                ASTBuilderUtil.createVariableRef(pos, mapVariable.symbol), typeCastExpr.type);
        String entriesVarName = "$map$ref$entries$" + restNum;
        BType entriesType = new BMapType(TypeTags.MAP,
                new BTupleType(Arrays.asList(symTable.stringType, ((BMapType) targetType).constraint)), null);
        BLangSimpleVariable entriesInvocationVar = defVariable(pos, entriesType, parentBlockStmt,
                addConversionExprIfRequired(entriesInvocation, entriesType),
                entriesVarName);

        BLangLambdaFunction filter = createFuncToFilterOutRestParam(keysToRemove, pos);

        BLangInvocation filterInvocation = generateMapFilterInvocation(pos, entriesInvocationVar, filter);
        String filteredEntriesName = "$filtered$detail$entries" + restNum;
        BLangSimpleVariable filteredVar = defVariable(pos, entriesType, parentBlockStmt, filterInvocation,
                filteredEntriesName);

        String filteredVarName = "$detail$filtered" + restNum;
        BLangLambdaFunction backToMapLambda = generateEntriesToMapLambda(pos);
        BLangInvocation mapInvocation = generateMapMapInvocation(pos, filteredVar, backToMapLambda);
        BLangSimpleVariable filtered = defVariable(pos, targetType, parentBlockStmt,
                mapInvocation,
                filteredVarName);

        String filteredRestVarName = "$restVar$" + restNum;
        BLangInvocation constructed = generateConstructFromInvocation(pos, targetType, filtered.symbol);
        return defVariable(pos, targetType, parentBlockStmt,
                addConversionExprIfRequired(constructed, targetType),
                filteredRestVarName);
    }

    private BLangInvocation generateMapEntriesInvocation(BLangExpression expr, BType type) {
        BLangInvocation invocationNode = createInvocationNode("entries", new ArrayList<>(), type);

        invocationNode.expr = expr;
        invocationNode.symbol = symResolver.lookupLangLibMethod(type, names.fromString("entries"));
        invocationNode.requiredArgs = Lists.of(expr);
        invocationNode.type = invocationNode.symbol.type.getReturnType();
        invocationNode.langLibInvocation = true;
        return invocationNode;
    }

    private BLangInvocation generateMapMapInvocation(DiagnosticPos pos, BLangSimpleVariable filteredVar,
                                                     BLangLambdaFunction backToMapLambda) {
        BLangInvocation invocationNode = createInvocationNode("map", new ArrayList<>(), filteredVar.type);

        invocationNode.expr = ASTBuilderUtil.createVariableRef(pos, filteredVar.symbol);
        invocationNode.symbol = symResolver.lookupLangLibMethod(filteredVar.type, names.fromString("map"));
        invocationNode.requiredArgs = Lists.of(ASTBuilderUtil.createVariableRef(pos, filteredVar.symbol));
        invocationNode.type = invocationNode.symbol.type.getReturnType();
        invocationNode.requiredArgs.add(backToMapLambda);
        return invocationNode;
    }

    private BLangLambdaFunction generateEntriesToMapLambda(DiagnosticPos pos) {
        

        String anonfuncName = "$anonGetValFunc$" + lambdaFunctionCount++;
        BLangFunction function = ASTBuilderUtil.createFunction(pos, anonfuncName);

        BVarSymbol keyValSymbol = new BVarSymbol(0, names.fromString("$lambdaArg$0"), this.env.scope.owner.pkgID,
                getStringAnyTupleType(), this.env.scope.owner);

        BLangSimpleVariable inputParameter = ASTBuilderUtil.createVariable(pos, null, getStringAnyTupleType(),
                                                                           null, keyValSymbol);
        function.requiredParams.add(inputParameter);

        BLangValueType anyType = new BLangValueType();
        anyType.typeKind = TypeKind.ANY;
        anyType.type = symTable.anyType;
        function.returnTypeNode = anyType;

        BLangBlockFunctionBody functionBlock = ASTBuilderUtil.createBlockFunctionBody(pos, new ArrayList<>());
        function.body = functionBlock;

        BLangIndexBasedAccess indexBasesAccessExpr =
                ASTBuilderUtil.createIndexBasesAccessExpr(pos, symTable.anyType, keyValSymbol,
                                                          ASTBuilderUtil
                                                                  .createLiteral(pos, symTable.intType, (long) 1));
        BLangSimpleVariableDef tupSecondElem = createVarDef("val", indexBasesAccessExpr.type,
                                                            indexBasesAccessExpr, pos);
        functionBlock.addStatement(tupSecondElem);

        
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(pos, functionBlock);
        returnStmt.expr = ASTBuilderUtil.createVariableRef(pos, tupSecondElem.var.symbol);

        
        BInvokableSymbol functionSymbol = Symbols.createFunctionSymbol(Flags.asMask(function.flagSet),
                new Name(function.name.value), env.enclPkg.packageID, function.type, env.enclEnv.enclVarSym, true);
        functionSymbol.retType = function.returnTypeNode.type;
        functionSymbol.params = function.requiredParams.stream()
                .map(param -> param.symbol)
                .collect(Collectors.toList());
        functionSymbol.scope = env.scope;
        functionSymbol.type = new BInvokableType(Collections.singletonList(getStringAnyTupleType()),
                symTable.anyType, null);
        function.symbol = functionSymbol;
        rewrite(function, env);
        env.enclPkg.addFunction(function);

        
        return createLambdaFunction(function, functionSymbol);
    }

    private BLangInvocation generateMapFilterInvocation(DiagnosticPos pos,
                                                        BLangSimpleVariable entriesInvocationVar,
                                                        BLangLambdaFunction filter) {
        BLangInvocation invocationNode = createInvocationNode("filter", new ArrayList<>(), entriesInvocationVar.type);

        invocationNode.expr = ASTBuilderUtil.createVariableRef(pos, entriesInvocationVar.symbol);
        invocationNode.symbol = symResolver.lookupLangLibMethod(entriesInvocationVar.type, names.fromString("filter"));
        invocationNode.requiredArgs = Lists.of(ASTBuilderUtil.createVariableRef(pos, entriesInvocationVar.symbol));
        invocationNode.type = invocationNode.symbol.type.getReturnType();
        invocationNode.requiredArgs.add(filter);

        return invocationNode;
    }

    private BLangSimpleVariable defVariable(DiagnosticPos pos, BType varType, BLangBlockStmt parentBlockStmt,
                                            BLangExpression expression, String name) {
        Name varName = names.fromString(name);
        BLangSimpleVariable detailMap = ASTBuilderUtil.createVariable(pos, name, varType, expression,
                new BVarSymbol(Flags.PUBLIC, varName, env.enclPkg.packageID, varType, env.scope.owner));
        BLangSimpleVariableDef constructedMap = ASTBuilderUtil.createVariableDef(pos, detailMap);
        constructedMap.type = varType;
        parentBlockStmt.addStatement(constructedMap);
        env.scope.define(varName, detailMap.symbol);
        return detailMap;
    }

    private void createAndAddBoundVariableDef(BLangBlockStmt parentBlockStmt,
                                              BLangErrorVariable.BLangErrorDetailEntry detailEntry,
                                              BLangExpression detailEntryVar) {
        if (detailEntry.valueBindingPattern.getKind() == NodeKind.VARIABLE) {
            BLangSimpleVariableDef errorDetailVar = createVarDef(
                    ((BLangSimpleVariable) detailEntry.valueBindingPattern).name.value,
                    detailEntry.valueBindingPattern.type,
                    detailEntryVar,
                    detailEntry.valueBindingPattern.pos);
            parentBlockStmt.addStatement(errorDetailVar);

        } else if (detailEntry.valueBindingPattern.getKind() == NodeKind.RECORD_VARIABLE) {
            BLangRecordVariableDef recordVariableDef = ASTBuilderUtil.createRecordVariableDef(
                    detailEntry.valueBindingPattern.pos,
                    (BLangRecordVariable) detailEntry.valueBindingPattern);
            recordVariableDef.var.expr = detailEntryVar;
            recordVariableDef.type = symTable.recordType;
            parentBlockStmt.addStatement(recordVariableDef);

        } else if (detailEntry.valueBindingPattern.getKind() == NodeKind.TUPLE_VARIABLE) {
            BLangTupleVariableDef tupleVariableDef = ASTBuilderUtil.createTupleVariableDef(
                    detailEntry.valueBindingPattern.pos, (BLangTupleVariable) detailEntry.valueBindingPattern);
            parentBlockStmt.addStatement(tupleVariableDef);
        }
    }

    private BLangExpression createErrorDetailVar(BLangErrorVariable.BLangErrorDetailEntry detailEntry,
                                                 BVarSymbol tempDetailVarSymbol) {
        BLangExpression detailEntryVar = createIndexBasedAccessExpr(
                detailEntry.valueBindingPattern.type,
                detailEntry.valueBindingPattern.pos,
                createStringLiteral(detailEntry.key.pos, detailEntry.key.value),
                tempDetailVarSymbol, null);
        if (detailEntryVar.getKind() == NodeKind.INDEX_BASED_ACCESS_EXPR) {
            BLangIndexBasedAccess bLangIndexBasedAccess = (BLangIndexBasedAccess) detailEntryVar;
            bLangIndexBasedAccess.originalType = symTable.pureType;
        }
        return detailEntryVar;
    }

    private BLangExpression constructStringTemplateConcatExpression(List<BLangExpression> exprs) {
        BLangExpression concatExpr = null;
        BLangExpression currentExpr;
        for (BLangExpression expr : exprs) {
            currentExpr = expr;
            if (expr.type.tag != TypeTags.STRING && expr.type.tag != TypeTags.XML) {
                currentExpr = getToStringInvocationOnExpr(expr);
            }

            if (concatExpr == null) {
                concatExpr = currentExpr;
                continue;
            }

            BType binaryExprType =
                    TypeTags.isXMLTypeTag(concatExpr.type.tag) || TypeTags.isXMLTypeTag(currentExpr.type.tag)
                            ? symTable.xmlType
                            : symTable.stringType;
            concatExpr =
                    ASTBuilderUtil.createBinaryExpr(concatExpr.pos, concatExpr, currentExpr,
                            binaryExprType, OperatorKind.ADD, null);
        }
        return concatExpr;
    }

    private BLangInvocation getToStringInvocationOnExpr(BLangExpression expression) {
        BInvokableSymbol symbol = (BInvokableSymbol) symTable.langValueModuleSymbol.scope
                .lookup(names.fromString(TO_STRING_FUNCTION_NAME)).symbol;

        List<BLangExpression> requiredArgs = new ArrayList<BLangExpression>() {{
            add(addConversionExprIfRequired(expression, symbol.params.get(0).type));
        }};
        return ASTBuilderUtil.createInvocationExprMethod(expression.pos, symbol, requiredArgs, new ArrayList<>(),
                                                         symResolver);
    }

    
    private BLangInvocation generateErrorDetailBuiltinFunction(DiagnosticPos pos, BVarSymbol errorVarySymbol,
                                                               BLangIndexBasedAccess parentIndexBasedAccess) {
        BLangExpression onExpr =
                parentIndexBasedAccess != null
                        ? parentIndexBasedAccess : ASTBuilderUtil.createVariableRef(pos, errorVarySymbol);

        return createLangLibInvocationNode(ERROR_DETAIL_FUNCTION_NAME, onExpr, new ArrayList<>(), null, pos);
    }

    private BLangInvocation generateErrorReasonBuiltinFunction(DiagnosticPos pos, BType reasonType,
                                                               BVarSymbol errorVarSymbol,
                                                               BLangIndexBasedAccess parentIndexBasedAccess) {
        BLangExpression onExpr =
                parentIndexBasedAccess != null
                        ? parentIndexBasedAccess : ASTBuilderUtil.createVariableRef(pos, errorVarSymbol);
        return createLangLibInvocationNode(ERROR_REASON_FUNCTION_NAME, onExpr, new ArrayList<>(), reasonType, pos);
    }

    private BLangInvocation generateConstructFromInvocation(DiagnosticPos pos,
                                                            BType targetType,
                                                            BVarSymbol source) {
        BType typedescType = new BTypedescType(targetType, symTable.typeDesc.tsymbol);
        BLangInvocation invocationNode = createInvocationNode(CONSTRUCT_FROM, new ArrayList<>(), typedescType);

        BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
        typedescExpr.resolvedType = targetType;
        typedescExpr.type = typedescType;

        invocationNode.expr = typedescExpr;
        invocationNode.symbol = symResolver.lookupLangLibMethod(typedescType, names.fromString(CONSTRUCT_FROM));
        invocationNode.requiredArgs = Lists.of(typedescExpr, ASTBuilderUtil.createVariableRef(pos, source));
        invocationNode.type = BUnionType.create(null, targetType, symTable.errorType);
        return invocationNode;
    }

    private BLangLambdaFunction createFuncToFilterOutRestParam(List<String> toRemoveList, DiagnosticPos pos) {

        
        
        
        
        
        
        
        
        
        
        
        

        String anonfuncName = "$anonRestParamFilterFunc$" + lambdaFunctionCount++;
        BLangFunction function = ASTBuilderUtil.createFunction(pos, anonfuncName);

        BVarSymbol keyValSymbol = new BVarSymbol(0, names.fromString("$lambdaArg$0"), this.env.scope.owner.pkgID,
                                                 getStringAnyTupleType(), this.env.scope.owner);
        BLangBlockFunctionBody functionBlock = createAnonymousFunctionBlock(pos, function, keyValSymbol);

        BLangIndexBasedAccess indexBasesAccessExpr =
                ASTBuilderUtil.createIndexBasesAccessExpr(pos, symTable.anyType, keyValSymbol, ASTBuilderUtil
                        .createLiteral(pos, symTable.intType, (long) 0));
        BLangSimpleVariableDef tupFirstElem = createVarDef("key", indexBasesAccessExpr.type,
                                                           indexBasesAccessExpr, pos);
        functionBlock.addStatement(tupFirstElem);

        
        for (String toRemoveItem : toRemoveList) {
            createIfStmt(pos, tupFirstElem.var.symbol, functionBlock, toRemoveItem);
        }

        
        BInvokableSymbol functionSymbol = createReturnTrueStatement(pos, function, functionBlock);

        
        return createLambdaFunction(function, functionSymbol);
    }

    private BLangLambdaFunction createFuncToFilterOutRestParam(BLangRecordVariable recordVariable, DiagnosticPos pos) {
        List<String> fieldNamesToRemove = recordVariable.variableList.stream()
                .map(var -> var.getKey().getValue())
                .collect(Collectors.toList());
        return createFuncToFilterOutRestParam(fieldNamesToRemove, pos);
    }

    private void createIfStmt(DiagnosticPos pos, BVarSymbol inputParamSymbol, BLangBlockFunctionBody blockStmt,
                              String key) {
        BLangSimpleVarRef firstElemRef = ASTBuilderUtil.createVariableRef(pos, inputParamSymbol);
        BLangExpression converted = addConversionExprIfRequired(firstElemRef, symTable.stringType);

        BLangIf ifStmt = ASTBuilderUtil.createIfStmt(pos, blockStmt);

        BLangBlockStmt ifBlock = ASTBuilderUtil.createBlockStmt(pos, new ArrayList<>());
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(pos, ifBlock);
        returnStmt.expr = ASTBuilderUtil.createLiteral(pos, symTable.booleanType, false);
        ifStmt.body = ifBlock;

        BLangGroupExpr groupExpr = new BLangGroupExpr();
        groupExpr.type = symTable.booleanType;

        BLangBinaryExpr binaryExpr = ASTBuilderUtil.createBinaryExpr(pos, converted,
                ASTBuilderUtil.createLiteral(pos, symTable.stringType, key),
                symTable.booleanType, OperatorKind.EQUAL, null);

        binaryExpr.opSymbol = (BOperatorSymbol) symResolver.resolveBinaryOperator(
                binaryExpr.opKind, binaryExpr.lhsExpr.type, binaryExpr.rhsExpr.type);

        groupExpr.expression = binaryExpr;
        ifStmt.expr = groupExpr;
    }

    BLangLambdaFunction createLambdaFunction(BLangFunction function, BInvokableSymbol functionSymbol) {
        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        lambdaFunction.function = function;
        lambdaFunction.type = functionSymbol.type;
        return lambdaFunction;
    }

    private BInvokableSymbol createReturnTrueStatement(DiagnosticPos pos, BLangFunction function,
                                                       BLangBlockFunctionBody functionBlock) {
        BLangReturn trueReturnStmt = ASTBuilderUtil.createReturnStmt(pos, functionBlock);
        trueReturnStmt.expr = ASTBuilderUtil.createLiteral(pos, symTable.booleanType, true);

        
        BInvokableSymbol functionSymbol = Symbols.createFunctionSymbol(Flags.asMask(function.flagSet),
                                                                       new Name(function.name.value),
                                                                       env.enclPkg.packageID, function.type,
                                                                       env.enclEnv.enclVarSym, true);
        functionSymbol.retType = function.returnTypeNode.type;
        functionSymbol.params = function.requiredParams.stream()
                .map(param -> param.symbol)
                .collect(Collectors.toList());
        functionSymbol.scope = env.scope;
        functionSymbol.type = new BInvokableType(Collections.singletonList(getStringAnyTupleType()),
                                                 getRestType(functionSymbol), symTable.booleanType, null);
        function.symbol = functionSymbol;
        rewrite(function, env);
        env.enclPkg.addFunction(function);
        return functionSymbol;
    }

    private BLangBlockFunctionBody createAnonymousFunctionBlock(DiagnosticPos pos, BLangFunction function,
                                                                BVarSymbol keyValSymbol) {
        BLangSimpleVariable inputParameter = ASTBuilderUtil.createVariable(pos, null, getStringAnyTupleType(),
                                                                           null, keyValSymbol);
        function.requiredParams.add(inputParameter);
        BLangValueType booleanTypeKind = new BLangValueType();
        booleanTypeKind.typeKind = TypeKind.BOOLEAN;
        booleanTypeKind.type = symTable.booleanType;
        function.returnTypeNode = booleanTypeKind;

        BLangBlockFunctionBody functionBlock = ASTBuilderUtil.createBlockFunctionBody(pos, new ArrayList<>());
        function.body = functionBlock;
        return functionBlock;
    }

    private BTupleType getStringAnyTupleType() {
        ArrayList<BType> typeList = new ArrayList<BType>() {{
            add(symTable.stringType);
            add(symTable.anyType);
        }};
        return new BTupleType(typeList);
    }

    /**
     * This method creates a simple variable def and assigns and array expression based on the given indexExpr.
     *
     *  case 1: when there is no parent array access expression, but with the indexExpr : 1
     *  string s = x[1];
     *
     *  case 2: when there is a parent array expression : x[2] and indexExpr : 3
     *  string s = x[2][3];
     *
     *  case 3: when there is no parent array access expression, but with the indexExpr : name
     *  string s = x[name];
     *
     *  case 4: when there is a parent map expression : x[name] and indexExpr : fName
     *  string s = x[name][fName]; 
     *
     *  case 5: when there is a parent map expression : x[name] and indexExpr : 1
     *  string s = x[name][1]; 
     */
    private void createSimpleVarDefStmt(BLangSimpleVariable simpleVariable, BLangBlockStmt parentBlockStmt,
                                        BLangLiteral indexExpr, BVarSymbol tupleVarSymbol,
                                        BLangIndexBasedAccess parentArrayAccessExpr) {

        Name varName = names.fromIdNode(simpleVariable.name);
        if (varName == Names.IGNORE) {
            return;
        }

        final BLangSimpleVariableDef simpleVariableDef = ASTBuilderUtil.createVariableDefStmt(simpleVariable.pos,
                parentBlockStmt);
        simpleVariableDef.var = simpleVariable;

        simpleVariable.expr = createIndexBasedAccessExpr(simpleVariable.type, simpleVariable.pos,
                indexExpr, tupleVarSymbol, parentArrayAccessExpr);
    }

    @Override
    public void visit(BLangAssignment assignNode) {
        if (safeNavigateLHS(assignNode.varRef)) {
            BLangAccessExpression accessExpr = (BLangAccessExpression) assignNode.varRef;
            accessExpr.leafNode = true;
            result = rewriteSafeNavigationAssignment(accessExpr, assignNode.expr, assignNode.safeAssignment);
            result = rewrite(result, env);
            return;
        }

        assignNode.varRef = rewriteExpr(assignNode.varRef);
        assignNode.expr = rewriteExpr(assignNode.expr);
        assignNode.expr = addConversionExprIfRequired(rewriteExpr(assignNode.expr), assignNode.varRef.type);
        result = assignNode;
    }

    @Override
    public void visit(BLangTupleDestructure tupleDestructure) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        


        
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(tupleDestructure.pos);

        
        BType runTimeType = new BArrayType(symTable.anyType);

        
        String name = "tuple";
        final BLangSimpleVariable tuple = ASTBuilderUtil.createVariable(tupleDestructure.pos, name, runTimeType, null,
                new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, runTimeType,
                        this.env.scope.owner));
        tuple.expr = tupleDestructure.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(tupleDestructure.pos,
                blockStmt);
        variableDef.var = tuple;

        
        createVarRefAssignmentStmts(tupleDestructure.varRef, blockStmt, tuple.symbol, null);
        createRestFieldAssignmentStmt(tupleDestructure, blockStmt, tuple.symbol);

        
        result = rewrite(blockStmt, env);
    }

    private void createRestFieldAssignmentStmt(BLangTupleDestructure tupleDestructure, BLangBlockStmt blockStmt,
                                               BVarSymbol tupleVarSymbol) {
        BLangTupleVarRef tupleVarRef = tupleDestructure.varRef;
        DiagnosticPos pos = blockStmt.pos;
        if (tupleVarRef.restParam != null) {
            BLangExpression tupleExpr = tupleDestructure.expr;

            
            BLangSimpleVarRef restParam = (BLangSimpleVarRef) tupleVarRef.restParam;
            BArrayType restParamType = (BArrayType) restParam.type;
            BLangArrayLiteral arrayExpr = createArrayLiteralExprNode();
            arrayExpr.type = restParamType;

            BLangAssignment restParamAssignment = ASTBuilderUtil.createAssignmentStmt(pos, blockStmt);
            restParamAssignment.varRef = restParam;
            restParamAssignment.varRef.type = restParamType;
            restParamAssignment.expr = arrayExpr;

            
            
            
            BLangLiteral startIndexLiteral = (BLangLiteral) TreeBuilder.createLiteralExpression();
            startIndexLiteral.value = (long) tupleVarRef.expressions.size();
            startIndexLiteral.type = symTable.intType;
            BLangInvocation lengthInvocation = createLengthInvocation(pos, tupleExpr);
            BLangInvocation intRangeInvocation = replaceWithIntRange(pos, startIndexLiteral,
                    getModifiedIntRangeEndExpr(lengthInvocation));

            BLangForeach foreach = (BLangForeach) TreeBuilder.createForeachNode();
            foreach.pos = pos;
            foreach.collection = intRangeInvocation;
            types.setForeachTypedBindingPatternType(foreach);

            final BLangSimpleVariable foreachVariable = ASTBuilderUtil.createVariable(pos,
                    "$foreach$i", foreach.varType);
            foreachVariable.symbol = new BVarSymbol(0, names.fromIdNode(foreachVariable.name),
                    this.env.scope.owner.pkgID, foreachVariable.type, this.env.scope.owner);
            BLangSimpleVarRef foreachVarRef = ASTBuilderUtil.createVariableRef(pos, foreachVariable.symbol);
            foreach.variableDefinitionNode = ASTBuilderUtil.createVariableDef(pos, foreachVariable);
            foreach.isDeclaredWithVar = true;
            BLangBlockStmt foreachBody = ASTBuilderUtil.createBlockStmt(pos);

            
            BLangIndexBasedAccess indexAccessExpr = ASTBuilderUtil.createIndexAccessExpr(restParam,
                    createLengthInvocation(pos, restParam));
            indexAccessExpr.type = restParamType.eType;
            createSimpleVarRefAssignmentStmt(indexAccessExpr, foreachBody, foreachVarRef, tupleVarSymbol, null);

            foreach.body = foreachBody;
            blockStmt.addStatement(foreach);
        }
    }

    private BLangInvocation createLengthInvocation(DiagnosticPos pos, BLangExpression collection) {
        BInvokableSymbol lengthInvokableSymbol = (BInvokableSymbol) symResolver
                .lookupLangLibMethod(collection.type, names.fromString(LENGTH_FUNCTION_NAME));
        BLangInvocation lengthInvocation = ASTBuilderUtil.createInvocationExprForMethod(pos, lengthInvokableSymbol,
                Lists.of(collection), symResolver);
        lengthInvocation.argExprs = lengthInvocation.requiredArgs;
        lengthInvocation.type = lengthInvokableSymbol.type.getReturnType();
        return lengthInvocation;
    }

    /**
     * This method iterate through each member of the tupleVarRef and create the relevant var ref assignment statements.
     * This method does the check for node kind of each member and call the related var ref creation method.
     *
     * Example:
     * ((a, b), c)) = (tuple)
     *
     * (a, b) is again a tuple, so it is a recursive var ref creation.
     *
     * c is a simple var, so a simple var def will be created.
     *
     */
    private void createVarRefAssignmentStmts(BLangTupleVarRef parentTupleVariable, BLangBlockStmt parentBlockStmt,
                                             BVarSymbol tupleVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {

        final List<BLangExpression> expressions = parentTupleVariable.expressions;
        for (int index = 0; index < expressions.size(); index++) {
            BLangExpression expression = expressions.get(index);
            if (NodeKind.SIMPLE_VARIABLE_REF == expression.getKind() ||
                    NodeKind.FIELD_BASED_ACCESS_EXPR == expression.getKind() ||
                    NodeKind.INDEX_BASED_ACCESS_EXPR == expression.getKind() ||
                    NodeKind.XML_ATTRIBUTE_ACCESS_EXPR == expression.getKind()) {
                
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(expression.pos, symTable.intType, (long) index);
                createSimpleVarRefAssignmentStmt((BLangVariableReference) expression, parentBlockStmt, indexExpr,
                        tupleVarSymbol, parentIndexAccessExpr);
                continue;
            }

            if (expression.getKind() == NodeKind.TUPLE_VARIABLE_REF) {
                
                BLangTupleVarRef tupleVarRef = (BLangTupleVarRef) expression;
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(tupleVarRef.pos, symTable.intType, (long) index);
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVarRef.pos,
                        new BArrayType(symTable.anyType), tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangTupleVarRef) expression, parentBlockStmt, tupleVarSymbol,
                        arrayAccessExpr);
                continue;
            }

            if (expression.getKind() == NodeKind.RECORD_VARIABLE_REF) {
                
                BLangRecordVarRef recordVarRef = (BLangRecordVarRef) expression;
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(recordVarRef.pos, symTable.intType,
                                                                      (long) index);
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, symTable.mapType, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangRecordVarRef) expression, parentBlockStmt, tupleVarSymbol,
                        arrayAccessExpr);

                TypeDefBuilderHelper.addTypeDefinition(recordVarRef.type, recordVarRef.type.tsymbol,
                                                       TypeDefBuilderHelper.createRecordTypeNode(
                                                                  (BRecordType) recordVarRef.type,
                                                                  env.enclPkg.packageID, symTable, recordVarRef.pos),
                                                       env);

                continue;
            }

            if (expression.getKind() == NodeKind.ERROR_VARIABLE_REF) {
                
                BLangErrorVarRef errorVarRef = (BLangErrorVarRef) expression;
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(errorVarRef.pos, symTable.intType,
                        (long) index);
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, expression.type, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangErrorVarRef) expression, parentBlockStmt, tupleVarSymbol,
                        arrayAccessExpr);
            }
        }
    }

    /**
     * This method creates a assignment statement and assigns and array expression based on the given indexExpr.
     *
     */
    private void createSimpleVarRefAssignmentStmt(BLangVariableReference simpleVarRef, BLangBlockStmt parentBlockStmt,
                                                  BLangExpression indexExpr, BVarSymbol tupleVarSymbol,
                                                  BLangIndexBasedAccess parentArrayAccessExpr) {

        if (simpleVarRef.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
            Name varName = names.fromIdNode(((BLangSimpleVarRef) simpleVarRef).variableName);
            if (varName == Names.IGNORE) {
                return;
            }
        }

        BLangExpression assignmentExpr = createIndexBasedAccessExpr(simpleVarRef.type, simpleVarRef.pos,
                indexExpr, tupleVarSymbol, parentArrayAccessExpr);

        assignmentExpr = addConversionExprIfRequired(assignmentExpr, simpleVarRef.type);

        final BLangAssignment assignmentStmt = ASTBuilderUtil.createAssignmentStmt(parentBlockStmt.pos,
                parentBlockStmt);
        assignmentStmt.varRef = simpleVarRef;
        assignmentStmt.expr = assignmentExpr;
    }

    private BLangExpression createIndexBasedAccessExpr(BType varType, DiagnosticPos varPos, BLangExpression indexExpr,
                                                       BVarSymbol tupleVarSymbol, BLangIndexBasedAccess parentExpr) {

        BLangIndexBasedAccess arrayAccess = ASTBuilderUtil.createIndexBasesAccessExpr(varPos,
                symTable.anyType, tupleVarSymbol, indexExpr);
        arrayAccess.originalType = varType;

        if (parentExpr != null) {
            arrayAccess.expr = parentExpr;
        }

        final BLangExpression assignmentExpr;
        if (types.isValueType(varType)) {
            BLangTypeConversionExpr castExpr = (BLangTypeConversionExpr) TreeBuilder.createTypeConversionNode();
            castExpr.expr = arrayAccess;
            castExpr.type = varType;
            assignmentExpr = castExpr;
        } else {
            assignmentExpr = arrayAccess;
        }
        return assignmentExpr;
    }

    @Override
    public void visit(BLangRecordDestructure recordDestructure) {

        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(recordDestructure.pos);

        BType runTimeType = new BMapType(TypeTags.MAP, symTable.anyType, null);

        String name = "$map$0";
        final BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(recordDestructure.pos, name, runTimeType,
                null, new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID,
                        runTimeType, this.env.scope.owner));
        mapVariable.expr = recordDestructure.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.
                createVariableDefStmt(recordDestructure.pos, blockStmt);
        variableDef.var = mapVariable;

        
        createVarRefAssignmentStmts(recordDestructure.varRef, blockStmt, mapVariable.symbol, null);

        
        result = rewrite(blockStmt, env);
    }

    @Override
    public void visit(BLangErrorDestructure errorDestructure) {
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(errorDestructure.pos);
        String name = "$error$";
        final BLangSimpleVariable errorVar = ASTBuilderUtil.createVariable(errorDestructure.pos, name,
                symTable.errorType, null, new BVarSymbol(0, names.fromString(name),
                        this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner));
        errorVar.expr = errorDestructure.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(errorDestructure.pos,
                blockStmt);
        variableDef.var = errorVar;
        createVarRefAssignmentStmts(errorDestructure.varRef, blockStmt, errorVar.symbol, null);
        result = rewrite(blockStmt, env);
    }

    private void createVarRefAssignmentStmts(BLangRecordVarRef parentRecordVarRef, BLangBlockStmt parentBlockStmt,
                                             BVarSymbol recordVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {
        final List<BLangRecordVarRefKeyValue> variableRefList = parentRecordVarRef.recordRefFields;
        for (BLangRecordVarRefKeyValue varRefKeyValue : variableRefList) {
            BLangExpression variableReference = varRefKeyValue.variableReference;
            BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(variableReference.pos, symTable.stringType,
                    varRefKeyValue.variableName.getValue());

            if (NodeKind.SIMPLE_VARIABLE_REF == variableReference.getKind() ||
                    NodeKind.FIELD_BASED_ACCESS_EXPR == variableReference.getKind() ||
                    NodeKind.INDEX_BASED_ACCESS_EXPR == variableReference.getKind() ||
                    NodeKind.XML_ATTRIBUTE_ACCESS_EXPR == variableReference.getKind()) {
                createSimpleVarRefAssignmentStmt((BLangVariableReference) variableReference, parentBlockStmt,
                        indexExpr, recordVarSymbol, parentIndexAccessExpr);
                continue;
            }

            if (NodeKind.RECORD_VARIABLE_REF == variableReference.getKind()) {
                BLangRecordVarRef recordVariable = (BLangRecordVarRef) variableReference;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentRecordVarRef.pos, symTable.mapType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts(recordVariable, parentBlockStmt, recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (NodeKind.TUPLE_VARIABLE_REF == variableReference.getKind()) {
                BLangTupleVarRef tupleVariable = (BLangTupleVarRef) variableReference;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVariable.pos,
                        symTable.tupleType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts(tupleVariable, parentBlockStmt, recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (NodeKind.ERROR_VARIABLE_REF == variableReference.getKind()) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(variableReference.pos,
                        symTable.errorType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangErrorVarRef) variableReference, parentBlockStmt, recordVarSymbol,
                        arrayAccessExpr);
            }
        }

        if (parentRecordVarRef.restParam != null) {
            
            
            

            DiagnosticPos pos = parentBlockStmt.pos;
            BMapType restParamType = (BMapType) ((BLangSimpleVarRef) parentRecordVarRef.restParam).type;
            BLangSimpleVarRef variableReference;

            if (parentIndexAccessExpr != null) {
                BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(pos, "$map$1", restParamType,
                        null, new BVarSymbol(0, names.fromString("$map$1"), this.env.scope.owner.pkgID,
                                restParamType, this.env.scope.owner));
                mapVariable.expr = parentIndexAccessExpr;
                BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(pos, parentBlockStmt);
                variableDef.var = mapVariable;

                variableReference = ASTBuilderUtil.createVariableRef(pos, mapVariable.symbol);
            } else {
                variableReference = ASTBuilderUtil.createVariableRef(pos,
                        ((BLangSimpleVariableDef) parentBlockStmt.stmts.get(0)).var.symbol);
            }

            BLangSimpleVarRef restParam = (BLangSimpleVarRef) parentRecordVarRef.restParam;

            List<String> keysToRemove = parentRecordVarRef.recordRefFields.stream()
                    .map(field -> field.variableName.value)
                    .collect(Collectors.toList());

            BLangSimpleVariable filteredDetail = generateRestFilter(variableReference, pos,
                    keysToRemove, restParamType, parentBlockStmt);

            BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol);

            
            BLangAssignment restParamAssignment = ASTBuilderUtil.createAssignmentStmt(pos, parentBlockStmt);
            restParamAssignment.varRef = restParam;
            restParamAssignment.varRef.type = restParamType;
            restParamAssignment.expr = varRef;
        }
    }

    private void createVarRefAssignmentStmts(BLangErrorVarRef parentErrorVarRef, BLangBlockStmt parentBlockStmt,
                                             BVarSymbol errorVarySymbol, BLangIndexBasedAccess parentIndexAccessExpr) {
        if (parentErrorVarRef.reason.getKind() != NodeKind.SIMPLE_VARIABLE_REF ||
                names.fromIdNode(((BLangSimpleVarRef) parentErrorVarRef.reason).variableName) != Names.IGNORE) {
            BLangAssignment reasonAssignment = ASTBuilderUtil
                    .createAssignmentStmt(parentBlockStmt.pos, parentBlockStmt);
            reasonAssignment.expr = generateErrorReasonBuiltinFunction(parentErrorVarRef.reason.pos,
                    symTable.stringType, errorVarySymbol, parentIndexAccessExpr);
            reasonAssignment.expr = addConversionExprIfRequired(reasonAssignment.expr, parentErrorVarRef.reason.type);
            reasonAssignment.varRef = parentErrorVarRef.reason;
        }

        
        if (parentErrorVarRef.detail.isEmpty() && isIgnoredErrorRefRestVar(parentErrorVarRef)) {
            return;
        }

        BLangInvocation errorDetailBuiltinFunction = generateErrorDetailBuiltinFunction(parentErrorVarRef.pos,
                errorVarySymbol,
                parentIndexAccessExpr);

        BLangSimpleVariableDef detailTempVarDef = createVarDef("$error$detail$" + errorCount++,
                                                               symTable.detailType, errorDetailBuiltinFunction,
                                                               parentErrorVarRef.pos);
        detailTempVarDef.type = symTable.detailType;
        parentBlockStmt.addStatement(detailTempVarDef);
        this.env.scope.define(names.fromIdNode(detailTempVarDef.var.name), detailTempVarDef.var.symbol);

        List<String> extractedKeys = new ArrayList<>();
        for (BLangNamedArgsExpression detail : parentErrorVarRef.detail) {
            extractedKeys.add(detail.name.value);
            BLangVariableReference ref = (BLangVariableReference) detail.expr;

            
            BLangExpression detailEntryVar = createIndexBasedAccessExpr(ref.type, ref.pos,
                    createStringLiteral(detail.name.pos, detail.name.value),
                    detailTempVarDef.var.symbol, null);
            if (detailEntryVar.getKind() == NodeKind.INDEX_BASED_ACCESS_EXPR) {
                BLangIndexBasedAccess bLangIndexBasedAccess = (BLangIndexBasedAccess) detailEntryVar;
                bLangIndexBasedAccess.originalType = symTable.pureType;
            }

            BLangAssignment detailAssignment = ASTBuilderUtil.createAssignmentStmt(ref.pos, parentBlockStmt);
            detailAssignment.varRef = ref;
            detailAssignment.expr = detailEntryVar;
        }

        if (!isIgnoredErrorRefRestVar(parentErrorVarRef)) {
            BLangSimpleVarRef detailVarRef = ASTBuilderUtil.createVariableRef(parentErrorVarRef.restVar.pos,
                    detailTempVarDef.var.symbol);

            BLangSimpleVariable filteredDetail = generateRestFilter(detailVarRef, parentErrorVarRef.restVar.pos,
                    extractedKeys,
                    parentErrorVarRef.restVar.type, parentBlockStmt);
            BLangAssignment restAssignment = ASTBuilderUtil.createAssignmentStmt(parentErrorVarRef.restVar.pos,
                    parentBlockStmt);
            restAssignment.varRef = parentErrorVarRef.restVar;
            restAssignment.expr = ASTBuilderUtil.createVariableRef(parentErrorVarRef.restVar.pos,
                    filteredDetail.symbol);
        }

        BErrorType errorType = (BErrorType) parentErrorVarRef.type;
        if (errorType.detailType.getKind() == TypeKind.RECORD) {
            
            BRecordTypeSymbol tsymbol = (BRecordTypeSymbol) errorType.detailType.tsymbol;
            tsymbol.initializerFunc = createRecordInitFunc();
            tsymbol.scope.define(tsymbol.initializerFunc.funcName, tsymbol.initializerFunc.symbol);
        }
    }

    private boolean isIgnoredErrorRefRestVar(BLangErrorVarRef parentErrorVarRef) {
        if (parentErrorVarRef.restVar == null) {
            return true;
        }
        if (parentErrorVarRef.restVar.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
            return (((BLangSimpleVarRef) parentErrorVarRef.restVar).variableName.value.equals(IGNORE.value));
        }
        return false;
    }

    @Override
    public void visit(BLangAbort abortNode) {
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(abortNode.pos, symTable.intType, -1L);
        result = rewrite(returnStmt, env);
    }

    @Override
    public void visit(BLangRetry retryNode) {
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(retryNode.pos, symTable.intType, 1L);
        result = rewrite(returnStmt, env);
    }

    @Override
    public void visit(BLangContinue nextNode) {
        result = nextNode;
    }

    @Override
    public void visit(BLangBreak breakNode) {
        result = breakNode;
    }

    @Override
    public void visit(BLangReturn returnNode) {
        
        
        if (returnNode.expr != null) {
            returnNode.expr = rewriteExpr(returnNode.expr);
        }
        result = returnNode;
    }

    @Override
    public void visit(BLangPanic panicNode) {
        panicNode.expr = rewriteExpr(panicNode.expr);
        result = panicNode;
    }

    @Override
    public void visit(BLangXMLNSStatement xmlnsStmtNode) {
        xmlnsStmtNode.xmlnsDecl = rewrite(xmlnsStmtNode.xmlnsDecl, env);
        result = xmlnsStmtNode;
    }

    @Override
    public void visit(BLangXMLNS xmlnsNode) {
        BLangXMLNS generatedXMLNSNode;
        xmlnsNode.namespaceURI = rewriteExpr(xmlnsNode.namespaceURI);
        BSymbol ownerSymbol = xmlnsNode.symbol.owner;

        
        if ((ownerSymbol.tag & SymTag.INVOKABLE) == SymTag.INVOKABLE ||
                (ownerSymbol.tag & SymTag.SERVICE) == SymTag.SERVICE) {
            generatedXMLNSNode = new BLangLocalXMLNS();
        } else {
            generatedXMLNSNode = new BLangPackageXMLNS();
        }

        generatedXMLNSNode.namespaceURI = xmlnsNode.namespaceURI;
        generatedXMLNSNode.prefix = xmlnsNode.prefix;
        generatedXMLNSNode.symbol = xmlnsNode.symbol;
        result = generatedXMLNSNode;
    }

    public void visit(BLangCompoundAssignment compoundAssignment) {

        BLangVariableReference varRef = compoundAssignment.varRef;
        if (compoundAssignment.varRef.getKind() != NodeKind.INDEX_BASED_ACCESS_EXPR) {
            
            
            
            if (varRef.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
                varRef = ASTBuilderUtil.createVariableRef(compoundAssignment.varRef.pos, varRef.symbol);
                varRef.lhsVar = true;
            }

            result = ASTBuilderUtil.createAssignmentStmt(compoundAssignment.pos, rewriteExpr(varRef),
                    rewriteExpr(compoundAssignment.modifiedExpr));
            return;
        }
        
        
        
        
        
        
        List<BLangStatement> statements = new ArrayList<>();
        List<BLangSimpleVarRef> varRefs = new ArrayList<>();
        List<BType> types = new ArrayList<>();

        
        
        
        
        do {
            BLangSimpleVariableDef tempIndexVarDef = createVarDef("$temp" + ++indexExprCount + "$",
                    ((BLangIndexBasedAccess) varRef).indexExpr.type, ((BLangIndexBasedAccess) varRef).indexExpr,
                    compoundAssignment.pos);
            BLangSimpleVarRef tempVarRef = ASTBuilderUtil.createVariableRef(tempIndexVarDef.pos,
                    tempIndexVarDef.var.symbol);
            statements.add(0, tempIndexVarDef);
            varRefs.add(0, tempVarRef);
            types.add(0, varRef.type);

            varRef = (BLangVariableReference) ((BLangIndexBasedAccess) varRef).expr;
        } while (varRef.getKind() == NodeKind.INDEX_BASED_ACCESS_EXPR);

        
        BLangVariableReference var = varRef;
        for (int ref = 0; ref < varRefs.size(); ref++) {
            var = ASTBuilderUtil.createIndexAccessExpr(var, varRefs.get(ref));
            var.type = types.get(ref);
        }
        var.type = compoundAssignment.varRef.type;

        
        BLangExpression rhsExpression = ASTBuilderUtil.createBinaryExpr(compoundAssignment.pos, var,
                compoundAssignment.expr, compoundAssignment.type, compoundAssignment.opKind, null);
        rhsExpression.type = compoundAssignment.modifiedExpr.type;

        
        BLangAssignment assignStmt = ASTBuilderUtil.createAssignmentStmt(compoundAssignment.pos, var,
                rhsExpression);

        statements.add(assignStmt);
        
        
        BLangBlockStmt bLangBlockStmt = ASTBuilderUtil.createBlockStmt(compoundAssignment.pos, statements);
        result = rewrite(bLangBlockStmt, env);
    }

    @Override
    public void visit(BLangExpressionStmt exprStmtNode) {
        exprStmtNode.expr = rewriteExpr(exprStmtNode.expr);
        result = exprStmtNode;
    }

    @Override
    public void visit(BLangIf ifNode) {
        ifNode.expr = rewriteExpr(ifNode.expr);
        ifNode.body = rewrite(ifNode.body, env);
        ifNode.elseStmt = rewrite(ifNode.elseStmt, env);

        result = ifNode;
    }

    @Override
    public void visit(BLangMatch matchStmt) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        

        
        BLangBlockStmt matchBlockStmt = (BLangBlockStmt) TreeBuilder.createBlockNode();
        matchBlockStmt.pos = matchStmt.pos;

        
        String matchExprVarName = GEN_VAR_PREFIX.value;
        BLangSimpleVariable matchExprVar = ASTBuilderUtil.createVariable(matchStmt.expr.pos,
                matchExprVarName, matchStmt.expr.type, matchStmt.expr, new BVarSymbol(0,
                        names.fromString(matchExprVarName),
                        this.env.scope.owner.pkgID, matchStmt.expr.type, this.env.scope.owner));

        
        BLangSimpleVariableDef matchExprVarDef = ASTBuilderUtil.createVariableDef(matchBlockStmt.pos, matchExprVar);

        
        
        matchBlockStmt.stmts.add(matchExprVarDef);

        
        matchBlockStmt.stmts.add(generateIfElseStmt(matchStmt, matchExprVar));

        rewrite(matchBlockStmt, this.env);
        result = matchBlockStmt;
    }

    @Override
    public void visit(BLangForeach foreach) {
        BLangBlockStmt blockNode;

        
        
        BVarSymbol dataSymbol = new BVarSymbol(0, names.fromString("$data$"), this.env.scope.owner.pkgID,
                foreach.collection.type, this.env.scope.owner);
        BLangSimpleVariable dataVariable = ASTBuilderUtil.createVariable(foreach.pos, "$data$",
                foreach.collection.type, foreach.collection, dataSymbol);
        BLangSimpleVariableDef dataVarDef = ASTBuilderUtil.createVariableDef(foreach.pos, dataVariable);

        
        BVarSymbol collectionSymbol = dataVariable.symbol;
        switch (foreach.collection.type.tag) {
            case TypeTags.STRING:
            case TypeTags.ARRAY:
            case TypeTags.TUPLE:
            case TypeTags.XML:
            case TypeTags.MAP:
            case TypeTags.STREAM:
            case TypeTags.RECORD:
                BInvokableSymbol iteratorSymbol = getLangLibIteratorInvokableSymbol(collectionSymbol);
                blockNode = desugarForeachWithIteratorDef(foreach, dataVarDef, collectionSymbol, iteratorSymbol, true);
                break;
            case TypeTags.OBJECT: 
                iteratorSymbol = getIterableObjectIteratorInvokableSymbol(collectionSymbol);
                blockNode = desugarForeachWithIteratorDef(foreach, dataVarDef, collectionSymbol, iteratorSymbol, false);
                break;
            default:
                blockNode = ASTBuilderUtil.createBlockStmt(foreach.pos);
                blockNode.stmts.add(0, dataVarDef);
                break;
        }

        
        rewrite(blockNode, this.env);
        result = blockNode;
    }

    private BLangBlockStmt desugarForeachWithIteratorDef(BLangForeach foreach,
                                                         BLangSimpleVariableDef dataVariableDefinition,
                                                         BVarSymbol collectionSymbol,
                                                         BInvokableSymbol iteratorInvokableSymbol,
                                                         boolean isIteratorFuncFromLangLib) {
        BLangSimpleVariableDef iteratorVarDef = getIteratorVariableDefinition(foreach.pos, collectionSymbol,
                iteratorInvokableSymbol, isIteratorFuncFromLangLib);
        BLangBlockStmt blockNode = desugarForeachToWhile(foreach, iteratorVarDef);
        blockNode.stmts.add(0, dataVariableDefinition);
        return blockNode;
    }

    public BInvokableSymbol getIterableObjectIteratorInvokableSymbol(BVarSymbol collectionSymbol) {
        BObjectTypeSymbol typeSymbol = (BObjectTypeSymbol) collectionSymbol.type.tsymbol;
        
        BAttachedFunction iteratorFunc = null;
        for (BAttachedFunction func : typeSymbol.attachedFuncs) {
            if (func.funcName.value.equals(BLangCompilerConstants.ITERABLE_OBJECT_ITERATOR_FUNC)) {
                iteratorFunc = func;
                break;
            }
        }
        BAttachedFunction function = iteratorFunc;
        return function.symbol;
    }

    BInvokableSymbol getLangLibIteratorInvokableSymbol(BVarSymbol collectionSymbol) {
        return (BInvokableSymbol) symResolver.lookupLangLibMethod(collectionSymbol.type,
                names.fromString(BLangCompilerConstants.ITERABLE_COLLECTION_ITERATOR_FUNC));
    }

    private BLangBlockStmt desugarForeachToWhile(BLangForeach foreach, BLangSimpleVariableDef varDef) {

        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        

        
        

        

        BVarSymbol iteratorSymbol = varDef.var.symbol;

        
        BVarSymbol resultSymbol = new BVarSymbol(0, names.fromString("$result$"), this.env.scope.owner.pkgID,
                foreach.nillableResultType, this.env.scope.owner);

        
        BLangSimpleVariableDef resultVariableDefinition = getIteratorNextVariableDefinition(foreach.pos,
                foreach.nillableResultType, iteratorSymbol, resultSymbol);

        
        BLangType userDefineType = getUserDefineTypeNode(foreach.resultType);
        BLangSimpleVarRef resultReferenceInWhile = ASTBuilderUtil.createVariableRef(foreach.pos, resultSymbol);
        BLangTypeTestExpr typeTestExpr = ASTBuilderUtil
                .createTypeTestExpr(foreach.pos, resultReferenceInWhile, userDefineType);
        
        BLangWhile whileNode = (BLangWhile) TreeBuilder.createWhileNode();
        whileNode.pos = foreach.pos;
        whileNode.expr = typeTestExpr;
        whileNode.body = foreach.body;

        
        BLangAssignment resultAssignment = getIteratorNextAssignment(foreach.pos, iteratorSymbol, resultSymbol);
        VariableDefinitionNode variableDefinitionNode = foreach.variableDefinitionNode;

        
        
        
        BLangFieldBasedAccess valueAccessExpr = getValueAccessExpression(foreach.pos, foreach.varType, resultSymbol);
        valueAccessExpr.expr = addConversionExprIfRequired(valueAccessExpr.expr,
                types.getSafeType(valueAccessExpr.expr.type, true, false));
        variableDefinitionNode.getVariable()
                .setInitialExpression(addConversionExprIfRequired(valueAccessExpr, foreach.varType));
        whileNode.body.stmts.add(0, (BLangStatement) variableDefinitionNode);
        whileNode.body.stmts.add(1, resultAssignment);

        
        BLangBlockStmt blockNode = ASTBuilderUtil.createBlockStmt(foreach.pos);

        
        blockNode.addStatement(varDef);

        
        blockNode.addStatement(resultVariableDefinition);

        
        blockNode.addStatement(whileNode);
        return blockNode;
    }

    private BLangType getUserDefineTypeNode(BType type) {
        BLangUserDefinedType recordType =
                new BLangUserDefinedType(ASTBuilderUtil.createIdentifier(null, ""),
                                         ASTBuilderUtil.createIdentifier(null, ""));
        recordType.type = type;
        return recordType;
    }

    @Override
    public void visit(BLangWhile whileNode) {
        whileNode.expr = rewriteExpr(whileNode.expr);
        whileNode.body = rewrite(whileNode.body, env);
        result = whileNode;
    }

    @Override
    public void visit(BLangLock lockNode) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(lockNode.pos);

        BLangLockStmt lockStmt = new BLangLockStmt(lockNode.pos);
        blockStmt.addStatement(lockStmt);

        enclLocks.push(lockStmt);

        BLangLiteral nilLiteral = ASTBuilderUtil.createLiteral(lockNode.pos, symTable.nilType, Names.NIL_VALUE);
        BType nillableError = BUnionType.create(null, symTable.errorType, symTable.nilType);
        BLangStatementExpression statementExpression = createStatementExpression(lockNode.body, nilLiteral);
        statementExpression.type = symTable.nilType;

        BLangTrapExpr trapExpr = (BLangTrapExpr) TreeBuilder.createTrapExpressionNode();
        trapExpr.type = nillableError;
        trapExpr.expr = statementExpression;
        BVarSymbol nillableErrorVarSymbol = new BVarSymbol(0, names.fromString("$errorResult"),
                this.env.scope.owner.pkgID, nillableError, this.env.scope.owner);
        BLangSimpleVariable simpleVariable = ASTBuilderUtil.createVariable(lockNode.pos, "$errorResult",
                nillableError, trapExpr, nillableErrorVarSymbol);
        BLangSimpleVariableDef simpleVariableDef = ASTBuilderUtil.createVariableDef(lockNode.pos, simpleVariable);
        blockStmt.addStatement(simpleVariableDef);

        BLangUnLockStmt unLockStmt = new BLangUnLockStmt(lockNode.pos);
        blockStmt.addStatement(unLockStmt);
        BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(lockNode.pos, nillableErrorVarSymbol);

        BLangBlockStmt ifBody = ASTBuilderUtil.createBlockStmt(lockNode.pos);
        BLangPanic panicNode = (BLangPanic) TreeBuilder.createPanicNode();
        panicNode.pos = lockNode.pos;
        panicNode.expr = addConversionExprIfRequired(varRef, symTable.errorType);
        ifBody.addStatement(panicNode);

        BLangTypeTestExpr isErrorTest =
                ASTBuilderUtil.createTypeTestExpr(lockNode.pos, varRef, getErrorTypeNode());
        isErrorTest.type = symTable.booleanType;

        BLangIf ifelse = ASTBuilderUtil.createIfElseStmt(lockNode.pos, isErrorTest, ifBody, null);
        blockStmt.addStatement(ifelse);
        result = rewrite(blockStmt, env);
        enclLocks.pop();
    }

    @Override
    public void visit(BLangLockStmt lockStmt) {
        result = lockStmt;
    }

    @Override
    public void visit(BLangUnLockStmt unLockStmt) {
        result = unLockStmt;
    }

    @Override
    public void visit(BLangTransaction transactionNode) {

        
        
        
        

        DiagnosticPos pos = transactionNode.pos;
        BType trxReturnType = symTable.intType;
        BType otherReturnType = symTable.nilType;
        BLangType trxReturnNode = ASTBuilderUtil.createTypeNode(trxReturnType);
        BLangType otherReturnNode = ASTBuilderUtil.createTypeNode(otherReturnType);
        DiagnosticPos invPos = transactionNode.pos;
        /* transaction block code will be desugar to function which returns int. Return value determines the status of
         the transaction code.
         ex.
            0 = successful
            1 = retry
            -1 = abort

            Since transaction block code doesn't return anything, we need to add return statement at end of the
            block unless we have abort or retry statement.
        */
        DiagnosticPos returnStmtPos = new DiagnosticPos(invPos.src,
                                                        invPos.eLine, invPos.eLine, invPos.sCol, invPos.sCol);
        BLangStatement statement = null;
        if (!transactionNode.transactionBody.stmts.isEmpty()) {
            statement = transactionNode.transactionBody.stmts.get(transactionNode.transactionBody.stmts.size() - 1);
        }
        if (statement == null || !(statement.getKind() == NodeKind.ABORT) && !(statement.getKind() == NodeKind.ABORT)) {
            BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(returnStmtPos, trxReturnType, 0L);
            transactionNode.transactionBody.addStatement(returnStmt);
        }

        
        if (transactionNode.abortedBody == null) {
            transactionNode.abortedBody = ASTBuilderUtil.createBlockStmt(transactionNode.pos);
        }
        if (transactionNode.committedBody == null) {
            transactionNode.committedBody = ASTBuilderUtil.createBlockStmt(transactionNode.pos);
        }
        if (transactionNode.onRetryBody == null) {
            transactionNode.onRetryBody = ASTBuilderUtil.createBlockStmt(transactionNode.pos);
        }

        if (transactionNode.retryCount == null) {
            transactionNode.retryCount = ASTBuilderUtil.createLiteral(pos, symTable.intType, 3L);
        }

        
        BLangLambdaFunction trxMainFunc = createLambdaFunction(pos, "$anonTrxMainFunc$", Collections.emptyList(),
                                                               trxReturnNode, transactionNode.transactionBody.stmts,
                                                               env, transactionNode.transactionBody.scope);
        BLangLambdaFunction trxOnRetryFunc = createLambdaFunction(pos, "$anonTrxOnRetryFunc$", Collections.emptyList(),
                                                                  otherReturnNode, transactionNode.onRetryBody.stmts,
                                                                  env, transactionNode.onRetryBody.scope);
        BLangLambdaFunction trxCommittedFunc = createLambdaFunction(pos, "$anonTrxCommittedFunc$",
                                                                    Collections.emptyList(), otherReturnNode,
                                                                    transactionNode.committedBody.stmts, env,
                                                                    transactionNode.committedBody.scope);
        BLangLambdaFunction trxAbortedFunc = createLambdaFunction(pos, "$anonTrxAbortedFunc$", Collections.emptyList(),
                                                                  otherReturnNode, transactionNode.abortedBody.stmts,
                                                                  env, transactionNode.abortedBody.scope);
        trxMainFunc.capturedClosureEnv = env.createClone();
        trxOnRetryFunc.capturedClosureEnv = env.createClone();
        trxCommittedFunc.capturedClosureEnv = env.createClone();
        trxAbortedFunc.capturedClosureEnv = env.createClone();

        
        PackageID packageID = new PackageID(Names.BALLERINA_ORG, Names.TRANSACTION_PACKAGE, Names.EMPTY);
        BPackageSymbol transactionPkgSymbol = new BPackageSymbol(packageID, null, 0);
        BInvokableSymbol invokableSymbol =
                (BInvokableSymbol) symResolver.lookupSymbolInMainSpace(symTable.pkgEnvMap.get(transactionPkgSymbol),
                        TRX_INITIATOR_BEGIN_FUNCTION);
        BLangLiteral transactionBlockId = ASTBuilderUtil.createLiteral(pos, symTable.stringType,
                                                                       getTransactionBlockId());
        List<BLangExpression> requiredArgs = Lists.of(transactionBlockId, transactionNode.retryCount, trxMainFunc,
                                                      trxOnRetryFunc,
                                                      trxCommittedFunc, trxAbortedFunc);
        BLangInvocation trxInvocation = ASTBuilderUtil.createInvocationExprMethod(pos, invokableSymbol,
                                                                                  requiredArgs,
                                                                                  Collections.emptyList(),
                                                                                  symResolver);
        BLangExpressionStmt stmt = ASTBuilderUtil.createExpressionStmt(pos, ASTBuilderUtil.createBlockStmt(pos));
        stmt.expr = trxInvocation;
        result = rewrite(stmt, env);
    }

    private String getTransactionBlockId() {
        return env.enclPkg.packageID.orgName + "$" + env.enclPkg.packageID.name + "$"
                + transactionIndex++;
    }

    private BLangLambdaFunction createLambdaFunction(DiagnosticPos pos, String functionNamePrefix,
                                                     List<BLangSimpleVariable> lambdaFunctionVariable,
                                                     TypeNode returnType, BLangFunctionBody lambdaBody) {
        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        BLangFunction func = ASTBuilderUtil.createFunction(pos, functionNamePrefix + lambdaFunctionCount++);
        lambdaFunction.function = func;
        func.requiredParams.addAll(lambdaFunctionVariable);
        func.setReturnTypeNode(returnType);
        func.desugaredReturnType = true;
        defineFunction(func, env.enclPkg);
        lambdaFunctionVariable = func.requiredParams;

        func.body = lambdaBody;
        func.desugared = false;
        lambdaFunction.pos = pos;
        List<BType> paramTypes = new ArrayList<>();
        lambdaFunctionVariable.forEach(variable -> paramTypes.add(variable.symbol.type));
        lambdaFunction.type = new BInvokableType(paramTypes, func.symbol.type.getReturnType(),
                                                 null);
        return lambdaFunction;
    }

    private BLangLambdaFunction createLambdaFunction(DiagnosticPos pos, String functionNamePrefix,
                                                     List<BLangSimpleVariable> lambdaFunctionVariable,
                                                     TypeNode returnType, List<BLangStatement> fnBodyStmts,
                                                     SymbolEnv env, Scope trxScope) {
        BLangBlockFunctionBody body = (BLangBlockFunctionBody) TreeBuilder.createBlockFunctionBodyNode();
        body.scope = trxScope;
        SymbolEnv bodyEnv = SymbolEnv.createFuncBodyEnv(body, env);
        body.stmts = rewriteStmt(fnBodyStmts, bodyEnv);
        return createLambdaFunction(pos, functionNamePrefix, lambdaFunctionVariable, returnType, body);
    }

    private BLangLambdaFunction createLambdaFunction(DiagnosticPos pos, String functionNamePrefix,
                                                     TypeNode returnType) {
        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        BLangFunction func = ASTBuilderUtil.createFunction(pos, functionNamePrefix + lambdaFunctionCount++);
        lambdaFunction.function = func;
        func.setReturnTypeNode(returnType);
        func.desugaredReturnType = true;
        defineFunction(func, env.enclPkg);
        func.desugared = false;
        lambdaFunction.pos = pos;
        return lambdaFunction;
    }

    private void defineFunction(BLangFunction funcNode, BLangPackage targetPkg) {
        final BPackageSymbol packageSymbol = targetPkg.symbol;
        final SymbolEnv packageEnv = this.symTable.pkgEnvMap.get(packageSymbol);
        symbolEnter.defineNode(funcNode, packageEnv);
        packageEnv.enclPkg.functions.add(funcNode);
        packageEnv.enclPkg.topLevelNodes.add(funcNode);
    }

    @Override
    public void visit(BLangForkJoin forkJoin) {
         result = forkJoin;
    }

    

    @Override
    public void visit(BLangLiteral literalExpr) {
        if (literalExpr.type.tag == TypeTags.ARRAY && ((BArrayType) literalExpr.type).eType.tag == TypeTags.BYTE) {
            
            result = rewriteBlobLiteral(literalExpr);
            return;
        }
        result = literalExpr;
    }

    private BLangNode rewriteBlobLiteral(BLangLiteral literalExpr) {
        String[] result = getBlobTextValue((String) literalExpr.value);
        byte[] values;
        if (BASE_64.equals(result[0])) {
            values = Base64.getDecoder().decode(result[1].getBytes(StandardCharsets.UTF_8));
        } else {
            values = hexStringToByteArray(result[1]);
        }
        BLangArrayLiteral arrayLiteralNode = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
        arrayLiteralNode.type = literalExpr.type;
        arrayLiteralNode.pos = literalExpr.pos;
        arrayLiteralNode.exprs = new ArrayList<>();
        for (byte b : values) {
            arrayLiteralNode.exprs.add(createByteLiteral(literalExpr.pos, b));
        }
        return arrayLiteralNode;
    }

    private String[] getBlobTextValue(String blobLiteralNodeText) {
        String nodeText = blobLiteralNodeText.replaceAll(" ", "");
        String[] result = new String[2];
        result[0] = nodeText.substring(0, nodeText.indexOf('`'));
        result[1] = nodeText.substring(nodeText.indexOf('`') + 1, nodeText.lastIndexOf('`'));
        return result;
    }

    private static byte[] hexStringToByteArray(String str) {
        int len = str.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(str.charAt(i), 16) << 4) + Character.digit(str.charAt(i + 1), 16));
        }
        return data;
    }

    @Override
    public void visit(BLangListConstructorExpr listConstructor) {
        listConstructor.exprs = rewriteExprs(listConstructor.exprs);
        BLangExpression expr;
        if (listConstructor.type.tag == TypeTags.TUPLE) {
            expr = new BLangTupleLiteral(listConstructor.pos, listConstructor.exprs, listConstructor.type);
            result = rewriteExpr(expr);
        } else if (listConstructor.type.tag == TypeTags.JSON) {
            expr = new BLangJSONArrayLiteral(listConstructor.exprs, new BArrayType(listConstructor.type));
            result = rewriteExpr(expr);
        } else if (getElementType(listConstructor.type).tag == TypeTags.JSON) {
            expr = new BLangJSONArrayLiteral(listConstructor.exprs, listConstructor.type);
            result = rewriteExpr(expr);
        } else if (listConstructor.type.tag == TypeTags.TYPEDESC) {
            final BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
            typedescExpr.resolvedType = listConstructor.typedescType;
            typedescExpr.type = symTable.typeDesc;
            result = rewriteExpr(typedescExpr);
        } else {
            expr = new BLangArrayLiteral(listConstructor.pos, listConstructor.exprs, listConstructor.type);
            result = rewriteExpr(expr);
        }
    }

    @Override
    public void visit(BLangArrayLiteral arrayLiteral) {
        arrayLiteral.exprs = rewriteExprs(arrayLiteral.exprs);

        if (arrayLiteral.type.tag == TypeTags.JSON) {
            result = new BLangJSONArrayLiteral(arrayLiteral.exprs, new BArrayType(arrayLiteral.type));
            return;
        } else if (getElementType(arrayLiteral.type).tag == TypeTags.JSON) {
            result = new BLangJSONArrayLiteral(arrayLiteral.exprs, arrayLiteral.type);
            return;
        }
        result = arrayLiteral;
    }

    @Override
    public void visit(BLangTupleLiteral tupleLiteral) {
        if (tupleLiteral.isTypedescExpr) {
            final BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
            typedescExpr.resolvedType = tupleLiteral.typedescType;
            typedescExpr.type = symTable.typeDesc;
            result = rewriteExpr(typedescExpr);
            return;
        }
        tupleLiteral.exprs.forEach(expr -> {
            BType expType = expr.impConversionExpr == null ? expr.type : expr.impConversionExpr.type;
            types.setImplicitCastExpr(expr, expType, symTable.anyType);
        });
        tupleLiteral.exprs = rewriteExprs(tupleLiteral.exprs);
        result = tupleLiteral;
    }

    @Override
    public void visit(BLangGroupExpr groupExpr) {
        if (groupExpr.isTypedescExpr) {
            final BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
            typedescExpr.resolvedType = groupExpr.typedescType;
            typedescExpr.type = symTable.typeDesc;
            result = rewriteExpr(typedescExpr);
        } else {
            result = rewriteExpr(groupExpr.expression);
        }
    }

    @Override
    public void visit(BLangRecordLiteral recordLiteral) {
        List<RecordLiteralNode.RecordField> fields =  recordLiteral.fields;
        fields.sort((v1, v2) -> Boolean.compare(isComputedKey(v1), isComputedKey(v2)));
        result = rewriteExpr(rewriteMappingConstructor(recordLiteral));
    }

    @Override
    public void visit(BLangSimpleVarRef varRefExpr) {
        BLangSimpleVarRef genVarRefExpr = varRefExpr;

        
        if (varRefExpr.pkgSymbol != null && varRefExpr.pkgSymbol.tag == SymTag.XMLNS) {
            BLangXMLQName qnameExpr = new BLangXMLQName(varRefExpr.variableName);
            qnameExpr.nsSymbol = (BXMLNSSymbol) varRefExpr.pkgSymbol;
            qnameExpr.localname = varRefExpr.variableName;
            qnameExpr.prefix = varRefExpr.pkgAlias;
            qnameExpr.namespaceURI = qnameExpr.nsSymbol.namespaceURI;
            qnameExpr.isUsedInXML = false;
            qnameExpr.pos = varRefExpr.pos;
            qnameExpr.type = symTable.stringType;
            result = qnameExpr;
            return;
        }

        if (varRefExpr.symbol == null) {
            result = varRefExpr;
            return;
        }

        
        if ((varRefExpr.symbol.tag & SymTag.VARIABLE) == SymTag.VARIABLE) {
            BVarSymbol varSymbol = (BVarSymbol) varRefExpr.symbol;
            if (varSymbol.originalSymbol != null) {
                varRefExpr.symbol = varSymbol.originalSymbol;
            }
        }

        BSymbol ownerSymbol = varRefExpr.symbol.owner;
        if ((varRefExpr.symbol.tag & SymTag.FUNCTION) == SymTag.FUNCTION &&
                varRefExpr.symbol.type.tag == TypeTags.INVOKABLE) {
            genVarRefExpr = new BLangFunctionVarRef((BVarSymbol) varRefExpr.symbol);
        } else if ((varRefExpr.symbol.tag & SymTag.TYPE) == SymTag.TYPE &&
                !((varRefExpr.symbol.tag & SymTag.CONSTANT) == SymTag.CONSTANT)) {
            genVarRefExpr = new BLangTypeLoad(varRefExpr.symbol);
        } else if ((ownerSymbol.tag & SymTag.INVOKABLE) == SymTag.INVOKABLE ||
                (ownerSymbol.tag & SymTag.LET) == SymTag.LET) {
            
            genVarRefExpr = new BLangLocalVarRef((BVarSymbol) varRefExpr.symbol);
        } else if ((ownerSymbol.tag & SymTag.STRUCT) == SymTag.STRUCT) {
            genVarRefExpr = new BLangFieldVarRef((BVarSymbol) varRefExpr.symbol);
        } else if ((ownerSymbol.tag & SymTag.PACKAGE) == SymTag.PACKAGE ||
                (ownerSymbol.tag & SymTag.SERVICE) == SymTag.SERVICE) {

            
            
            if ((varRefExpr.symbol.tag & SymTag.CONSTANT) == SymTag.CONSTANT) {
                BConstantSymbol constSymbol = (BConstantSymbol) varRefExpr.symbol;
                if (constSymbol.literalType.tag <= TypeTags.BOOLEAN || constSymbol.literalType.tag == TypeTags.NIL) {
                    BLangLiteral literal = ASTBuilderUtil.createLiteral(varRefExpr.pos, constSymbol.literalType,
                            constSymbol.value.value);
                    result = rewriteExpr(addConversionExprIfRequired(literal, varRefExpr.type));
                    return;
                }
            }

            
            
            genVarRefExpr = new BLangPackageVarRef((BVarSymbol) varRefExpr.symbol);
        }

        genVarRefExpr.type = varRefExpr.type;
        genVarRefExpr.pos = varRefExpr.pos;

        if ((varRefExpr.lhsVar)
                || genVarRefExpr.symbol.name.equals(IGNORE)) { 
            genVarRefExpr.lhsVar = varRefExpr.lhsVar;
            genVarRefExpr.type = varRefExpr.symbol.type;
            result = genVarRefExpr;
            return;
        }

        
        
        genVarRefExpr.lhsVar = varRefExpr.lhsVar;
        BType targetType = genVarRefExpr.type;
        genVarRefExpr.type = genVarRefExpr.symbol.type;
        BLangExpression expression = addConversionExprIfRequired(genVarRefExpr, targetType);
        result = expression.impConversionExpr != null ? expression.impConversionExpr : expression;
    }

    @Override
    public void visit(BLangFieldBasedAccess fieldAccessExpr) {
        if (safeNavigate(fieldAccessExpr)) {
            result = rewriteExpr(rewriteSafeNavigationExpr(fieldAccessExpr));
            return;
        }

        BLangAccessExpression targetVarRef = fieldAccessExpr;

        
        
        BType varRefType = fieldAccessExpr.expr.type;
        fieldAccessExpr.expr = rewriteExpr(fieldAccessExpr.expr);
        if (!types.isSameType(fieldAccessExpr.expr.type, varRefType)) {
            fieldAccessExpr.expr = addConversionExprIfRequired(fieldAccessExpr.expr, varRefType);
        }

        BLangLiteral stringLit = createStringLiteral(fieldAccessExpr.pos, fieldAccessExpr.field.value);
        int varRefTypeTag = varRefType.tag;
        if (varRefTypeTag == TypeTags.OBJECT ||
                (varRefTypeTag == TypeTags.UNION &&
                         ((BUnionType) varRefType).getMemberTypes().iterator().next().tag == TypeTags.OBJECT)) {
            if (fieldAccessExpr.symbol != null && fieldAccessExpr.symbol.type.tag == TypeTags.INVOKABLE &&
                    ((fieldAccessExpr.symbol.flags & Flags.ATTACHED) == Flags.ATTACHED)) {
                targetVarRef = new BLangStructFunctionVarRef(fieldAccessExpr.expr, (BVarSymbol) fieldAccessExpr.symbol);
            } else {
                targetVarRef = new BLangStructFieldAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit,
                        (BVarSymbol) fieldAccessExpr.symbol, false);
                
            }
        } else if (varRefTypeTag == TypeTags.RECORD ||
                (varRefTypeTag == TypeTags.UNION &&
                         ((BUnionType) varRefType).getMemberTypes().iterator().next().tag == TypeTags.RECORD)) {
            if (fieldAccessExpr.symbol != null && fieldAccessExpr.symbol.type.tag == TypeTags.INVOKABLE
                    && ((fieldAccessExpr.symbol.flags & Flags.ATTACHED) == Flags.ATTACHED)) {
                targetVarRef = new BLangStructFunctionVarRef(fieldAccessExpr.expr, (BVarSymbol) fieldAccessExpr.symbol);
            } else {
                targetVarRef = new BLangStructFieldAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit,
                        (BVarSymbol) fieldAccessExpr.symbol, false);
            }
        } else if (types.isLax(varRefType)) {
            if (!(varRefType.tag == TypeTags.XML || varRefType.tag == TypeTags.XML_ELEMENT)) {
                if (varRefType.tag == TypeTags.MAP && TypeTags.isXMLTypeTag(((BMapType) varRefType).constraint.tag)) {
                    result = rewriteExpr(rewriteLaxMapAccess(fieldAccessExpr));
                    return;
                }
                
                
                fieldAccessExpr.expr = addConversionExprIfRequired(fieldAccessExpr.expr, symTable.jsonType);
                targetVarRef = new BLangJSONAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit);
            } else {
                targetVarRef = rewriteXMLAttributeOrElemNameAccess(fieldAccessExpr);
            }
        } else if (varRefTypeTag == TypeTags.MAP) {
            
            targetVarRef = new BLangMapAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit);
        } else if (TypeTags.isXMLTypeTag(varRefTypeTag)) {
            targetVarRef = new BLangXMLAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit,
                    fieldAccessExpr.fieldKind);
        }

        targetVarRef.lhsVar = fieldAccessExpr.lhsVar;
        targetVarRef.type = fieldAccessExpr.type;
        targetVarRef.optionalFieldAccess = fieldAccessExpr.optionalFieldAccess;
        result = targetVarRef;
    }

    private BLangStatementExpression rewriteLaxMapAccess(BLangFieldBasedAccess fieldAccessExpr) {
        BLangStatementExpression statementExpression = new BLangStatementExpression();
        BLangBlockStmt block = new BLangBlockStmt();
        statementExpression.stmt = block;
        BUnionType fieldAccessType = BUnionType.create(null, fieldAccessExpr.type, symTable.errorType);
        DiagnosticPos pos = fieldAccessExpr.pos;
        BLangSimpleVariableDef result = createVarDef("$mapAccessResult$", fieldAccessType, null, pos);
        block.addStatement(result);
        BLangSimpleVarRef resultRef = ASTBuilderUtil.createVariableRef(pos, result.var.symbol);
        resultRef.type = fieldAccessType;
        statementExpression.type = fieldAccessType;


        
        
        BLangLiteral mapIndex = ASTBuilderUtil.createLiteral(
                        fieldAccessExpr.field.pos, symTable.stringType, fieldAccessExpr.field.value);
        BLangMapAccessExpr mapAccessExpr = new BLangMapAccessExpr(pos, fieldAccessExpr.expr, mapIndex);
        BUnionType xmlOrNil = BUnionType.create(null, fieldAccessExpr.type, symTable.nilType);
        mapAccessExpr.type = xmlOrNil;
        BLangSimpleVariableDef mapResult = createVarDef("$mapAccess", xmlOrNil, mapAccessExpr, pos);
        BLangSimpleVarRef mapResultRef = ASTBuilderUtil.createVariableRef(pos, mapResult.var.symbol);
        block.addStatement(mapResult);

        BLangIf ifStmt = ASTBuilderUtil.createIfStmt(pos, block);

        BLangIsLikeExpr isLikeNilExpr = createIsLikeExpression(pos, mapResultRef, symTable.nilType);

        ifStmt.expr = isLikeNilExpr;
        BLangBlockStmt resultNilBody = new BLangBlockStmt();
        ifStmt.body = resultNilBody;
        BLangBlockStmt resultHasValueBody = new BLangBlockStmt();
        ifStmt.elseStmt = resultHasValueBody;



        BLangInvocation errorInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue("error");
        errorInvocation.name = name;
        errorInvocation.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        errorInvocation.symbol = symTable.errorConstructor;
        errorInvocation.type = symTable.errorType;
        ArrayList<BLangExpression> errorCtorArgs = new ArrayList<>();
        errorInvocation.requiredArgs = errorCtorArgs;
        errorCtorArgs.add(createStringLiteral(pos, "{" + BLangConstants.MAP_LANG_LIB + "}InvalidKey"));
        BLangNamedArgsExpression message = new BLangNamedArgsExpression();
        message.name = ASTBuilderUtil.createIdentifier(pos, "key");
        message.expr = createStringLiteral(pos, fieldAccessExpr.field.value);
        errorCtorArgs.add(message);

        BLangSimpleVariableDef errorDef =
                createVarDef("_$_invalid_key_error", symTable.errorType, errorInvocation, pos);
        resultNilBody.addStatement(errorDef);

        BLangSimpleVarRef errorRef = ASTBuilderUtil.createVariableRef(pos, errorDef.var.symbol);

        BLangAssignment errorVarAssignment = ASTBuilderUtil.createAssignmentStmt(pos, resultNilBody);
        errorVarAssignment.varRef = resultRef;
        errorVarAssignment.expr = errorRef;

        BLangAssignment mapResultAssignment = ASTBuilderUtil.createAssignmentStmt(
                pos, resultHasValueBody);
        mapResultAssignment.varRef = resultRef;
        mapResultAssignment.expr = mapResultRef;

        statementExpression.expr = resultRef;
        return statementExpression;
    }

    private BLangAccessExpression rewriteXMLAttributeOrElemNameAccess(BLangFieldBasedAccess fieldAccessExpr) {
        ArrayList<BLangExpression> args = new ArrayList<>();

        String fieldName = fieldAccessExpr.field.value;
        if (fieldAccessExpr.fieldKind == FieldKind.WITH_NS) {
            BLangFieldBasedAccess.BLangNSPrefixedFieldBasedAccess nsPrefixAccess =
                    (BLangFieldBasedAccess.BLangNSPrefixedFieldBasedAccess) fieldAccessExpr;
            fieldName = createExpandedQName(nsPrefixAccess.nsSymbol.namespaceURI, fieldName);
        }

        
        if (fieldName.equals("_")) {
            return createLanglibXMLInvocation(fieldAccessExpr.pos, XML_INTERNAL_GET_ELEMENT_NAME_NIL_LIFTING,
                    fieldAccessExpr.expr, new ArrayList<>(), new ArrayList<>());
        }

        BLangLiteral attributeNameLiteral = createStringLiteral(fieldAccessExpr.field.pos, fieldName);
        args.add(attributeNameLiteral);
        args.add(isOptionalAccessToLiteral(fieldAccessExpr));

        return createLanglibXMLInvocation(fieldAccessExpr.pos, XML_INTERNAL_GET_ATTRIBUTE, fieldAccessExpr.expr, args,
                new ArrayList<>());
    }

    private BLangExpression isOptionalAccessToLiteral(BLangFieldBasedAccess fieldAccessExpr) {
        return rewrite(
                createLiteral(fieldAccessExpr.pos, symTable.booleanType, fieldAccessExpr.isOptionalFieldAccess()), env);
    }

    private String createExpandedQName(String nsURI, String localName) {
        return "{" + nsURI + "}" + localName;
    }

    @Override
    public void visit(BLangIndexBasedAccess indexAccessExpr) {
        if (safeNavigate(indexAccessExpr)) {
            result = rewriteExpr(rewriteSafeNavigationExpr(indexAccessExpr));
            return;
        }

        BLangVariableReference targetVarRef = indexAccessExpr;
        indexAccessExpr.indexExpr = rewriteExpr(indexAccessExpr.indexExpr);

        
        
        BType varRefType = indexAccessExpr.expr.type;
        indexAccessExpr.expr = rewriteExpr(indexAccessExpr.expr);
        if (!types.isSameType(indexAccessExpr.expr.type, varRefType)) {
            indexAccessExpr.expr = addConversionExprIfRequired(indexAccessExpr.expr, varRefType);
        }

        if (varRefType.tag == TypeTags.MAP) {
            targetVarRef = new BLangMapAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr, indexAccessExpr.indexExpr);
        } else if (types.isSubTypeOfMapping(types.getSafeType(varRefType, true, false))) {
            targetVarRef = new BLangStructFieldAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                    indexAccessExpr.indexExpr, (BVarSymbol) indexAccessExpr.symbol, false);
        } else if (types.isSubTypeOfList(varRefType)) {
            targetVarRef = new BLangArrayAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                    indexAccessExpr.indexExpr);
        } else if (types.isAssignable(varRefType, symTable.stringType)) {
            indexAccessExpr.expr = addConversionExprIfRequired(indexAccessExpr.expr, symTable.stringType);
            targetVarRef = new BLangStringAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                                                     indexAccessExpr.indexExpr);
        } else if (TypeTags.isXMLTypeTag(varRefType.tag)) {
            targetVarRef = new BLangXMLAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                    indexAccessExpr.indexExpr);
        }

        targetVarRef.lhsVar = indexAccessExpr.lhsVar;
        targetVarRef.type = indexAccessExpr.type;
        result = targetVarRef;
    }

    @Override
    public void visit(BLangInvocation iExpr) {
        BLangInvocation genIExpr = iExpr;

        if (iExpr.symbol != null && iExpr.symbol.kind == SymbolKind.ERROR_CONSTRUCTOR) {
            result = rewriteErrorConstructor(iExpr);
        }

        
        reorderArguments(iExpr);

        iExpr.requiredArgs = rewriteExprs(iExpr.requiredArgs);
        fixNonRestArgTypeCastInTypeParamInvocation(iExpr);

        iExpr.restArgs = rewriteExprs(iExpr.restArgs);

        annotationDesugar.defineStatementAnnotations(iExpr.annAttachments, iExpr.pos, iExpr.symbol.pkgID,
                                                     iExpr.symbol.owner, env);

        if (iExpr.functionPointerInvocation) {
            visitFunctionPointerInvocation(iExpr);
            return;
        }
        iExpr.expr = rewriteExpr(iExpr.expr);
        result = genIExpr;


        if (iExpr.expr == null) {
            fixTypeCastInTypeParamInvocation(iExpr, genIExpr);
            if (iExpr.exprSymbol == null) {
                return;
            }
            iExpr.expr = ASTBuilderUtil.createVariableRef(iExpr.pos, iExpr.exprSymbol);
            iExpr.expr = rewriteExpr(iExpr.expr);
        }
        switch (iExpr.expr.type.tag) {
            case TypeTags.OBJECT:
            case TypeTags.RECORD:
                if (!iExpr.langLibInvocation) {
                    List<BLangExpression> argExprs = new ArrayList<>(iExpr.requiredArgs);
                    argExprs.add(0, iExpr.expr);
                    BLangAttachedFunctionInvocation attachedFunctionInvocation =
                            new BLangAttachedFunctionInvocation(iExpr.pos, argExprs, iExpr.restArgs, iExpr.symbol,
                                                                iExpr.type, iExpr.expr, iExpr.async);
                    attachedFunctionInvocation.actionInvocation = iExpr.actionInvocation;
                    attachedFunctionInvocation.name = iExpr.name;
                    attachedFunctionInvocation.annAttachments = iExpr.annAttachments;
                    result = genIExpr = attachedFunctionInvocation;
                }
                break;
        }

        fixTypeCastInTypeParamInvocation(iExpr, genIExpr);
    }

    private void fixNonRestArgTypeCastInTypeParamInvocation(BLangInvocation iExpr) {
        if (!iExpr.langLibInvocation) {
            return;
        }

        List<BLangExpression> requiredArgs = iExpr.requiredArgs;

        List<BVarSymbol> params = ((BInvokableSymbol) iExpr.symbol).params;

        
        for (int i = 1; i < requiredArgs.size(); i++) {
            requiredArgs.set(i, addConversionExprIfRequired(requiredArgs.get(i), params.get(i).type));
        }
    }

    private void fixTypeCastInTypeParamInvocation(BLangInvocation iExpr, BLangInvocation genIExpr) {

        if (iExpr.langLibInvocation || TypeParamAnalyzer.containsTypeParam(((BInvokableSymbol) iExpr.symbol).retType)) {
            BType originalInvType = genIExpr.type;
            genIExpr.type = ((BInvokableSymbol) genIExpr.symbol).retType;
            BLangExpression expr = addConversionExprIfRequired(genIExpr, originalInvType);

            
            if (expr.getKind() == NodeKind.TYPE_CONVERSION_EXPR) {
                this.result = expr;
                return;
            }

            BLangTypeConversionExpr conversionExpr = (BLangTypeConversionExpr) TreeBuilder.createTypeConversionNode();
            conversionExpr.expr = genIExpr;
            conversionExpr.targetType = originalInvType;
            conversionExpr.type = originalInvType;
            conversionExpr.pos = genIExpr.pos;

            this.result = conversionExpr;
        }
    }

    private BLangInvocation rewriteErrorConstructor(BLangInvocation iExpr) {
        BLangExpression reasonExpr = iExpr.requiredArgs.get(0);
        if (reasonExpr.impConversionExpr != null &&
                reasonExpr.impConversionExpr.targetType.tag != TypeTags.STRING) {
            
            
            reasonExpr.impConversionExpr = null;
        }
        reasonExpr = addConversionExprIfRequired(reasonExpr, symTable.stringType);
        reasonExpr = rewriteExpr(reasonExpr);
        iExpr.requiredArgs.remove(0);
        iExpr.requiredArgs.add(reasonExpr);

        BLangExpression errorDetail;
        BLangRecordLiteral recordLiteral = ASTBuilderUtil.createEmptyRecordLiteral(iExpr.pos,
                ((BErrorType) iExpr.symbol.type).detailType);
        List<BLangExpression> namedArgs = iExpr.requiredArgs.stream()
                .filter(a -> a.getKind() == NodeKind.NAMED_ARGS_EXPR)
                .collect(Collectors.toList());
        if (namedArgs.isEmpty()) {
            errorDetail = visitCloneReadonly(rewriteExpr(recordLiteral), recordLiteral.type);
        } else {
            for (BLangExpression arg : namedArgs) {
                BLangNamedArgsExpression namedArg = (BLangNamedArgsExpression) arg;
                BLangRecordLiteral.BLangRecordKeyValueField member = new BLangRecordLiteral.BLangRecordKeyValueField();
                member.key = new BLangRecordLiteral.BLangRecordKey(ASTBuilderUtil.createLiteral(namedArg.name.pos,
                        symTable.stringType, namedArg.name.value));

                if (recordLiteral.type.tag == TypeTags.RECORD) {
                    member.valueExpr = addConversionExprIfRequired(namedArg.expr, symTable.anyType);
                } else {
                    member.valueExpr = addConversionExprIfRequired(namedArg.expr, namedArg.expr.type);
                }
                recordLiteral.fields.add(member);
                iExpr.requiredArgs.remove(arg);
            }
            errorDetail = visitCloneReadonly(rewriteExpr(recordLiteral), ((BErrorType) iExpr.symbol.type).detailType);
        }
        iExpr.requiredArgs.add(errorDetail);
        return iExpr;
    }

    public void visit(BLangTypeInit typeInitExpr) {
        if (typeInitExpr.type.tag == TypeTags.STREAM) {
            result = rewriteExpr(desugarStreamTypeInit(typeInitExpr));
        } else {
            result = rewrite(desugarObjectTypeInit(typeInitExpr), env);
        }
    }

    private BLangStatementExpression desugarObjectTypeInit(BLangTypeInit typeInitExpr) {
        typeInitExpr.desugared = true;
        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(typeInitExpr.pos);

        
        BType objType = getObjectType(typeInitExpr.type);
        BLangSimpleVariableDef objVarDef = createVarDef("$obj$", objType, typeInitExpr, typeInitExpr.pos);
        BLangSimpleVarRef objVarRef = ASTBuilderUtil.createVariableRef(typeInitExpr.pos, objVarDef.var.symbol);
        blockStmt.addStatement(objVarDef);
        typeInitExpr.initInvocation.exprSymbol = objVarDef.var.symbol;
        typeInitExpr.initInvocation.symbol = ((BObjectTypeSymbol) objType.tsymbol).generatedInitializerFunc.symbol;

        
        if (typeInitExpr.initInvocation.type.tag == TypeTags.NIL) {
            BLangExpressionStmt initInvExpr = ASTBuilderUtil.createExpressionStmt(typeInitExpr.pos, blockStmt);
            initInvExpr.expr = typeInitExpr.initInvocation;
            typeInitExpr.initInvocation.name.value = Names.GENERATED_INIT_SUFFIX.value;
            BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, objVarRef);
            stmtExpr.type = objVarRef.symbol.type;
            return stmtExpr;
        }

        
        BLangSimpleVariableDef initInvRetValVarDef = createVarDef("$temp$", typeInitExpr.initInvocation.type,
                                                                  typeInitExpr.initInvocation, typeInitExpr.pos);
        blockStmt.addStatement(initInvRetValVarDef);

        
        BLangSimpleVariableDef resultVarDef = createVarDef("$result$", typeInitExpr.type, null, typeInitExpr.pos);
        blockStmt.addStatement(resultVarDef);

        
        
        
        
        

        
        BLangSimpleVarRef initRetValVarRefInCondition =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, initInvRetValVarDef.var.symbol);
        BLangBlockStmt thenStmt = ASTBuilderUtil.createBlockStmt(typeInitExpr.pos);
        BLangTypeTestExpr isErrorTest =
                ASTBuilderUtil.createTypeTestExpr(typeInitExpr.pos, initRetValVarRefInCondition, getErrorTypeNode());
        isErrorTest.type = symTable.booleanType;

        
        BLangSimpleVarRef thenInitRetValVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, initInvRetValVarDef.var.symbol);
        BLangSimpleVarRef thenResultVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, resultVarDef.var.symbol);
        BLangAssignment errAssignment =
                ASTBuilderUtil.createAssignmentStmt(typeInitExpr.pos, thenResultVarRef, thenInitRetValVarRef);
        thenStmt.addStatement(errAssignment);

        
        BLangSimpleVarRef elseResultVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, resultVarDef.var.symbol);
        BLangAssignment objAssignment =
                ASTBuilderUtil.createAssignmentStmt(typeInitExpr.pos, elseResultVarRef, objVarRef);
        BLangBlockStmt elseStmt = ASTBuilderUtil.createBlockStmt(typeInitExpr.pos);
        elseStmt.addStatement(objAssignment);

        BLangIf ifelse = ASTBuilderUtil.createIfElseStmt(typeInitExpr.pos, isErrorTest, thenStmt, elseStmt);
        blockStmt.addStatement(ifelse);

        BLangSimpleVarRef resultVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, resultVarDef.var.symbol);
        BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, resultVarRef);
        stmtExpr.type = resultVarRef.symbol.type;
        return stmtExpr;
    }

    private BLangInvocation desugarStreamTypeInit(BLangTypeInit typeInitExpr) {
        BInvokableSymbol symbol = (BInvokableSymbol) symTable.langInternalModuleSymbol.scope
                .lookup(Names.CONSTRUCT_STREAM).symbol;
        BType targetType = ((BStreamType) typeInitExpr.type).constraint;
        BType errorType = ((BStreamType) typeInitExpr.type).error;
        BType typedescType = new BTypedescType(targetType, symTable.typeDesc.tsymbol);
        BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
        typedescExpr.resolvedType = targetType;
        typedescExpr.type = typedescType;
        BLangExpression iteratorObj = typeInitExpr.argsExpr.get(0);

        BLangInvocation streamConstructInvocation = ASTBuilderUtil.createInvocationExprForMethod(
                typeInitExpr.pos, symbol, new ArrayList<>(Lists.of(typedescExpr, iteratorObj)),
                symResolver);
        streamConstructInvocation.type = new BStreamType(TypeTags.STREAM, targetType, errorType, null);
        return streamConstructInvocation;
    }

    private BLangSimpleVariableDef createVarDef(String name, BType type, BLangExpression expr, DiagnosticPos pos) {
        BSymbol objSym = symResolver.lookupSymbolInMainSpace(env, names.fromString(name));
        if (objSym == null || objSym == symTable.notFoundSymbol) {
            objSym = new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, type, this.env.scope.owner);
        }
        BLangSimpleVariable objVar = ASTBuilderUtil.createVariable(pos, "$" + name + "$", type, expr,
                (BVarSymbol) objSym);
        BLangSimpleVariableDef objVarDef = ASTBuilderUtil.createVariableDef(pos);
        objVarDef.var = objVar;
        objVarDef.type = objVar.type;
        return objVarDef;
    }

    private BType getObjectType(BType type) {
        if (type.tag == TypeTags.OBJECT) {
            return type;
        } else if (type.tag == TypeTags.UNION) {
            return ((BUnionType) type).getMemberTypes().stream()
                    .filter(t -> t.tag == TypeTags.OBJECT)
                    .findFirst()
                    .orElse(symTable.noType);
        }

        throw new IllegalStateException("None object type '" + type.toString() + "' found in object init context");
    }

    BLangErrorType getErrorTypeNode() {
        BLangErrorType errorTypeNode = (BLangErrorType) TreeBuilder.createErrorTypeNode();
        errorTypeNode.type = symTable.errorType;
        return errorTypeNode;
    }

    @Override
    public void visit(BLangTernaryExpr ternaryExpr) {
        /*
         * First desugar to if-else:
         * 
         * T $result$;
         * if () {
         *    $result$ = thenExpr;
         * } else {
         *    $result$ = elseExpr;
         * }
         * 
         */
        BLangSimpleVariableDef resultVarDef = createVarDef("$ternary_result$", ternaryExpr.type, null, ternaryExpr.pos);
        BLangBlockStmt thenBody = ASTBuilderUtil.createBlockStmt(ternaryExpr.pos);
        BLangBlockStmt elseBody = ASTBuilderUtil.createBlockStmt(ternaryExpr.pos);

        
        BLangSimpleVarRef thenResultVarRef = ASTBuilderUtil.createVariableRef(ternaryExpr.pos, resultVarDef.var.symbol);
        BLangAssignment thenAssignment =
                ASTBuilderUtil.createAssignmentStmt(ternaryExpr.pos, thenResultVarRef, ternaryExpr.thenExpr);
        thenBody.addStatement(thenAssignment);

        
        BLangSimpleVarRef elseResultVarRef = ASTBuilderUtil.createVariableRef(ternaryExpr.pos, resultVarDef.var.symbol);
        BLangAssignment elseAssignment =
                ASTBuilderUtil.createAssignmentStmt(ternaryExpr.pos, elseResultVarRef, ternaryExpr.elseExpr);
        elseBody.addStatement(elseAssignment);

        
        BLangSimpleVarRef resultVarRef = ASTBuilderUtil.createVariableRef(ternaryExpr.pos, resultVarDef.var.symbol);
        BLangIf ifElse = ASTBuilderUtil.createIfElseStmt(ternaryExpr.pos, ternaryExpr.expr, thenBody, elseBody);

        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(ternaryExpr.pos, Lists.of(resultVarDef, ifElse));
        BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, resultVarRef);
        stmtExpr.type = ternaryExpr.type;

        result = rewriteExpr(stmtExpr);
    }

    @Override
    public void visit(BLangWaitExpr waitExpr) {
        
        if (waitExpr.getExpression().getKind() == NodeKind.BINARY_EXPR) {
            waitExpr.exprList = collectAllBinaryExprs((BLangBinaryExpr) waitExpr.getExpression(), new ArrayList<>());
        } else { 
            waitExpr.exprList = Collections.singletonList(rewriteExpr(waitExpr.getExpression()));
        }
        result = waitExpr;
    }

    private List<BLangExpression> collectAllBinaryExprs(BLangBinaryExpr binaryExpr, List<BLangExpression> exprs) {
        visitBinaryExprOfWait(binaryExpr.lhsExpr, exprs);
        visitBinaryExprOfWait(binaryExpr.rhsExpr, exprs);
        return exprs;
    }

    private void visitBinaryExprOfWait(BLangExpression expr, List<BLangExpression> exprs) {
        if (expr.getKind() == NodeKind.BINARY_EXPR) {
            collectAllBinaryExprs((BLangBinaryExpr) expr, exprs);
        } else {
            expr = rewriteExpr(expr);
            exprs.add(expr);
        }
    }

    @Override
    public void visit(BLangWaitForAllExpr waitExpr) {
        waitExpr.keyValuePairs.forEach(keyValue -> {
            if (keyValue.valueExpr != null) {
                keyValue.valueExpr = rewriteExpr(keyValue.valueExpr);
            } else {
                keyValue.keyExpr = rewriteExpr(keyValue.keyExpr);
            }
        });
        BLangExpression expr = new BLangWaitForAllExpr.BLangWaitLiteral(waitExpr.keyValuePairs, waitExpr.type);
        result = rewriteExpr(expr);
    }

    @Override
    public void visit(BLangTrapExpr trapExpr) {
        trapExpr.expr = rewriteExpr(trapExpr.expr);
        if (trapExpr.expr.type.tag != TypeTags.NIL) {
            trapExpr.expr = addConversionExprIfRequired(trapExpr.expr, trapExpr.type);
        }
        result = trapExpr;
    }

    @Override
    public void visit(BLangBinaryExpr binaryExpr) {
        if (binaryExpr.opKind == OperatorKind.HALF_OPEN_RANGE || binaryExpr.opKind == OperatorKind.CLOSED_RANGE) {
            if (binaryExpr.opKind == OperatorKind.HALF_OPEN_RANGE) {
                binaryExpr.rhsExpr = getModifiedIntRangeEndExpr(binaryExpr.rhsExpr);
            }
            result = rewriteExpr(replaceWithIntRange(binaryExpr.pos, binaryExpr.lhsExpr, binaryExpr.rhsExpr));
            return;
        }

        if (binaryExpr.opKind == OperatorKind.AND || binaryExpr.opKind == OperatorKind.OR) {
            visitBinaryLogicalExpr(binaryExpr);
            return;
        }

        OperatorKind binaryOpKind = binaryExpr.opKind;

        if (binaryOpKind == OperatorKind.ADD || binaryOpKind == OperatorKind.SUB ||
                binaryOpKind == OperatorKind.MUL || binaryOpKind == OperatorKind.DIV ||
                binaryOpKind == OperatorKind.MOD || binaryOpKind == OperatorKind.BITWISE_AND ||
                binaryOpKind == OperatorKind.BITWISE_OR || binaryOpKind == OperatorKind.BITWISE_XOR) {
            checkByteTypeIncompatibleOperations(binaryExpr);
        }

        binaryExpr.lhsExpr = rewriteExpr(binaryExpr.lhsExpr);
        binaryExpr.rhsExpr = rewriteExpr(binaryExpr.rhsExpr);
        result = binaryExpr;

        int rhsExprTypeTag = binaryExpr.rhsExpr.type.tag;
        int lhsExprTypeTag = binaryExpr.lhsExpr.type.tag;

        
        if (rhsExprTypeTag != lhsExprTypeTag && (binaryExpr.opKind == OperatorKind.EQUAL ||
                                                         binaryExpr.opKind == OperatorKind.NOT_EQUAL ||
                                                         binaryExpr.opKind == OperatorKind.REF_EQUAL ||
                                                         binaryExpr.opKind == OperatorKind.REF_NOT_EQUAL)) {
            if (lhsExprTypeTag == TypeTags.INT && rhsExprTypeTag == TypeTags.BYTE) {
                binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, symTable.intType);
                return;
            }

            if (lhsExprTypeTag == TypeTags.BYTE && rhsExprTypeTag == TypeTags.INT) {
                binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, symTable.intType);
                return;
            }
        }

        
        if (lhsExprTypeTag == rhsExprTypeTag) {
            return;
        }

        if (TypeTags.isStringTypeTag(lhsExprTypeTag) && binaryExpr.opKind == OperatorKind.ADD) {
            
            if (TypeTags.isXMLTypeTag(rhsExprTypeTag)) {
                binaryExpr.lhsExpr = ASTBuilderUtil.createXMLTextLiteralNode(binaryExpr, binaryExpr.lhsExpr,
                        binaryExpr.lhsExpr.pos, symTable.xmlType);
                return;
            }
            binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, binaryExpr.lhsExpr.type);
            return;
        }

        if (TypeTags.isStringTypeTag(rhsExprTypeTag) && binaryExpr.opKind == OperatorKind.ADD) {
            
            if (TypeTags.isXMLTypeTag(lhsExprTypeTag)) {
                binaryExpr.rhsExpr = ASTBuilderUtil.createXMLTextLiteralNode(binaryExpr, binaryExpr.rhsExpr,
                        binaryExpr.rhsExpr.pos, symTable.xmlType);
                return;
            }
            binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, binaryExpr.rhsExpr.type);
            return;
        }

        if (lhsExprTypeTag == TypeTags.DECIMAL) {
            binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, binaryExpr.lhsExpr.type);
            return;
        }

        if (rhsExprTypeTag == TypeTags.DECIMAL) {
            binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, binaryExpr.rhsExpr.type);
            return;
        }

        if (lhsExprTypeTag == TypeTags.FLOAT) {
            binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, binaryExpr.lhsExpr.type);
            return;
        }

        if (rhsExprTypeTag == TypeTags.FLOAT) {
            binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, binaryExpr.rhsExpr.type);
        }
    }

    private BLangInvocation replaceWithIntRange(DiagnosticPos pos, BLangExpression lhsExpr, BLangExpression rhsExpr) {
        BInvokableSymbol symbol = (BInvokableSymbol) symTable.langInternalModuleSymbol.scope
                .lookup(Names.CREATE_INT_RANGE).symbol;
        BLangInvocation createIntRangeInvocation = ASTBuilderUtil.createInvocationExprForMethod(pos, symbol,
                new ArrayList<>(Lists.of(lhsExpr, rhsExpr)), symResolver);
        createIntRangeInvocation.type = symTable.intRangeType;
        return createIntRangeInvocation;
    }

    private void checkByteTypeIncompatibleOperations(BLangBinaryExpr binaryExpr) {
        if (binaryExpr.parent == null || binaryExpr.parent.type == null) {
            return;
        }

        int rhsExprTypeTag = binaryExpr.rhsExpr.type.tag;
        int lhsExprTypeTag = binaryExpr.lhsExpr.type.tag;
        if (rhsExprTypeTag != TypeTags.BYTE && lhsExprTypeTag != TypeTags.BYTE) {
            return;
        }

        int resultTypeTag = binaryExpr.type.tag;
        if (resultTypeTag == TypeTags.INT) {
            if (rhsExprTypeTag == TypeTags.BYTE) {
                binaryExpr.rhsExpr = addConversionExprIfRequired(binaryExpr.rhsExpr, symTable.intType);
            }

            if (lhsExprTypeTag == TypeTags.BYTE) {
                binaryExpr.lhsExpr = addConversionExprIfRequired(binaryExpr.lhsExpr, symTable.intType);
            }
        }
    }

    /**
     * This method checks whether given binary expression is related to shift operation.
     * If its true, then both lhs and rhs of the binary expression will be converted to 'int' type.
     * <p>
     * byte a = 12;
     * byte b = 34;
     * int i = 234;
     * int j = -4;
     * <p>
     * true: where binary expression's expected type is 'int'
     * int i1 = a >> b;
     * int i2 = a << b;
     * int i3 = a >> i;
     * int i4 = a << i;
     * int i5 = i >> j;
     * int i6 = i << j;
     */
    private boolean isBitwiseShiftOperation(BLangBinaryExpr binaryExpr) {
        return binaryExpr.opKind == OperatorKind.BITWISE_LEFT_SHIFT ||
                binaryExpr.opKind == OperatorKind.BITWISE_RIGHT_SHIFT ||
                binaryExpr.opKind == OperatorKind.BITWISE_UNSIGNED_RIGHT_SHIFT;
    }

    public void visit(BLangElvisExpr elvisExpr) {
        BLangMatchExpression matchExpr = ASTBuilderUtil.createMatchExpression(elvisExpr.lhsExpr);
        matchExpr.patternClauses.add(getMatchNullPatternGivenExpression(elvisExpr.pos,
                rewriteExpr(elvisExpr.rhsExpr)));
        matchExpr.type = elvisExpr.type;
        matchExpr.pos = elvisExpr.pos;
        result = rewriteExpr(matchExpr);
    }

    @Override
    public void visit(BLangUnaryExpr unaryExpr) {
        if (OperatorKind.BITWISE_COMPLEMENT == unaryExpr.operator) {
            
            
            rewriteBitwiseComplementOperator(unaryExpr);
            return;
        }
        unaryExpr.expr = rewriteExpr(unaryExpr.expr);
        result = unaryExpr;
    }

    /**
     * This method desugar a bitwise complement (~) unary expressions into a bitwise xor binary expression as below.
     * Example : ~a  -> a ^ -1;
     * ~ 11110011 -> 00001100
     * 11110011 ^ 11111111 -> 00001100
     *
     * @param unaryExpr the bitwise complement expression
     */
    private void rewriteBitwiseComplementOperator(BLangUnaryExpr unaryExpr) {
        final DiagnosticPos pos = unaryExpr.pos;
        final BLangBinaryExpr binaryExpr = (BLangBinaryExpr) TreeBuilder.createBinaryExpressionNode();
        binaryExpr.pos = pos;
        binaryExpr.opKind = OperatorKind.BITWISE_XOR;
        binaryExpr.lhsExpr = unaryExpr.expr;
        if (TypeTags.BYTE == unaryExpr.type.tag) {
            binaryExpr.type = symTable.byteType;
            binaryExpr.rhsExpr = ASTBuilderUtil.createLiteral(pos, symTable.byteType, 0xffL);
            binaryExpr.opSymbol = (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.BITWISE_XOR,
                    symTable.byteType, symTable.byteType);
        } else {
            binaryExpr.type = symTable.intType;
            binaryExpr.rhsExpr = ASTBuilderUtil.createLiteral(pos, symTable.intType, -1L);
            binaryExpr.opSymbol = (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.BITWISE_XOR,
                    symTable.intType, symTable.intType);
        }
        result = rewriteExpr(binaryExpr);
    }

    @Override
    public void visit(BLangTypeConversionExpr conversionExpr) {
        
        
        
        

        
        if (conversionExpr.typeNode == null && !conversionExpr.annAttachments.isEmpty()) {
            result = rewriteExpr(conversionExpr.expr);
            return;
        }
        conversionExpr.typeNode = rewrite(conversionExpr.typeNode, env);
        conversionExpr.expr = rewriteExpr(conversionExpr.expr);
        result = conversionExpr;
    }

    @Override
    public void visit(BLangLambdaFunction bLangLambdaFunction) {
        
        env.enclPkg.lambdaFunctions.add(bLangLambdaFunction);
        result = bLangLambdaFunction;
    }

    @Override
    public void visit(BLangArrowFunction bLangArrowFunction) {
        BLangFunction bLangFunction = (BLangFunction) TreeBuilder.createFunctionNode();
        bLangFunction.setName(bLangArrowFunction.functionName);

        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        lambdaFunction.pos = bLangArrowFunction.pos;
        bLangFunction.addFlag(Flag.LAMBDA);
        lambdaFunction.function = bLangFunction;

        
        BLangValueType returnType = (BLangValueType) TreeBuilder.createValueTypeNode();
        returnType.type = bLangArrowFunction.body.expr.type;
        bLangFunction.setReturnTypeNode(returnType);
        bLangFunction.setBody(populateArrowExprBodyBlock(bLangArrowFunction));

        bLangArrowFunction.params.forEach(bLangFunction::addParameter);
        lambdaFunction.parent = bLangArrowFunction.parent;
        lambdaFunction.type = bLangArrowFunction.funcType;

        
        BLangFunction funcNode = lambdaFunction.function;
        BInvokableSymbol funcSymbol = Symbols.createFunctionSymbol(Flags.asMask(funcNode.flagSet),
                new Name(funcNode.name.value), env.enclPkg.symbol.pkgID, bLangArrowFunction.funcType,
                env.enclEnv.enclVarSym, true);
        SymbolEnv invokableEnv = SymbolEnv.createFunctionEnv(funcNode, funcSymbol.scope, env);
        defineInvokableSymbol(funcNode, funcSymbol, invokableEnv);

        List<BVarSymbol> paramSymbols = funcNode.requiredParams.stream().peek(varNode -> {
            Scope enclScope = invokableEnv.scope;
            varNode.symbol.kind = SymbolKind.FUNCTION;
            varNode.symbol.owner = invokableEnv.scope.owner;
            enclScope.define(varNode.symbol.name, varNode.symbol);
        }).map(varNode -> varNode.symbol).collect(Collectors.toList());

        funcSymbol.params = paramSymbols;
        funcSymbol.restParam = getRestSymbol(funcNode);
        funcSymbol.retType = funcNode.returnTypeNode.type;

        
        List<BType> paramTypes = paramSymbols.stream().map(paramSym -> paramSym.type).collect(Collectors.toList());
        funcNode.type = new BInvokableType(paramTypes, getRestType(funcSymbol), funcNode.returnTypeNode.type, null);

        lambdaFunction.function.pos = bLangArrowFunction.pos;
        lambdaFunction.function.body.pos = bLangArrowFunction.pos;
        
        lambdaFunction.capturedClosureEnv = env;
        rewrite(lambdaFunction.function, env);
        env.enclPkg.addFunction(lambdaFunction.function);
        bLangArrowFunction.function = lambdaFunction.function;
        result = rewriteExpr(lambdaFunction);
    }

    private void defineInvokableSymbol(BLangInvokableNode invokableNode, BInvokableSymbol funcSymbol,
                                       SymbolEnv invokableEnv) {
        invokableNode.symbol = funcSymbol;
        funcSymbol.scope = new Scope(funcSymbol);
        invokableEnv.scope = funcSymbol.scope;
    }

    @Override
    public void visit(BLangXMLQName xmlQName) {
        result = xmlQName;
    }

    @Override
    public void visit(BLangXMLAttribute xmlAttribute) {
        xmlAttribute.name = rewriteExpr(xmlAttribute.name);
        xmlAttribute.value = rewriteExpr(xmlAttribute.value);
        result = xmlAttribute;
    }

    @Override
    public void visit(BLangXMLElementLiteral xmlElementLiteral) {
        xmlElementLiteral.startTagName = rewriteExpr(xmlElementLiteral.startTagName);
        xmlElementLiteral.endTagName = rewriteExpr(xmlElementLiteral.endTagName);
        xmlElementLiteral.modifiedChildren = rewriteExprs(xmlElementLiteral.modifiedChildren);
        xmlElementLiteral.attributes = rewriteExprs(xmlElementLiteral.attributes);

        
        Iterator<BLangXMLAttribute> attributesItr = xmlElementLiteral.attributes.iterator();
        while (attributesItr.hasNext()) {
            BLangXMLAttribute attribute = attributesItr.next();
            if (!attribute.isNamespaceDeclr) {
                continue;
            }

            
            BLangXMLNS xmlns;
            if ((xmlElementLiteral.scope.owner.tag & SymTag.PACKAGE) == SymTag.PACKAGE) {
                xmlns = new BLangPackageXMLNS();
            } else {
                xmlns = new BLangLocalXMLNS();
            }
            xmlns.namespaceURI = attribute.value.concatExpr;
            xmlns.prefix = ((BLangXMLQName) attribute.name).localname;
            xmlns.symbol = attribute.symbol;

            xmlElementLiteral.inlineNamespaces.add(xmlns);
        }

        result = xmlElementLiteral;
    }

    @Override
    public void visit(BLangXMLTextLiteral xmlTextLiteral) {
        xmlTextLiteral.concatExpr = rewriteExpr(constructStringTemplateConcatExpression(xmlTextLiteral.textFragments));
        result = xmlTextLiteral;
    }

    @Override
    public void visit(BLangXMLCommentLiteral xmlCommentLiteral) {
        xmlCommentLiteral.concatExpr = rewriteExpr(
                constructStringTemplateConcatExpression(xmlCommentLiteral.textFragments));
        result = xmlCommentLiteral;
    }

    @Override
    public void visit(BLangXMLProcInsLiteral xmlProcInsLiteral) {
        xmlProcInsLiteral.target = rewriteExpr(xmlProcInsLiteral.target);
        xmlProcInsLiteral.dataConcatExpr =
                rewriteExpr(constructStringTemplateConcatExpression(xmlProcInsLiteral.dataFragments));
        result = xmlProcInsLiteral;
    }

    @Override
    public void visit(BLangXMLQuotedString xmlQuotedString) {
        xmlQuotedString.concatExpr = rewriteExpr(
                constructStringTemplateConcatExpression(xmlQuotedString.textFragments));
        result = xmlQuotedString;
    }

    @Override
    public void visit(BLangStringTemplateLiteral stringTemplateLiteral) {
        result = rewriteExpr(constructStringTemplateConcatExpression(stringTemplateLiteral.exprs));
    }

    @Override
    public void visit(BLangWorkerSend workerSendNode) {
        workerSendNode.expr = visitCloneInvocation(rewriteExpr(workerSendNode.expr), workerSendNode.expr.type);
        if (workerSendNode.keyExpr != null) {
            workerSendNode.keyExpr = rewriteExpr(workerSendNode.keyExpr);
        }
        result = workerSendNode;
    }

    @Override
    public void visit(BLangWorkerSyncSendExpr syncSendExpr) {
        syncSendExpr.expr = visitCloneInvocation(rewriteExpr(syncSendExpr.expr), syncSendExpr.expr.type);
        result = syncSendExpr;
    }

    @Override
    public void visit(BLangWorkerReceive workerReceiveNode) {
        if (workerReceiveNode.keyExpr != null) {
            workerReceiveNode.keyExpr = rewriteExpr(workerReceiveNode.keyExpr);
        }
        result = workerReceiveNode;
    }

    @Override
    public void visit(BLangWorkerFlushExpr workerFlushExpr) {
        workerFlushExpr.workerIdentifierList = workerFlushExpr.cachedWorkerSendStmts
                .stream().map(send -> send.workerIdentifier).distinct().collect(Collectors.toList());
        result = workerFlushExpr;
    }

    @Override
    public void visit(BLangXMLAttributeAccess xmlAttributeAccessExpr) {
        xmlAttributeAccessExpr.indexExpr = rewriteExpr(xmlAttributeAccessExpr.indexExpr);
        xmlAttributeAccessExpr.expr = rewriteExpr(xmlAttributeAccessExpr.expr);

        if (xmlAttributeAccessExpr.indexExpr != null
                && xmlAttributeAccessExpr.indexExpr.getKind() == NodeKind.XML_QNAME) {
            ((BLangXMLQName) xmlAttributeAccessExpr.indexExpr).isUsedInXML = true;
        }

        xmlAttributeAccessExpr.desugared = true;

        
        
        if (xmlAttributeAccessExpr.lhsVar || xmlAttributeAccessExpr.indexExpr != null) {
            result = xmlAttributeAccessExpr;
        } else {
            result = rewriteExpr(xmlAttributeAccessExpr);
        }
    }

    
    

    @Override
    public void visit(BLangLocalVarRef localVarRef) {
        result = localVarRef;
    }

    @Override
    public void visit(BLangFieldVarRef fieldVarRef) {
        result = fieldVarRef;
    }

    @Override
    public void visit(BLangPackageVarRef packageVarRef) {
        result = packageVarRef;
    }

    @Override
    public void visit(BLangFunctionVarRef functionVarRef) {
        result = functionVarRef;
    }

    @Override
    public void visit(BLangStructFieldAccessExpr fieldAccessExpr) {
        result = fieldAccessExpr;
    }

    @Override
    public void visit(BLangStructFunctionVarRef functionVarRef) {
        result = functionVarRef;
    }

    @Override
    public void visit(BLangMapAccessExpr mapKeyAccessExpr) {
        result = mapKeyAccessExpr;
    }

    @Override
    public void visit(BLangArrayAccessExpr arrayIndexAccessExpr) {
        result = arrayIndexAccessExpr;
    }

    @Override
    public void visit(BLangTupleAccessExpr arrayIndexAccessExpr) {
        result = arrayIndexAccessExpr;
    }

    @Override
    public void visit(BLangMapLiteral mapLiteral) {
        result = mapLiteral;
    }

    @Override
    public void visit(BLangStructLiteral structLiteral) {
        result = structLiteral;
    }

    @Override
    public void visit(BLangWaitForAllExpr.BLangWaitLiteral waitLiteral) {
        result = waitLiteral;
    }

    @Override
    public void visit(BLangXMLElementAccess xmlElementAccess) {
        
        
        xmlElementAccess.expr = rewriteExpr(xmlElementAccess.expr);

        ArrayList<BLangExpression> filters = expandFilters(xmlElementAccess.filters);

        BLangInvocation invocationNode = createLanglibXMLInvocation(xmlElementAccess.pos, XML_INTERNAL_GET_ELEMENTS,
                xmlElementAccess.expr, new ArrayList<>(), filters);
        result = rewriteExpr(invocationNode);
    }

    private ArrayList<BLangExpression> expandFilters(List<BLangXMLElementFilter> filters) {
        Map<Name, BXMLNSSymbol> nameBXMLNSSymbolMap = symResolver.resolveAllNamespaces(env);
        BXMLNSSymbol defaultNSSymbol = nameBXMLNSSymbolMap.get(names.fromString(XMLConstants.DEFAULT_NS_PREFIX));
        String defaultNS = defaultNSSymbol != null ? defaultNSSymbol.namespaceURI : null;

        ArrayList<BLangExpression> args = new ArrayList<>();
        for (BLangXMLElementFilter filter : filters) {
            BSymbol nsSymbol = symResolver.lookupSymbolInPrefixSpace(env, names.fromString(filter.namespace));
            if (nsSymbol == symTable.notFoundSymbol) {
                if (defaultNS != null && !filter.name.equals("*")) {
                    String expandedName = createExpandedQName(defaultNS, filter.name);
                    args.add(createStringLiteral(filter.elemNamePos, expandedName));
                } else {
                    args.add(createStringLiteral(filter.elemNamePos, filter.name));
                }
            } else {
                BXMLNSSymbol bxmlnsSymbol = (BXMLNSSymbol) nsSymbol;
                String expandedName = createExpandedQName(bxmlnsSymbol.namespaceURI, filter.name);
                BLangLiteral stringLiteral = createStringLiteral(filter.elemNamePos, expandedName);
                args.add(stringLiteral);
            }
        }
        return args;
    }

    private BLangInvocation createLanglibXMLInvocation(DiagnosticPos pos, String functionName,
                                                       BLangExpression invokeOnExpr,
                                                       ArrayList<BLangExpression> args,
                                                       ArrayList<BLangExpression> restArgs) {
        invokeOnExpr = rewriteExpr(invokeOnExpr);

        BLangInvocation invocationNode = (BLangInvocation) TreeBuilder.createInvocationNode();
        invocationNode.pos = pos;
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue(functionName);
        name.pos = pos;
        invocationNode.name = name;
        invocationNode.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        invocationNode.expr = invokeOnExpr;

        invocationNode.symbol = symResolver.lookupLangLibMethod(symTable.xmlType, names.fromString(functionName));

        ArrayList<BLangExpression> requiredArgs = new ArrayList<>();
        requiredArgs.add(invokeOnExpr);
        requiredArgs.addAll(args);
        invocationNode.requiredArgs = requiredArgs;
        invocationNode.restArgs = rewriteExprs(restArgs);

        invocationNode.type = ((BInvokableType) invocationNode.symbol.type).getReturnType();
        invocationNode.langLibInvocation = true;
        return invocationNode;
    }

    @Override
    public void visit(BLangXMLNavigationAccess xmlNavigation) {
        xmlNavigation.expr = rewriteExpr(xmlNavigation.expr);
        xmlNavigation.childIndex = rewriteExpr(xmlNavigation.childIndex);

        ArrayList<BLangExpression> filters = expandFilters(xmlNavigation.filters);

        
        if (xmlNavigation.navAccessType == XMLNavigationAccess.NavAccessType.DESCENDANTS) {
            BLangInvocation invocationNode = createLanglibXMLInvocation(xmlNavigation.pos,
                    XML_INTERNAL_SELECT_DESCENDANTS, xmlNavigation.expr, new ArrayList<>(), filters);
            result = rewriteExpr(invocationNode);
        } else if (xmlNavigation.navAccessType == XMLNavigationAccess.NavAccessType.CHILDREN) {
            
            BLangInvocation invocationNode = createLanglibXMLInvocation(xmlNavigation.pos, XML_INTERNAL_CHILDREN,
                    xmlNavigation.expr, new ArrayList<>(), new ArrayList<>());
            result = rewriteExpr(invocationNode);
        } else {
            BLangExpression childIndexExpr;
            
            if (xmlNavigation.childIndex == null) {
                childIndexExpr = new BLangLiteral(Long.valueOf(-1), symTable.intType);
            } else {
                
                childIndexExpr = xmlNavigation.childIndex;
            }
            ArrayList<BLangExpression> args = new ArrayList<>();
            args.add(rewriteExpr(childIndexExpr));

            BLangInvocation invocationNode = createLanglibXMLInvocation(xmlNavigation.pos,
                    XML_INTERNAL_GET_FILTERED_CHILDREN_FLAT, xmlNavigation.expr, args, filters);
            result = rewriteExpr(invocationNode);
        }
    }

    @Override
    public void visit(BLangIsAssignableExpr assignableExpr) {
        assignableExpr.lhsExpr = rewriteExpr(assignableExpr.lhsExpr);
        result = assignableExpr;
    }

    @Override
    public void visit(BFunctionPointerInvocation fpInvocation) {
        result = fpInvocation;
    }

    @Override
    public void visit(BLangTypedescExpr typedescExpr) {
        typedescExpr.typeNode = rewrite(typedescExpr.typeNode, env);
        result = typedescExpr;
    }

    @Override
    public void visit(BLangIntRangeExpression intRangeExpression) {
        if (!intRangeExpression.includeStart) {
            intRangeExpression.startExpr = getModifiedIntRangeStartExpr(intRangeExpression.startExpr);
        }
        if (!intRangeExpression.includeEnd) {
            intRangeExpression.endExpr = getModifiedIntRangeEndExpr(intRangeExpression.endExpr);
        }

        intRangeExpression.startExpr = rewriteExpr(intRangeExpression.startExpr);
        intRangeExpression.endExpr = rewriteExpr(intRangeExpression.endExpr);
        result = intRangeExpression;
    }

    @Override
    public void visit(BLangRestArgsExpression bLangVarArgsExpression) {
        result = rewriteExpr(bLangVarArgsExpression.expr);
    }

    @Override
    public void visit(BLangNamedArgsExpression bLangNamedArgsExpression) {
        bLangNamedArgsExpression.expr = rewriteExpr(bLangNamedArgsExpression.expr);
        result = bLangNamedArgsExpression.expr;
    }

    @Override
    public void visit(BLangMatchExpression bLangMatchExpression) {
        
        addMatchExprDefaultCase(bLangMatchExpression);

        
        
        String matchTempResultVarName = GEN_VAR_PREFIX.value + "temp_result";
        BLangSimpleVariable tempResultVar = ASTBuilderUtil.createVariable(bLangMatchExpression.pos,
                matchTempResultVarName, bLangMatchExpression.type, null,
                new BVarSymbol(0, names.fromString(matchTempResultVarName), this.env.scope.owner.pkgID,
                        bLangMatchExpression.type, this.env.scope.owner));

        BLangSimpleVariableDef tempResultVarDef =
                ASTBuilderUtil.createVariableDef(bLangMatchExpression.pos, tempResultVar);
        tempResultVarDef.desugared = true;

        BLangBlockStmt stmts = ASTBuilderUtil.createBlockStmt(bLangMatchExpression.pos, Lists.of(tempResultVarDef));
        List<BLangMatchTypedBindingPatternClause> patternClauses = new ArrayList<>();

        for (int i = 0; i < bLangMatchExpression.patternClauses.size(); i++) {
            BLangMatchExprPatternClause pattern = bLangMatchExpression.patternClauses.get(i);
            pattern.expr = rewriteExpr(pattern.expr);

            
            
            BLangVariableReference tempResultVarRef =
                    ASTBuilderUtil.createVariableRef(bLangMatchExpression.pos, tempResultVar.symbol);

            
            pattern.expr = addConversionExprIfRequired(pattern.expr, tempResultVarRef.type);
            BLangAssignment assignmentStmt =
                    ASTBuilderUtil.createAssignmentStmt(pattern.pos, tempResultVarRef, pattern.expr);
            BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(pattern.pos, Lists.of(assignmentStmt));

            
            
            patternClauses.add(ASTBuilderUtil.createMatchStatementPattern(pattern.pos, pattern.variable, patternBody));
        }

        stmts.addStatement(ASTBuilderUtil.createMatchStatement(bLangMatchExpression.pos, bLangMatchExpression.expr,
                patternClauses));
        BLangVariableReference tempResultVarRef =
                ASTBuilderUtil.createVariableRef(bLangMatchExpression.pos, tempResultVar.symbol);
        BLangStatementExpression statementExpr = createStatementExpression(stmts, tempResultVarRef);
        statementExpr.type = bLangMatchExpression.type;
        result = rewriteExpr(statementExpr);
    }

    @Override
    public void visit(BLangCheckedExpr checkedExpr) {
        visitCheckAndCheckPanicExpr(checkedExpr, false);
    }

    @Override
    public void visit(BLangCheckPanickedExpr checkedExpr) {
        visitCheckAndCheckPanicExpr(checkedExpr, true);
    }

    private void visitCheckAndCheckPanicExpr(BLangCheckedExpr checkedExpr, boolean isCheckPanic) {
        
        
        
        
        
        
        
        
        
        
        

        
        String checkedExprVarName = GEN_VAR_PREFIX.value;
        BLangSimpleVariable checkedExprVar = ASTBuilderUtil.createVariable(checkedExpr.pos,
                checkedExprVarName, checkedExpr.type, null, new BVarSymbol(0,
                        names.fromString(checkedExprVarName),
                        this.env.scope.owner.pkgID, checkedExpr.type, this.env.scope.owner));
        BLangSimpleVariableDef checkedExprVarDef = ASTBuilderUtil.createVariableDef(checkedExpr.pos, checkedExprVar);
        checkedExprVarDef.desugared = true;

        
        BLangMatchTypedBindingPatternClause patternSuccessCase =
                getSafeAssignSuccessPattern(checkedExprVar.pos, checkedExprVar.symbol.type, true,
                        checkedExprVar.symbol, null);
        BLangMatchTypedBindingPatternClause patternErrorCase = getSafeAssignErrorPattern(checkedExpr.pos,
                this.env.scope.owner, checkedExpr.equivalentErrorTypeList, isCheckPanic);

        
        BLangMatch matchStmt = ASTBuilderUtil.createMatchStatement(checkedExpr.pos, checkedExpr.expr,
                new ArrayList<BLangMatchTypedBindingPatternClause>() {{
                    add(patternSuccessCase);
                    add(patternErrorCase);
                }});

        
        BLangBlockStmt generatedStmtBlock = ASTBuilderUtil.createBlockStmt(checkedExpr.pos,
                new ArrayList<BLangStatement>() {{
                    add(checkedExprVarDef);
                    add(matchStmt);
                }});

        
        BLangSimpleVarRef tempCheckedExprVarRef = ASTBuilderUtil.createVariableRef(
                checkedExpr.pos, checkedExprVar.symbol);

        BLangStatementExpression statementExpr = createStatementExpression(
                generatedStmtBlock, tempCheckedExprVarRef);
        statementExpr.type = checkedExpr.type;
        result = rewriteExpr(statementExpr);
    }

    @Override
    public void visit(BLangServiceConstructorExpr serviceConstructorExpr) {
        final BLangTypeInit typeInit = ASTBuilderUtil.createEmptyTypeInit(serviceConstructorExpr.pos,
                serviceConstructorExpr.serviceNode.serviceTypeDefinition.symbol.type);
        serviceConstructorExpr.serviceNode.annAttachments.forEach(attachment ->  rewrite(attachment, env));
        result = rewriteExpr(typeInit);
    }

    @Override
    public void visit(BLangTypeTestExpr typeTestExpr) {
        BLangExpression expr = typeTestExpr.expr;
        if (types.isValueType(expr.type)) {
            addConversionExprIfRequired(expr, symTable.anyType);
        }
        typeTestExpr.expr = rewriteExpr(expr);
        typeTestExpr.typeNode = rewrite(typeTestExpr.typeNode, env);
        result = typeTestExpr;
    }

    @Override
    public void visit(BLangAnnotAccessExpr annotAccessExpr) {
        BLangBinaryExpr binaryExpr = (BLangBinaryExpr) TreeBuilder.createBinaryExpressionNode();
        binaryExpr.pos = annotAccessExpr.pos;
        binaryExpr.opKind = OperatorKind.ANNOT_ACCESS;
        binaryExpr.lhsExpr = annotAccessExpr.expr;
        binaryExpr.rhsExpr = ASTBuilderUtil.createLiteral(annotAccessExpr.pkgAlias.pos, symTable.stringType,
                                                          annotAccessExpr.annotationSymbol.bvmAlias());
        binaryExpr.type = annotAccessExpr.type;
        binaryExpr.opSymbol = new BOperatorSymbol(names.fromString(OperatorKind.ANNOT_ACCESS.value()), null,
                                                  new BInvokableType(Lists.of(binaryExpr.lhsExpr.type,
                                                                              binaryExpr.rhsExpr.type),
                                                          annotAccessExpr.type, null), null);
        result = rewriteExpr(binaryExpr);
    }

    @Override
    public void visit(BLangIsLikeExpr isLikeExpr) {
        isLikeExpr.expr = rewriteExpr(isLikeExpr.expr);
        result = isLikeExpr;
    }

    @Override
    public void visit(BLangStatementExpression bLangStatementExpression) {
        bLangStatementExpression.expr = rewriteExpr(bLangStatementExpression.expr);
        bLangStatementExpression.stmt = rewrite(bLangStatementExpression.stmt, env);
        result = bLangStatementExpression;
    }

    @Override
    public void visit(BLangQueryExpr queryExpr) {
        BLangStatementExpression stmtExpr = queryDesugar.desugarQueryExpr(queryExpr, env);
        result = rewrite(stmtExpr, env);
    }

    @Override
    public void visit(BLangQueryAction queryAction) {
        BLangStatementExpression stmtExpr = queryDesugar.desugarQueryAction(queryAction, env);
        result = rewrite(stmtExpr, env);
    }

    @Override
    public void visit(BLangJSONArrayLiteral jsonArrayLiteral) {
        jsonArrayLiteral.exprs = rewriteExprs(jsonArrayLiteral.exprs);
        result = jsonArrayLiteral;
    }

    @Override
    public void visit(BLangConstant constant) {

        BConstantSymbol constSymbol = constant.symbol;
        if (constSymbol.literalType.tag <= TypeTags.BOOLEAN || constSymbol.literalType.tag == TypeTags.NIL) {
            if (constSymbol.literalType.tag != TypeTags.NIL && constSymbol.value.value == null) {
                throw new IllegalStateException();
            }
            BLangLiteral literal = ASTBuilderUtil.createLiteral(constant.expr.pos, constSymbol.literalType,
                    constSymbol.value.value);
            constant.expr = rewriteExpr(literal);
        } else {
            constant.expr = rewriteExpr(constant.expr);
        }
        constant.annAttachments.forEach(attachment ->  rewrite(attachment, env));
        result = constant;
    }

    @Override
    public void visit(BLangIgnoreExpr ignoreExpr) {
        result = ignoreExpr;
    }

    @Override
    public void visit(BLangConstRef constantRef) {
        result = ASTBuilderUtil.createLiteral(constantRef.pos, constantRef.type, constantRef.value);
    }

    

    
    BLangSimpleVariableDef getIteratorVariableDefinition(DiagnosticPos pos, BVarSymbol collectionSymbol,
                                                                 BInvokableSymbol iteratorInvokableSymbol,
                                                                 boolean isIteratorFuncFromLangLib) {


        BLangSimpleVarRef dataReference = ASTBuilderUtil.createVariableRef(pos, collectionSymbol);
        BLangInvocation iteratorInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
        iteratorInvocation.pos = pos;
        iteratorInvocation.expr = dataReference;
        iteratorInvocation.symbol = iteratorInvokableSymbol;
        iteratorInvocation.type = iteratorInvokableSymbol.retType;
        iteratorInvocation.argExprs = Lists.of(dataReference);
        iteratorInvocation.requiredArgs = iteratorInvocation.argExprs;
        iteratorInvocation.langLibInvocation = isIteratorFuncFromLangLib;
        BVarSymbol iteratorSymbol = new BVarSymbol(0, names.fromString("$iterator$"), this.env.scope.owner.pkgID,
                iteratorInvokableSymbol.retType, this.env.scope.owner);

        
        BLangSimpleVariable iteratorVariable = ASTBuilderUtil.createVariable(pos, "$iterator$",
                iteratorInvokableSymbol.retType, iteratorInvocation, iteratorSymbol);
        return ASTBuilderUtil.createVariableDef(pos, iteratorVariable);
    }

    
    BLangSimpleVariableDef getIteratorNextVariableDefinition(DiagnosticPos pos, BType nillableResultType,
                                                                     BVarSymbol iteratorSymbol,
                                                                     BVarSymbol resultSymbol) {
        BLangInvocation nextInvocation = createIteratorNextInvocation(pos, iteratorSymbol);
        BLangSimpleVariable resultVariable = ASTBuilderUtil.createVariable(pos, "$result$",
                nillableResultType, nextInvocation, resultSymbol);
        return ASTBuilderUtil.createVariableDef(pos, resultVariable);
    }

    
    BLangAssignment getIteratorNextAssignment(DiagnosticPos pos,
                                                      BVarSymbol iteratorSymbol, BVarSymbol resultSymbol) {
        BLangSimpleVarRef resultReferenceInAssignment = ASTBuilderUtil.createVariableRef(pos, resultSymbol);

        
        BLangInvocation nextInvocation = createIteratorNextInvocation(pos, iteratorSymbol);

        
        nextInvocation.expr.type = types.getSafeType(nextInvocation.expr.type, true, false);

        return ASTBuilderUtil.createAssignmentStmt(pos, resultReferenceInAssignment, nextInvocation, false);
    }

    BLangInvocation createIteratorNextInvocation(DiagnosticPos pos, BVarSymbol iteratorSymbol) {
        BLangIdentifier nextIdentifier = ASTBuilderUtil.createIdentifier(pos, "next");
        BLangSimpleVarRef iteratorReferenceInNext = ASTBuilderUtil.createVariableRef(pos, iteratorSymbol);
        BInvokableSymbol nextFuncSymbol = getNextFunc((BObjectType) iteratorSymbol.type).symbol;
        BLangInvocation nextInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
        nextInvocation.pos = pos;
        nextInvocation.name = nextIdentifier;
        nextInvocation.expr = iteratorReferenceInNext;
        nextInvocation.requiredArgs = Lists.of(ASTBuilderUtil.createVariableRef(pos, iteratorSymbol));
        nextInvocation.argExprs = nextInvocation.requiredArgs;
        nextInvocation.symbol = nextFuncSymbol;
        nextInvocation.type = nextFuncSymbol.retType;
        return nextInvocation;
    }

    private BAttachedFunction getNextFunc(BObjectType iteratorType) {
        BObjectTypeSymbol iteratorSymbol = (BObjectTypeSymbol) iteratorType.tsymbol;
        for (BAttachedFunction bAttachedFunction : iteratorSymbol.attachedFuncs) {
            if (bAttachedFunction.funcName.value.equals("next")) {
                return bAttachedFunction;
            }
        }
        return null;
    }

    
    BLangFieldBasedAccess getValueAccessExpression(DiagnosticPos pos, BType varType, BVarSymbol resultSymbol) {
        BLangSimpleVarRef resultReferenceInVariableDef = ASTBuilderUtil.createVariableRef(pos, resultSymbol);
        BLangIdentifier valueIdentifier = ASTBuilderUtil.createIdentifier(pos, "value");

        BLangFieldBasedAccess fieldBasedAccessExpression =
                ASTBuilderUtil.createFieldAccessExpr(resultReferenceInVariableDef, valueIdentifier);
        fieldBasedAccessExpression.pos = pos;
        fieldBasedAccessExpression.type = varType;
        fieldBasedAccessExpression.originalType = fieldBasedAccessExpression.type;
        return fieldBasedAccessExpression;
    }

    private BlockFunctionBodyNode populateArrowExprBodyBlock(BLangArrowFunction bLangArrowFunction) {
        BlockFunctionBodyNode blockNode = TreeBuilder.createBlockFunctionBodyNode();
        BLangReturn returnNode = (BLangReturn) TreeBuilder.createReturnNode();
        returnNode.pos = bLangArrowFunction.body.expr.pos;
        returnNode.setExpression(bLangArrowFunction.body.expr);
        blockNode.addStatement(returnNode);
        return blockNode;
    }

    private BLangInvocation createInvocationNode(String functionName, List<BLangExpression> args, BType retType) {
        BLangInvocation invocationNode = (BLangInvocation) TreeBuilder.createInvocationNode();
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue(functionName);
        invocationNode.name = name;
        invocationNode.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        
        invocationNode.symbol = symTable.rootScope.lookup(new Name(functionName)).symbol;
        invocationNode.type = retType;
        invocationNode.requiredArgs = args;
        return invocationNode;
    }

    private BLangInvocation createLangLibInvocationNode(String functionName,
                                                        BLangExpression onExpr,
                                                        List<BLangExpression> args,
                                                        BType retType,
                                                        DiagnosticPos pos) {
        BLangInvocation invocationNode = (BLangInvocation) TreeBuilder.createInvocationNode();
        invocationNode.pos = pos;
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue(functionName);
        name.pos = pos;
        invocationNode.name = name;
        invocationNode.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        invocationNode.expr = onExpr;



        invocationNode.symbol = symResolver.lookupLangLibMethod(onExpr.type, names.fromString(functionName));

        ArrayList<BLangExpression> requiredArgs = new ArrayList<>();
        requiredArgs.add(onExpr);
        requiredArgs.addAll(args);
        invocationNode.requiredArgs = requiredArgs;

        invocationNode.type = retType != null ? retType : ((BInvokableSymbol) invocationNode.symbol).retType;
        invocationNode.langLibInvocation = true;
        return invocationNode;
    }

    private BLangArrayLiteral createArrayLiteralExprNode() {
        BLangArrayLiteral expr = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
        expr.exprs = new ArrayList<>();
        expr.type = new BArrayType(symTable.anyType);
        return expr;
    }

    private void visitFunctionPointerInvocation(BLangInvocation iExpr) {
        BLangVariableReference expr;
        if (iExpr.expr == null) {
            expr = new BLangSimpleVarRef();
        } else {
            BLangFieldBasedAccess fieldBasedAccess = new BLangFieldBasedAccess();
            fieldBasedAccess.expr = iExpr.expr;
            fieldBasedAccess.field = iExpr.name;
            expr = fieldBasedAccess;
        }
        expr.symbol = iExpr.symbol;
        expr.type = iExpr.symbol.type;

        BLangExpression rewritten = rewriteExpr(expr);
        result = new BFunctionPointerInvocation(iExpr, rewritten);
    }

    private BLangExpression visitCloneInvocation(BLangExpression expr, BType lhsType) {
        if (types.isValueType(expr.type)) {
            return expr;
        }
        if (expr.type.tag == TypeTags.ERROR) {
            return expr;
        }
        BLangInvocation cloneInvok = createLangLibInvocationNode("clone", expr, new ArrayList<>(), expr.type, expr.pos);
        return addConversionExprIfRequired(cloneInvok, lhsType);
    }

    private BLangExpression visitCloneReadonly(BLangExpression expr, BType lhsType) {
        if (types.isValueType(expr.type)) {
            return expr;
        }
        if (expr.type.tag == TypeTags.ERROR) {
            return expr;
        }
        BLangInvocation cloneInvok = createLangLibInvocationNode("cloneReadOnly", expr, new ArrayList<>(), expr.type,
                expr.pos);
        return addConversionExprIfRequired(cloneInvok, lhsType);
    }

    @SuppressWarnings("unchecked")
    <E extends BLangNode> E rewrite(E node, SymbolEnv env) {
        if (node == null) {
            return null;
        }

        if (node.desugared) {
            return node;
        }

        SymbolEnv previousEnv = this.env;
        this.env = env;

        node.accept(this);
        BLangNode resultNode = this.result;
        this.result = null;
        resultNode.desugared = true;

        this.env = previousEnv;
        return (E) resultNode;
    }

    @SuppressWarnings("unchecked")
    <E extends BLangExpression> E rewriteExpr(E node) {
        if (node == null) {
            return null;
        }

        if (node.desugared) {
            return node;
        }

        BLangExpression expr = node;
        if (node.impConversionExpr != null) {
            expr = node.impConversionExpr;
            node.impConversionExpr = null;
        }

        expr.accept(this);
        BLangNode resultNode = this.result;
        this.result = null;
        resultNode.desugared = true;

        return (E) resultNode;
    }

    @SuppressWarnings("unchecked")
    <E extends BLangStatement> E rewrite(E statement, SymbolEnv env) {
        if (statement == null) {
            return null;
        }
        BLangStatementLink link = new BLangStatementLink();
        link.parent = currentLink;
        currentLink = link;
        BLangStatement stmt = (BLangStatement) rewrite((BLangNode) statement, env);
        
        link.statement = stmt;
        stmt.statementLink = link;
        currentLink = link.parent;
        return (E) stmt;
    }

    private <E extends BLangStatement> List<E> rewriteStmt(List<E> nodeList, SymbolEnv env) {
        for (int i = 0; i < nodeList.size(); i++) {
            nodeList.set(i, rewrite(nodeList.get(i), env));
        }
        return nodeList;
    }

    private <E extends BLangNode> List<E> rewrite(List<E> nodeList, SymbolEnv env) {
        for (int i = 0; i < nodeList.size(); i++) {
            nodeList.set(i, rewrite(nodeList.get(i), env));
        }
        return nodeList;
    }

    private <E extends BLangExpression> List<E> rewriteExprs(List<E> nodeList) {
        for (int i = 0; i < nodeList.size(); i++) {
            nodeList.set(i, rewriteExpr(nodeList.get(i)));
        }
        return nodeList;
    }

    private BLangLiteral createStringLiteral(DiagnosticPos pos, String value) {
        BLangLiteral stringLit = new BLangLiteral(value, symTable.stringType);
        stringLit.pos = pos;
        return stringLit;
    }

    private BLangLiteral createIntLiteral(long value) {
        BLangLiteral literal = (BLangLiteral) TreeBuilder.createLiteralExpression();
        literal.value = value;
        literal.type = symTable.intType;
        return literal;
    }

    private BLangLiteral createByteLiteral(DiagnosticPos pos, Byte value) {
        BLangLiteral byteLiteral = new BLangLiteral(Byte.toUnsignedInt(value), symTable.byteType);
        byteLiteral.pos = pos;
        return byteLiteral;
    }

    private BLangExpression createTypeCastExpr(BLangExpression expr, BType targetType) {
        BLangTypeConversionExpr conversionExpr = (BLangTypeConversionExpr) TreeBuilder.createTypeConversionNode();
        conversionExpr.pos = expr.pos;
        conversionExpr.expr = expr;
        conversionExpr.type = targetType;
        conversionExpr.targetType = targetType;
        return conversionExpr;
    }

    private BType getElementType(BType type) {
        if (type.tag != TypeTags.ARRAY) {
            return type;
        }

        return getElementType(((BArrayType) type).getElementType());
    }

    
    private void addReturnIfNotPresent(BLangInvokableNode invokableNode) {
        if (Symbols.isNative(invokableNode.symbol) ||
                (invokableNode.hasBody() && invokableNode.body.getKind() != NodeKind.BLOCK_FUNCTION_BODY)) {
            return;
        }
        
        
        BLangBlockFunctionBody funcBody = (BLangBlockFunctionBody) invokableNode.body;
        if (invokableNode.workers.size() == 0 && invokableNode.symbol.type.getReturnType().isNullable()
                && (funcBody.stmts.size() < 1
                || funcBody.stmts.get(funcBody.stmts.size() - 1).getKind() != NodeKind.RETURN)) {
            DiagnosticPos invPos = invokableNode.pos;
            DiagnosticPos returnStmtPos = new DiagnosticPos(invPos.src, invPos.eLine, invPos.eLine, invPos.sCol,
                                                            invPos.sCol);
            BLangReturn returnStmt = ASTBuilderUtil.createNilReturnStmt(returnStmtPos, symTable.nilType);
            funcBody.addStatement(returnStmt);
        }
    }

    /**
     * Reorder the invocation arguments to match the original function signature.
     *
     * @param iExpr Function invocation expressions to reorder the arguments
     */
    private void reorderArguments(BLangInvocation iExpr) {
        BSymbol symbol = iExpr.symbol;

        if (symbol == null || symbol.type.tag != TypeTags.INVOKABLE) {
            return;
        }

        BInvokableSymbol invokableSymbol = (BInvokableSymbol) symbol;

        List<BLangExpression> restArgs = iExpr.restArgs;
        int originalRequiredArgCount = iExpr.requiredArgs.size();

        
        BLangExpression varargRef = null;
        BLangBlockStmt blockStmt = null;

        if (!iExpr.restArgs.isEmpty() &&
                restArgs.get(restArgs.size() - 1).getKind() == NodeKind.REST_ARGS_EXPR &&
                iExpr.requiredArgs.size() < invokableSymbol.params.size()) {
            
            
            
            BLangExpression expr = ((BLangRestArgsExpression) restArgs.get(restArgs.size() - 1)).expr;
            DiagnosticPos varargExpPos = expr.pos;
            BType varargVarType = expr.type;
            String varargVarName = DESUGARED_VARARG_KEY + this.varargCount++;

            BVarSymbol varargVarSymbol = new BVarSymbol(0, names.fromString(varargVarName), this.env.scope.owner.pkgID,
                                                        varargVarType, this.env.scope.owner);
            varargRef = ASTBuilderUtil.createVariableRef(varargExpPos, varargVarSymbol);

            BLangSimpleVariable var = createVariable(varargExpPos, varargVarName, varargVarType,
                                                     ((BLangRestArgsExpression) restArgs.get(restArgs.size() - 1)).expr,
                                                     varargVarSymbol);

            BLangSimpleVariableDef varDef = ASTBuilderUtil.createVariableDef(varargExpPos);
            varDef.var = var;
            varDef.type = varargVarType;

            blockStmt = createBlockStmt(varargExpPos);
            blockStmt.stmts.add(varDef);
        }

        if (!invokableSymbol.params.isEmpty()) {
            
            reorderNamedArgs(iExpr, invokableSymbol, varargRef);
        }

        
        if (restArgs.isEmpty() || restArgs.get(restArgs.size() - 1).getKind() != NodeKind.REST_ARGS_EXPR) {
            if (invokableSymbol.restParam == null) {
                return;
            }

            BLangArrayLiteral arrayLiteral = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
            List<BLangExpression> exprs = new ArrayList<>();

            BArrayType arrayType = (BArrayType) invokableSymbol.restParam.type;
            BType elemType = arrayType.eType;

            for (BLangExpression restArg : restArgs) {
                exprs.add(addConversionExprIfRequired(restArg, elemType));
            }

            arrayLiteral.exprs = exprs;
            arrayLiteral.type = arrayType;
            iExpr.restArgs = new ArrayList<>();
            iExpr.restArgs.add(arrayLiteral);
            return;
        }

        
        if (restArgs.size() == 1 && restArgs.get(0).getKind() == NodeKind.REST_ARGS_EXPR) {

            
            
            if (iExpr.requiredArgs.size() == originalRequiredArgCount) {
                return;
            }

            
            
            
            
            BLangExpression firstNonRestArg = iExpr.requiredArgs.remove(0);
            BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, firstNonRestArg);
            stmtExpression.type = firstNonRestArg.type;
            iExpr.requiredArgs.add(0, stmtExpression);

            
            
            if (invokableSymbol.restParam == null) {
                return;
            }

            BLangLiteral startIndex = createIntLiteral(invokableSymbol.params.size() - originalRequiredArgCount);
            BLangInvocation sliceInvocation =
                    createLangLibInvocationNode(SLICE_LANGLIB_METHOD, varargRef,
                                                new ArrayList<BLangExpression>() {{
                                                    add(startIndex);
                                                }},
                                                varargRef.type, varargRef.pos);
            restArgs.remove(0);
            restArgs.add(addConversionExprIfRequired(sliceInvocation, invokableSymbol.restParam.type));
            return;
        }

        
        
        BArrayType type = (BArrayType) invokableSymbol.restParam.type;

        BLangArrayLiteral arrayLiteral = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
        arrayLiteral.type = type;

        BType elemType = type.eType;
        DiagnosticPos pos = restArgs.get(0).pos;

        List<BLangExpression> exprs = new ArrayList<>();

        for (int i = 0; i < restArgs.size() - 1; i++) {
            exprs.add(addConversionExprIfRequired(restArgs.get(i), elemType));
        }
        arrayLiteral.exprs = exprs;

        BLangRestArgsExpression pushRestArgsExpr = (BLangRestArgsExpression) TreeBuilder.createVarArgsNode();
        pushRestArgsExpr.pos = pos;
        pushRestArgsExpr.expr = restArgs.remove(restArgs.size() - 1);

        String name = DESUGARED_VARARG_KEY + this.varargCount++;
        BVarSymbol varSymbol = new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, type,
                                              this.env.scope.owner);
        BLangSimpleVarRef arrayVarRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        BLangSimpleVariable var = createVariable(pos, name, type, arrayLiteral, varSymbol);
        BLangSimpleVariableDef varDef = ASTBuilderUtil.createVariableDef(pos);
        varDef.var = var;
        varDef.type = type;

        BLangBlockStmt pushBlockStmt = createBlockStmt(pos);
        pushBlockStmt.stmts.add(varDef);

        BLangExpressionStmt expressionStmt = createExpressionStmt(pos, pushBlockStmt);
        BLangInvocation pushInvocation = createLangLibInvocationNode(PUSH_LANGLIB_METHOD, arrayVarRef,
                                                                     new ArrayList<BLangExpression>() {{
                                                                         add(pushRestArgsExpr);
                                                                     }}, type, pos);
        pushInvocation.restArgs.add(pushInvocation.requiredArgs.remove(1));
        expressionStmt.expr = pushInvocation;

        BLangStatementExpression stmtExpression = createStatementExpression(pushBlockStmt, arrayVarRef);
        stmtExpression.type = type;

        iExpr.restArgs = new ArrayList<BLangExpression>(1) {{ add(stmtExpression); }};
    }

    private void reorderNamedArgs(BLangInvocation iExpr, BInvokableSymbol invokableSymbol, BLangExpression varargRef) {
        List<BLangExpression> args = new ArrayList<>();
        Map<String, BLangExpression> namedArgs = new HashMap<>();
        iExpr.requiredArgs.stream()
                .filter(expr -> expr.getKind() == NodeKind.NAMED_ARGS_EXPR)
                .forEach(expr -> namedArgs.put(((NamedArgNode) expr).getName().value, expr));

        List<BVarSymbol> params = invokableSymbol.params;

        int varargIndex = 0;

        BType varargType = null;
        boolean tupleTypedVararg = false;

        if (varargRef != null) {
            varargType = varargRef.type;
            tupleTypedVararg = varargType.tag == TypeTags.TUPLE;
        }

        
        for (int i = 0; i < params.size(); i++) {
            BVarSymbol param = params.get(i);
            if (iExpr.requiredArgs.size() > i && iExpr.requiredArgs.get(i).getKind() != NodeKind.NAMED_ARGS_EXPR) {
                
                args.add(iExpr.requiredArgs.get(i));
            } else if (namedArgs.containsKey(param.name.value)) {
                
                args.add(namedArgs.get(param.name.value));
            } else if (varargRef == null) {
                
                BLangExpression expr = new BLangIgnoreExpr();
                expr.type = param.type;
                args.add(expr);
            } else {
                
                
                BLangIndexBasedAccess memberAccessExpr =
                        (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
                memberAccessExpr.pos = varargRef.pos;
                memberAccessExpr.expr = varargRef;
                memberAccessExpr.indexExpr = rewriteExpr(createIntLiteral(varargIndex));
                memberAccessExpr.type = tupleTypedVararg ? ((BTupleType) varargType).tupleTypes.get(varargIndex) :
                        ((BArrayType) varargType).eType;
                varargIndex++;
                args.add(addConversionExprIfRequired(memberAccessExpr, param.type));
            }
        }
        iExpr.requiredArgs = args;
    }

    private BLangMatchTypedBindingPatternClause getSafeAssignErrorPattern(
            DiagnosticPos pos, BSymbol invokableSymbol, List<BType> equivalentErrorTypes, boolean isCheckPanicExpr) {
        
        
        BType enclosingFuncReturnType = ((BInvokableType) invokableSymbol.type).retType;
        Set<BType> returnTypeSet = enclosingFuncReturnType.tag == TypeTags.UNION ?
                ((BUnionType) enclosingFuncReturnType).getMemberTypes() :
                new LinkedHashSet<BType>() {{
                    add(enclosingFuncReturnType);
                }};

        
        boolean returnOnError = equivalentErrorTypes.stream()
                .allMatch(errorType -> returnTypeSet.stream()
                        .anyMatch(retType -> types.isAssignable(errorType, retType)));

        
        
        String patternFailureCaseVarName = GEN_VAR_PREFIX.value + "t_failure";
        BLangSimpleVariable patternFailureCaseVar = ASTBuilderUtil.createVariable(pos,
                patternFailureCaseVarName, symTable.errorType, null, new BVarSymbol(0,
                        names.fromString(patternFailureCaseVarName),
                        this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner));

        
        BLangVariableReference patternFailureCaseVarRef = ASTBuilderUtil.createVariableRef(pos,
                patternFailureCaseVar.symbol);

        BLangBlockStmt patternBlockFailureCase = (BLangBlockStmt) TreeBuilder.createBlockNode();
        patternBlockFailureCase.pos = pos;
        if (!isCheckPanicExpr && returnOnError) {
            
            BLangReturn returnStmt = (BLangReturn) TreeBuilder.createReturnNode();
            returnStmt.pos = pos;
            returnStmt.expr = patternFailureCaseVarRef;
            patternBlockFailureCase.stmts.add(returnStmt);
        } else {
            
            BLangPanic panicNode = (BLangPanic) TreeBuilder.createPanicNode();
            panicNode.pos = pos;
            panicNode.expr = patternFailureCaseVarRef;
            patternBlockFailureCase.stmts.add(panicNode);
        }

        return ASTBuilderUtil.createMatchStatementPattern(pos, patternFailureCaseVar, patternBlockFailureCase);
    }

    private BLangMatchTypedBindingPatternClause getSafeAssignSuccessPattern(DiagnosticPos pos, BType lhsType,
            boolean isVarDef, BVarSymbol varSymbol, BLangExpression lhsExpr) {
        
        
        String patternSuccessCaseVarName = GEN_VAR_PREFIX.value + "t_match";
        BLangSimpleVariable patternSuccessCaseVar = ASTBuilderUtil.createVariable(pos,
                patternSuccessCaseVarName, lhsType, null, new BVarSymbol(0,
                        names.fromString(patternSuccessCaseVarName),
                        this.env.scope.owner.pkgID, lhsType, this.env.scope.owner));

        
        BLangExpression varRefExpr;
        if (isVarDef) {
            varRefExpr = ASTBuilderUtil.createVariableRef(pos, varSymbol);
        } else {
            varRefExpr = lhsExpr;
        }

        BLangVariableReference patternSuccessCaseVarRef = ASTBuilderUtil.createVariableRef(pos,
                patternSuccessCaseVar.symbol);
        BLangAssignment assignmentStmtSuccessCase = ASTBuilderUtil.createAssignmentStmt(pos,
                varRefExpr, patternSuccessCaseVarRef, false);

        BLangBlockStmt patternBlockSuccessCase = ASTBuilderUtil.createBlockStmt(pos,
                new ArrayList<BLangStatement>() {{
                    add(assignmentStmtSuccessCase);
                }});
        return ASTBuilderUtil.createMatchStatementPattern(pos,
                patternSuccessCaseVar, patternBlockSuccessCase);
    }

    private BLangStatement generateIfElseStmt(BLangMatch matchStmt, BLangSimpleVariable matchExprVar) {
        List<BLangMatchBindingPatternClause> patterns = matchStmt.patternClauses;

        BLangIf parentIfNode = generateIfElseStmt(patterns.get(0), matchExprVar);
        BLangIf currentIfNode = parentIfNode;
        for (int i = 1; i < patterns.size(); i++) {
            BLangMatchBindingPatternClause patternClause = patterns.get(i);
            if (i == patterns.size() - 1 && patternClause.isLastPattern) { 
                currentIfNode.elseStmt = getMatchPatternElseBody(patternClause, matchExprVar);
            } else {
                currentIfNode.elseStmt = generateIfElseStmt(patternClause, matchExprVar);
                currentIfNode = (BLangIf) currentIfNode.elseStmt;
            }
        }

        
        
        
        
        
        return parentIfNode;
    }


    /**
     * Generate an if-else statement from the given match statement.
     *
     * @param pattern match pattern statement node
     * @param matchExprVar  variable node of the match expression
     * @return if else statement node
     */
    private BLangIf generateIfElseStmt(BLangMatchBindingPatternClause pattern, BLangSimpleVariable matchExprVar) {
        BLangExpression ifCondition = createPatternIfCondition(pattern, matchExprVar.symbol);
        if (NodeKind.MATCH_TYPED_PATTERN_CLAUSE == pattern.getKind()) {
            BLangBlockStmt patternBody = getMatchPatternBody(pattern, matchExprVar);
            return ASTBuilderUtil.createIfElseStmt(pattern.pos, ifCondition, patternBody, null);
        }

        
        BType expectedType = matchExprVar.type;
        if (pattern.getKind() == NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE) {
            BLangMatchStructuredBindingPatternClause matchPattern = (BLangMatchStructuredBindingPatternClause) pattern;
            expectedType = getStructuredBindingPatternType(matchPattern.bindingPatternVariable);
        }

        if (NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE == pattern.getKind()) { 
            BLangMatchStructuredBindingPatternClause structuredPattern =
                    (BLangMatchStructuredBindingPatternClause) pattern;
            BLangSimpleVariableDef varDef = forceCastIfApplicable(matchExprVar.symbol, pattern.pos, expectedType);

            
            BLangSimpleVarRef matchExprVarRef = ASTBuilderUtil.createVariableRef(pattern.pos, varDef.var.symbol);
            structuredPattern.bindingPatternVariable.expr = matchExprVarRef;

            BLangStatement varDefStmt;
            if (NodeKind.TUPLE_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createTupleVariableDef(pattern.pos,
                        (BLangTupleVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.RECORD_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createRecordVariableDef(pattern.pos,
                        (BLangRecordVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.ERROR_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createErrorVariableDef(pattern.pos,
                        (BLangErrorVariable) structuredPattern.bindingPatternVariable);
            } else {
                varDefStmt = ASTBuilderUtil
                        .createVariableDef(pattern.pos, (BLangSimpleVariable) structuredPattern.bindingPatternVariable);
            }

            if (structuredPattern.typeGuardExpr != null) {
                BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(structuredPattern.pos);
                blockStmt.addStatement(varDef);
                blockStmt.addStatement(varDefStmt);
                BLangStatementExpression stmtExpr = createStatementExpression(blockStmt,
                                                                              structuredPattern.typeGuardExpr);
                stmtExpr.type = symTable.booleanType;

                ifCondition = ASTBuilderUtil
                        .createBinaryExpr(pattern.pos, ifCondition, stmtExpr, symTable.booleanType, OperatorKind.AND,
                                (BOperatorSymbol) symResolver
                                        .resolveBinaryOperator(OperatorKind.AND, symTable.booleanType,
                                                symTable.booleanType));
            } else {
                structuredPattern.body.stmts.add(0, varDef);
                structuredPattern.body.stmts.add(1, varDefStmt);
            }
        }

        return ASTBuilderUtil.createIfElseStmt(pattern.pos, ifCondition, pattern.body, null);
    }

    private BLangBlockStmt getMatchPatternBody(BLangMatchBindingPatternClause pattern,
                                               BLangSimpleVariable matchExprVar) {

        BLangBlockStmt body;

        BLangMatchTypedBindingPatternClause patternClause = (BLangMatchTypedBindingPatternClause) pattern;
        
        if (patternClause.variable.name.value.equals(Names.IGNORE.value)) {
            return patternClause.body;
        }

        
        
        BLangSimpleVarRef matchExprVarRef = ASTBuilderUtil.createVariableRef(patternClause.pos,
                matchExprVar.symbol);
        BLangExpression patternVarExpr = addConversionExprIfRequired(matchExprVarRef, patternClause.variable.type);

        
        BLangSimpleVariable patternVar = ASTBuilderUtil.createVariable(patternClause.pos, "",
                patternClause.variable.type, patternVarExpr, patternClause.variable.symbol);
        BLangSimpleVariableDef patternVarDef = ASTBuilderUtil.createVariableDef(patternVar.pos, patternVar);
        patternClause.body.stmts.add(0, patternVarDef);
        body = patternClause.body;

        return body;
    }

    private BLangBlockStmt getMatchPatternElseBody(BLangMatchBindingPatternClause pattern,
            BLangSimpleVariable matchExprVar) {

        BLangBlockStmt body = pattern.body;

        if (NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE == pattern.getKind()) { 

            
            BLangSimpleVarRef matchExprVarRef = ASTBuilderUtil.createVariableRef(pattern.pos, matchExprVar.symbol);

            BLangMatchStructuredBindingPatternClause structuredPattern =
                    (BLangMatchStructuredBindingPatternClause) pattern;

            structuredPattern.bindingPatternVariable.expr = matchExprVarRef;

            BLangStatement varDefStmt;
            if (NodeKind.TUPLE_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createTupleVariableDef(pattern.pos,
                        (BLangTupleVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.RECORD_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createRecordVariableDef(pattern.pos,
                        (BLangRecordVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.ERROR_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createErrorVariableDef(pattern.pos,
                        (BLangErrorVariable) structuredPattern.bindingPatternVariable);
            } else {
                varDefStmt = ASTBuilderUtil
                        .createVariableDef(pattern.pos, (BLangSimpleVariable) structuredPattern.bindingPatternVariable);
            }
            structuredPattern.body.stmts.add(0, varDefStmt);
            body = structuredPattern.body;
        }

        return body;
    }

    BLangExpression addConversionExprIfRequired(BLangExpression expr, BType lhsType) {
        if (lhsType.tag == TypeTags.NONE) {
            return expr;
        }

        BType rhsType = expr.type;
        if (types.isSameType(rhsType, lhsType)) {
            return expr;
        }

        types.setImplicitCastExpr(expr, rhsType, lhsType);
        if (expr.impConversionExpr != null) {
            return expr;
        }

        if (lhsType.tag == TypeTags.JSON && rhsType.tag == TypeTags.NIL) {
            return expr;
        }

        if (lhsType.tag == TypeTags.NIL && rhsType.isNullable()) {
            return expr;
        }

        if (lhsType.tag == TypeTags.ARRAY && rhsType.tag == TypeTags.TUPLE) {
            return expr;
        }

        
        BLangTypeConversionExpr conversionExpr = (BLangTypeConversionExpr)
                TreeBuilder.createTypeConversionNode();
        conversionExpr.expr = expr;
        conversionExpr.targetType = lhsType;
        conversionExpr.type = lhsType;
        conversionExpr.pos = expr.pos;
        conversionExpr.checkTypes = false;
        return conversionExpr;
    }

    private BLangExpression createPatternIfCondition(BLangMatchBindingPatternClause patternClause,
                                                     BVarSymbol varSymbol) {
        BType patternType;

        switch (patternClause.getKind()) {
            case MATCH_STATIC_PATTERN_CLAUSE:
                BLangMatchStaticBindingPatternClause staticPattern =
                        (BLangMatchStaticBindingPatternClause) patternClause;
                patternType = staticPattern.literal.type;
                break;
            case MATCH_STRUCTURED_PATTERN_CLAUSE:
                BLangMatchStructuredBindingPatternClause structuredPattern =
                        (BLangMatchStructuredBindingPatternClause) patternClause;
                patternType = getStructuredBindingPatternType(structuredPattern.bindingPatternVariable);
                break;
            default:
                BLangMatchTypedBindingPatternClause simplePattern = (BLangMatchTypedBindingPatternClause) patternClause;
                patternType = simplePattern.variable.type;
                break;
        }

        BLangExpression binaryExpr;
        BType[] memberTypes;
        if (patternType.tag == TypeTags.UNION) {
            BUnionType unionType = (BUnionType) patternType;
            memberTypes = unionType.getMemberTypes().toArray(new BType[0]);
        } else {
            memberTypes = new BType[1];
            memberTypes[0] = patternType;
        }

        if (memberTypes.length == 1) {
            binaryExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[0]);
        } else {
            BLangExpression lhsExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[0]);
            BLangExpression rhsExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[1]);
            binaryExpr = ASTBuilderUtil.createBinaryExpr(patternClause.pos, lhsExpr, rhsExpr,
                    symTable.booleanType, OperatorKind.OR,
                    (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.OR,
                            lhsExpr.type, rhsExpr.type));
            for (int i = 2; i < memberTypes.length; i++) {
                lhsExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[i]);
                rhsExpr = binaryExpr;
                binaryExpr = ASTBuilderUtil.createBinaryExpr(patternClause.pos, lhsExpr, rhsExpr,
                        symTable.booleanType, OperatorKind.OR,
                        (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.OR,
                                lhsExpr.type, rhsExpr.type));
            }
        }
        return binaryExpr;
    }

    private BType getStructuredBindingPatternType(BLangVariable bindingPatternVariable) {
        if (NodeKind.TUPLE_VARIABLE == bindingPatternVariable.getKind()) {
            BLangTupleVariable tupleVariable = (BLangTupleVariable) bindingPatternVariable;
            List<BType> memberTypes = new ArrayList<>();
            for (int i = 0; i < tupleVariable.memberVariables.size(); i++) {
                memberTypes.add(getStructuredBindingPatternType(tupleVariable.memberVariables.get(i)));
            }
            BTupleType tupleType = new BTupleType(memberTypes);
            if (tupleVariable.restVariable != null) {
                BArrayType restArrayType = (BArrayType) getStructuredBindingPatternType(tupleVariable.restVariable);
                tupleType.restType = restArrayType.eType;
            }
            return tupleType;
        }

        if (NodeKind.RECORD_VARIABLE == bindingPatternVariable.getKind()) {
            BLangRecordVariable recordVariable = (BLangRecordVariable) bindingPatternVariable;

            BRecordTypeSymbol recordSymbol =
                    Symbols.createRecordSymbol(0, names.fromString("$anonRecordType$" + recordCount++),
                                               env.enclPkg.symbol.pkgID, null, env.scope.owner);
            recordSymbol.initializerFunc = createRecordInitFunc();
            recordSymbol.scope = new Scope(recordSymbol);
            recordSymbol.scope.define(
                    names.fromString(recordSymbol.name.value + "." + recordSymbol.initializerFunc.funcName.value),
                    recordSymbol.initializerFunc.symbol);

            List<BField> fields = new ArrayList<>();
            List<BLangSimpleVariable> typeDefFields = new ArrayList<>();

            for (int i = 0; i < recordVariable.variableList.size(); i++) {
                String fieldNameStr = recordVariable.variableList.get(i).key.value;
                Name fieldName = names.fromString(fieldNameStr);
                BType fieldType = getStructuredBindingPatternType(
                        recordVariable.variableList.get(i).valueBindingPattern);
                BVarSymbol fieldSymbol = new BVarSymbol(Flags.REQUIRED, fieldName,
                        env.enclPkg.symbol.pkgID, fieldType, recordSymbol);

                
                fields.add(new BField(fieldName, bindingPatternVariable.pos, fieldSymbol));
                typeDefFields.add(ASTBuilderUtil.createVariable(null, fieldNameStr, fieldType, null, fieldSymbol));
                recordSymbol.scope.define(fieldName, fieldSymbol);
            }

            BRecordType recordVarType = new BRecordType(recordSymbol);
            recordVarType.fields = fields;

            
            recordVarType.restFieldType = recordVariable.restParam != null ?
                        ((BMapType) ((BLangSimpleVariable) recordVariable.restParam).type).constraint :
                    symTable.anydataType;
            recordSymbol.type = recordVarType;
            recordVarType.tsymbol = recordSymbol;

            BLangRecordTypeNode recordTypeNode = TypeDefBuilderHelper.createRecordTypeNode(typeDefFields,
                                                                                           recordVarType,
                                                                                           bindingPatternVariable.pos);
            recordTypeNode.initFunction =
                    rewrite(TypeDefBuilderHelper.createInitFunctionForRecordType(recordTypeNode, env, names, symTable),
                            env);
            TypeDefBuilderHelper.addTypeDefinition(recordVarType, recordSymbol, recordTypeNode, env);

            return recordVarType;
        }

        if (NodeKind.ERROR_VARIABLE == bindingPatternVariable.getKind()) {
            BLangErrorVariable errorVariable = (BLangErrorVariable) bindingPatternVariable;
            BErrorTypeSymbol errorTypeSymbol = new BErrorTypeSymbol(
                    SymTag.ERROR,
                    Flags.PUBLIC,
                    names.fromString("$anonErrorType$" + errorCount++),
                    env.enclPkg.symbol.pkgID,
                    null, null);
            BType detailType;
            if ((errorVariable.detail == null || errorVariable.detail.isEmpty()) && errorVariable.restDetail != null) {
                detailType = symTable.detailType;
            } else {
                detailType = createDetailType(errorVariable.detail, errorVariable.restDetail, errorCount++);

                BLangRecordTypeNode recordTypeNode = createRecordTypeNode(errorVariable, (BRecordType) detailType);
                TypeDefBuilderHelper.addTypeDefinition(detailType, detailType.tsymbol, recordTypeNode, env);
            }
            BErrorType errorType = new BErrorType(errorTypeSymbol,
                    ((BErrorType) errorVariable.type).reasonType,
                    detailType);
            errorTypeSymbol.type = errorType;

            TypeDefBuilderHelper.addTypeDefinition(errorType, errorTypeSymbol, createErrorTypeNode(errorType), env);
            return errorType;
        }

        return bindingPatternVariable.type;
    }

    private BLangRecordTypeNode createRecordTypeNode(BLangErrorVariable errorVariable, BRecordType detailType) {
        List<BLangSimpleVariable> fieldList = new ArrayList<>();
        for (BLangErrorVariable.BLangErrorDetailEntry field : errorVariable.detail) {
            BVarSymbol symbol = field.valueBindingPattern.symbol;
            if (symbol == null) {
                symbol = new BVarSymbol(
                        Flags.PUBLIC,
                        names.fromString(field.key.value + "$"),
                        this.env.enclPkg.packageID,
                        symTable.pureType,
                        null);
            }
            BLangSimpleVariable fieldVar = ASTBuilderUtil.createVariable(
                    field.valueBindingPattern.pos,
                    symbol.name.value,
                    field.valueBindingPattern.type,
                    field.valueBindingPattern.expr,
                    symbol);
            fieldList.add(fieldVar);
        }
        return TypeDefBuilderHelper.createRecordTypeNode(fieldList, detailType, errorVariable.pos);
    }

    private BType createDetailType(List<BLangErrorVariable.BLangErrorDetailEntry> detail,
                                   BLangSimpleVariable restDetail, int errorNo) {
        BRecordTypeSymbol detailRecordTypeSymbol = new BRecordTypeSymbol(
                SymTag.RECORD,
                Flags.PUBLIC,
                names.fromString("$anonErrorType$" + errorNo + "$detailType"),
                env.enclPkg.symbol.pkgID, null, null);

        detailRecordTypeSymbol.initializerFunc = createRecordInitFunc();
        detailRecordTypeSymbol.scope = new Scope(detailRecordTypeSymbol);
        detailRecordTypeSymbol.scope.define(
                names.fromString(detailRecordTypeSymbol.name.value + "." +
                        detailRecordTypeSymbol.initializerFunc.funcName.value),
                detailRecordTypeSymbol.initializerFunc.symbol);

        BRecordType detailRecordType = new BRecordType(detailRecordTypeSymbol);
        detailRecordType.restFieldType = symTable.anydataType;

        if (restDetail == null) {
            detailRecordType.sealed = true;
        }

        for (BLangErrorVariable.BLangErrorDetailEntry detailEntry : detail) {
            Name fieldName = names.fromIdNode(detailEntry.key);
            BType fieldType = getStructuredBindingPatternType(detailEntry.valueBindingPattern);
            BVarSymbol fieldSym = new BVarSymbol(
                        Flags.PUBLIC, fieldName, detailRecordTypeSymbol.pkgID, fieldType, detailRecordTypeSymbol);
            detailRecordType.fields.add(new BField(fieldName, detailEntry.key.pos, fieldSym));
            detailRecordTypeSymbol.scope.define(fieldName, fieldSym);
        }

        return detailRecordType;
    }

    private BAttachedFunction createRecordInitFunc() {
        BInvokableType bInvokableType = new BInvokableType(new ArrayList<>(), symTable.nilType, null);
        BInvokableSymbol initFuncSymbol = Symbols.createFunctionSymbol(
                Flags.PUBLIC, Names.EMPTY, env.enclPkg.symbol.pkgID, bInvokableType, env.scope.owner, false);
        initFuncSymbol.retType = symTable.nilType;
        return new BAttachedFunction(Names.INIT_FUNCTION_SUFFIX, initFuncSymbol, bInvokableType);
    }

    BLangErrorType createErrorTypeNode(BErrorType errorType) {
        BLangErrorType errorTypeNode = (BLangErrorType) TreeBuilder.createErrorTypeNode();
        errorTypeNode.type = errorType;
        return errorTypeNode;
    }

    private BLangExpression createPatternMatchBinaryExpr(BLangMatchBindingPatternClause patternClause,
                                                         BVarSymbol varSymbol, BType patternType) {
        DiagnosticPos pos = patternClause.pos;

        BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        if (NodeKind.MATCH_STATIC_PATTERN_CLAUSE == patternClause.getKind()) {
            BLangMatchStaticBindingPatternClause pattern = (BLangMatchStaticBindingPatternClause) patternClause;
            return createBinaryExpression(pos, varRef, pattern.literal);
        }

        if (NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE == patternClause.getKind()) {
            return createIsLikeExpression(pos, ASTBuilderUtil.createVariableRef(pos, varSymbol), patternType);
        }

        if (patternType == symTable.nilType) {
            BLangLiteral bLangLiteral = ASTBuilderUtil.createLiteral(pos, symTable.nilType, null);
            return ASTBuilderUtil.createBinaryExpr(pos, varRef, bLangLiteral, symTable.booleanType,
                    OperatorKind.EQUAL, (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.EQUAL,
                            symTable.anyType, symTable.nilType));
        } else {
            return createIsAssignableExpression(pos, varSymbol, patternType);
        }
    }

    private BLangExpression createBinaryExpression(DiagnosticPos pos, BLangSimpleVarRef varRef,
            BLangExpression expression) {

        BLangBinaryExpr binaryExpr;
        if (NodeKind.GROUP_EXPR == expression.getKind()) {
            return createBinaryExpression(pos, varRef, ((BLangGroupExpr) expression).expression);
        }

        if (NodeKind.BINARY_EXPR == expression.getKind()) {
            binaryExpr = (BLangBinaryExpr) expression;
            BLangExpression lhsExpr = createBinaryExpression(pos, varRef, binaryExpr.lhsExpr);
            BLangExpression rhsExpr = createBinaryExpression(pos, varRef, binaryExpr.rhsExpr);

            binaryExpr = ASTBuilderUtil.createBinaryExpr(pos, lhsExpr, rhsExpr, symTable.booleanType, OperatorKind.OR,
                    (BOperatorSymbol) symResolver
                            .resolveBinaryOperator(OperatorKind.OR, symTable.booleanType, symTable.booleanType));
        } else if (expression.getKind() == NodeKind.SIMPLE_VARIABLE_REF
                && ((BLangSimpleVarRef) expression).variableName.value.equals(IGNORE.value)) {
            BLangValueType anyType = (BLangValueType) TreeBuilder.createValueTypeNode();
            anyType.type = symTable.anyType;
            anyType.typeKind = TypeKind.ANY;
            return ASTBuilderUtil.createTypeTestExpr(pos, varRef, anyType);
        } else {
            binaryExpr = ASTBuilderUtil
                    .createBinaryExpr(pos, varRef, expression, symTable.booleanType, OperatorKind.EQUAL, null);

            BSymbol opSymbol = symResolver.resolveBinaryOperator(OperatorKind.EQUAL, varRef.type, expression.type);
            if (opSymbol == symTable.notFoundSymbol) {
                opSymbol = symResolver
                        .getBinaryEqualityForTypeSets(OperatorKind.EQUAL, symTable.anydataType, expression.type,
                                binaryExpr);
            }
            binaryExpr.opSymbol = (BOperatorSymbol) opSymbol;
        }
        return binaryExpr;
    }

    private BLangIsAssignableExpr createIsAssignableExpression(DiagnosticPos pos,
                                                               BVarSymbol varSymbol,
                                                               BType patternType) {
        
        
        BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        
        return ASTBuilderUtil.createIsAssignableExpr(pos, varRef, patternType, symTable.booleanType, names);
    }

    private BLangIsLikeExpr createIsLikeExpression(DiagnosticPos pos, BLangExpression expr, BType type) {
        return ASTBuilderUtil.createIsLikeExpr(pos, expr, ASTBuilderUtil.createTypeNode(type), symTable.booleanType);
    }

    private BLangAssignment createAssignmentStmt(BLangSimpleVariable variable) {
        BLangSimpleVarRef varRef = (BLangSimpleVarRef) TreeBuilder.createSimpleVariableReferenceNode();
        varRef.pos = variable.pos;
        varRef.variableName = variable.name;
        varRef.symbol = variable.symbol;
        varRef.type = variable.type;

        BLangAssignment assignmentStmt = (BLangAssignment) TreeBuilder.createAssignmentNode();
        assignmentStmt.expr = variable.expr;
        assignmentStmt.pos = variable.pos;
        assignmentStmt.setVariable(varRef);
        return assignmentStmt;
    }

    private BLangAssignment createStructFieldUpdate(BLangFunction function, BLangSimpleVariable variable,
                                                    BVarSymbol symbol) {
        BLangSimpleVarRef selfVarRef = ASTBuilderUtil.createVariableRef(variable.pos, symbol);
        BLangFieldBasedAccess fieldAccess = ASTBuilderUtil.createFieldAccessExpr(selfVarRef, variable.name);
        fieldAccess.symbol = variable.symbol;
        fieldAccess.type = variable.type;

        BLangAssignment assignmentStmt = (BLangAssignment) TreeBuilder.createAssignmentNode();
        assignmentStmt.expr = variable.expr;
        assignmentStmt.pos = variable.pos;
        assignmentStmt.setVariable(fieldAccess);

        SymbolEnv initFuncEnv = SymbolEnv.createFunctionEnv(function, function.symbol.scope, env);
        return rewrite(assignmentStmt, initFuncEnv);
    }

    private void addMatchExprDefaultCase(BLangMatchExpression bLangMatchExpression) {
        List<BType> exprTypes;
        List<BType> unmatchedTypes = new ArrayList<>();

        if (bLangMatchExpression.expr.type.tag == TypeTags.UNION) {
            BUnionType unionType = (BUnionType) bLangMatchExpression.expr.type;
            exprTypes = new ArrayList<>(unionType.getMemberTypes());
        } else {
            exprTypes = Lists.of(bLangMatchExpression.type);
        }

        
        for (BType type : exprTypes) {
            boolean assignable = false;
            for (BLangMatchExprPatternClause pattern : bLangMatchExpression.patternClauses) {
                if (this.types.isAssignable(type, pattern.variable.type)) {
                    assignable = true;
                    break;
                }
            }

            if (!assignable) {
                unmatchedTypes.add(type);
            }
        }

        if (unmatchedTypes.isEmpty()) {
            return;
        }

        BType defaultPatternType;
        if (unmatchedTypes.size() == 1) {
            defaultPatternType = unmatchedTypes.get(0);
        } else {
            defaultPatternType = BUnionType.create(null, new LinkedHashSet<>(unmatchedTypes));
        }

        String patternCaseVarName = GEN_VAR_PREFIX.value + "t_match_default";
        BLangSimpleVariable patternMatchCaseVar = ASTBuilderUtil.createVariable(bLangMatchExpression.pos,
                patternCaseVarName, defaultPatternType, null, new BVarSymbol(0, names.fromString(patternCaseVarName),
                        this.env.scope.owner.pkgID, defaultPatternType, this.env.scope.owner));

        BLangMatchExprPatternClause defaultPattern =
                (BLangMatchExprPatternClause) TreeBuilder.createMatchExpressionPattern();
        defaultPattern.variable = patternMatchCaseVar;
        defaultPattern.expr = ASTBuilderUtil.createVariableRef(bLangMatchExpression.pos, patternMatchCaseVar.symbol);
        defaultPattern.pos = bLangMatchExpression.pos;
        bLangMatchExpression.patternClauses.add(defaultPattern);
    }

    private boolean safeNavigate(BLangAccessExpression accessExpr) {
        if (accessExpr.lhsVar || accessExpr.expr == null) {
            return false;
        }

        if (accessExpr.errorSafeNavigation || accessExpr.nilSafeNavigation) {
            return true;
        }

        NodeKind kind = accessExpr.expr.getKind();
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR ||
                kind == NodeKind.INDEX_BASED_ACCESS_EXPR) {
            return safeNavigate((BLangAccessExpression) accessExpr.expr);
        }

        return false;
    }

    private BLangExpression rewriteSafeNavigationExpr(BLangAccessExpression accessExpr) {
        BType originalExprType = accessExpr.type;
        
        String matchTempResultVarName = GEN_VAR_PREFIX.value + "temp_result";
        BLangSimpleVariable tempResultVar = ASTBuilderUtil.createVariable(accessExpr.pos, matchTempResultVarName,
                accessExpr.type, null, new BVarSymbol(0, names.fromString(matchTempResultVarName),
                        this.env.scope.owner.pkgID, accessExpr.type, this.env.scope.owner));
        BLangSimpleVariableDef tempResultVarDef = ASTBuilderUtil.createVariableDef(accessExpr.pos, tempResultVar);
        BLangVariableReference tempResultVarRef =
                ASTBuilderUtil.createVariableRef(accessExpr.pos, tempResultVar.symbol);

        
        handleSafeNavigation(accessExpr, accessExpr.type, tempResultVar);

        
        BLangMatch matcEXpr = this.matchStmtStack.firstElement();
        BLangBlockStmt blockStmt =
                ASTBuilderUtil.createBlockStmt(accessExpr.pos, Lists.of(tempResultVarDef, matcEXpr));
        BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, tempResultVarRef);
        stmtExpression.type = originalExprType;

        
        this.matchStmtStack = new Stack<>();
        this.accessExprStack = new Stack<>();
        this.successPattern = null;
        this.safeNavigationAssignment = null;
        return stmtExpression;
    }

    private void handleSafeNavigation(BLangAccessExpression accessExpr, BType type, BLangSimpleVariable tempResultVar) {
        if (accessExpr.expr == null) {
            return;
        }

        
        NodeKind kind = accessExpr.expr.getKind();
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR ||
                kind == NodeKind.INDEX_BASED_ACCESS_EXPR ||
                kind == NodeKind.INVOCATION) {
            handleSafeNavigation((BLangAccessExpression) accessExpr.expr, type, tempResultVar);
        }

        if (!(accessExpr.errorSafeNavigation || accessExpr.nilSafeNavigation)) {
            BType originalType = accessExpr.originalType;
            if (TypeTags.isXMLTypeTag(originalType.tag)) {
                accessExpr.type = BUnionType.create(null, originalType, symTable.errorType);
            } else {
                accessExpr.type = originalType;
            }
            if (this.safeNavigationAssignment != null) {
                this.safeNavigationAssignment.expr = addConversionExprIfRequired(accessExpr, tempResultVar.type);
            }
            return;
        }

        /*
         * If the field access is a safe navigation, create a match expression.
         * Then chain the current expression as the success-pattern of the parent
         * match expr, if available.
         * eg:
         * x but {              <--- parent match expr
         *   error e => e,
         *   T t => t.y but {   <--- current expr
         *      error e => e,
         *      R r => r.z
         *   }
         * }
         */

        BLangMatch matchStmt = ASTBuilderUtil.createMatchStatement(accessExpr.pos, accessExpr.expr, new ArrayList<>());

        
        if (accessExpr.nilSafeNavigation) {
            matchStmt.patternClauses.add(getMatchNullPattern(accessExpr, tempResultVar));
            matchStmt.type = type;
        }

        
        if (accessExpr.errorSafeNavigation) {
            matchStmt.patternClauses.add(getMatchErrorPattern(accessExpr, tempResultVar));
            matchStmt.type = type;
            matchStmt.pos = accessExpr.pos;

        }

        
        BLangMatchTypedBindingPatternClause successPattern =
                getSuccessPattern(accessExpr, tempResultVar, accessExpr.errorSafeNavigation);
        matchStmt.patternClauses.add(successPattern);
        this.matchStmtStack.push(matchStmt);
        if (this.successPattern != null) {
            this.successPattern.body = ASTBuilderUtil.createBlockStmt(accessExpr.pos, Lists.of(matchStmt));
        }
        this.successPattern = successPattern;
    }

    private BLangMatchTypedBindingPatternClause getMatchErrorPattern(BLangExpression expr,
                                                                         BLangSimpleVariable tempResultVar) {
        String errorPatternVarName = GEN_VAR_PREFIX.value + "t_match_error";
        BLangSimpleVariable errorPatternVar = ASTBuilderUtil.createVariable(expr.pos, errorPatternVarName,
                symTable.errorType, null, new BVarSymbol(0, names.fromString(errorPatternVarName),
                        this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner));

        
        BLangSimpleVarRef assignmentRhsExpr = ASTBuilderUtil.createVariableRef(expr.pos, errorPatternVar.symbol);
        BLangVariableReference tempResultVarRef = ASTBuilderUtil.createVariableRef(expr.pos, tempResultVar.symbol);
        BLangAssignment assignmentStmt =
                ASTBuilderUtil.createAssignmentStmt(expr.pos, tempResultVarRef, assignmentRhsExpr, false);
        BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(expr.pos, Lists.of(assignmentStmt));

        
        
        BLangMatchTypedBindingPatternClause errorPattern = ASTBuilderUtil
                .createMatchStatementPattern(expr.pos, errorPatternVar, patternBody);
        return errorPattern;
    }

    private BLangMatchExprPatternClause getMatchNullPatternGivenExpression(DiagnosticPos pos,
                                                                           BLangExpression expr) {
        String nullPatternVarName = IGNORE.toString();
        BLangSimpleVariable errorPatternVar = ASTBuilderUtil.createVariable(pos, nullPatternVarName, symTable.nilType,
                null, new BVarSymbol(0, names.fromString(nullPatternVarName),
                        this.env.scope.owner.pkgID, symTable.nilType, this.env.scope.owner));

        BLangMatchExprPatternClause nullPattern =
                (BLangMatchExprPatternClause) TreeBuilder.createMatchExpressionPattern();
        nullPattern.variable = errorPatternVar;
        nullPattern.expr = expr;
        nullPattern.pos = pos;
        return nullPattern;
    }

    private BLangMatchTypedBindingPatternClause getMatchNullPattern(BLangExpression expr,
            BLangSimpleVariable tempResultVar) {
        
        String nullPatternVarName = GEN_VAR_PREFIX.value + "t_match_null";
        BLangSimpleVariable nullPatternVar = ASTBuilderUtil.createVariable(expr.pos, nullPatternVarName,
                symTable.nilType, null, new BVarSymbol(0, names.fromString(nullPatternVarName),
                        this.env.scope.owner.pkgID, symTable.nilType, this.env.scope.owner));

        
        BLangSimpleVarRef assignmentRhsExpr = ASTBuilderUtil.createVariableRef(expr.pos, nullPatternVar.symbol);
        BLangVariableReference tempResultVarRef = ASTBuilderUtil.createVariableRef(expr.pos, tempResultVar.symbol);
        BLangAssignment assignmentStmt =
                ASTBuilderUtil.createAssignmentStmt(expr.pos, tempResultVarRef, assignmentRhsExpr, false);
        BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(expr.pos, Lists.of(assignmentStmt));

        
        
        BLangMatchTypedBindingPatternClause nullPattern = ASTBuilderUtil
                .createMatchStatementPattern(expr.pos, nullPatternVar, patternBody);
        return nullPattern;
    }

    private BLangMatchTypedBindingPatternClause getSuccessPattern(BLangAccessExpression accessExpr,
            BLangSimpleVariable tempResultVar, boolean liftError) {
        BType type = types.getSafeType(accessExpr.expr.type, true, liftError);
        String successPatternVarName = GEN_VAR_PREFIX.value + "t_match_success";

        BVarSymbol  successPatternSymbol;
        if (type.tag == TypeTags.INVOKABLE) {
            successPatternSymbol = new BInvokableSymbol(SymTag.VARIABLE, 0, names.fromString(successPatternVarName),
                    this.env.scope.owner.pkgID, type, this.env.scope.owner);
        } else {
            successPatternSymbol = new BVarSymbol(0, names.fromString(successPatternVarName),
                    this.env.scope.owner.pkgID, type, this.env.scope.owner);
        }

        BLangSimpleVariable successPatternVar = ASTBuilderUtil.createVariable(accessExpr.pos, successPatternVarName,
                type, null, successPatternSymbol);

        
        accessExpr.expr = ASTBuilderUtil.createVariableRef(accessExpr.pos, successPatternVar.symbol);
        accessExpr.errorSafeNavigation = false;
        accessExpr.nilSafeNavigation = false;

        
        
        
        if (TypeTags.isXMLTypeTag(accessExpr.expr.type.tag)) {
            
            accessExpr.type = BUnionType.create(null, accessExpr.originalType, symTable.errorType, symTable.nilType);
        } else {
            accessExpr.type = accessExpr.originalType;
        }

        BLangVariableReference tempResultVarRef =
                ASTBuilderUtil.createVariableRef(accessExpr.pos, tempResultVar.symbol);

        BLangExpression assignmentRhsExpr = addConversionExprIfRequired(accessExpr, tempResultVarRef.type);
        BLangAssignment assignmentStmt =
                ASTBuilderUtil.createAssignmentStmt(accessExpr.pos, tempResultVarRef, assignmentRhsExpr, false);
        BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(accessExpr.pos, Lists.of(assignmentStmt));

        
        
        BLangMatchTypedBindingPatternClause successPattern =
                ASTBuilderUtil.createMatchStatementPattern(accessExpr.pos, successPatternVar, patternBody);
        this.safeNavigationAssignment = assignmentStmt;
        return successPattern;
    }

    private boolean safeNavigateLHS(BLangExpression expr) {
        if (expr.getKind() != NodeKind.FIELD_BASED_ACCESS_EXPR && expr.getKind() != NodeKind.INDEX_BASED_ACCESS_EXPR) {
            return false;
        }

        BLangExpression varRef = ((BLangAccessExpression) expr).expr;
        if (varRef.type.isNullable()) {
            return true;
        }

        return safeNavigateLHS(varRef);
    }

    private BLangStatement rewriteSafeNavigationAssignment(BLangAccessExpression accessExpr, BLangExpression rhsExpr,
                                                           boolean safeAssignment) {
        
        
        
        
        
        
        
        
        
        
        
        
        this.accessExprStack = new Stack<>();
        List<BLangStatement> stmts = new ArrayList<>();
        createLHSSafeNavigation(stmts, accessExpr.expr);
        BLangAssignment assignment = ASTBuilderUtil.createAssignmentStmt(accessExpr.pos,
                cloneExpression(accessExpr), rhsExpr);
        stmts.add(assignment);
        return ASTBuilderUtil.createBlockStmt(accessExpr.pos, stmts);
    }

    private void createLHSSafeNavigation(List<BLangStatement> stmts, BLangExpression expr) {
        NodeKind kind = expr.getKind();
        boolean root = false;
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR || kind == NodeKind.INDEX_BASED_ACCESS_EXPR ||
                kind == NodeKind.INVOCATION) {
            BLangAccessExpression accessExpr = (BLangAccessExpression) expr;
            createLHSSafeNavigation(stmts, accessExpr.expr);
            accessExpr.expr = accessExprStack.pop();
        } else {
            root = true;
        }

        
        
        if (expr.getKind() == NodeKind.INVOCATION) {
            BLangInvocation invocation = (BLangInvocation) expr;
            BVarSymbol interMediateSymbol = new BVarSymbol(0, names.fromString(GEN_VAR_PREFIX.value
                    + "i_intermediate"), this.env.scope.owner.pkgID, invocation.type, this.env.scope.owner);
            BLangSimpleVariable intermediateVariable = ASTBuilderUtil.createVariable(expr.pos,
                    interMediateSymbol.name.value, invocation.type, invocation, interMediateSymbol);
            BLangSimpleVariableDef intermediateVariableDefinition = ASTBuilderUtil.createVariableDef(invocation.pos,
                    intermediateVariable);
            stmts.add(intermediateVariableDefinition);

            expr = ASTBuilderUtil.createVariableRef(invocation.pos, interMediateSymbol);
        }

        if (expr.type.isNullable()) {
            BLangTypeTestExpr isNillTest = ASTBuilderUtil.createTypeTestExpr(expr.pos, expr, getNillTypeNode());
            isNillTest.type = symTable.booleanType;

            BLangBlockStmt thenStmt = ASTBuilderUtil.createBlockStmt(expr.pos);

            
            expr = cloneExpression(expr);
            expr.type = types.getSafeType(expr.type, true, false);

            if (isDefaultableMappingType(expr.type) && !root) { 
                
                BLangRecordLiteral jsonLiteral = (BLangRecordLiteral) TreeBuilder.createRecordLiteralNode();
                jsonLiteral.type = expr.type;
                jsonLiteral.pos = expr.pos;
                BLangAssignment assignment = ASTBuilderUtil.createAssignmentStmt(expr.pos,
                        expr, jsonLiteral);
                thenStmt.addStatement(assignment);
            } else {
                BLangLiteral literal = (BLangLiteral) TreeBuilder.createLiteralExpression();
                literal.value = ERROR_REASON_NULL_REFERENCE_ERROR;
                literal.type = symTable.stringType;

                BLangInvocation errorCtorInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
                errorCtorInvocation.pos = expr.pos;
                errorCtorInvocation.argExprs.add(literal);
                errorCtorInvocation.requiredArgs.add(literal);
                errorCtorInvocation.type = symTable.errorType;
                errorCtorInvocation.symbol = symTable.errorConstructor;

                BLangPanic panicNode = (BLangPanic) TreeBuilder.createPanicNode();
                panicNode.expr = errorCtorInvocation;
                panicNode.pos = expr.pos;
                thenStmt.addStatement(panicNode);
            }

            BLangIf ifelse = ASTBuilderUtil.createIfElseStmt(expr.pos, isNillTest, thenStmt, null);
            stmts.add(ifelse);
        }

        accessExprStack.push(expr);
    }

    BLangValueType getNillTypeNode() {
        BLangValueType nillTypeNode = (BLangValueType) TreeBuilder.createValueTypeNode();
        nillTypeNode.typeKind = TypeKind.NIL;
        nillTypeNode.type = symTable.nilType;
        return nillTypeNode;
    }

    private BLangVariableReference cloneExpression(BLangExpression expr) {
        switch (expr.getKind()) {
            case SIMPLE_VARIABLE_REF:
                return ASTBuilderUtil.createVariableRef(expr.pos, ((BLangSimpleVarRef) expr).symbol);
            case FIELD_BASED_ACCESS_EXPR:
            case INDEX_BASED_ACCESS_EXPR:
            case INVOCATION:
                return cloneAccessExpr((BLangAccessExpression) expr);
            default:
                throw new IllegalStateException();
        }
    }

    private BLangAccessExpression cloneAccessExpr(BLangAccessExpression originalAccessExpr) {
        if (originalAccessExpr.expr == null) {
            return originalAccessExpr;
        }

        BLangVariableReference varRef;
        NodeKind kind = originalAccessExpr.expr.getKind();
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR || kind == NodeKind.INDEX_BASED_ACCESS_EXPR ||
                kind == NodeKind.INVOCATION) {
            varRef = cloneAccessExpr((BLangAccessExpression) originalAccessExpr.expr);
        } else {
            varRef = cloneExpression(originalAccessExpr.expr);
        }
        varRef.type = types.getSafeType(originalAccessExpr.expr.type, true, false);

        BLangAccessExpression accessExpr;
        switch (originalAccessExpr.getKind()) {
            case FIELD_BASED_ACCESS_EXPR:
                accessExpr = ASTBuilderUtil.createFieldAccessExpr(varRef,
                        ((BLangFieldBasedAccess) originalAccessExpr).field);
                break;
            case INDEX_BASED_ACCESS_EXPR:
                accessExpr = ASTBuilderUtil.createIndexAccessExpr(varRef,
                        ((BLangIndexBasedAccess) originalAccessExpr).indexExpr);
                break;
            case INVOCATION:
                
                accessExpr = null;
                break;
            default:
                throw new IllegalStateException();
        }

        accessExpr.originalType = originalAccessExpr.originalType;
        accessExpr.pos = originalAccessExpr.pos;
        accessExpr.lhsVar = originalAccessExpr.lhsVar;
        accessExpr.symbol = originalAccessExpr.symbol;
        accessExpr.errorSafeNavigation = false;
        accessExpr.nilSafeNavigation = false;

        
        
        
        accessExpr.type = originalAccessExpr.originalType;
        return accessExpr;
    }

    private BLangBinaryExpr getModifiedIntRangeStartExpr(BLangExpression expr) {
        BLangLiteral constOneLiteral = ASTBuilderUtil.createLiteral(expr.pos, symTable.intType, 1L);
        return ASTBuilderUtil.createBinaryExpr(expr.pos, expr, constOneLiteral, symTable.intType, OperatorKind.ADD,
                (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.ADD,
                        symTable.intType,
                        symTable.intType));
    }

    private BLangBinaryExpr getModifiedIntRangeEndExpr(BLangExpression expr) {
        BLangLiteral constOneLiteral = ASTBuilderUtil.createLiteral(expr.pos, symTable.intType, 1L);
        return ASTBuilderUtil.createBinaryExpr(expr.pos, expr, constOneLiteral, symTable.intType, OperatorKind.SUB,
                (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.SUB,
                        symTable.intType,
                        symTable.intType));
    }

    private BLangLiteral getBooleanLiteral(boolean value) {
        BLangLiteral literal = (BLangLiteral) TreeBuilder.createLiteralExpression();
        literal.value = value;
        literal.type = symTable.booleanType;
        return literal;
    }

    private boolean isDefaultableMappingType(BType type) {
        switch (types.getSafeType(type, true, false).tag) {
            case TypeTags.JSON:
            case TypeTags.MAP:
            case TypeTags.RECORD:
                return true;
            default:
                return false;
        }
    }

    private BLangFunction createInitFunctionForObjectType(BLangObjectTypeNode structureTypeNode, SymbolEnv env) {
        BLangFunction initFunction =
                TypeDefBuilderHelper.createInitFunctionForStructureType(structureTypeNode, env,
                                                                        Names.GENERATED_INIT_SUFFIX, names, symTable);
        BObjectTypeSymbol typeSymbol = ((BObjectTypeSymbol) structureTypeNode.type.tsymbol);
        typeSymbol.generatedInitializerFunc = new BAttachedFunction(Names.GENERATED_INIT_SUFFIX, initFunction.symbol,
                (BInvokableType) initFunction.type);
        structureTypeNode.generatedInitFunction = initFunction;
        initFunction.returnTypeNode.type = symTable.nilType;
        return rewrite(initFunction, env);
    }

    private void visitBinaryLogicalExpr(BLangBinaryExpr binaryExpr) {
        /*
         * Desugar (lhsExpr && rhsExpr) to following if-else:
         * 
         * logical AND:
         * -------------
         * T $result$;
         * if (lhsExpr) {
         *    $result$ = rhsExpr;
         * } else {
         *    $result$ = false;
         * }
         * 
         * logical OR:
         * -------------
         * T $result$;
         * if (lhsExpr) {
         *    $result$ = true;
         * } else {
         *    $result$ = rhsExpr;
         * }
         * 
         */
        BLangSimpleVariableDef resultVarDef = createVarDef("$result$", binaryExpr.type, null, binaryExpr.pos);
        BLangBlockStmt thenBody = ASTBuilderUtil.createBlockStmt(binaryExpr.pos);
        BLangBlockStmt elseBody = ASTBuilderUtil.createBlockStmt(binaryExpr.pos);

        
        BLangSimpleVarRef thenResultVarRef = ASTBuilderUtil.createVariableRef(binaryExpr.pos, resultVarDef.var.symbol);
        BLangExpression thenResult;
        if (binaryExpr.opKind == OperatorKind.AND) {
            thenResult = binaryExpr.rhsExpr;
        } else {
            thenResult = getBooleanLiteral(true);
        }
        BLangAssignment thenAssignment =
                ASTBuilderUtil.createAssignmentStmt(binaryExpr.pos, thenResultVarRef, thenResult);
        thenBody.addStatement(thenAssignment);

        
        BLangExpression elseResult;
        BLangSimpleVarRef elseResultVarRef = ASTBuilderUtil.createVariableRef(binaryExpr.pos, resultVarDef.var.symbol);
        if (binaryExpr.opKind == OperatorKind.AND) {
            elseResult = getBooleanLiteral(false);
        } else {
            elseResult = binaryExpr.rhsExpr;
        }
        BLangAssignment elseAssignment =
                ASTBuilderUtil.createAssignmentStmt(binaryExpr.pos, elseResultVarRef, elseResult);
        elseBody.addStatement(elseAssignment);

        
        BLangSimpleVarRef resultVarRef = ASTBuilderUtil.createVariableRef(binaryExpr.pos, resultVarDef.var.symbol);
        BLangIf ifElse = ASTBuilderUtil.createIfElseStmt(binaryExpr.pos, binaryExpr.lhsExpr, thenBody, elseBody);

        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(binaryExpr.pos, Lists.of(resultVarDef, ifElse));
        BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, resultVarRef);
        stmtExpr.type = binaryExpr.type;

        result = rewriteExpr(stmtExpr);
    }

    /**
     * Split packahe init function into several smaller functions.
     *
     * @param packageNode package node
     * @param env symbol environment
     * @return initial init function but trimmed in size
     */
    private BLangFunction splitInitFunction(BLangPackage packageNode, SymbolEnv env) {
        int methodSize = INIT_METHOD_SPLIT_SIZE;
        BLangBlockFunctionBody funcBody = (BLangBlockFunctionBody) packageNode.initFunction.body;
        if (funcBody.stmts.size() < methodSize || !isJvmTarget) {
            return packageNode.initFunction;
        }
        BLangFunction initFunction = packageNode.initFunction;

        List<BLangFunction> generatedFunctions = new ArrayList<>();
        List<BLangStatement> stmts = new ArrayList<>(funcBody.stmts);
        funcBody.stmts.clear();
        BLangFunction newFunc = initFunction;
        BLangBlockFunctionBody newFuncBody = (BLangBlockFunctionBody) newFunc.body;

        
        int varDefIndex = 0;
        for (int i = 0; i < stmts.size(); i++) {
            if (stmts.get(i).getKind() == NodeKind.VARIABLE_DEF) {
                break;
            }
            varDefIndex++;
            if (i > 0 && i % methodSize == 0) {
                generatedFunctions.add(newFunc);
                newFunc = createIntermediateInitFunction(packageNode, env);
                newFuncBody = (BLangBlockFunctionBody) newFunc.body;
                symTable.rootScope.define(names.fromIdNode(newFunc.name), newFunc.symbol);
            }

            newFuncBody.stmts.add(stmts.get(i));
        }

        
        List<BLangStatement> chunkStmts = new ArrayList<>();
        for (int i = varDefIndex; i < stmts.size(); i++) {
            BLangStatement stmt = stmts.get(i);
            chunkStmts.add(stmt);
            varDefIndex++;
            if ((stmt.getKind() == NodeKind.ASSIGNMENT) &&
                    (((BLangAssignment) stmt).expr.getKind() == NodeKind.SERVICE_CONSTRUCTOR) &&
                    (newFuncBody.stmts.size() + chunkStmts.size() > methodSize)) {
                
                if (newFuncBody.stmts.size() + chunkStmts.size() > methodSize) {
                    generatedFunctions.add(newFunc);
                    newFunc = createIntermediateInitFunction(packageNode, env);
                    newFuncBody = (BLangBlockFunctionBody) newFunc.body;
                    symTable.rootScope.define(names.fromIdNode(newFunc.name), newFunc.symbol);
                }
                newFuncBody.stmts.addAll(chunkStmts);
                chunkStmts.clear();
            } else if ((stmt.getKind() == NodeKind.ASSIGNMENT) &&
                    (((BLangAssignment) stmt).varRef instanceof BLangPackageVarRef) &&
                    Symbols.isFlagOn(((BLangPackageVarRef) ((BLangAssignment) stmt).varRef).varSymbol.flags,
                            Flags.LISTENER)
            ) {
                
                break;
            }
        }
        newFuncBody.stmts.addAll(chunkStmts);

        
        for (int i = varDefIndex; i < stmts.size(); i++) {
            if (i > 0 && i % methodSize == 0) {
                generatedFunctions.add(newFunc);
                newFunc = createIntermediateInitFunction(packageNode, env);
                newFuncBody = (BLangBlockFunctionBody) newFunc.body;
                symTable.rootScope.define(names.fromIdNode(newFunc.name), newFunc.symbol);
            }
            newFuncBody.stmts.add(stmts.get(i));
        }

        generatedFunctions.add(newFunc);

        for (int j = 0; j < generatedFunctions.size() - 1; j++) {
            BLangFunction thisFunction = generatedFunctions.get(j);

            BLangCheckedExpr checkedExpr =
                    ASTBuilderUtil.createCheckExpr(initFunction.pos,
                                                   createInvocationNode(generatedFunctions.get(j + 1).name.value,
                                                                        new ArrayList<>(), symTable.errorOrNilType),
                                                   symTable.nilType);
            checkedExpr.equivalentErrorTypeList.add(symTable.errorType);

            BLangExpressionStmt expressionStmt = ASTBuilderUtil
                    .createExpressionStmt(thisFunction.pos, (BLangBlockFunctionBody) thisFunction.body);
            expressionStmt.expr = checkedExpr;
            expressionStmt.expr.pos = initFunction.pos;

            if (j > 0) { 
                thisFunction = rewrite(thisFunction, env);
                packageNode.functions.add(thisFunction);
                packageNode.topLevelNodes.add(thisFunction);
            }
        }

        if (generatedFunctions.size() > 1) {
            
            BLangFunction lastFunc = generatedFunctions.get(generatedFunctions.size() - 1);
            lastFunc = rewrite(lastFunc, env);
            packageNode.functions.add(lastFunc);
            packageNode.topLevelNodes.add(lastFunc);
        }

        return generatedFunctions.get(0);
    }

    /**
     * Create an intermediate package init function.
     *
     * @param pkgNode package node
     * @param env     symbol environment of package
     */
    private BLangFunction createIntermediateInitFunction(BLangPackage pkgNode, SymbolEnv env) {
        String alias = pkgNode.symbol.pkgID.toString();
        BLangFunction initFunction = ASTBuilderUtil
                .createInitFunctionWithErrorOrNilReturn(pkgNode.pos, alias,
                                                        new Name(Names.INIT_FUNCTION_SUFFIX.value
                                                                + this.initFuncIndex++), symTable);
        
        createInvokableSymbol(initFunction, env);
        return initFunction;
    }

    private BType getRestType(BInvokableSymbol invokableSymbol) {
        if (invokableSymbol != null && invokableSymbol.restParam != null) {
            return invokableSymbol.restParam.type;
        }
        return null;
    }

    private BType getRestType(BLangFunction function) {
        if (function != null && function.restParam != null) {
            return function.restParam.type;
        }
        return null;
    }

    private BVarSymbol getRestSymbol(BLangFunction function) {
        if (function != null && function.restParam != null) {
            return function.restParam.symbol;
        }
        return null;
    }

    private boolean isComputedKey(RecordLiteralNode.RecordField field) {
        if (!field.isKeyValueField()) {
            return false;
        }
        return ((BLangRecordLiteral.BLangRecordKeyValueField) field).key.computedKey;
    }

    private BLangStatementExpression rewriteMappingConstructor(BLangRecordLiteral mappingConstructorExpr) {
        List<RecordLiteralNode.RecordField> fields = mappingConstructorExpr.fields;

        BType type = mappingConstructorExpr.type;
        DiagnosticPos pos = mappingConstructorExpr.pos;

        BLangRecordLiteral recordLiteral = type.tag == TypeTags.RECORD ? new BLangStructLiteral(pos, type) :
                new BLangMapLiteral(pos, type);

        String name = DESUGARED_MAPPING_CONSTR_KEY + this.annonVarCount++;

        BVarSymbol varSymbol = new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, type,
                                              this.env.scope.owner);
        BLangSimpleVariable var = createVariable(pos, name, type, recordLiteral, varSymbol);
        BLangSimpleVariableDef varDef = ASTBuilderUtil.createVariableDef(pos);
        varDef.var = var;
        varDef.type = type;

        BLangBlockStmt blockStmt = createBlockStmt(pos);
        blockStmt.stmts.add(varDef);

        BLangSimpleVarRef mappingVarRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        for (RecordLiteralNode.RecordField field : fields) {
            if (field.isKeyValueField()) {
                BLangRecordLiteral.BLangRecordKeyValueField keyValueField =
                        (BLangRecordLiteral.BLangRecordKeyValueField) field;

                BLangRecordLiteral.BLangRecordKey key = keyValueField.key;
                BLangExpression keyExpr = key.expr;
                BLangExpression indexExpr = key.computedKey ? keyExpr :
                        keyExpr.getKind() == NodeKind.SIMPLE_VARIABLE_REF ?
                                createStringLiteral(pos, ((BLangSimpleVarRef) keyExpr).variableName.value) :
                                ((BLangLiteral) keyExpr);;
                addMemberStoreForKeyValuePair(pos, blockStmt, mappingVarRef, indexExpr, keyValueField.valueExpr);
            } else if (field.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
                BLangSimpleVarRef varRefField = (BLangSimpleVarRef) field;
                addMemberStoreForKeyValuePair(pos, blockStmt, mappingVarRef,
                                              createStringLiteral(pos, varRefField.variableName.value),
                                              varRefField);
            } else {
                BLangRecordLiteral.BLangRecordSpreadOperatorField spreadOpField =
                        (BLangRecordLiteral.BLangRecordSpreadOperatorField) field;

                BLangForeach foreach = (BLangForeach) TreeBuilder.createForeachNode();
                foreach.pos = pos;

                foreach.collection = generateMapEntriesInvocation(spreadOpField.expr, spreadOpField.expr.type);
                types.setForeachTypedBindingPatternType(foreach);

                BLangSimpleVariable foreachVariable = ASTBuilderUtil.createVariable(pos, "$foreach$i", foreach.varType);
                foreachVariable.symbol = new BVarSymbol(0, names.fromIdNode(foreachVariable.name),
                                                        this.env.scope.owner.pkgID, foreachVariable.type,
                                                        this.env.scope.owner);
                BLangSimpleVarRef foreachVarRef = ASTBuilderUtil.createVariableRef(pos, foreachVariable.symbol);
                foreach.variableDefinitionNode = ASTBuilderUtil.createVariableDef(pos, foreachVariable);
                foreach.isDeclaredWithVar = true;
                BLangBlockStmt foreachBodyBlock = ASTBuilderUtil.createBlockStmt(pos);

                BTupleType foreachVarRefType = (BTupleType) foreachVarRef.type;

                BLangIndexBasedAccess indexExpr = (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
                indexExpr.pos = pos;
                indexExpr.expr = foreachVarRef;
                indexExpr.indexExpr = rewriteExpr(createIntLiteral(0));
                indexExpr.type = foreachVarRefType.tupleTypes.get(0);

                BLangIndexBasedAccess valueExpr = (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
                valueExpr.pos = pos;
                valueExpr.expr = foreachVarRef;
                valueExpr.indexExpr = rewriteExpr(createIntLiteral(1));
                valueExpr.type = foreachVarRefType.tupleTypes.get(1);

                addMemberStoreForKeyValuePair(pos, foreachBodyBlock, mappingVarRef, indexExpr, valueExpr);

                foreach.body = foreachBodyBlock;
                blockStmt.addStatement(foreach);
            }
        }

        BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, mappingVarRef);
        stmtExpression.type = type;
        return stmtExpression;
    }

    private void addMemberStoreForKeyValuePair(DiagnosticPos pos, BLangBlockStmt blockStmt,
                                               BLangExpression mappingVarRef, BLangExpression indexExpr,
                                               BLangExpression value) {
        BLangAssignment assignmentStmt = ASTBuilderUtil.createAssignmentStmt(pos, blockStmt);
        assignmentStmt.expr = rewriteExpr(value);

        BLangIndexBasedAccess indexAccessNode = (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
        indexAccessNode.pos = pos;
        indexAccessNode.expr = mappingVarRef;
        indexAccessNode.indexExpr = rewriteExpr(indexExpr);
        indexAccessNode.type = value.type;
        assignmentStmt.varRef = indexAccessNode;
    }

    private Map<String, BLangExpression> getKeyValuePairs(BLangStatementExpression desugaredMappingConst) {
        List<BLangStatement> stmts = ((BLangBlockStmt) desugaredMappingConst.stmt).stmts;

        Map<String, BLangExpression> keyValuePairs = new HashMap<>();

        for (int i = 1; i < stmts.size(); i++) {
            BLangAssignment assignmentStmt = (BLangAssignment) stmts.get(i);

            BLangExpression indexExpr = ((BLangIndexBasedAccess) assignmentStmt.varRef).indexExpr;
            if (indexExpr.getKind() != NodeKind.LITERAL) {
                continue;
            }

            keyValuePairs.put((String) ((BLangLiteral) indexExpr).value, assignmentStmt.expr);
        }
        return keyValuePairs;
    }
}

Line commented on: restArgs.get(restArgs.size() - 1).getKind() == NodeKind.REST_ARGS_EXPR &&

Revised code:
public void visit(BLangFunction funcNode) {
        SymbolEnv funcEnv = SymbolEnv.createFunctionEnv(funcNode, funcNode.symbol.scope, env);
        if (!funcNode.interfaceFunction) {
            addReturnIfNotPresent(funcNode);
        }

        
        funcNode.originalFuncSymbol = funcNode.symbol;
        funcNode.symbol = ASTBuilderUtil.duplicateInvokableSymbol(funcNode.symbol);
        funcNode.requiredParams = rewrite(funcNode.requiredParams, funcEnv);
        funcNode.restParam = rewrite(funcNode.restParam, funcEnv);
        funcNode.workers = rewrite(funcNode.workers, funcEnv);

        if (funcNode.returnTypeNode != null && funcNode.returnTypeNode.getKind() != null) {
            funcNode.returnTypeNode = rewrite(funcNode.returnTypeNode, funcEnv);
        }

        List<BLangAnnotationAttachment> participantAnnotation
                = funcNode.annAttachments.stream()
                .filter(a -> Transactions.isTransactionsAnnotation(a.pkgAlias.value,
                                                                   a.annotationName.value))
                .collect(Collectors.toList());
        funcNode.body = rewrite(funcNode.body, funcEnv);
        funcNode.annAttachments.forEach(attachment -> rewrite(attachment, env));
        if (funcNode.returnTypeNode != null) {
            funcNode.returnTypeAnnAttachments.forEach(attachment -> rewrite(attachment, env));
        }

        if (participantAnnotation.isEmpty()) {
            
            result = funcNode;
            return;
        }

        
        
        
        
        
        result = desugarParticipantFunction(funcNode, participantAnnotation);
    }

    private BLangFunction desugarParticipantFunction(BLangFunction funcNode,
                                                     List<BLangAnnotationAttachment> participantAnnotation) {
        BLangAnnotationAttachment annotation = participantAnnotation.get(0);
        BLangBlockFunctionBody onCommitBody = null;
        BLangBlockFunctionBody onAbortBody = null;
        funcNode.requiredParams.forEach(bLangSimpleVariable -> bLangSimpleVariable.symbol.closure = true);
        
        if (funcNode.receiver != null) {
            funcNode.receiver.symbol.closure = true;
        }
        BType trxReturnType = BUnionType.create(null, symTable.errorType, symTable.anyType);
        BLangType trxReturnNode = ASTBuilderUtil.createTypeNode(trxReturnType);
        
        BLangLambdaFunction commitFunc = createLambdaFunction(funcNode.pos, "$anonOnCommitFunc$",
                                                              ASTBuilderUtil.createTypeNode(symTable.nilType));
        BLangLambdaFunction abortFunc = createLambdaFunction(funcNode.pos, "$anonOnAbortFunc$",
                                                             ASTBuilderUtil.createTypeNode(symTable.nilType));

        BLangSimpleVariable onCommitTrxVar = ASTBuilderUtil
                .createVariable(funcNode.pos, "$trxId$0", symTable.stringType, null,
                                new BVarSymbol(0, names.fromString("$trxId$0"), this.env.scope.owner.pkgID,
                                               symTable.stringType, commitFunc.function.symbol));
        BLangSimpleVariable onAbortTrxVar = ASTBuilderUtil
                .createVariable(funcNode.pos, "$trxId$0", symTable.stringType, null,
                                new BVarSymbol(0, names.fromString("$trxId$0"), this.env.scope.owner.pkgID,
                                               symTable.stringType, abortFunc.function.symbol));

        BLangSimpleVarRef trxIdOnCommitRef = ASTBuilderUtil.createVariableRef(funcNode.pos, onCommitTrxVar.symbol);

        BLangSimpleVarRef trxIdOnAbortRef = ASTBuilderUtil.createVariableRef(funcNode.pos, onAbortTrxVar.symbol);

        for (Map.Entry<String, BLangExpression> entry :
                getKeyValuePairs((BLangStatementExpression) annotation.expr).entrySet()) {
            switch (entry.getKey()) {
                case Transactions.TRX_ONCOMMIT_FUNC:
                    BInvokableSymbol commitSym = (BInvokableSymbol) ((BLangSimpleVarRef) entry.getValue()).symbol;
                    BLangInvocation onCommit = ASTBuilderUtil
                            .createInvocationExprMethod(funcNode.pos, commitSym, Lists.of(trxIdOnCommitRef),
                                                        Collections.emptyList(), symResolver);
                    BLangStatement onCommitStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onCommit);
                    onCommitBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos, Lists.of(onCommitStmt));
                    break;
                case Transactions.TRX_ONABORT_FUNC:
                    BInvokableSymbol abortSym = (BInvokableSymbol) ((BLangSimpleVarRef) entry.getValue()).symbol;
                    BLangInvocation onAbort = ASTBuilderUtil
                            .createInvocationExprMethod(funcNode.pos, abortSym, Lists.of(trxIdOnAbortRef),
                                                        Collections.emptyList(), symResolver);
                    BLangStatement onAbortStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onAbort);
                    onAbortBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos, Lists.of(onAbortStmt));
                    break;
            }
        }

        if (onCommitBody == null) {
            onCommitBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos);
            BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onCommitBody);
            returnStmt.expr = ASTBuilderUtil.createLiteral(funcNode.pos, symTable.nilType, Names.NIL_VALUE);

        }
        if (onAbortBody == null) {
            onAbortBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos);
            BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, onAbortBody);
            returnStmt.expr = ASTBuilderUtil.createLiteral(funcNode.pos, symTable.nilType, Names.NIL_VALUE);
        }

        commitFunc.function.body = onCommitBody;
        commitFunc.function.requiredParams.add(onCommitTrxVar);
        commitFunc.type = new BInvokableType(Lists.of(onCommitTrxVar.symbol.type),
                                             commitFunc.function.symbol.type.getReturnType(), null);
        commitFunc.function.symbol.type = commitFunc.type;
        commitFunc.function.symbol.params = Lists.of(onCommitTrxVar.symbol);

        abortFunc.function.body = onAbortBody;
        abortFunc.function.requiredParams.add(onAbortTrxVar);
        abortFunc.type = new BInvokableType(Lists.of(onAbortTrxVar.symbol.type),
                                            abortFunc.function.symbol.type.getReturnType(), null);
        abortFunc.function.symbol.type = abortFunc.type;
        abortFunc.function.symbol.params = Lists.of(onAbortTrxVar.symbol);

        BSymbol trxModSym = env.enclPkg.imports
                .stream()
                .filter(importPackage -> importPackage.symbol.
                        pkgID.toString().equals(Names.TRANSACTION_ORG.value + Names.ORG_NAME_SEPARATOR.value
                                                        + Names.TRANSACTION_PACKAGE.value))
                .findAny().get().symbol;
        
        BInvokableSymbol invokableSymbol =
                (BInvokableSymbol) symResolver.lookupSymbolInMainSpace(symTable.pkgEnvMap.get(trxModSym),
                        getParticipantFunctionName(funcNode));
        BLangLiteral transactionBlockId = ASTBuilderUtil.createLiteral(funcNode.pos, symTable.stringType,
                getTransactionBlockId());

        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        BLangLambdaFunction trxMainWrapperFunc = createLambdaFunction(funcNode.pos, "$anonTrxWrapperFunc$",
                                                                      Collections.emptyList(),
                                                                      funcNode.returnTypeNode,
                                                                      funcNode.body);

        for (BLangSimpleVariable var : funcNode.requiredParams) {
            trxMainWrapperFunc.function.closureVarSymbols.add(new ClosureVarSymbol(var.symbol, var.pos));
        }

        BLangBlockFunctionBody trxMainBody = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos);
        BLangLambdaFunction trxMainFunc
                = createLambdaFunction(funcNode.pos, "$anonTrxParticipantFunc$", Collections.emptyList(),
                                       trxReturnNode, trxMainBody);
        trxMainWrapperFunc.capturedClosureEnv = trxMainFunc.function.clonedEnv;
        commitFunc.capturedClosureEnv = env.createClone();
        abortFunc.capturedClosureEnv = env.createClone();
        BVarSymbol wrapperSym = new BVarSymbol(0, names.fromString("$wrapper$1"), this.env.scope.owner.pkgID,
                                               trxMainWrapperFunc.type, trxMainFunc.function.symbol);
        BLangSimpleVariable wrapperFuncVar = ASTBuilderUtil.createVariable(funcNode.pos, "$wrapper$1",
                                                                           trxMainWrapperFunc.type, trxMainWrapperFunc,
                                                                           wrapperSym);

        BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(funcNode.pos, trxMainBody);
        variableDef.var = wrapperFuncVar;

        BLangSimpleVarRef wrapperVarRef = rewrite(ASTBuilderUtil.createVariableRef(variableDef.pos, 
                                                                         wrapperFuncVar.symbol), env);
        BLangInvocation wrapperInvocation = new BFunctionPointerInvocation(trxMainWrapperFunc.pos, wrapperVarRef, 
                                                                           wrapperFuncVar.symbol, 
                                                                           trxMainWrapperFunc.function.symbol.retType);
        BLangReturn wrapperReturn = ASTBuilderUtil.createReturnStmt(funcNode.pos, addConversionExprIfRequired
                (wrapperInvocation, trxReturnNode.type));

        trxMainWrapperFunc.function.receiver = funcNode.receiver;
        trxMainFunc.function.receiver = funcNode.receiver;
        trxMainBody.stmts.add(wrapperReturn);
        rewrite(trxMainFunc.function, env);

        List<BLangExpression> requiredArgs = Lists.of(transactionBlockId, trxMainFunc, commitFunc, abortFunc);
        BLangInvocation participantInvocation
                = ASTBuilderUtil.createInvocationExprMethod(funcNode.pos, invokableSymbol, requiredArgs,
                                                            Collections.emptyList(), symResolver);
        participantInvocation.type = ((BInvokableType) invokableSymbol.type).retType;
        BLangStatement stmt = ASTBuilderUtil.createReturnStmt(funcNode.pos, addConversionExprIfRequired
                (participantInvocation, funcNode.symbol.retType));
        funcNode.body = ASTBuilderUtil.createBlockFunctionBody(funcNode.pos, Lists.of(rewrite(stmt, env)));
        
        return funcNode;
    }

    private Name getParticipantFunctionName(BLangFunction function) {
        if (Symbols.isFlagOn((function).symbol.flags, Flags.RESOURCE)) {
            return TRX_REMOTE_PARTICIPANT_BEGIN_FUNCTION;
        }
        return TRX_LOCAL_PARTICIPANT_BEGIN_FUNCTION;
    }

    @Override
    public void visit(BLangResource resourceNode) {
    }

    public void visit(BLangAnnotation annotationNode) {
        annotationNode.annAttachments.forEach(attachment ->  rewrite(attachment, env));
    }

    public void visit(BLangAnnotationAttachment annAttachmentNode) {
        annAttachmentNode.expr = rewrite(annAttachmentNode.expr, env);
        result = annAttachmentNode;
    }

    @Override
    public void visit(BLangSimpleVariable varNode) {
        if (((varNode.symbol.owner.tag & SymTag.INVOKABLE) != SymTag.INVOKABLE)
                && (varNode.symbol.owner.tag & SymTag.LET) != SymTag.LET) {
            varNode.expr = null;
            result = varNode;
            return;
        }

        if (varNode.typeNode != null && varNode.typeNode.getKind() != null) {
            varNode.typeNode = rewrite(varNode.typeNode, env);
        }

        
        BLangExpression bLangExpression = rewriteExpr(varNode.expr);
        if (bLangExpression != null) {
            bLangExpression = addConversionExprIfRequired(bLangExpression, varNode.type);
        }
        varNode.expr = bLangExpression;

        varNode.annAttachments.forEach(attachment -> rewrite(attachment, env));

        result = varNode;
    }

    @Override
    public void visit(BLangLetExpression letExpression) {
        SymbolEnv prevEnv = this.env;
        this.env = letExpression.env;
        BLangExpression expr = letExpression.expr;
        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(letExpression.pos);
        for (BLangLetVariable letVariable : letExpression.letVarDeclarations) {
            BLangNode node  = rewrite((BLangNode) letVariable.definitionNode, env);
            if (node.getKind() == NodeKind.BLOCK) {
                blockStmt.stmts.addAll(((BLangBlockStmt) node).stmts);
            } else {
                blockStmt.addStatement((BLangSimpleVariableDef) node);
            }
        }
        BLangSimpleVariableDef tempVarDef = createVarDef(String.format("$let_var_%d_$", letCount++),
                expr.type, expr, expr.pos);
        BLangSimpleVarRef tempVarRef = ASTBuilderUtil.createVariableRef(expr.pos, tempVarDef.var.symbol);
        blockStmt.addStatement(tempVarDef);
        BLangStatementExpression stmtExpr = ASTBuilderUtil.createStatementExpression(blockStmt, tempVarRef);
        stmtExpr.type = expr.type;
        result = rewrite(stmtExpr, env);
        this.env = prevEnv;
    }

    @Override
    public void visit(BLangTupleVariable varNode) {
        result = varNode;
    }

    @Override
    public void visit(BLangRecordVariable varNode) {
        result = varNode;
    }

    @Override
    public void visit(BLangErrorVariable varNode) {
        result = varNode;
    }

    

    @Override
    public void visit(BLangBlockStmt block) {
        SymbolEnv blockEnv = SymbolEnv.createBlockEnv(block, env);
        block.stmts = rewriteStmt(block.stmts, blockEnv);
        result = block;
    }

    @Override
    public void visit(BLangSimpleVariableDef varDefNode) {
        varDefNode.var = rewrite(varDefNode.var, env);
        result = varDefNode;
    }

    @Override
    public void visit(BLangTupleVariableDef varDefNode) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        varDefNode.var = rewrite(varDefNode.var, env);
        BLangTupleVariable tupleVariable = varDefNode.var;

        
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(varDefNode.pos);

        
        BType runTimeType = new BArrayType(symTable.anyType);

        
        String name = "tuple";
        final BLangSimpleVariable tuple = ASTBuilderUtil.createVariable(varDefNode.pos, name, runTimeType, null,
                new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, runTimeType,
                        this.env.scope.owner));
        tuple.expr = tupleVariable.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(varDefNode.pos, blockStmt);
        variableDef.var = tuple;

        
        createVarDefStmts(tupleVariable, blockStmt, tuple.symbol, null);
        createRestFieldVarDefStmts(tupleVariable, blockStmt, tuple.symbol);

        
        result = rewrite(blockStmt, env);
    }

    private void createRestFieldVarDefStmts(BLangTupleVariable parentTupleVariable, BLangBlockStmt blockStmt,
                                            BVarSymbol tupleVarSymbol) {
        final BLangSimpleVariable arrayVar = (BLangSimpleVariable) parentTupleVariable.restVariable;
        boolean isTupleType = parentTupleVariable.type.tag == TypeTags.TUPLE;
        DiagnosticPos pos = blockStmt.pos;
        if (arrayVar != null) {
            
            BLangArrayLiteral arrayExpr = createArrayLiteralExprNode();
            arrayExpr.type = arrayVar.type;
            arrayVar.expr = arrayExpr;
            BLangSimpleVariableDef arrayVarDef = ASTBuilderUtil.createVariableDefStmt(arrayVar.pos, blockStmt);
            arrayVarDef.var = arrayVar;

            
            
            
            BLangExpression tupleExpr = parentTupleVariable.expr;
            BLangSimpleVarRef arrayVarRef = ASTBuilderUtil.createVariableRef(pos, arrayVar.symbol);

            BLangLiteral startIndexLiteral = (BLangLiteral) TreeBuilder.createLiteralExpression();
            startIndexLiteral.value = (long) (isTupleType ? ((BTupleType) parentTupleVariable.type).tupleTypes.size()
                    : parentTupleVariable.memberVariables.size());
            startIndexLiteral.type = symTable.intType;
            BLangInvocation lengthInvocation = createLengthInvocation(pos, tupleExpr);
            BLangInvocation intRangeInvocation = replaceWithIntRange(pos, startIndexLiteral,
                    getModifiedIntRangeEndExpr(lengthInvocation));

            BLangForeach foreach = (BLangForeach) TreeBuilder.createForeachNode();
            foreach.pos = pos;
            foreach.collection = intRangeInvocation;
            types.setForeachTypedBindingPatternType(foreach);

            final BLangSimpleVariable foreachVariable = ASTBuilderUtil.createVariable(pos,
                    "$foreach$i", foreach.varType);
            foreachVariable.symbol = new BVarSymbol(0, names.fromIdNode(foreachVariable.name),
                    this.env.scope.owner.pkgID, foreachVariable.type, this.env.scope.owner);
            BLangSimpleVarRef foreachVarRef = ASTBuilderUtil.createVariableRef(pos, foreachVariable.symbol);
            foreach.variableDefinitionNode = ASTBuilderUtil.createVariableDef(pos, foreachVariable);
            foreach.isDeclaredWithVar = true;
            BLangBlockStmt foreachBody = ASTBuilderUtil.createBlockStmt(pos);

            
            BLangIndexBasedAccess indexAccessExpr = ASTBuilderUtil.createIndexAccessExpr(arrayVarRef,
                    createLengthInvocation(pos, arrayVarRef));
            indexAccessExpr.type = (isTupleType ? ((BTupleType) parentTupleVariable.type).restType : symTable.anyType);
            createSimpleVarRefAssignmentStmt(indexAccessExpr, foreachBody, foreachVarRef, tupleVarSymbol, null);
            foreach.body = foreachBody;
            blockStmt.addStatement(foreach);
        }
    }

    @Override
    public void visit(BLangRecordVariableDef varDefNode) {

        BLangRecordVariable varNode = varDefNode.var;

        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(varDefNode.pos);

        BType runTimeType = new BMapType(TypeTags.MAP, symTable.anyType, null);

        final BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(varDefNode.pos, "$map$0", runTimeType,
                null, new BVarSymbol(0, names.fromString("$map$0"), this.env.scope.owner.pkgID,
                        runTimeType, this.env.scope.owner));
        mapVariable.expr = varDefNode.var.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(varDefNode.pos, blockStmt);
        variableDef.var = mapVariable;

        createVarDefStmts(varNode, blockStmt, mapVariable.symbol, null);

        result = rewrite(blockStmt, env);
    }

    @Override
    public void visit(BLangErrorVariableDef varDefNode) {
        BLangErrorVariable errorVariable = varDefNode.errorVariable;

        
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(varDefNode.pos);

        
        BVarSymbol errorVarSymbol = new BVarSymbol(0, names.fromString("$error$"),
                this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner);
        final BLangSimpleVariable error = ASTBuilderUtil.createVariable(varDefNode.pos, errorVarSymbol.name.value,
                symTable.errorType, null, errorVarSymbol);
        error.expr = errorVariable.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(varDefNode.pos, blockStmt);
        variableDef.var = error;

        
        createVarDefStmts(errorVariable, blockStmt, error.symbol, null);

        
        result = rewrite(blockStmt, env);
    }

    /**
     * This method iterate through each member of the tupleVar and create the relevant var def statements. This method
     * does the check for node kind of each member and call the related var def creation method.
     *
     * Example:
     * ((string, float) int)) ((a, b), c)) = (tuple)
     *
     * (a, b) is again a tuple, so it is a recursive var def creation.
     *
     * c is a simple var, so a simple var def will be created.
     *
     */
    private void createVarDefStmts(BLangTupleVariable parentTupleVariable, BLangBlockStmt parentBlockStmt,
                                   BVarSymbol tupleVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {

        final List<BLangVariable> memberVars = parentTupleVariable.memberVariables;
        for (int index = 0; index < memberVars.size(); index++) {
            BLangVariable variable = memberVars.get(index);
            BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(variable.pos, symTable.intType, (long) index);

            if (NodeKind.VARIABLE == variable.getKind()) { 
                createSimpleVarDefStmt((BLangSimpleVariable) variable, parentBlockStmt, indexExpr, tupleVarSymbol,
                        parentIndexAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.TUPLE_VARIABLE) { 
                BLangTupleVariable tupleVariable = (BLangTupleVariable) variable;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVariable.pos,
                        new BArrayType(symTable.anyType), tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangTupleVariable) variable, parentBlockStmt, tupleVarSymbol, arrayAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.RECORD_VARIABLE) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, symTable.mapType, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangRecordVariable) variable, parentBlockStmt, tupleVarSymbol, arrayAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.ERROR_VARIABLE) {

                BType accessedElemType = symTable.errorType;
                if (tupleVarSymbol.type.tag == TypeTags.ARRAY) {
                    BArrayType arrayType = (BArrayType) tupleVarSymbol.type;
                    accessedElemType = arrayType.eType;
                }
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, accessedElemType, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangErrorVariable) variable, parentBlockStmt, tupleVarSymbol, arrayAccessExpr);
            }
        }
    }

    /**
     * Overloaded method to handle record variables.
     * This method iterate through each member of the recordVar and create the relevant var def statements. This method
     * does the check for node kind of each member and call the related var def creation method.
     *
     * Example:
     * type Foo record {
     *     string name;
     *     (int, string) age;
     *     Address address;
     * };
     *
     * Foo {name: a, age: (b, c), address: d} = {record literal}
     *
     *  a is a simple var, so a simple var def will be created.
     *
     * (b, c) is a tuple, so it is a recursive var def creation.
     *
     * d is a record, so it is a recursive var def creation.
     *
     */
    private void createVarDefStmts(BLangRecordVariable parentRecordVariable, BLangBlockStmt parentBlockStmt,
                                   BVarSymbol recordVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {

        List<BLangRecordVariableKeyValue> variableList = parentRecordVariable.variableList;
        for (BLangRecordVariableKeyValue recordFieldKeyValue : variableList) {
            BLangVariable variable = recordFieldKeyValue.valueBindingPattern;
            BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(variable.pos, symTable.stringType,
                    recordFieldKeyValue.key.value);

            if (recordFieldKeyValue.valueBindingPattern.getKind() == NodeKind.VARIABLE) {
                createSimpleVarDefStmt((BLangSimpleVariable) recordFieldKeyValue.valueBindingPattern, parentBlockStmt,
                        indexExpr, recordVarSymbol, parentIndexAccessExpr);
                continue;
            }

            if (recordFieldKeyValue.valueBindingPattern.getKind() == NodeKind.TUPLE_VARIABLE) {
                BLangTupleVariable tupleVariable = (BLangTupleVariable) recordFieldKeyValue.valueBindingPattern;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVariable.pos,
                        new BArrayType(symTable.anyType), recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangTupleVariable) recordFieldKeyValue.valueBindingPattern,
                        parentBlockStmt, recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (recordFieldKeyValue.valueBindingPattern.getKind() == NodeKind.RECORD_VARIABLE) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentRecordVariable.pos, symTable.mapType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangRecordVariable) recordFieldKeyValue.valueBindingPattern, parentBlockStmt,
                        recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (variable.getKind() == NodeKind.ERROR_VARIABLE) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentRecordVariable.pos, variable.type, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarDefStmts((BLangErrorVariable) variable, parentBlockStmt, recordVarSymbol, arrayAccessExpr);
            }
        }

        if (parentRecordVariable.restParam != null) {
            
            
            

            DiagnosticPos pos = parentBlockStmt.pos;
            BMapType restParamType = (BMapType) ((BLangVariable) parentRecordVariable.restParam).type;
            BLangSimpleVarRef variableReference;

            if (parentIndexAccessExpr != null) {
                BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(pos, "$map$1",
                        parentIndexAccessExpr.type, null, new BVarSymbol(0, names.fromString("$map$1"),
                                this.env.scope.owner.pkgID, parentIndexAccessExpr.type, this.env.scope.owner));
                mapVariable.expr = parentIndexAccessExpr;
                BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(pos, parentBlockStmt);
                variableDef.var = mapVariable;

                variableReference = ASTBuilderUtil.createVariableRef(pos, mapVariable.symbol);
            } else {
                variableReference = ASTBuilderUtil.createVariableRef(pos,
                        ((BLangSimpleVariableDef) parentBlockStmt.stmts.get(0)).var.symbol);
            }

            List<String> keysToRemove = parentRecordVariable.variableList.stream()
                    .map(var -> var.getKey().getValue())
                    .collect(Collectors.toList());

            BLangSimpleVariable filteredDetail = generateRestFilter(variableReference, pos,
                    keysToRemove, restParamType, parentBlockStmt);

            BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol);

            
            BLangSimpleVariable restParam = (BLangSimpleVariable) parentRecordVariable.restParam;
            BLangSimpleVariableDef restParamVarDef = ASTBuilderUtil.createVariableDefStmt(pos,
                    parentBlockStmt);
            restParamVarDef.var = restParam;
            restParamVarDef.var.type = restParamType;
            restParam.expr = varRef;
        }
    }

    /**
     * This method will create the relevant var def statements for reason and details of the error variable.
     * The var def statements are created by creating the reason() and detail() builtin methods.
     */
    private void createVarDefStmts(BLangErrorVariable parentErrorVariable, BLangBlockStmt parentBlockStmt,
                                   BVarSymbol errorVariableSymbol, BLangIndexBasedAccess parentIndexBasedAccess) {

        BVarSymbol convertedErrorVarSymbol;
        if (parentIndexBasedAccess != null) {
            BType prevType = parentIndexBasedAccess.type;
            parentIndexBasedAccess.type = symTable.anyType;
            BLangSimpleVariableDef errorVarDef = createVarDef("$error$" + errorCount++,
                    symTable.errorType,
                    addConversionExprIfRequired(parentIndexBasedAccess, symTable.errorType),
                    parentErrorVariable.pos);
            parentIndexBasedAccess.type = prevType;
            parentBlockStmt.addStatement(errorVarDef);
            convertedErrorVarSymbol = errorVarDef.var.symbol;
        } else {
            convertedErrorVarSymbol = errorVariableSymbol;
        }

        parentErrorVariable.reason.expr = generateErrorReasonBuiltinFunction(parentErrorVariable.reason.pos,
                parentErrorVariable.reason.type, convertedErrorVarSymbol, null);

        if (names.fromIdNode((parentErrorVariable.reason).name) == Names.IGNORE) {
            parentErrorVariable.reason = null;
        } else {
            BLangSimpleVariableDef reasonVariableDef =
                    ASTBuilderUtil.createVariableDefStmt(parentErrorVariable.reason.pos, parentBlockStmt);
            reasonVariableDef.var = parentErrorVariable.reason;
        }

        if ((parentErrorVariable.detail == null || parentErrorVariable.detail.isEmpty())
            && parentErrorVariable.restDetail == null) {
            return;
        }

        BType detailMapType;
        BType detailType = ((BErrorType) parentErrorVariable.type).detailType;
        if (detailType.tag == TypeTags.MAP) {
            detailMapType = detailType;
        } else {
            detailMapType = symTable.detailType;
        }

        parentErrorVariable.detailExpr = generateErrorDetailBuiltinFunction(
                parentErrorVariable.pos,
                convertedErrorVarSymbol, null);

        BLangSimpleVariableDef detailTempVarDef = createVarDef("$error$detail",
                parentErrorVariable.detailExpr.type, parentErrorVariable.detailExpr, parentErrorVariable.pos);
        detailTempVarDef.type = parentErrorVariable.detailExpr.type;
        parentBlockStmt.addStatement(detailTempVarDef);
        this.env.scope.define(names.fromIdNode(detailTempVarDef.var.name), detailTempVarDef.var.symbol);

        for (BLangErrorVariable.BLangErrorDetailEntry detailEntry : parentErrorVariable.detail) {
            BLangExpression detailEntryVar = createErrorDetailVar(detailEntry, detailTempVarDef.var.symbol);

            
            createAndAddBoundVariableDef(parentBlockStmt, detailEntry, detailEntryVar);

        }
        if (parentErrorVariable.restDetail != null && !parentErrorVariable.restDetail.name.value.equals(IGNORE.value)) {
            DiagnosticPos pos = parentErrorVariable.restDetail.pos;
            BLangSimpleVarRef detailVarRef = ASTBuilderUtil.createVariableRef(
                    pos, detailTempVarDef.var.symbol);
            List<String> keysToRemove = parentErrorVariable.detail.stream()
                    .map(detail -> detail.key.getValue())
                    .collect(Collectors.toList());

            BLangSimpleVariable filteredDetail = generateRestFilter(detailVarRef, parentErrorVariable.pos, keysToRemove,
                    parentErrorVariable.restDetail.type, parentBlockStmt);
            BLangSimpleVariableDef variableDefStmt = ASTBuilderUtil.createVariableDefStmt(pos, parentBlockStmt);
            variableDefStmt.var = ASTBuilderUtil.createVariable(pos,
                    parentErrorVariable.restDetail.name.value,
                    filteredDetail.type,
                    ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol),
                    parentErrorVariable.restDetail.symbol);
            BLangAssignment assignmentStmt = ASTBuilderUtil.createAssignmentStmt(pos,
                    ASTBuilderUtil.createVariableRef(pos, parentErrorVariable.restDetail.symbol),
                    ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol));
            parentBlockStmt.addStatement(assignmentStmt);
        }
        rewrite(parentBlockStmt, env);
    }

    private BLangSimpleVariableDef forceCastIfApplicable(BVarSymbol errorVarySymbol, DiagnosticPos pos,
                                                         BType targetType) {
        BVarSymbol errorVarSym = new BVarSymbol(Flags.PUBLIC, names.fromString("$cast$temp$"),
                this.env.enclPkg.packageID, targetType, this.env.scope.owner);
        BLangSimpleVarRef variableRef = ASTBuilderUtil.createVariableRef(pos, errorVarySymbol);

        BLangExpression expr;
        if (targetType.tag == TypeTags.RECORD) {
            expr = variableRef;
        } else {
            expr = addConversionExprIfRequired(variableRef, targetType);
        }
        BLangSimpleVariable errorVar = ASTBuilderUtil.createVariable(pos, errorVarSym.name.value, targetType, expr,
                errorVarSym);
        return ASTBuilderUtil.createVariableDef(pos, errorVar);
    }

    private BLangSimpleVariable generateRestFilter(BLangSimpleVarRef mapVarRef, DiagnosticPos pos,
                                                   List<String> keysToRemove, BType targetType,
                                                   BLangBlockStmt parentBlockStmt) {
        
        
        
        
        

        BLangExpression typeCastExpr = addConversionExprIfRequired(mapVarRef, targetType);

        int restNum = annonVarCount++;
        String name = "$map$ref$" + restNum;
        BLangSimpleVariable mapVariable = defVariable(pos, targetType, parentBlockStmt, typeCastExpr, name);

        BLangInvocation entriesInvocation = generateMapEntriesInvocation(
                ASTBuilderUtil.createVariableRef(pos, mapVariable.symbol), typeCastExpr.type);
        String entriesVarName = "$map$ref$entries$" + restNum;
        BType entriesType = new BMapType(TypeTags.MAP,
                new BTupleType(Arrays.asList(symTable.stringType, ((BMapType) targetType).constraint)), null);
        BLangSimpleVariable entriesInvocationVar = defVariable(pos, entriesType, parentBlockStmt,
                addConversionExprIfRequired(entriesInvocation, entriesType),
                entriesVarName);

        BLangLambdaFunction filter = createFuncToFilterOutRestParam(keysToRemove, pos);

        BLangInvocation filterInvocation = generateMapFilterInvocation(pos, entriesInvocationVar, filter);
        String filteredEntriesName = "$filtered$detail$entries" + restNum;
        BLangSimpleVariable filteredVar = defVariable(pos, entriesType, parentBlockStmt, filterInvocation,
                filteredEntriesName);

        String filteredVarName = "$detail$filtered" + restNum;
        BLangLambdaFunction backToMapLambda = generateEntriesToMapLambda(pos);
        BLangInvocation mapInvocation = generateMapMapInvocation(pos, filteredVar, backToMapLambda);
        BLangSimpleVariable filtered = defVariable(pos, targetType, parentBlockStmt,
                mapInvocation,
                filteredVarName);

        String filteredRestVarName = "$restVar$" + restNum;
        BLangInvocation constructed = generateConstructFromInvocation(pos, targetType, filtered.symbol);
        return defVariable(pos, targetType, parentBlockStmt,
                addConversionExprIfRequired(constructed, targetType),
                filteredRestVarName);
    }

    private BLangInvocation generateMapEntriesInvocation(BLangExpression expr, BType type) {
        BLangInvocation invocationNode = createInvocationNode("entries", new ArrayList<>(), type);

        invocationNode.expr = expr;
        invocationNode.symbol = symResolver.lookupLangLibMethod(type, names.fromString("entries"));
        invocationNode.requiredArgs = Lists.of(expr);
        invocationNode.type = invocationNode.symbol.type.getReturnType();
        invocationNode.langLibInvocation = true;
        return invocationNode;
    }

    private BLangInvocation generateMapMapInvocation(DiagnosticPos pos, BLangSimpleVariable filteredVar,
                                                     BLangLambdaFunction backToMapLambda) {
        BLangInvocation invocationNode = createInvocationNode("map", new ArrayList<>(), filteredVar.type);

        invocationNode.expr = ASTBuilderUtil.createVariableRef(pos, filteredVar.symbol);
        invocationNode.symbol = symResolver.lookupLangLibMethod(filteredVar.type, names.fromString("map"));
        invocationNode.requiredArgs = Lists.of(ASTBuilderUtil.createVariableRef(pos, filteredVar.symbol));
        invocationNode.type = invocationNode.symbol.type.getReturnType();
        invocationNode.requiredArgs.add(backToMapLambda);
        return invocationNode;
    }

    private BLangLambdaFunction generateEntriesToMapLambda(DiagnosticPos pos) {
        

        String anonfuncName = "$anonGetValFunc$" + lambdaFunctionCount++;
        BLangFunction function = ASTBuilderUtil.createFunction(pos, anonfuncName);

        BVarSymbol keyValSymbol = new BVarSymbol(0, names.fromString("$lambdaArg$0"), this.env.scope.owner.pkgID,
                getStringAnyTupleType(), this.env.scope.owner);

        BLangSimpleVariable inputParameter = ASTBuilderUtil.createVariable(pos, null, getStringAnyTupleType(),
                                                                           null, keyValSymbol);
        function.requiredParams.add(inputParameter);

        BLangValueType anyType = new BLangValueType();
        anyType.typeKind = TypeKind.ANY;
        anyType.type = symTable.anyType;
        function.returnTypeNode = anyType;

        BLangBlockFunctionBody functionBlock = ASTBuilderUtil.createBlockFunctionBody(pos, new ArrayList<>());
        function.body = functionBlock;

        BLangIndexBasedAccess indexBasesAccessExpr =
                ASTBuilderUtil.createIndexBasesAccessExpr(pos, symTable.anyType, keyValSymbol,
                                                          ASTBuilderUtil
                                                                  .createLiteral(pos, symTable.intType, (long) 1));
        BLangSimpleVariableDef tupSecondElem = createVarDef("val", indexBasesAccessExpr.type,
                                                            indexBasesAccessExpr, pos);
        functionBlock.addStatement(tupSecondElem);

        
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(pos, functionBlock);
        returnStmt.expr = ASTBuilderUtil.createVariableRef(pos, tupSecondElem.var.symbol);

        
        BInvokableSymbol functionSymbol = Symbols.createFunctionSymbol(Flags.asMask(function.flagSet),
                new Name(function.name.value), env.enclPkg.packageID, function.type, env.enclEnv.enclVarSym, true);
        functionSymbol.retType = function.returnTypeNode.type;
        functionSymbol.params = function.requiredParams.stream()
                .map(param -> param.symbol)
                .collect(Collectors.toList());
        functionSymbol.scope = env.scope;
        functionSymbol.type = new BInvokableType(Collections.singletonList(getStringAnyTupleType()),
                symTable.anyType, null);
        function.symbol = functionSymbol;
        rewrite(function, env);
        env.enclPkg.addFunction(function);

        
        return createLambdaFunction(function, functionSymbol);
    }

    private BLangInvocation generateMapFilterInvocation(DiagnosticPos pos,
                                                        BLangSimpleVariable entriesInvocationVar,
                                                        BLangLambdaFunction filter) {
        BLangInvocation invocationNode = createInvocationNode("filter", new ArrayList<>(), entriesInvocationVar.type);

        invocationNode.expr = ASTBuilderUtil.createVariableRef(pos, entriesInvocationVar.symbol);
        invocationNode.symbol = symResolver.lookupLangLibMethod(entriesInvocationVar.type, names.fromString("filter"));
        invocationNode.requiredArgs = Lists.of(ASTBuilderUtil.createVariableRef(pos, entriesInvocationVar.symbol));
        invocationNode.type = invocationNode.symbol.type.getReturnType();
        invocationNode.requiredArgs.add(filter);

        return invocationNode;
    }

    private BLangSimpleVariable defVariable(DiagnosticPos pos, BType varType, BLangBlockStmt parentBlockStmt,
                                            BLangExpression expression, String name) {
        Name varName = names.fromString(name);
        BLangSimpleVariable detailMap = ASTBuilderUtil.createVariable(pos, name, varType, expression,
                new BVarSymbol(Flags.PUBLIC, varName, env.enclPkg.packageID, varType, env.scope.owner));
        BLangSimpleVariableDef constructedMap = ASTBuilderUtil.createVariableDef(pos, detailMap);
        constructedMap.type = varType;
        parentBlockStmt.addStatement(constructedMap);
        env.scope.define(varName, detailMap.symbol);
        return detailMap;
    }

    private void createAndAddBoundVariableDef(BLangBlockStmt parentBlockStmt,
                                              BLangErrorVariable.BLangErrorDetailEntry detailEntry,
                                              BLangExpression detailEntryVar) {
        if (detailEntry.valueBindingPattern.getKind() == NodeKind.VARIABLE) {
            BLangSimpleVariableDef errorDetailVar = createVarDef(
                    ((BLangSimpleVariable) detailEntry.valueBindingPattern).name.value,
                    detailEntry.valueBindingPattern.type,
                    detailEntryVar,
                    detailEntry.valueBindingPattern.pos);
            parentBlockStmt.addStatement(errorDetailVar);

        } else if (detailEntry.valueBindingPattern.getKind() == NodeKind.RECORD_VARIABLE) {
            BLangRecordVariableDef recordVariableDef = ASTBuilderUtil.createRecordVariableDef(
                    detailEntry.valueBindingPattern.pos,
                    (BLangRecordVariable) detailEntry.valueBindingPattern);
            recordVariableDef.var.expr = detailEntryVar;
            recordVariableDef.type = symTable.recordType;
            parentBlockStmt.addStatement(recordVariableDef);

        } else if (detailEntry.valueBindingPattern.getKind() == NodeKind.TUPLE_VARIABLE) {
            BLangTupleVariableDef tupleVariableDef = ASTBuilderUtil.createTupleVariableDef(
                    detailEntry.valueBindingPattern.pos, (BLangTupleVariable) detailEntry.valueBindingPattern);
            parentBlockStmt.addStatement(tupleVariableDef);
        }
    }

    private BLangExpression createErrorDetailVar(BLangErrorVariable.BLangErrorDetailEntry detailEntry,
                                                 BVarSymbol tempDetailVarSymbol) {
        BLangExpression detailEntryVar = createIndexBasedAccessExpr(
                detailEntry.valueBindingPattern.type,
                detailEntry.valueBindingPattern.pos,
                createStringLiteral(detailEntry.key.pos, detailEntry.key.value),
                tempDetailVarSymbol, null);
        if (detailEntryVar.getKind() == NodeKind.INDEX_BASED_ACCESS_EXPR) {
            BLangIndexBasedAccess bLangIndexBasedAccess = (BLangIndexBasedAccess) detailEntryVar;
            bLangIndexBasedAccess.originalType = symTable.pureType;
        }
        return detailEntryVar;
    }

    private BLangExpression constructStringTemplateConcatExpression(List<BLangExpression> exprs) {
        BLangExpression concatExpr = null;
        BLangExpression currentExpr;
        for (BLangExpression expr : exprs) {
            currentExpr = expr;
            if (expr.type.tag != TypeTags.STRING && expr.type.tag != TypeTags.XML) {
                currentExpr = getToStringInvocationOnExpr(expr);
            }

            if (concatExpr == null) {
                concatExpr = currentExpr;
                continue;
            }

            BType binaryExprType =
                    TypeTags.isXMLTypeTag(concatExpr.type.tag) || TypeTags.isXMLTypeTag(currentExpr.type.tag)
                            ? symTable.xmlType
                            : symTable.stringType;
            concatExpr =
                    ASTBuilderUtil.createBinaryExpr(concatExpr.pos, concatExpr, currentExpr,
                            binaryExprType, OperatorKind.ADD, null);
        }
        return concatExpr;
    }

    private BLangInvocation getToStringInvocationOnExpr(BLangExpression expression) {
        BInvokableSymbol symbol = (BInvokableSymbol) symTable.langValueModuleSymbol.scope
                .lookup(names.fromString(TO_STRING_FUNCTION_NAME)).symbol;

        List<BLangExpression> requiredArgs = new ArrayList<BLangExpression>() {{
            add(addConversionExprIfRequired(expression, symbol.params.get(0).type));
        }};
        return ASTBuilderUtil.createInvocationExprMethod(expression.pos, symbol, requiredArgs, new ArrayList<>(),
                                                         symResolver);
    }

    
    private BLangInvocation generateErrorDetailBuiltinFunction(DiagnosticPos pos, BVarSymbol errorVarySymbol,
                                                               BLangIndexBasedAccess parentIndexBasedAccess) {
        BLangExpression onExpr =
                parentIndexBasedAccess != null
                        ? parentIndexBasedAccess : ASTBuilderUtil.createVariableRef(pos, errorVarySymbol);

        return createLangLibInvocationNode(ERROR_DETAIL_FUNCTION_NAME, onExpr, new ArrayList<>(), null, pos);
    }

    private BLangInvocation generateErrorReasonBuiltinFunction(DiagnosticPos pos, BType reasonType,
                                                               BVarSymbol errorVarSymbol,
                                                               BLangIndexBasedAccess parentIndexBasedAccess) {
        BLangExpression onExpr =
                parentIndexBasedAccess != null
                        ? parentIndexBasedAccess : ASTBuilderUtil.createVariableRef(pos, errorVarSymbol);
        return createLangLibInvocationNode(ERROR_REASON_FUNCTION_NAME, onExpr, new ArrayList<>(), reasonType, pos);
    }

    private BLangInvocation generateConstructFromInvocation(DiagnosticPos pos,
                                                            BType targetType,
                                                            BVarSymbol source) {
        BType typedescType = new BTypedescType(targetType, symTable.typeDesc.tsymbol);
        BLangInvocation invocationNode = createInvocationNode(CONSTRUCT_FROM, new ArrayList<>(), typedescType);

        BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
        typedescExpr.resolvedType = targetType;
        typedescExpr.type = typedescType;

        invocationNode.expr = typedescExpr;
        invocationNode.symbol = symResolver.lookupLangLibMethod(typedescType, names.fromString(CONSTRUCT_FROM));
        invocationNode.requiredArgs = Lists.of(typedescExpr, ASTBuilderUtil.createVariableRef(pos, source));
        invocationNode.type = BUnionType.create(null, targetType, symTable.errorType);
        return invocationNode;
    }

    private BLangLambdaFunction createFuncToFilterOutRestParam(List<String> toRemoveList, DiagnosticPos pos) {

        
        
        
        
        
        
        
        
        
        
        
        

        String anonfuncName = "$anonRestParamFilterFunc$" + lambdaFunctionCount++;
        BLangFunction function = ASTBuilderUtil.createFunction(pos, anonfuncName);

        BVarSymbol keyValSymbol = new BVarSymbol(0, names.fromString("$lambdaArg$0"), this.env.scope.owner.pkgID,
                                                 getStringAnyTupleType(), this.env.scope.owner);
        BLangBlockFunctionBody functionBlock = createAnonymousFunctionBlock(pos, function, keyValSymbol);

        BLangIndexBasedAccess indexBasesAccessExpr =
                ASTBuilderUtil.createIndexBasesAccessExpr(pos, symTable.anyType, keyValSymbol, ASTBuilderUtil
                        .createLiteral(pos, symTable.intType, (long) 0));
        BLangSimpleVariableDef tupFirstElem = createVarDef("key", indexBasesAccessExpr.type,
                                                           indexBasesAccessExpr, pos);
        functionBlock.addStatement(tupFirstElem);

        
        for (String toRemoveItem : toRemoveList) {
            createIfStmt(pos, tupFirstElem.var.symbol, functionBlock, toRemoveItem);
        }

        
        BInvokableSymbol functionSymbol = createReturnTrueStatement(pos, function, functionBlock);

        
        return createLambdaFunction(function, functionSymbol);
    }

    private BLangLambdaFunction createFuncToFilterOutRestParam(BLangRecordVariable recordVariable, DiagnosticPos pos) {
        List<String> fieldNamesToRemove = recordVariable.variableList.stream()
                .map(var -> var.getKey().getValue())
                .collect(Collectors.toList());
        return createFuncToFilterOutRestParam(fieldNamesToRemove, pos);
    }

    private void createIfStmt(DiagnosticPos pos, BVarSymbol inputParamSymbol, BLangBlockFunctionBody blockStmt,
                              String key) {
        BLangSimpleVarRef firstElemRef = ASTBuilderUtil.createVariableRef(pos, inputParamSymbol);
        BLangExpression converted = addConversionExprIfRequired(firstElemRef, symTable.stringType);

        BLangIf ifStmt = ASTBuilderUtil.createIfStmt(pos, blockStmt);

        BLangBlockStmt ifBlock = ASTBuilderUtil.createBlockStmt(pos, new ArrayList<>());
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(pos, ifBlock);
        returnStmt.expr = ASTBuilderUtil.createLiteral(pos, symTable.booleanType, false);
        ifStmt.body = ifBlock;

        BLangGroupExpr groupExpr = new BLangGroupExpr();
        groupExpr.type = symTable.booleanType;

        BLangBinaryExpr binaryExpr = ASTBuilderUtil.createBinaryExpr(pos, converted,
                ASTBuilderUtil.createLiteral(pos, symTable.stringType, key),
                symTable.booleanType, OperatorKind.EQUAL, null);

        binaryExpr.opSymbol = (BOperatorSymbol) symResolver.resolveBinaryOperator(
                binaryExpr.opKind, binaryExpr.lhsExpr.type, binaryExpr.rhsExpr.type);

        groupExpr.expression = binaryExpr;
        ifStmt.expr = groupExpr;
    }

    BLangLambdaFunction createLambdaFunction(BLangFunction function, BInvokableSymbol functionSymbol) {
        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        lambdaFunction.function = function;
        lambdaFunction.type = functionSymbol.type;
        return lambdaFunction;
    }

    private BInvokableSymbol createReturnTrueStatement(DiagnosticPos pos, BLangFunction function,
                                                       BLangBlockFunctionBody functionBlock) {
        BLangReturn trueReturnStmt = ASTBuilderUtil.createReturnStmt(pos, functionBlock);
        trueReturnStmt.expr = ASTBuilderUtil.createLiteral(pos, symTable.booleanType, true);

        
        BInvokableSymbol functionSymbol = Symbols.createFunctionSymbol(Flags.asMask(function.flagSet),
                                                                       new Name(function.name.value),
                                                                       env.enclPkg.packageID, function.type,
                                                                       env.enclEnv.enclVarSym, true);
        functionSymbol.retType = function.returnTypeNode.type;
        functionSymbol.params = function.requiredParams.stream()
                .map(param -> param.symbol)
                .collect(Collectors.toList());
        functionSymbol.scope = env.scope;
        functionSymbol.type = new BInvokableType(Collections.singletonList(getStringAnyTupleType()),
                                                 getRestType(functionSymbol), symTable.booleanType, null);
        function.symbol = functionSymbol;
        rewrite(function, env);
        env.enclPkg.addFunction(function);
        return functionSymbol;
    }

    private BLangBlockFunctionBody createAnonymousFunctionBlock(DiagnosticPos pos, BLangFunction function,
                                                                BVarSymbol keyValSymbol) {
        BLangSimpleVariable inputParameter = ASTBuilderUtil.createVariable(pos, null, getStringAnyTupleType(),
                                                                           null, keyValSymbol);
        function.requiredParams.add(inputParameter);
        BLangValueType booleanTypeKind = new BLangValueType();
        booleanTypeKind.typeKind = TypeKind.BOOLEAN;
        booleanTypeKind.type = symTable.booleanType;
        function.returnTypeNode = booleanTypeKind;

        BLangBlockFunctionBody functionBlock = ASTBuilderUtil.createBlockFunctionBody(pos, new ArrayList<>());
        function.body = functionBlock;
        return functionBlock;
    }

    private BTupleType getStringAnyTupleType() {
        ArrayList<BType> typeList = new ArrayList<BType>() {{
            add(symTable.stringType);
            add(symTable.anyType);
        }};
        return new BTupleType(typeList);
    }

    /**
     * This method creates a simple variable def and assigns and array expression based on the given indexExpr.
     *
     *  case 1: when there is no parent array access expression, but with the indexExpr : 1
     *  string s = x[1];
     *
     *  case 2: when there is a parent array expression : x[2] and indexExpr : 3
     *  string s = x[2][3];
     *
     *  case 3: when there is no parent array access expression, but with the indexExpr : name
     *  string s = x[name];
     *
     *  case 4: when there is a parent map expression : x[name] and indexExpr : fName
     *  string s = x[name][fName]; 
     *
     *  case 5: when there is a parent map expression : x[name] and indexExpr : 1
     *  string s = x[name][1]; 
     */
    private void createSimpleVarDefStmt(BLangSimpleVariable simpleVariable, BLangBlockStmt parentBlockStmt,
                                        BLangLiteral indexExpr, BVarSymbol tupleVarSymbol,
                                        BLangIndexBasedAccess parentArrayAccessExpr) {

        Name varName = names.fromIdNode(simpleVariable.name);
        if (varName == Names.IGNORE) {
            return;
        }

        final BLangSimpleVariableDef simpleVariableDef = ASTBuilderUtil.createVariableDefStmt(simpleVariable.pos,
                parentBlockStmt);
        simpleVariableDef.var = simpleVariable;

        simpleVariable.expr = createIndexBasedAccessExpr(simpleVariable.type, simpleVariable.pos,
                indexExpr, tupleVarSymbol, parentArrayAccessExpr);
    }

    @Override
    public void visit(BLangAssignment assignNode) {
        if (safeNavigateLHS(assignNode.varRef)) {
            BLangAccessExpression accessExpr = (BLangAccessExpression) assignNode.varRef;
            accessExpr.leafNode = true;
            result = rewriteSafeNavigationAssignment(accessExpr, assignNode.expr, assignNode.safeAssignment);
            result = rewrite(result, env);
            return;
        }

        assignNode.varRef = rewriteExpr(assignNode.varRef);
        assignNode.expr = rewriteExpr(assignNode.expr);
        assignNode.expr = addConversionExprIfRequired(rewriteExpr(assignNode.expr), assignNode.varRef.type);
        result = assignNode;
    }

    @Override
    public void visit(BLangTupleDestructure tupleDestructure) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        


        
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(tupleDestructure.pos);

        
        BType runTimeType = new BArrayType(symTable.anyType);

        
        String name = "tuple";
        final BLangSimpleVariable tuple = ASTBuilderUtil.createVariable(tupleDestructure.pos, name, runTimeType, null,
                new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, runTimeType,
                        this.env.scope.owner));
        tuple.expr = tupleDestructure.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(tupleDestructure.pos,
                blockStmt);
        variableDef.var = tuple;

        
        createVarRefAssignmentStmts(tupleDestructure.varRef, blockStmt, tuple.symbol, null);
        createRestFieldAssignmentStmt(tupleDestructure, blockStmt, tuple.symbol);

        
        result = rewrite(blockStmt, env);
    }

    private void createRestFieldAssignmentStmt(BLangTupleDestructure tupleDestructure, BLangBlockStmt blockStmt,
                                               BVarSymbol tupleVarSymbol) {
        BLangTupleVarRef tupleVarRef = tupleDestructure.varRef;
        DiagnosticPos pos = blockStmt.pos;
        if (tupleVarRef.restParam != null) {
            BLangExpression tupleExpr = tupleDestructure.expr;

            
            BLangSimpleVarRef restParam = (BLangSimpleVarRef) tupleVarRef.restParam;
            BArrayType restParamType = (BArrayType) restParam.type;
            BLangArrayLiteral arrayExpr = createArrayLiteralExprNode();
            arrayExpr.type = restParamType;

            BLangAssignment restParamAssignment = ASTBuilderUtil.createAssignmentStmt(pos, blockStmt);
            restParamAssignment.varRef = restParam;
            restParamAssignment.varRef.type = restParamType;
            restParamAssignment.expr = arrayExpr;

            
            
            
            BLangLiteral startIndexLiteral = (BLangLiteral) TreeBuilder.createLiteralExpression();
            startIndexLiteral.value = (long) tupleVarRef.expressions.size();
            startIndexLiteral.type = symTable.intType;
            BLangInvocation lengthInvocation = createLengthInvocation(pos, tupleExpr);
            BLangInvocation intRangeInvocation = replaceWithIntRange(pos, startIndexLiteral,
                    getModifiedIntRangeEndExpr(lengthInvocation));

            BLangForeach foreach = (BLangForeach) TreeBuilder.createForeachNode();
            foreach.pos = pos;
            foreach.collection = intRangeInvocation;
            types.setForeachTypedBindingPatternType(foreach);

            final BLangSimpleVariable foreachVariable = ASTBuilderUtil.createVariable(pos,
                    "$foreach$i", foreach.varType);
            foreachVariable.symbol = new BVarSymbol(0, names.fromIdNode(foreachVariable.name),
                    this.env.scope.owner.pkgID, foreachVariable.type, this.env.scope.owner);
            BLangSimpleVarRef foreachVarRef = ASTBuilderUtil.createVariableRef(pos, foreachVariable.symbol);
            foreach.variableDefinitionNode = ASTBuilderUtil.createVariableDef(pos, foreachVariable);
            foreach.isDeclaredWithVar = true;
            BLangBlockStmt foreachBody = ASTBuilderUtil.createBlockStmt(pos);

            
            BLangIndexBasedAccess indexAccessExpr = ASTBuilderUtil.createIndexAccessExpr(restParam,
                    createLengthInvocation(pos, restParam));
            indexAccessExpr.type = restParamType.eType;
            createSimpleVarRefAssignmentStmt(indexAccessExpr, foreachBody, foreachVarRef, tupleVarSymbol, null);

            foreach.body = foreachBody;
            blockStmt.addStatement(foreach);
        }
    }

    private BLangInvocation createLengthInvocation(DiagnosticPos pos, BLangExpression collection) {
        BInvokableSymbol lengthInvokableSymbol = (BInvokableSymbol) symResolver
                .lookupLangLibMethod(collection.type, names.fromString(LENGTH_FUNCTION_NAME));
        BLangInvocation lengthInvocation = ASTBuilderUtil.createInvocationExprForMethod(pos, lengthInvokableSymbol,
                Lists.of(collection), symResolver);
        lengthInvocation.argExprs = lengthInvocation.requiredArgs;
        lengthInvocation.type = lengthInvokableSymbol.type.getReturnType();
        return lengthInvocation;
    }

    /**
     * This method iterate through each member of the tupleVarRef and create the relevant var ref assignment statements.
     * This method does the check for node kind of each member and call the related var ref creation method.
     *
     * Example:
     * ((a, b), c)) = (tuple)
     *
     * (a, b) is again a tuple, so it is a recursive var ref creation.
     *
     * c is a simple var, so a simple var def will be created.
     *
     */
    private void createVarRefAssignmentStmts(BLangTupleVarRef parentTupleVariable, BLangBlockStmt parentBlockStmt,
                                             BVarSymbol tupleVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {

        final List<BLangExpression> expressions = parentTupleVariable.expressions;
        for (int index = 0; index < expressions.size(); index++) {
            BLangExpression expression = expressions.get(index);
            if (NodeKind.SIMPLE_VARIABLE_REF == expression.getKind() ||
                    NodeKind.FIELD_BASED_ACCESS_EXPR == expression.getKind() ||
                    NodeKind.INDEX_BASED_ACCESS_EXPR == expression.getKind() ||
                    NodeKind.XML_ATTRIBUTE_ACCESS_EXPR == expression.getKind()) {
                
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(expression.pos, symTable.intType, (long) index);
                createSimpleVarRefAssignmentStmt((BLangVariableReference) expression, parentBlockStmt, indexExpr,
                        tupleVarSymbol, parentIndexAccessExpr);
                continue;
            }

            if (expression.getKind() == NodeKind.TUPLE_VARIABLE_REF) {
                
                BLangTupleVarRef tupleVarRef = (BLangTupleVarRef) expression;
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(tupleVarRef.pos, symTable.intType, (long) index);
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVarRef.pos,
                        new BArrayType(symTable.anyType), tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangTupleVarRef) expression, parentBlockStmt, tupleVarSymbol,
                        arrayAccessExpr);
                continue;
            }

            if (expression.getKind() == NodeKind.RECORD_VARIABLE_REF) {
                
                BLangRecordVarRef recordVarRef = (BLangRecordVarRef) expression;
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(recordVarRef.pos, symTable.intType,
                                                                      (long) index);
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, symTable.mapType, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangRecordVarRef) expression, parentBlockStmt, tupleVarSymbol,
                        arrayAccessExpr);

                TypeDefBuilderHelper.addTypeDefinition(recordVarRef.type, recordVarRef.type.tsymbol,
                                                       TypeDefBuilderHelper.createRecordTypeNode(
                                                                  (BRecordType) recordVarRef.type,
                                                                  env.enclPkg.packageID, symTable, recordVarRef.pos),
                                                       env);

                continue;
            }

            if (expression.getKind() == NodeKind.ERROR_VARIABLE_REF) {
                
                BLangErrorVarRef errorVarRef = (BLangErrorVarRef) expression;
                BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(errorVarRef.pos, symTable.intType,
                        (long) index);
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentTupleVariable.pos, expression.type, tupleVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangErrorVarRef) expression, parentBlockStmt, tupleVarSymbol,
                        arrayAccessExpr);
            }
        }
    }

    /**
     * This method creates a assignment statement and assigns and array expression based on the given indexExpr.
     *
     */
    private void createSimpleVarRefAssignmentStmt(BLangVariableReference simpleVarRef, BLangBlockStmt parentBlockStmt,
                                                  BLangExpression indexExpr, BVarSymbol tupleVarSymbol,
                                                  BLangIndexBasedAccess parentArrayAccessExpr) {

        if (simpleVarRef.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
            Name varName = names.fromIdNode(((BLangSimpleVarRef) simpleVarRef).variableName);
            if (varName == Names.IGNORE) {
                return;
            }
        }

        BLangExpression assignmentExpr = createIndexBasedAccessExpr(simpleVarRef.type, simpleVarRef.pos,
                indexExpr, tupleVarSymbol, parentArrayAccessExpr);

        assignmentExpr = addConversionExprIfRequired(assignmentExpr, simpleVarRef.type);

        final BLangAssignment assignmentStmt = ASTBuilderUtil.createAssignmentStmt(parentBlockStmt.pos,
                parentBlockStmt);
        assignmentStmt.varRef = simpleVarRef;
        assignmentStmt.expr = assignmentExpr;
    }

    private BLangExpression createIndexBasedAccessExpr(BType varType, DiagnosticPos varPos, BLangExpression indexExpr,
                                                       BVarSymbol tupleVarSymbol, BLangIndexBasedAccess parentExpr) {

        BLangIndexBasedAccess arrayAccess = ASTBuilderUtil.createIndexBasesAccessExpr(varPos,
                symTable.anyType, tupleVarSymbol, indexExpr);
        arrayAccess.originalType = varType;

        if (parentExpr != null) {
            arrayAccess.expr = parentExpr;
        }

        final BLangExpression assignmentExpr;
        if (types.isValueType(varType)) {
            BLangTypeConversionExpr castExpr = (BLangTypeConversionExpr) TreeBuilder.createTypeConversionNode();
            castExpr.expr = arrayAccess;
            castExpr.type = varType;
            assignmentExpr = castExpr;
        } else {
            assignmentExpr = arrayAccess;
        }
        return assignmentExpr;
    }

    @Override
    public void visit(BLangRecordDestructure recordDestructure) {

        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(recordDestructure.pos);

        BType runTimeType = new BMapType(TypeTags.MAP, symTable.anyType, null);

        String name = "$map$0";
        final BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(recordDestructure.pos, name, runTimeType,
                null, new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID,
                        runTimeType, this.env.scope.owner));
        mapVariable.expr = recordDestructure.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.
                createVariableDefStmt(recordDestructure.pos, blockStmt);
        variableDef.var = mapVariable;

        
        createVarRefAssignmentStmts(recordDestructure.varRef, blockStmt, mapVariable.symbol, null);

        
        result = rewrite(blockStmt, env);
    }

    @Override
    public void visit(BLangErrorDestructure errorDestructure) {
        final BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(errorDestructure.pos);
        String name = "$error$";
        final BLangSimpleVariable errorVar = ASTBuilderUtil.createVariable(errorDestructure.pos, name,
                symTable.errorType, null, new BVarSymbol(0, names.fromString(name),
                        this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner));
        errorVar.expr = errorDestructure.expr;
        final BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(errorDestructure.pos,
                blockStmt);
        variableDef.var = errorVar;
        createVarRefAssignmentStmts(errorDestructure.varRef, blockStmt, errorVar.symbol, null);
        result = rewrite(blockStmt, env);
    }

    private void createVarRefAssignmentStmts(BLangRecordVarRef parentRecordVarRef, BLangBlockStmt parentBlockStmt,
                                             BVarSymbol recordVarSymbol, BLangIndexBasedAccess parentIndexAccessExpr) {
        final List<BLangRecordVarRefKeyValue> variableRefList = parentRecordVarRef.recordRefFields;
        for (BLangRecordVarRefKeyValue varRefKeyValue : variableRefList) {
            BLangExpression variableReference = varRefKeyValue.variableReference;
            BLangLiteral indexExpr = ASTBuilderUtil.createLiteral(variableReference.pos, symTable.stringType,
                    varRefKeyValue.variableName.getValue());

            if (NodeKind.SIMPLE_VARIABLE_REF == variableReference.getKind() ||
                    NodeKind.FIELD_BASED_ACCESS_EXPR == variableReference.getKind() ||
                    NodeKind.INDEX_BASED_ACCESS_EXPR == variableReference.getKind() ||
                    NodeKind.XML_ATTRIBUTE_ACCESS_EXPR == variableReference.getKind()) {
                createSimpleVarRefAssignmentStmt((BLangVariableReference) variableReference, parentBlockStmt,
                        indexExpr, recordVarSymbol, parentIndexAccessExpr);
                continue;
            }

            if (NodeKind.RECORD_VARIABLE_REF == variableReference.getKind()) {
                BLangRecordVarRef recordVariable = (BLangRecordVarRef) variableReference;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(
                        parentRecordVarRef.pos, symTable.mapType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts(recordVariable, parentBlockStmt, recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (NodeKind.TUPLE_VARIABLE_REF == variableReference.getKind()) {
                BLangTupleVarRef tupleVariable = (BLangTupleVarRef) variableReference;
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(tupleVariable.pos,
                        symTable.tupleType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts(tupleVariable, parentBlockStmt, recordVarSymbol, arrayAccessExpr);
                continue;
            }

            if (NodeKind.ERROR_VARIABLE_REF == variableReference.getKind()) {
                BLangIndexBasedAccess arrayAccessExpr = ASTBuilderUtil.createIndexBasesAccessExpr(variableReference.pos,
                        symTable.errorType, recordVarSymbol, indexExpr);
                if (parentIndexAccessExpr != null) {
                    arrayAccessExpr.expr = parentIndexAccessExpr;
                }
                createVarRefAssignmentStmts((BLangErrorVarRef) variableReference, parentBlockStmt, recordVarSymbol,
                        arrayAccessExpr);
            }
        }

        if (parentRecordVarRef.restParam != null) {
            
            
            

            DiagnosticPos pos = parentBlockStmt.pos;
            BMapType restParamType = (BMapType) ((BLangSimpleVarRef) parentRecordVarRef.restParam).type;
            BLangSimpleVarRef variableReference;

            if (parentIndexAccessExpr != null) {
                BLangSimpleVariable mapVariable = ASTBuilderUtil.createVariable(pos, "$map$1", restParamType,
                        null, new BVarSymbol(0, names.fromString("$map$1"), this.env.scope.owner.pkgID,
                                restParamType, this.env.scope.owner));
                mapVariable.expr = parentIndexAccessExpr;
                BLangSimpleVariableDef variableDef = ASTBuilderUtil.createVariableDefStmt(pos, parentBlockStmt);
                variableDef.var = mapVariable;

                variableReference = ASTBuilderUtil.createVariableRef(pos, mapVariable.symbol);
            } else {
                variableReference = ASTBuilderUtil.createVariableRef(pos,
                        ((BLangSimpleVariableDef) parentBlockStmt.stmts.get(0)).var.symbol);
            }

            BLangSimpleVarRef restParam = (BLangSimpleVarRef) parentRecordVarRef.restParam;

            List<String> keysToRemove = parentRecordVarRef.recordRefFields.stream()
                    .map(field -> field.variableName.value)
                    .collect(Collectors.toList());

            BLangSimpleVariable filteredDetail = generateRestFilter(variableReference, pos,
                    keysToRemove, restParamType, parentBlockStmt);

            BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, filteredDetail.symbol);

            
            BLangAssignment restParamAssignment = ASTBuilderUtil.createAssignmentStmt(pos, parentBlockStmt);
            restParamAssignment.varRef = restParam;
            restParamAssignment.varRef.type = restParamType;
            restParamAssignment.expr = varRef;
        }
    }

    private void createVarRefAssignmentStmts(BLangErrorVarRef parentErrorVarRef, BLangBlockStmt parentBlockStmt,
                                             BVarSymbol errorVarySymbol, BLangIndexBasedAccess parentIndexAccessExpr) {
        if (parentErrorVarRef.reason.getKind() != NodeKind.SIMPLE_VARIABLE_REF ||
                names.fromIdNode(((BLangSimpleVarRef) parentErrorVarRef.reason).variableName) != Names.IGNORE) {
            BLangAssignment reasonAssignment = ASTBuilderUtil
                    .createAssignmentStmt(parentBlockStmt.pos, parentBlockStmt);
            reasonAssignment.expr = generateErrorReasonBuiltinFunction(parentErrorVarRef.reason.pos,
                    symTable.stringType, errorVarySymbol, parentIndexAccessExpr);
            reasonAssignment.expr = addConversionExprIfRequired(reasonAssignment.expr, parentErrorVarRef.reason.type);
            reasonAssignment.varRef = parentErrorVarRef.reason;
        }

        
        if (parentErrorVarRef.detail.isEmpty() && isIgnoredErrorRefRestVar(parentErrorVarRef)) {
            return;
        }

        BLangInvocation errorDetailBuiltinFunction = generateErrorDetailBuiltinFunction(parentErrorVarRef.pos,
                errorVarySymbol,
                parentIndexAccessExpr);

        BLangSimpleVariableDef detailTempVarDef = createVarDef("$error$detail$" + errorCount++,
                                                               symTable.detailType, errorDetailBuiltinFunction,
                                                               parentErrorVarRef.pos);
        detailTempVarDef.type = symTable.detailType;
        parentBlockStmt.addStatement(detailTempVarDef);
        this.env.scope.define(names.fromIdNode(detailTempVarDef.var.name), detailTempVarDef.var.symbol);

        List<String> extractedKeys = new ArrayList<>();
        for (BLangNamedArgsExpression detail : parentErrorVarRef.detail) {
            extractedKeys.add(detail.name.value);
            BLangVariableReference ref = (BLangVariableReference) detail.expr;

            
            BLangExpression detailEntryVar = createIndexBasedAccessExpr(ref.type, ref.pos,
                    createStringLiteral(detail.name.pos, detail.name.value),
                    detailTempVarDef.var.symbol, null);
            if (detailEntryVar.getKind() == NodeKind.INDEX_BASED_ACCESS_EXPR) {
                BLangIndexBasedAccess bLangIndexBasedAccess = (BLangIndexBasedAccess) detailEntryVar;
                bLangIndexBasedAccess.originalType = symTable.pureType;
            }

            BLangAssignment detailAssignment = ASTBuilderUtil.createAssignmentStmt(ref.pos, parentBlockStmt);
            detailAssignment.varRef = ref;
            detailAssignment.expr = detailEntryVar;
        }

        if (!isIgnoredErrorRefRestVar(parentErrorVarRef)) {
            BLangSimpleVarRef detailVarRef = ASTBuilderUtil.createVariableRef(parentErrorVarRef.restVar.pos,
                    detailTempVarDef.var.symbol);

            BLangSimpleVariable filteredDetail = generateRestFilter(detailVarRef, parentErrorVarRef.restVar.pos,
                    extractedKeys,
                    parentErrorVarRef.restVar.type, parentBlockStmt);
            BLangAssignment restAssignment = ASTBuilderUtil.createAssignmentStmt(parentErrorVarRef.restVar.pos,
                    parentBlockStmt);
            restAssignment.varRef = parentErrorVarRef.restVar;
            restAssignment.expr = ASTBuilderUtil.createVariableRef(parentErrorVarRef.restVar.pos,
                    filteredDetail.symbol);
        }

        BErrorType errorType = (BErrorType) parentErrorVarRef.type;
        if (errorType.detailType.getKind() == TypeKind.RECORD) {
            
            BRecordTypeSymbol tsymbol = (BRecordTypeSymbol) errorType.detailType.tsymbol;
            tsymbol.initializerFunc = createRecordInitFunc();
            tsymbol.scope.define(tsymbol.initializerFunc.funcName, tsymbol.initializerFunc.symbol);
        }
    }

    private boolean isIgnoredErrorRefRestVar(BLangErrorVarRef parentErrorVarRef) {
        if (parentErrorVarRef.restVar == null) {
            return true;
        }
        if (parentErrorVarRef.restVar.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
            return (((BLangSimpleVarRef) parentErrorVarRef.restVar).variableName.value.equals(IGNORE.value));
        }
        return false;
    }

    @Override
    public void visit(BLangAbort abortNode) {
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(abortNode.pos, symTable.intType, -1L);
        result = rewrite(returnStmt, env);
    }

    @Override
    public void visit(BLangRetry retryNode) {
        BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(retryNode.pos, symTable.intType, 1L);
        result = rewrite(returnStmt, env);
    }

    @Override
    public void visit(BLangContinue nextNode) {
        result = nextNode;
    }

    @Override
    public void visit(BLangBreak breakNode) {
        result = breakNode;
    }

    @Override
    public void visit(BLangReturn returnNode) {
        
        
        if (returnNode.expr != null) {
            returnNode.expr = rewriteExpr(returnNode.expr);
        }
        result = returnNode;
    }

    @Override
    public void visit(BLangPanic panicNode) {
        panicNode.expr = rewriteExpr(panicNode.expr);
        result = panicNode;
    }

    @Override
    public void visit(BLangXMLNSStatement xmlnsStmtNode) {
        xmlnsStmtNode.xmlnsDecl = rewrite(xmlnsStmtNode.xmlnsDecl, env);
        result = xmlnsStmtNode;
    }

    @Override
    public void visit(BLangXMLNS xmlnsNode) {
        BLangXMLNS generatedXMLNSNode;
        xmlnsNode.namespaceURI = rewriteExpr(xmlnsNode.namespaceURI);
        BSymbol ownerSymbol = xmlnsNode.symbol.owner;

        
        if ((ownerSymbol.tag & SymTag.INVOKABLE) == SymTag.INVOKABLE ||
                (ownerSymbol.tag & SymTag.SERVICE) == SymTag.SERVICE) {
            generatedXMLNSNode = new BLangLocalXMLNS();
        } else {
            generatedXMLNSNode = new BLangPackageXMLNS();
        }

        generatedXMLNSNode.namespaceURI = xmlnsNode.namespaceURI;
        generatedXMLNSNode.prefix = xmlnsNode.prefix;
        generatedXMLNSNode.symbol = xmlnsNode.symbol;
        result = generatedXMLNSNode;
    }

    public void visit(BLangCompoundAssignment compoundAssignment) {

        BLangVariableReference varRef = compoundAssignment.varRef;
        if (compoundAssignment.varRef.getKind() != NodeKind.INDEX_BASED_ACCESS_EXPR) {
            
            
            
            if (varRef.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
                varRef = ASTBuilderUtil.createVariableRef(compoundAssignment.varRef.pos, varRef.symbol);
                varRef.lhsVar = true;
            }

            result = ASTBuilderUtil.createAssignmentStmt(compoundAssignment.pos, rewriteExpr(varRef),
                    rewriteExpr(compoundAssignment.modifiedExpr));
            return;
        }
        
        
        
        
        
        
        List<BLangStatement> statements = new ArrayList<>();
        List<BLangSimpleVarRef> varRefs = new ArrayList<>();
        List<BType> types = new ArrayList<>();

        
        
        
        
        do {
            BLangSimpleVariableDef tempIndexVarDef = createVarDef("$temp" + ++indexExprCount + "$",
                    ((BLangIndexBasedAccess) varRef).indexExpr.type, ((BLangIndexBasedAccess) varRef).indexExpr,
                    compoundAssignment.pos);
            BLangSimpleVarRef tempVarRef = ASTBuilderUtil.createVariableRef(tempIndexVarDef.pos,
                    tempIndexVarDef.var.symbol);
            statements.add(0, tempIndexVarDef);
            varRefs.add(0, tempVarRef);
            types.add(0, varRef.type);

            varRef = (BLangVariableReference) ((BLangIndexBasedAccess) varRef).expr;
        } while (varRef.getKind() == NodeKind.INDEX_BASED_ACCESS_EXPR);

        
        BLangVariableReference var = varRef;
        for (int ref = 0; ref < varRefs.size(); ref++) {
            var = ASTBuilderUtil.createIndexAccessExpr(var, varRefs.get(ref));
            var.type = types.get(ref);
        }
        var.type = compoundAssignment.varRef.type;

        
        BLangExpression rhsExpression = ASTBuilderUtil.createBinaryExpr(compoundAssignment.pos, var,
                compoundAssignment.expr, compoundAssignment.type, compoundAssignment.opKind, null);
        rhsExpression.type = compoundAssignment.modifiedExpr.type;

        
        BLangAssignment assignStmt = ASTBuilderUtil.createAssignmentStmt(compoundAssignment.pos, var,
                rhsExpression);

        statements.add(assignStmt);
        
        
        BLangBlockStmt bLangBlockStmt = ASTBuilderUtil.createBlockStmt(compoundAssignment.pos, statements);
        result = rewrite(bLangBlockStmt, env);
    }

    @Override
    public void visit(BLangExpressionStmt exprStmtNode) {
        exprStmtNode.expr = rewriteExpr(exprStmtNode.expr);
        result = exprStmtNode;
    }

    @Override
    public void visit(BLangIf ifNode) {
        ifNode.expr = rewriteExpr(ifNode.expr);
        ifNode.body = rewrite(ifNode.body, env);
        ifNode.elseStmt = rewrite(ifNode.elseStmt, env);

        result = ifNode;
    }

    @Override
    public void visit(BLangMatch matchStmt) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        

        
        BLangBlockStmt matchBlockStmt = (BLangBlockStmt) TreeBuilder.createBlockNode();
        matchBlockStmt.pos = matchStmt.pos;

        
        String matchExprVarName = GEN_VAR_PREFIX.value;
        BLangSimpleVariable matchExprVar = ASTBuilderUtil.createVariable(matchStmt.expr.pos,
                matchExprVarName, matchStmt.expr.type, matchStmt.expr, new BVarSymbol(0,
                        names.fromString(matchExprVarName),
                        this.env.scope.owner.pkgID, matchStmt.expr.type, this.env.scope.owner));

        
        BLangSimpleVariableDef matchExprVarDef = ASTBuilderUtil.createVariableDef(matchBlockStmt.pos, matchExprVar);

        
        
        matchBlockStmt.stmts.add(matchExprVarDef);

        
        matchBlockStmt.stmts.add(generateIfElseStmt(matchStmt, matchExprVar));

        rewrite(matchBlockStmt, this.env);
        result = matchBlockStmt;
    }

    @Override
    public void visit(BLangForeach foreach) {
        BLangBlockStmt blockNode;

        
        
        BVarSymbol dataSymbol = new BVarSymbol(0, names.fromString("$data$"), this.env.scope.owner.pkgID,
                foreach.collection.type, this.env.scope.owner);
        BLangSimpleVariable dataVariable = ASTBuilderUtil.createVariable(foreach.pos, "$data$",
                foreach.collection.type, foreach.collection, dataSymbol);
        BLangSimpleVariableDef dataVarDef = ASTBuilderUtil.createVariableDef(foreach.pos, dataVariable);

        
        BVarSymbol collectionSymbol = dataVariable.symbol;
        switch (foreach.collection.type.tag) {
            case TypeTags.STRING:
            case TypeTags.ARRAY:
            case TypeTags.TUPLE:
            case TypeTags.XML:
            case TypeTags.MAP:
            case TypeTags.STREAM:
            case TypeTags.RECORD:
                BInvokableSymbol iteratorSymbol = getLangLibIteratorInvokableSymbol(collectionSymbol);
                blockNode = desugarForeachWithIteratorDef(foreach, dataVarDef, collectionSymbol, iteratorSymbol, true);
                break;
            case TypeTags.OBJECT: 
                iteratorSymbol = getIterableObjectIteratorInvokableSymbol(collectionSymbol);
                blockNode = desugarForeachWithIteratorDef(foreach, dataVarDef, collectionSymbol, iteratorSymbol, false);
                break;
            default:
                blockNode = ASTBuilderUtil.createBlockStmt(foreach.pos);
                blockNode.stmts.add(0, dataVarDef);
                break;
        }

        
        rewrite(blockNode, this.env);
        result = blockNode;
    }

    private BLangBlockStmt desugarForeachWithIteratorDef(BLangForeach foreach,
                                                         BLangSimpleVariableDef dataVariableDefinition,
                                                         BVarSymbol collectionSymbol,
                                                         BInvokableSymbol iteratorInvokableSymbol,
                                                         boolean isIteratorFuncFromLangLib) {
        BLangSimpleVariableDef iteratorVarDef = getIteratorVariableDefinition(foreach.pos, collectionSymbol,
                iteratorInvokableSymbol, isIteratorFuncFromLangLib);
        BLangBlockStmt blockNode = desugarForeachToWhile(foreach, iteratorVarDef);
        blockNode.stmts.add(0, dataVariableDefinition);
        return blockNode;
    }

    public BInvokableSymbol getIterableObjectIteratorInvokableSymbol(BVarSymbol collectionSymbol) {
        BObjectTypeSymbol typeSymbol = (BObjectTypeSymbol) collectionSymbol.type.tsymbol;
        
        BAttachedFunction iteratorFunc = null;
        for (BAttachedFunction func : typeSymbol.attachedFuncs) {
            if (func.funcName.value.equals(BLangCompilerConstants.ITERABLE_OBJECT_ITERATOR_FUNC)) {
                iteratorFunc = func;
                break;
            }
        }
        BAttachedFunction function = iteratorFunc;
        return function.symbol;
    }

    BInvokableSymbol getLangLibIteratorInvokableSymbol(BVarSymbol collectionSymbol) {
        return (BInvokableSymbol) symResolver.lookupLangLibMethod(collectionSymbol.type,
                names.fromString(BLangCompilerConstants.ITERABLE_COLLECTION_ITERATOR_FUNC));
    }

    private BLangBlockStmt desugarForeachToWhile(BLangForeach foreach, BLangSimpleVariableDef varDef) {

        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        

        
        

        

        BVarSymbol iteratorSymbol = varDef.var.symbol;

        
        BVarSymbol resultSymbol = new BVarSymbol(0, names.fromString("$result$"), this.env.scope.owner.pkgID,
                foreach.nillableResultType, this.env.scope.owner);

        
        BLangSimpleVariableDef resultVariableDefinition = getIteratorNextVariableDefinition(foreach.pos,
                foreach.nillableResultType, iteratorSymbol, resultSymbol);

        
        BLangType userDefineType = getUserDefineTypeNode(foreach.resultType);
        BLangSimpleVarRef resultReferenceInWhile = ASTBuilderUtil.createVariableRef(foreach.pos, resultSymbol);
        BLangTypeTestExpr typeTestExpr = ASTBuilderUtil
                .createTypeTestExpr(foreach.pos, resultReferenceInWhile, userDefineType);
        
        BLangWhile whileNode = (BLangWhile) TreeBuilder.createWhileNode();
        whileNode.pos = foreach.pos;
        whileNode.expr = typeTestExpr;
        whileNode.body = foreach.body;

        
        BLangAssignment resultAssignment = getIteratorNextAssignment(foreach.pos, iteratorSymbol, resultSymbol);
        VariableDefinitionNode variableDefinitionNode = foreach.variableDefinitionNode;

        
        
        
        BLangFieldBasedAccess valueAccessExpr = getValueAccessExpression(foreach.pos, foreach.varType, resultSymbol);
        valueAccessExpr.expr = addConversionExprIfRequired(valueAccessExpr.expr,
                types.getSafeType(valueAccessExpr.expr.type, true, false));
        variableDefinitionNode.getVariable()
                .setInitialExpression(addConversionExprIfRequired(valueAccessExpr, foreach.varType));
        whileNode.body.stmts.add(0, (BLangStatement) variableDefinitionNode);
        whileNode.body.stmts.add(1, resultAssignment);

        
        BLangBlockStmt blockNode = ASTBuilderUtil.createBlockStmt(foreach.pos);

        
        blockNode.addStatement(varDef);

        
        blockNode.addStatement(resultVariableDefinition);

        
        blockNode.addStatement(whileNode);
        return blockNode;
    }

    private BLangType getUserDefineTypeNode(BType type) {
        BLangUserDefinedType recordType =
                new BLangUserDefinedType(ASTBuilderUtil.createIdentifier(null, ""),
                                         ASTBuilderUtil.createIdentifier(null, ""));
        recordType.type = type;
        return recordType;
    }

    @Override
    public void visit(BLangWhile whileNode) {
        whileNode.expr = rewriteExpr(whileNode.expr);
        whileNode.body = rewrite(whileNode.body, env);
        result = whileNode;
    }

    @Override
    public void visit(BLangLock lockNode) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(lockNode.pos);

        BLangLockStmt lockStmt = new BLangLockStmt(lockNode.pos);
        blockStmt.addStatement(lockStmt);

        enclLocks.push(lockStmt);

        BLangLiteral nilLiteral = ASTBuilderUtil.createLiteral(lockNode.pos, symTable.nilType, Names.NIL_VALUE);
        BType nillableError = BUnionType.create(null, symTable.errorType, symTable.nilType);
        BLangStatementExpression statementExpression = createStatementExpression(lockNode.body, nilLiteral);
        statementExpression.type = symTable.nilType;

        BLangTrapExpr trapExpr = (BLangTrapExpr) TreeBuilder.createTrapExpressionNode();
        trapExpr.type = nillableError;
        trapExpr.expr = statementExpression;
        BVarSymbol nillableErrorVarSymbol = new BVarSymbol(0, names.fromString("$errorResult"),
                this.env.scope.owner.pkgID, nillableError, this.env.scope.owner);
        BLangSimpleVariable simpleVariable = ASTBuilderUtil.createVariable(lockNode.pos, "$errorResult",
                nillableError, trapExpr, nillableErrorVarSymbol);
        BLangSimpleVariableDef simpleVariableDef = ASTBuilderUtil.createVariableDef(lockNode.pos, simpleVariable);
        blockStmt.addStatement(simpleVariableDef);

        BLangUnLockStmt unLockStmt = new BLangUnLockStmt(lockNode.pos);
        blockStmt.addStatement(unLockStmt);
        BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(lockNode.pos, nillableErrorVarSymbol);

        BLangBlockStmt ifBody = ASTBuilderUtil.createBlockStmt(lockNode.pos);
        BLangPanic panicNode = (BLangPanic) TreeBuilder.createPanicNode();
        panicNode.pos = lockNode.pos;
        panicNode.expr = addConversionExprIfRequired(varRef, symTable.errorType);
        ifBody.addStatement(panicNode);

        BLangTypeTestExpr isErrorTest =
                ASTBuilderUtil.createTypeTestExpr(lockNode.pos, varRef, getErrorTypeNode());
        isErrorTest.type = symTable.booleanType;

        BLangIf ifelse = ASTBuilderUtil.createIfElseStmt(lockNode.pos, isErrorTest, ifBody, null);
        blockStmt.addStatement(ifelse);
        result = rewrite(blockStmt, env);
        enclLocks.pop();
    }

    @Override
    public void visit(BLangLockStmt lockStmt) {
        result = lockStmt;
    }

    @Override
    public void visit(BLangUnLockStmt unLockStmt) {
        result = unLockStmt;
    }

    @Override
    public void visit(BLangTransaction transactionNode) {

        
        
        
        

        DiagnosticPos pos = transactionNode.pos;
        BType trxReturnType = symTable.intType;
        BType otherReturnType = symTable.nilType;
        BLangType trxReturnNode = ASTBuilderUtil.createTypeNode(trxReturnType);
        BLangType otherReturnNode = ASTBuilderUtil.createTypeNode(otherReturnType);
        DiagnosticPos invPos = transactionNode.pos;
        /* transaction block code will be desugar to function which returns int. Return value determines the status of
         the transaction code.
         ex.
            0 = successful
            1 = retry
            -1 = abort

            Since transaction block code doesn't return anything, we need to add return statement at end of the
            block unless we have abort or retry statement.
        */
        DiagnosticPos returnStmtPos = new DiagnosticPos(invPos.src,
                                                        invPos.eLine, invPos.eLine, invPos.sCol, invPos.sCol);
        BLangStatement statement = null;
        if (!transactionNode.transactionBody.stmts.isEmpty()) {
            statement = transactionNode.transactionBody.stmts.get(transactionNode.transactionBody.stmts.size() - 1);
        }
        if (statement == null || !(statement.getKind() == NodeKind.ABORT) && !(statement.getKind() == NodeKind.ABORT)) {
            BLangReturn returnStmt = ASTBuilderUtil.createReturnStmt(returnStmtPos, trxReturnType, 0L);
            transactionNode.transactionBody.addStatement(returnStmt);
        }

        
        if (transactionNode.abortedBody == null) {
            transactionNode.abortedBody = ASTBuilderUtil.createBlockStmt(transactionNode.pos);
        }
        if (transactionNode.committedBody == null) {
            transactionNode.committedBody = ASTBuilderUtil.createBlockStmt(transactionNode.pos);
        }
        if (transactionNode.onRetryBody == null) {
            transactionNode.onRetryBody = ASTBuilderUtil.createBlockStmt(transactionNode.pos);
        }

        if (transactionNode.retryCount == null) {
            transactionNode.retryCount = ASTBuilderUtil.createLiteral(pos, symTable.intType, 3L);
        }

        
        BLangLambdaFunction trxMainFunc = createLambdaFunction(pos, "$anonTrxMainFunc$", Collections.emptyList(),
                                                               trxReturnNode, transactionNode.transactionBody.stmts,
                                                               env, transactionNode.transactionBody.scope);
        BLangLambdaFunction trxOnRetryFunc = createLambdaFunction(pos, "$anonTrxOnRetryFunc$", Collections.emptyList(),
                                                                  otherReturnNode, transactionNode.onRetryBody.stmts,
                                                                  env, transactionNode.onRetryBody.scope);
        BLangLambdaFunction trxCommittedFunc = createLambdaFunction(pos, "$anonTrxCommittedFunc$",
                                                                    Collections.emptyList(), otherReturnNode,
                                                                    transactionNode.committedBody.stmts, env,
                                                                    transactionNode.committedBody.scope);
        BLangLambdaFunction trxAbortedFunc = createLambdaFunction(pos, "$anonTrxAbortedFunc$", Collections.emptyList(),
                                                                  otherReturnNode, transactionNode.abortedBody.stmts,
                                                                  env, transactionNode.abortedBody.scope);
        trxMainFunc.capturedClosureEnv = env.createClone();
        trxOnRetryFunc.capturedClosureEnv = env.createClone();
        trxCommittedFunc.capturedClosureEnv = env.createClone();
        trxAbortedFunc.capturedClosureEnv = env.createClone();

        
        PackageID packageID = new PackageID(Names.BALLERINA_ORG, Names.TRANSACTION_PACKAGE, Names.EMPTY);
        BPackageSymbol transactionPkgSymbol = new BPackageSymbol(packageID, null, 0);
        BInvokableSymbol invokableSymbol =
                (BInvokableSymbol) symResolver.lookupSymbolInMainSpace(symTable.pkgEnvMap.get(transactionPkgSymbol),
                        TRX_INITIATOR_BEGIN_FUNCTION);
        BLangLiteral transactionBlockId = ASTBuilderUtil.createLiteral(pos, symTable.stringType,
                                                                       getTransactionBlockId());
        List<BLangExpression> requiredArgs = Lists.of(transactionBlockId, transactionNode.retryCount, trxMainFunc,
                                                      trxOnRetryFunc,
                                                      trxCommittedFunc, trxAbortedFunc);
        BLangInvocation trxInvocation = ASTBuilderUtil.createInvocationExprMethod(pos, invokableSymbol,
                                                                                  requiredArgs,
                                                                                  Collections.emptyList(),
                                                                                  symResolver);
        BLangExpressionStmt stmt = ASTBuilderUtil.createExpressionStmt(pos, ASTBuilderUtil.createBlockStmt(pos));
        stmt.expr = trxInvocation;
        result = rewrite(stmt, env);
    }

    private String getTransactionBlockId() {
        return env.enclPkg.packageID.orgName + "$" + env.enclPkg.packageID.name + "$"
                + transactionIndex++;
    }

    private BLangLambdaFunction createLambdaFunction(DiagnosticPos pos, String functionNamePrefix,
                                                     List<BLangSimpleVariable> lambdaFunctionVariable,
                                                     TypeNode returnType, BLangFunctionBody lambdaBody) {
        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        BLangFunction func = ASTBuilderUtil.createFunction(pos, functionNamePrefix + lambdaFunctionCount++);
        lambdaFunction.function = func;
        func.requiredParams.addAll(lambdaFunctionVariable);
        func.setReturnTypeNode(returnType);
        func.desugaredReturnType = true;
        defineFunction(func, env.enclPkg);
        lambdaFunctionVariable = func.requiredParams;

        func.body = lambdaBody;
        func.desugared = false;
        lambdaFunction.pos = pos;
        List<BType> paramTypes = new ArrayList<>();
        lambdaFunctionVariable.forEach(variable -> paramTypes.add(variable.symbol.type));
        lambdaFunction.type = new BInvokableType(paramTypes, func.symbol.type.getReturnType(),
                                                 null);
        return lambdaFunction;
    }

    private BLangLambdaFunction createLambdaFunction(DiagnosticPos pos, String functionNamePrefix,
                                                     List<BLangSimpleVariable> lambdaFunctionVariable,
                                                     TypeNode returnType, List<BLangStatement> fnBodyStmts,
                                                     SymbolEnv env, Scope trxScope) {
        BLangBlockFunctionBody body = (BLangBlockFunctionBody) TreeBuilder.createBlockFunctionBodyNode();
        body.scope = trxScope;
        SymbolEnv bodyEnv = SymbolEnv.createFuncBodyEnv(body, env);
        body.stmts = rewriteStmt(fnBodyStmts, bodyEnv);
        return createLambdaFunction(pos, functionNamePrefix, lambdaFunctionVariable, returnType, body);
    }

    private BLangLambdaFunction createLambdaFunction(DiagnosticPos pos, String functionNamePrefix,
                                                     TypeNode returnType) {
        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        BLangFunction func = ASTBuilderUtil.createFunction(pos, functionNamePrefix + lambdaFunctionCount++);
        lambdaFunction.function = func;
        func.setReturnTypeNode(returnType);
        func.desugaredReturnType = true;
        defineFunction(func, env.enclPkg);
        func.desugared = false;
        lambdaFunction.pos = pos;
        return lambdaFunction;
    }

    private void defineFunction(BLangFunction funcNode, BLangPackage targetPkg) {
        final BPackageSymbol packageSymbol = targetPkg.symbol;
        final SymbolEnv packageEnv = this.symTable.pkgEnvMap.get(packageSymbol);
        symbolEnter.defineNode(funcNode, packageEnv);
        packageEnv.enclPkg.functions.add(funcNode);
        packageEnv.enclPkg.topLevelNodes.add(funcNode);
    }

    @Override
    public void visit(BLangForkJoin forkJoin) {
         result = forkJoin;
    }

    

    @Override
    public void visit(BLangLiteral literalExpr) {
        if (literalExpr.type.tag == TypeTags.ARRAY && ((BArrayType) literalExpr.type).eType.tag == TypeTags.BYTE) {
            
            result = rewriteBlobLiteral(literalExpr);
            return;
        }
        result = literalExpr;
    }

    private BLangNode rewriteBlobLiteral(BLangLiteral literalExpr) {
        String[] result = getBlobTextValue((String) literalExpr.value);
        byte[] values;
        if (BASE_64.equals(result[0])) {
            values = Base64.getDecoder().decode(result[1].getBytes(StandardCharsets.UTF_8));
        } else {
            values = hexStringToByteArray(result[1]);
        }
        BLangArrayLiteral arrayLiteralNode = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
        arrayLiteralNode.type = literalExpr.type;
        arrayLiteralNode.pos = literalExpr.pos;
        arrayLiteralNode.exprs = new ArrayList<>();
        for (byte b : values) {
            arrayLiteralNode.exprs.add(createByteLiteral(literalExpr.pos, b));
        }
        return arrayLiteralNode;
    }

    private String[] getBlobTextValue(String blobLiteralNodeText) {
        String nodeText = blobLiteralNodeText.replaceAll(" ", "");
        String[] result = new String[2];
        result[0] = nodeText.substring(0, nodeText.indexOf('`'));
        result[1] = nodeText.substring(nodeText.indexOf('`') + 1, nodeText.lastIndexOf('`'));
        return result;
    }

    private static byte[] hexStringToByteArray(String str) {
        int len = str.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(str.charAt(i), 16) << 4) + Character.digit(str.charAt(i + 1), 16));
        }
        return data;
    }

    @Override
    public void visit(BLangListConstructorExpr listConstructor) {
        listConstructor.exprs = rewriteExprs(listConstructor.exprs);
        BLangExpression expr;
        if (listConstructor.type.tag == TypeTags.TUPLE) {
            expr = new BLangTupleLiteral(listConstructor.pos, listConstructor.exprs, listConstructor.type);
            result = rewriteExpr(expr);
        } else if (listConstructor.type.tag == TypeTags.JSON) {
            expr = new BLangJSONArrayLiteral(listConstructor.exprs, new BArrayType(listConstructor.type));
            result = rewriteExpr(expr);
        } else if (getElementType(listConstructor.type).tag == TypeTags.JSON) {
            expr = new BLangJSONArrayLiteral(listConstructor.exprs, listConstructor.type);
            result = rewriteExpr(expr);
        } else if (listConstructor.type.tag == TypeTags.TYPEDESC) {
            final BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
            typedescExpr.resolvedType = listConstructor.typedescType;
            typedescExpr.type = symTable.typeDesc;
            result = rewriteExpr(typedescExpr);
        } else {
            expr = new BLangArrayLiteral(listConstructor.pos, listConstructor.exprs, listConstructor.type);
            result = rewriteExpr(expr);
        }
    }

    @Override
    public void visit(BLangArrayLiteral arrayLiteral) {
        arrayLiteral.exprs = rewriteExprs(arrayLiteral.exprs);

        if (arrayLiteral.type.tag == TypeTags.JSON) {
            result = new BLangJSONArrayLiteral(arrayLiteral.exprs, new BArrayType(arrayLiteral.type));
            return;
        } else if (getElementType(arrayLiteral.type).tag == TypeTags.JSON) {
            result = new BLangJSONArrayLiteral(arrayLiteral.exprs, arrayLiteral.type);
            return;
        }
        result = arrayLiteral;
    }

    @Override
    public void visit(BLangTupleLiteral tupleLiteral) {
        if (tupleLiteral.isTypedescExpr) {
            final BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
            typedescExpr.resolvedType = tupleLiteral.typedescType;
            typedescExpr.type = symTable.typeDesc;
            result = rewriteExpr(typedescExpr);
            return;
        }
        tupleLiteral.exprs.forEach(expr -> {
            BType expType = expr.impConversionExpr == null ? expr.type : expr.impConversionExpr.type;
            types.setImplicitCastExpr(expr, expType, symTable.anyType);
        });
        tupleLiteral.exprs = rewriteExprs(tupleLiteral.exprs);
        result = tupleLiteral;
    }

    @Override
    public void visit(BLangGroupExpr groupExpr) {
        if (groupExpr.isTypedescExpr) {
            final BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
            typedescExpr.resolvedType = groupExpr.typedescType;
            typedescExpr.type = symTable.typeDesc;
            result = rewriteExpr(typedescExpr);
        } else {
            result = rewriteExpr(groupExpr.expression);
        }
    }

    @Override
    public void visit(BLangRecordLiteral recordLiteral) {
        List<RecordLiteralNode.RecordField> fields =  recordLiteral.fields;
        fields.sort((v1, v2) -> Boolean.compare(isComputedKey(v1), isComputedKey(v2)));
        result = rewriteExpr(rewriteMappingConstructor(recordLiteral));
    }

    @Override
    public void visit(BLangSimpleVarRef varRefExpr) {
        BLangSimpleVarRef genVarRefExpr = varRefExpr;

        
        if (varRefExpr.pkgSymbol != null && varRefExpr.pkgSymbol.tag == SymTag.XMLNS) {
            BLangXMLQName qnameExpr = new BLangXMLQName(varRefExpr.variableName);
            qnameExpr.nsSymbol = (BXMLNSSymbol) varRefExpr.pkgSymbol;
            qnameExpr.localname = varRefExpr.variableName;
            qnameExpr.prefix = varRefExpr.pkgAlias;
            qnameExpr.namespaceURI = qnameExpr.nsSymbol.namespaceURI;
            qnameExpr.isUsedInXML = false;
            qnameExpr.pos = varRefExpr.pos;
            qnameExpr.type = symTable.stringType;
            result = qnameExpr;
            return;
        }

        if (varRefExpr.symbol == null) {
            result = varRefExpr;
            return;
        }

        
        if ((varRefExpr.symbol.tag & SymTag.VARIABLE) == SymTag.VARIABLE) {
            BVarSymbol varSymbol = (BVarSymbol) varRefExpr.symbol;
            if (varSymbol.originalSymbol != null) {
                varRefExpr.symbol = varSymbol.originalSymbol;
            }
        }

        BSymbol ownerSymbol = varRefExpr.symbol.owner;
        if ((varRefExpr.symbol.tag & SymTag.FUNCTION) == SymTag.FUNCTION &&
                varRefExpr.symbol.type.tag == TypeTags.INVOKABLE) {
            genVarRefExpr = new BLangFunctionVarRef((BVarSymbol) varRefExpr.symbol);
        } else if ((varRefExpr.symbol.tag & SymTag.TYPE) == SymTag.TYPE &&
                !((varRefExpr.symbol.tag & SymTag.CONSTANT) == SymTag.CONSTANT)) {
            genVarRefExpr = new BLangTypeLoad(varRefExpr.symbol);
        } else if ((ownerSymbol.tag & SymTag.INVOKABLE) == SymTag.INVOKABLE ||
                (ownerSymbol.tag & SymTag.LET) == SymTag.LET) {
            
            genVarRefExpr = new BLangLocalVarRef((BVarSymbol) varRefExpr.symbol);
        } else if ((ownerSymbol.tag & SymTag.STRUCT) == SymTag.STRUCT) {
            genVarRefExpr = new BLangFieldVarRef((BVarSymbol) varRefExpr.symbol);
        } else if ((ownerSymbol.tag & SymTag.PACKAGE) == SymTag.PACKAGE ||
                (ownerSymbol.tag & SymTag.SERVICE) == SymTag.SERVICE) {

            
            
            if ((varRefExpr.symbol.tag & SymTag.CONSTANT) == SymTag.CONSTANT) {
                BConstantSymbol constSymbol = (BConstantSymbol) varRefExpr.symbol;
                if (constSymbol.literalType.tag <= TypeTags.BOOLEAN || constSymbol.literalType.tag == TypeTags.NIL) {
                    BLangLiteral literal = ASTBuilderUtil.createLiteral(varRefExpr.pos, constSymbol.literalType,
                            constSymbol.value.value);
                    result = rewriteExpr(addConversionExprIfRequired(literal, varRefExpr.type));
                    return;
                }
            }

            
            
            genVarRefExpr = new BLangPackageVarRef((BVarSymbol) varRefExpr.symbol);
        }

        genVarRefExpr.type = varRefExpr.type;
        genVarRefExpr.pos = varRefExpr.pos;

        if ((varRefExpr.lhsVar)
                || genVarRefExpr.symbol.name.equals(IGNORE)) { 
            genVarRefExpr.lhsVar = varRefExpr.lhsVar;
            genVarRefExpr.type = varRefExpr.symbol.type;
            result = genVarRefExpr;
            return;
        }

        
        
        genVarRefExpr.lhsVar = varRefExpr.lhsVar;
        BType targetType = genVarRefExpr.type;
        genVarRefExpr.type = genVarRefExpr.symbol.type;
        BLangExpression expression = addConversionExprIfRequired(genVarRefExpr, targetType);
        result = expression.impConversionExpr != null ? expression.impConversionExpr : expression;
    }

    @Override
    public void visit(BLangFieldBasedAccess fieldAccessExpr) {
        if (safeNavigate(fieldAccessExpr)) {
            result = rewriteExpr(rewriteSafeNavigationExpr(fieldAccessExpr));
            return;
        }

        BLangAccessExpression targetVarRef = fieldAccessExpr;

        
        
        BType varRefType = fieldAccessExpr.expr.type;
        fieldAccessExpr.expr = rewriteExpr(fieldAccessExpr.expr);
        if (!types.isSameType(fieldAccessExpr.expr.type, varRefType)) {
            fieldAccessExpr.expr = addConversionExprIfRequired(fieldAccessExpr.expr, varRefType);
        }

        BLangLiteral stringLit = createStringLiteral(fieldAccessExpr.pos, fieldAccessExpr.field.value);
        int varRefTypeTag = varRefType.tag;
        if (varRefTypeTag == TypeTags.OBJECT ||
                (varRefTypeTag == TypeTags.UNION &&
                         ((BUnionType) varRefType).getMemberTypes().iterator().next().tag == TypeTags.OBJECT)) {
            if (fieldAccessExpr.symbol != null && fieldAccessExpr.symbol.type.tag == TypeTags.INVOKABLE &&
                    ((fieldAccessExpr.symbol.flags & Flags.ATTACHED) == Flags.ATTACHED)) {
                targetVarRef = new BLangStructFunctionVarRef(fieldAccessExpr.expr, (BVarSymbol) fieldAccessExpr.symbol);
            } else {
                targetVarRef = new BLangStructFieldAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit,
                        (BVarSymbol) fieldAccessExpr.symbol, false);
                
            }
        } else if (varRefTypeTag == TypeTags.RECORD ||
                (varRefTypeTag == TypeTags.UNION &&
                         ((BUnionType) varRefType).getMemberTypes().iterator().next().tag == TypeTags.RECORD)) {
            if (fieldAccessExpr.symbol != null && fieldAccessExpr.symbol.type.tag == TypeTags.INVOKABLE
                    && ((fieldAccessExpr.symbol.flags & Flags.ATTACHED) == Flags.ATTACHED)) {
                targetVarRef = new BLangStructFunctionVarRef(fieldAccessExpr.expr, (BVarSymbol) fieldAccessExpr.symbol);
            } else {
                targetVarRef = new BLangStructFieldAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit,
                        (BVarSymbol) fieldAccessExpr.symbol, false);
            }
        } else if (types.isLax(varRefType)) {
            if (!(varRefType.tag == TypeTags.XML || varRefType.tag == TypeTags.XML_ELEMENT)) {
                if (varRefType.tag == TypeTags.MAP && TypeTags.isXMLTypeTag(((BMapType) varRefType).constraint.tag)) {
                    result = rewriteExpr(rewriteLaxMapAccess(fieldAccessExpr));
                    return;
                }
                
                
                fieldAccessExpr.expr = addConversionExprIfRequired(fieldAccessExpr.expr, symTable.jsonType);
                targetVarRef = new BLangJSONAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit);
            } else {
                targetVarRef = rewriteXMLAttributeOrElemNameAccess(fieldAccessExpr);
            }
        } else if (varRefTypeTag == TypeTags.MAP) {
            
            targetVarRef = new BLangMapAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit);
        } else if (TypeTags.isXMLTypeTag(varRefTypeTag)) {
            targetVarRef = new BLangXMLAccessExpr(fieldAccessExpr.pos, fieldAccessExpr.expr, stringLit,
                    fieldAccessExpr.fieldKind);
        }

        targetVarRef.lhsVar = fieldAccessExpr.lhsVar;
        targetVarRef.type = fieldAccessExpr.type;
        targetVarRef.optionalFieldAccess = fieldAccessExpr.optionalFieldAccess;
        result = targetVarRef;
    }

    private BLangStatementExpression rewriteLaxMapAccess(BLangFieldBasedAccess fieldAccessExpr) {
        BLangStatementExpression statementExpression = new BLangStatementExpression();
        BLangBlockStmt block = new BLangBlockStmt();
        statementExpression.stmt = block;
        BUnionType fieldAccessType = BUnionType.create(null, fieldAccessExpr.type, symTable.errorType);
        DiagnosticPos pos = fieldAccessExpr.pos;
        BLangSimpleVariableDef result = createVarDef("$mapAccessResult$", fieldAccessType, null, pos);
        block.addStatement(result);
        BLangSimpleVarRef resultRef = ASTBuilderUtil.createVariableRef(pos, result.var.symbol);
        resultRef.type = fieldAccessType;
        statementExpression.type = fieldAccessType;


        
        
        BLangLiteral mapIndex = ASTBuilderUtil.createLiteral(
                        fieldAccessExpr.field.pos, symTable.stringType, fieldAccessExpr.field.value);
        BLangMapAccessExpr mapAccessExpr = new BLangMapAccessExpr(pos, fieldAccessExpr.expr, mapIndex);
        BUnionType xmlOrNil = BUnionType.create(null, fieldAccessExpr.type, symTable.nilType);
        mapAccessExpr.type = xmlOrNil;
        BLangSimpleVariableDef mapResult = createVarDef("$mapAccess", xmlOrNil, mapAccessExpr, pos);
        BLangSimpleVarRef mapResultRef = ASTBuilderUtil.createVariableRef(pos, mapResult.var.symbol);
        block.addStatement(mapResult);

        BLangIf ifStmt = ASTBuilderUtil.createIfStmt(pos, block);

        BLangIsLikeExpr isLikeNilExpr = createIsLikeExpression(pos, mapResultRef, symTable.nilType);

        ifStmt.expr = isLikeNilExpr;
        BLangBlockStmt resultNilBody = new BLangBlockStmt();
        ifStmt.body = resultNilBody;
        BLangBlockStmt resultHasValueBody = new BLangBlockStmt();
        ifStmt.elseStmt = resultHasValueBody;



        BLangInvocation errorInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue("error");
        errorInvocation.name = name;
        errorInvocation.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        errorInvocation.symbol = symTable.errorConstructor;
        errorInvocation.type = symTable.errorType;
        ArrayList<BLangExpression> errorCtorArgs = new ArrayList<>();
        errorInvocation.requiredArgs = errorCtorArgs;
        errorCtorArgs.add(createStringLiteral(pos, "{" + BLangConstants.MAP_LANG_LIB + "}InvalidKey"));
        BLangNamedArgsExpression message = new BLangNamedArgsExpression();
        message.name = ASTBuilderUtil.createIdentifier(pos, "key");
        message.expr = createStringLiteral(pos, fieldAccessExpr.field.value);
        errorCtorArgs.add(message);

        BLangSimpleVariableDef errorDef =
                createVarDef("_$_invalid_key_error", symTable.errorType, errorInvocation, pos);
        resultNilBody.addStatement(errorDef);

        BLangSimpleVarRef errorRef = ASTBuilderUtil.createVariableRef(pos, errorDef.var.symbol);

        BLangAssignment errorVarAssignment = ASTBuilderUtil.createAssignmentStmt(pos, resultNilBody);
        errorVarAssignment.varRef = resultRef;
        errorVarAssignment.expr = errorRef;

        BLangAssignment mapResultAssignment = ASTBuilderUtil.createAssignmentStmt(
                pos, resultHasValueBody);
        mapResultAssignment.varRef = resultRef;
        mapResultAssignment.expr = mapResultRef;

        statementExpression.expr = resultRef;
        return statementExpression;
    }

    private BLangAccessExpression rewriteXMLAttributeOrElemNameAccess(BLangFieldBasedAccess fieldAccessExpr) {
        ArrayList<BLangExpression> args = new ArrayList<>();

        String fieldName = fieldAccessExpr.field.value;
        if (fieldAccessExpr.fieldKind == FieldKind.WITH_NS) {
            BLangFieldBasedAccess.BLangNSPrefixedFieldBasedAccess nsPrefixAccess =
                    (BLangFieldBasedAccess.BLangNSPrefixedFieldBasedAccess) fieldAccessExpr;
            fieldName = createExpandedQName(nsPrefixAccess.nsSymbol.namespaceURI, fieldName);
        }

        
        if (fieldName.equals("_")) {
            return createLanglibXMLInvocation(fieldAccessExpr.pos, XML_INTERNAL_GET_ELEMENT_NAME_NIL_LIFTING,
                    fieldAccessExpr.expr, new ArrayList<>(), new ArrayList<>());
        }

        BLangLiteral attributeNameLiteral = createStringLiteral(fieldAccessExpr.field.pos, fieldName);
        args.add(attributeNameLiteral);
        args.add(isOptionalAccessToLiteral(fieldAccessExpr));

        return createLanglibXMLInvocation(fieldAccessExpr.pos, XML_INTERNAL_GET_ATTRIBUTE, fieldAccessExpr.expr, args,
                new ArrayList<>());
    }

    private BLangExpression isOptionalAccessToLiteral(BLangFieldBasedAccess fieldAccessExpr) {
        return rewrite(
                createLiteral(fieldAccessExpr.pos, symTable.booleanType, fieldAccessExpr.isOptionalFieldAccess()), env);
    }

    private String createExpandedQName(String nsURI, String localName) {
        return "{" + nsURI + "}" + localName;
    }

    @Override
    public void visit(BLangIndexBasedAccess indexAccessExpr) {
        if (safeNavigate(indexAccessExpr)) {
            result = rewriteExpr(rewriteSafeNavigationExpr(indexAccessExpr));
            return;
        }

        BLangVariableReference targetVarRef = indexAccessExpr;
        indexAccessExpr.indexExpr = rewriteExpr(indexAccessExpr.indexExpr);

        
        
        BType varRefType = indexAccessExpr.expr.type;
        indexAccessExpr.expr = rewriteExpr(indexAccessExpr.expr);
        if (!types.isSameType(indexAccessExpr.expr.type, varRefType)) {
            indexAccessExpr.expr = addConversionExprIfRequired(indexAccessExpr.expr, varRefType);
        }

        if (varRefType.tag == TypeTags.MAP) {
            targetVarRef = new BLangMapAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr, indexAccessExpr.indexExpr);
        } else if (types.isSubTypeOfMapping(types.getSafeType(varRefType, true, false))) {
            targetVarRef = new BLangStructFieldAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                    indexAccessExpr.indexExpr, (BVarSymbol) indexAccessExpr.symbol, false);
        } else if (types.isSubTypeOfList(varRefType)) {
            targetVarRef = new BLangArrayAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                    indexAccessExpr.indexExpr);
        } else if (types.isAssignable(varRefType, symTable.stringType)) {
            indexAccessExpr.expr = addConversionExprIfRequired(indexAccessExpr.expr, symTable.stringType);
            targetVarRef = new BLangStringAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                                                     indexAccessExpr.indexExpr);
        } else if (TypeTags.isXMLTypeTag(varRefType.tag)) {
            targetVarRef = new BLangXMLAccessExpr(indexAccessExpr.pos, indexAccessExpr.expr,
                    indexAccessExpr.indexExpr);
        }

        targetVarRef.lhsVar = indexAccessExpr.lhsVar;
        targetVarRef.type = indexAccessExpr.type;
        result = targetVarRef;
    }

    @Override
    public void visit(BLangInvocation iExpr) {
        BLangInvocation genIExpr = iExpr;

        if (iExpr.symbol != null && iExpr.symbol.kind == SymbolKind.ERROR_CONSTRUCTOR) {
            result = rewriteErrorConstructor(iExpr);
        }

        
        reorderArguments(iExpr);

        iExpr.requiredArgs = rewriteExprs(iExpr.requiredArgs);
        fixNonRestArgTypeCastInTypeParamInvocation(iExpr);

        iExpr.restArgs = rewriteExprs(iExpr.restArgs);

        annotationDesugar.defineStatementAnnotations(iExpr.annAttachments, iExpr.pos, iExpr.symbol.pkgID,
                                                     iExpr.symbol.owner, env);

        if (iExpr.functionPointerInvocation) {
            visitFunctionPointerInvocation(iExpr);
            return;
        }
        iExpr.expr = rewriteExpr(iExpr.expr);
        result = genIExpr;


        if (iExpr.expr == null) {
            fixTypeCastInTypeParamInvocation(iExpr, genIExpr);
            if (iExpr.exprSymbol == null) {
                return;
            }
            iExpr.expr = ASTBuilderUtil.createVariableRef(iExpr.pos, iExpr.exprSymbol);
            iExpr.expr = rewriteExpr(iExpr.expr);
        }
        switch (iExpr.expr.type.tag) {
            case TypeTags.OBJECT:
            case TypeTags.RECORD:
                if (!iExpr.langLibInvocation) {
                    List<BLangExpression> argExprs = new ArrayList<>(iExpr.requiredArgs);
                    argExprs.add(0, iExpr.expr);
                    BLangAttachedFunctionInvocation attachedFunctionInvocation =
                            new BLangAttachedFunctionInvocation(iExpr.pos, argExprs, iExpr.restArgs, iExpr.symbol,
                                                                iExpr.type, iExpr.expr, iExpr.async);
                    attachedFunctionInvocation.actionInvocation = iExpr.actionInvocation;
                    attachedFunctionInvocation.name = iExpr.name;
                    attachedFunctionInvocation.annAttachments = iExpr.annAttachments;
                    result = genIExpr = attachedFunctionInvocation;
                }
                break;
        }

        fixTypeCastInTypeParamInvocation(iExpr, genIExpr);
    }

    private void fixNonRestArgTypeCastInTypeParamInvocation(BLangInvocation iExpr) {
        if (!iExpr.langLibInvocation) {
            return;
        }

        List<BLangExpression> requiredArgs = iExpr.requiredArgs;

        List<BVarSymbol> params = ((BInvokableSymbol) iExpr.symbol).params;

        
        for (int i = 1; i < requiredArgs.size(); i++) {
            requiredArgs.set(i, addConversionExprIfRequired(requiredArgs.get(i), params.get(i).type));
        }
    }

    private void fixTypeCastInTypeParamInvocation(BLangInvocation iExpr, BLangInvocation genIExpr) {

        if (iExpr.langLibInvocation || TypeParamAnalyzer.containsTypeParam(((BInvokableSymbol) iExpr.symbol).retType)) {
            BType originalInvType = genIExpr.type;
            genIExpr.type = ((BInvokableSymbol) genIExpr.symbol).retType;
            BLangExpression expr = addConversionExprIfRequired(genIExpr, originalInvType);

            
            if (expr.getKind() == NodeKind.TYPE_CONVERSION_EXPR) {
                this.result = expr;
                return;
            }

            BLangTypeConversionExpr conversionExpr = (BLangTypeConversionExpr) TreeBuilder.createTypeConversionNode();
            conversionExpr.expr = genIExpr;
            conversionExpr.targetType = originalInvType;
            conversionExpr.type = originalInvType;
            conversionExpr.pos = genIExpr.pos;

            this.result = conversionExpr;
        }
    }

    private BLangInvocation rewriteErrorConstructor(BLangInvocation iExpr) {
        BLangExpression reasonExpr = iExpr.requiredArgs.get(0);
        if (reasonExpr.impConversionExpr != null &&
                reasonExpr.impConversionExpr.targetType.tag != TypeTags.STRING) {
            
            
            reasonExpr.impConversionExpr = null;
        }
        reasonExpr = addConversionExprIfRequired(reasonExpr, symTable.stringType);
        reasonExpr = rewriteExpr(reasonExpr);
        iExpr.requiredArgs.remove(0);
        iExpr.requiredArgs.add(reasonExpr);

        BLangExpression errorDetail;
        BLangRecordLiteral recordLiteral = ASTBuilderUtil.createEmptyRecordLiteral(iExpr.pos,
                ((BErrorType) iExpr.symbol.type).detailType);
        List<BLangExpression> namedArgs = iExpr.requiredArgs.stream()
                .filter(a -> a.getKind() == NodeKind.NAMED_ARGS_EXPR)
                .collect(Collectors.toList());
        if (namedArgs.isEmpty()) {
            errorDetail = visitCloneReadonly(rewriteExpr(recordLiteral), recordLiteral.type);
        } else {
            for (BLangExpression arg : namedArgs) {
                BLangNamedArgsExpression namedArg = (BLangNamedArgsExpression) arg;
                BLangRecordLiteral.BLangRecordKeyValueField member = new BLangRecordLiteral.BLangRecordKeyValueField();
                member.key = new BLangRecordLiteral.BLangRecordKey(ASTBuilderUtil.createLiteral(namedArg.name.pos,
                        symTable.stringType, namedArg.name.value));

                if (recordLiteral.type.tag == TypeTags.RECORD) {
                    member.valueExpr = addConversionExprIfRequired(namedArg.expr, symTable.anyType);
                } else {
                    member.valueExpr = addConversionExprIfRequired(namedArg.expr, namedArg.expr.type);
                }
                recordLiteral.fields.add(member);
                iExpr.requiredArgs.remove(arg);
            }
            errorDetail = visitCloneReadonly(rewriteExpr(recordLiteral), ((BErrorType) iExpr.symbol.type).detailType);
        }
        iExpr.requiredArgs.add(errorDetail);
        return iExpr;
    }

    public void visit(BLangTypeInit typeInitExpr) {
        if (typeInitExpr.type.tag == TypeTags.STREAM) {
            result = rewriteExpr(desugarStreamTypeInit(typeInitExpr));
        } else {
            result = rewrite(desugarObjectTypeInit(typeInitExpr), env);
        }
    }

    private BLangStatementExpression desugarObjectTypeInit(BLangTypeInit typeInitExpr) {
        typeInitExpr.desugared = true;
        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(typeInitExpr.pos);

        
        BType objType = getObjectType(typeInitExpr.type);
        BLangSimpleVariableDef objVarDef = createVarDef("$obj$", objType, typeInitExpr, typeInitExpr.pos);
        BLangSimpleVarRef objVarRef = ASTBuilderUtil.createVariableRef(typeInitExpr.pos, objVarDef.var.symbol);
        blockStmt.addStatement(objVarDef);
        typeInitExpr.initInvocation.exprSymbol = objVarDef.var.symbol;
        typeInitExpr.initInvocation.symbol = ((BObjectTypeSymbol) objType.tsymbol).generatedInitializerFunc.symbol;

        
        if (typeInitExpr.initInvocation.type.tag == TypeTags.NIL) {
            BLangExpressionStmt initInvExpr = ASTBuilderUtil.createExpressionStmt(typeInitExpr.pos, blockStmt);
            initInvExpr.expr = typeInitExpr.initInvocation;
            typeInitExpr.initInvocation.name.value = Names.GENERATED_INIT_SUFFIX.value;
            BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, objVarRef);
            stmtExpr.type = objVarRef.symbol.type;
            return stmtExpr;
        }

        
        BLangSimpleVariableDef initInvRetValVarDef = createVarDef("$temp$", typeInitExpr.initInvocation.type,
                                                                  typeInitExpr.initInvocation, typeInitExpr.pos);
        blockStmt.addStatement(initInvRetValVarDef);

        
        BLangSimpleVariableDef resultVarDef = createVarDef("$result$", typeInitExpr.type, null, typeInitExpr.pos);
        blockStmt.addStatement(resultVarDef);

        
        
        
        
        

        
        BLangSimpleVarRef initRetValVarRefInCondition =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, initInvRetValVarDef.var.symbol);
        BLangBlockStmt thenStmt = ASTBuilderUtil.createBlockStmt(typeInitExpr.pos);
        BLangTypeTestExpr isErrorTest =
                ASTBuilderUtil.createTypeTestExpr(typeInitExpr.pos, initRetValVarRefInCondition, getErrorTypeNode());
        isErrorTest.type = symTable.booleanType;

        
        BLangSimpleVarRef thenInitRetValVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, initInvRetValVarDef.var.symbol);
        BLangSimpleVarRef thenResultVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, resultVarDef.var.symbol);
        BLangAssignment errAssignment =
                ASTBuilderUtil.createAssignmentStmt(typeInitExpr.pos, thenResultVarRef, thenInitRetValVarRef);
        thenStmt.addStatement(errAssignment);

        
        BLangSimpleVarRef elseResultVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, resultVarDef.var.symbol);
        BLangAssignment objAssignment =
                ASTBuilderUtil.createAssignmentStmt(typeInitExpr.pos, elseResultVarRef, objVarRef);
        BLangBlockStmt elseStmt = ASTBuilderUtil.createBlockStmt(typeInitExpr.pos);
        elseStmt.addStatement(objAssignment);

        BLangIf ifelse = ASTBuilderUtil.createIfElseStmt(typeInitExpr.pos, isErrorTest, thenStmt, elseStmt);
        blockStmt.addStatement(ifelse);

        BLangSimpleVarRef resultVarRef =
                ASTBuilderUtil.createVariableRef(typeInitExpr.pos, resultVarDef.var.symbol);
        BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, resultVarRef);
        stmtExpr.type = resultVarRef.symbol.type;
        return stmtExpr;
    }

    private BLangInvocation desugarStreamTypeInit(BLangTypeInit typeInitExpr) {
        BInvokableSymbol symbol = (BInvokableSymbol) symTable.langInternalModuleSymbol.scope
                .lookup(Names.CONSTRUCT_STREAM).symbol;
        BType targetType = ((BStreamType) typeInitExpr.type).constraint;
        BType errorType = ((BStreamType) typeInitExpr.type).error;
        BType typedescType = new BTypedescType(targetType, symTable.typeDesc.tsymbol);
        BLangTypedescExpr typedescExpr = new BLangTypedescExpr();
        typedescExpr.resolvedType = targetType;
        typedescExpr.type = typedescType;
        BLangExpression iteratorObj = typeInitExpr.argsExpr.get(0);

        BLangInvocation streamConstructInvocation = ASTBuilderUtil.createInvocationExprForMethod(
                typeInitExpr.pos, symbol, new ArrayList<>(Lists.of(typedescExpr, iteratorObj)),
                symResolver);
        streamConstructInvocation.type = new BStreamType(TypeTags.STREAM, targetType, errorType, null);
        return streamConstructInvocation;
    }

    private BLangSimpleVariableDef createVarDef(String name, BType type, BLangExpression expr, DiagnosticPos pos) {
        BSymbol objSym = symResolver.lookupSymbolInMainSpace(env, names.fromString(name));
        if (objSym == null || objSym == symTable.notFoundSymbol) {
            objSym = new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, type, this.env.scope.owner);
        }
        BLangSimpleVariable objVar = ASTBuilderUtil.createVariable(pos, "$" + name + "$", type, expr,
                (BVarSymbol) objSym);
        BLangSimpleVariableDef objVarDef = ASTBuilderUtil.createVariableDef(pos);
        objVarDef.var = objVar;
        objVarDef.type = objVar.type;
        return objVarDef;
    }

    private BType getObjectType(BType type) {
        if (type.tag == TypeTags.OBJECT) {
            return type;
        } else if (type.tag == TypeTags.UNION) {
            return ((BUnionType) type).getMemberTypes().stream()
                    .filter(t -> t.tag == TypeTags.OBJECT)
                    .findFirst()
                    .orElse(symTable.noType);
        }

        throw new IllegalStateException("None object type '" + type.toString() + "' found in object init context");
    }

    BLangErrorType getErrorTypeNode() {
        BLangErrorType errorTypeNode = (BLangErrorType) TreeBuilder.createErrorTypeNode();
        errorTypeNode.type = symTable.errorType;
        return errorTypeNode;
    }

    @Override
    public void visit(BLangTernaryExpr ternaryExpr) {
        /*
         * First desugar to if-else:
         * 
         * T $result$;
         * if () {
         *    $result$ = thenExpr;
         * } else {
         *    $result$ = elseExpr;
         * }
         * 
         */
        BLangSimpleVariableDef resultVarDef = createVarDef("$ternary_result$", ternaryExpr.type, null, ternaryExpr.pos);
        BLangBlockStmt thenBody = ASTBuilderUtil.createBlockStmt(ternaryExpr.pos);
        BLangBlockStmt elseBody = ASTBuilderUtil.createBlockStmt(ternaryExpr.pos);

        
        BLangSimpleVarRef thenResultVarRef = ASTBuilderUtil.createVariableRef(ternaryExpr.pos, resultVarDef.var.symbol);
        BLangAssignment thenAssignment =
                ASTBuilderUtil.createAssignmentStmt(ternaryExpr.pos, thenResultVarRef, ternaryExpr.thenExpr);
        thenBody.addStatement(thenAssignment);

        
        BLangSimpleVarRef elseResultVarRef = ASTBuilderUtil.createVariableRef(ternaryExpr.pos, resultVarDef.var.symbol);
        BLangAssignment elseAssignment =
                ASTBuilderUtil.createAssignmentStmt(ternaryExpr.pos, elseResultVarRef, ternaryExpr.elseExpr);
        elseBody.addStatement(elseAssignment);

        
        BLangSimpleVarRef resultVarRef = ASTBuilderUtil.createVariableRef(ternaryExpr.pos, resultVarDef.var.symbol);
        BLangIf ifElse = ASTBuilderUtil.createIfElseStmt(ternaryExpr.pos, ternaryExpr.expr, thenBody, elseBody);

        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(ternaryExpr.pos, Lists.of(resultVarDef, ifElse));
        BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, resultVarRef);
        stmtExpr.type = ternaryExpr.type;

        result = rewriteExpr(stmtExpr);
    }

    @Override
    public void visit(BLangWaitExpr waitExpr) {
        
        if (waitExpr.getExpression().getKind() == NodeKind.BINARY_EXPR) {
            waitExpr.exprList = collectAllBinaryExprs((BLangBinaryExpr) waitExpr.getExpression(), new ArrayList<>());
        } else { 
            waitExpr.exprList = Collections.singletonList(rewriteExpr(waitExpr.getExpression()));
        }
        result = waitExpr;
    }

    private List<BLangExpression> collectAllBinaryExprs(BLangBinaryExpr binaryExpr, List<BLangExpression> exprs) {
        visitBinaryExprOfWait(binaryExpr.lhsExpr, exprs);
        visitBinaryExprOfWait(binaryExpr.rhsExpr, exprs);
        return exprs;
    }

    private void visitBinaryExprOfWait(BLangExpression expr, List<BLangExpression> exprs) {
        if (expr.getKind() == NodeKind.BINARY_EXPR) {
            collectAllBinaryExprs((BLangBinaryExpr) expr, exprs);
        } else {
            expr = rewriteExpr(expr);
            exprs.add(expr);
        }
    }

    @Override
    public void visit(BLangWaitForAllExpr waitExpr) {
        waitExpr.keyValuePairs.forEach(keyValue -> {
            if (keyValue.valueExpr != null) {
                keyValue.valueExpr = rewriteExpr(keyValue.valueExpr);
            } else {
                keyValue.keyExpr = rewriteExpr(keyValue.keyExpr);
            }
        });
        BLangExpression expr = new BLangWaitForAllExpr.BLangWaitLiteral(waitExpr.keyValuePairs, waitExpr.type);
        result = rewriteExpr(expr);
    }

    @Override
    public void visit(BLangTrapExpr trapExpr) {
        trapExpr.expr = rewriteExpr(trapExpr.expr);
        if (trapExpr.expr.type.tag != TypeTags.NIL) {
            trapExpr.expr = addConversionExprIfRequired(trapExpr.expr, trapExpr.type);
        }
        result = trapExpr;
    }

    @Override
    public void visit(BLangBinaryExpr binaryExpr) {
        if (binaryExpr.opKind == OperatorKind.HALF_OPEN_RANGE || binaryExpr.opKind == OperatorKind.CLOSED_RANGE) {
            if (binaryExpr.opKind == OperatorKind.HALF_OPEN_RANGE) {
                binaryExpr.rhsExpr = getModifiedIntRangeEndExpr(binaryExpr.rhsExpr);
            }
            result = rewriteExpr(replaceWithIntRange(binaryExpr.pos, binaryExpr.lhsExpr, binaryExpr.rhsExpr));
            return;
        }

        if (binaryExpr.opKind == OperatorKind.AND || binaryExpr.opKind == OperatorKind.OR) {
            visitBinaryLogicalExpr(binaryExpr);
            return;
        }

        OperatorKind binaryOpKind = binaryExpr.opKind;

        if (binaryOpKind == OperatorKind.ADD || binaryOpKind == OperatorKind.SUB ||
                binaryOpKind == OperatorKind.MUL || binaryOpKind == OperatorKind.DIV ||
                binaryOpKind == OperatorKind.MOD || binaryOpKind == OperatorKind.BITWISE_AND ||
                binaryOpKind == OperatorKind.BITWISE_OR || binaryOpKind == OperatorKind.BITWISE_XOR) {
            checkByteTypeIncompatibleOperations(binaryExpr);
        }

        binaryExpr.lhsExpr = rewriteExpr(binaryExpr.lhsExpr);
        binaryExpr.rhsExpr = rewriteExpr(binaryExpr.rhsExpr);
        result = binaryExpr;

        int rhsExprTypeTag = binaryExpr.rhsExpr.type.tag;
        int lhsExprTypeTag = binaryExpr.lhsExpr.type.tag;

        
        if (rhsExprTypeTag != lhsExprTypeTag && (binaryExpr.opKind == OperatorKind.EQUAL ||
                                                         binaryExpr.opKind == OperatorKind.NOT_EQUAL ||
                                                         binaryExpr.opKind == OperatorKind.REF_EQUAL ||
                                                         binaryExpr.opKind == OperatorKind.REF_NOT_EQUAL)) {
            if (lhsExprTypeTag == TypeTags.INT && rhsExprTypeTag == TypeTags.BYTE) {
                binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, symTable.intType);
                return;
            }

            if (lhsExprTypeTag == TypeTags.BYTE && rhsExprTypeTag == TypeTags.INT) {
                binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, symTable.intType);
                return;
            }
        }

        
        if (lhsExprTypeTag == rhsExprTypeTag) {
            return;
        }

        if (TypeTags.isStringTypeTag(lhsExprTypeTag) && binaryExpr.opKind == OperatorKind.ADD) {
            
            if (TypeTags.isXMLTypeTag(rhsExprTypeTag)) {
                binaryExpr.lhsExpr = ASTBuilderUtil.createXMLTextLiteralNode(binaryExpr, binaryExpr.lhsExpr,
                        binaryExpr.lhsExpr.pos, symTable.xmlType);
                return;
            }
            binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, binaryExpr.lhsExpr.type);
            return;
        }

        if (TypeTags.isStringTypeTag(rhsExprTypeTag) && binaryExpr.opKind == OperatorKind.ADD) {
            
            if (TypeTags.isXMLTypeTag(lhsExprTypeTag)) {
                binaryExpr.rhsExpr = ASTBuilderUtil.createXMLTextLiteralNode(binaryExpr, binaryExpr.rhsExpr,
                        binaryExpr.rhsExpr.pos, symTable.xmlType);
                return;
            }
            binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, binaryExpr.rhsExpr.type);
            return;
        }

        if (lhsExprTypeTag == TypeTags.DECIMAL) {
            binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, binaryExpr.lhsExpr.type);
            return;
        }

        if (rhsExprTypeTag == TypeTags.DECIMAL) {
            binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, binaryExpr.rhsExpr.type);
            return;
        }

        if (lhsExprTypeTag == TypeTags.FLOAT) {
            binaryExpr.rhsExpr = createTypeCastExpr(binaryExpr.rhsExpr, binaryExpr.lhsExpr.type);
            return;
        }

        if (rhsExprTypeTag == TypeTags.FLOAT) {
            binaryExpr.lhsExpr = createTypeCastExpr(binaryExpr.lhsExpr, binaryExpr.rhsExpr.type);
        }
    }

    private BLangInvocation replaceWithIntRange(DiagnosticPos pos, BLangExpression lhsExpr, BLangExpression rhsExpr) {
        BInvokableSymbol symbol = (BInvokableSymbol) symTable.langInternalModuleSymbol.scope
                .lookup(Names.CREATE_INT_RANGE).symbol;
        BLangInvocation createIntRangeInvocation = ASTBuilderUtil.createInvocationExprForMethod(pos, symbol,
                new ArrayList<>(Lists.of(lhsExpr, rhsExpr)), symResolver);
        createIntRangeInvocation.type = symTable.intRangeType;
        return createIntRangeInvocation;
    }

    private void checkByteTypeIncompatibleOperations(BLangBinaryExpr binaryExpr) {
        if (binaryExpr.expectedType == null) {
            return;
        }

        int rhsExprTypeTag = binaryExpr.rhsExpr.type.tag;
        int lhsExprTypeTag = binaryExpr.lhsExpr.type.tag;
        if (rhsExprTypeTag != TypeTags.BYTE && lhsExprTypeTag != TypeTags.BYTE) {
            return;
        }

        int resultTypeTag = binaryExpr.expectedType.tag;
        if (resultTypeTag == TypeTags.INT) {
            if (rhsExprTypeTag == TypeTags.BYTE) {
                binaryExpr.rhsExpr = addConversionExprIfRequired(binaryExpr.rhsExpr, symTable.intType);
            }

            if (lhsExprTypeTag == TypeTags.BYTE) {
                binaryExpr.lhsExpr = addConversionExprIfRequired(binaryExpr.lhsExpr, symTable.intType);
            }
        }
    }

    /**
     * This method checks whether given binary expression is related to shift operation.
     * If its true, then both lhs and rhs of the binary expression will be converted to 'int' type.
     * <p>
     * byte a = 12;
     * byte b = 34;
     * int i = 234;
     * int j = -4;
     * <p>
     * true: where binary expression's expected type is 'int'
     * int i1 = a >> b;
     * int i2 = a << b;
     * int i3 = a >> i;
     * int i4 = a << i;
     * int i5 = i >> j;
     * int i6 = i << j;
     */
    private boolean isBitwiseShiftOperation(BLangBinaryExpr binaryExpr) {
        return binaryExpr.opKind == OperatorKind.BITWISE_LEFT_SHIFT ||
                binaryExpr.opKind == OperatorKind.BITWISE_RIGHT_SHIFT ||
                binaryExpr.opKind == OperatorKind.BITWISE_UNSIGNED_RIGHT_SHIFT;
    }

    public void visit(BLangElvisExpr elvisExpr) {
        BLangMatchExpression matchExpr = ASTBuilderUtil.createMatchExpression(elvisExpr.lhsExpr);
        matchExpr.patternClauses.add(getMatchNullPatternGivenExpression(elvisExpr.pos,
                rewriteExpr(elvisExpr.rhsExpr)));
        matchExpr.type = elvisExpr.type;
        matchExpr.pos = elvisExpr.pos;
        result = rewriteExpr(matchExpr);
    }

    @Override
    public void visit(BLangUnaryExpr unaryExpr) {
        if (OperatorKind.BITWISE_COMPLEMENT == unaryExpr.operator) {
            
            
            rewriteBitwiseComplementOperator(unaryExpr);
            return;
        }
        unaryExpr.expr = rewriteExpr(unaryExpr.expr);
        result = unaryExpr;
    }

    /**
     * This method desugar a bitwise complement (~) unary expressions into a bitwise xor binary expression as below.
     * Example : ~a  -> a ^ -1;
     * ~ 11110011 -> 00001100
     * 11110011 ^ 11111111 -> 00001100
     *
     * @param unaryExpr the bitwise complement expression
     */
    private void rewriteBitwiseComplementOperator(BLangUnaryExpr unaryExpr) {
        final DiagnosticPos pos = unaryExpr.pos;
        final BLangBinaryExpr binaryExpr = (BLangBinaryExpr) TreeBuilder.createBinaryExpressionNode();
        binaryExpr.pos = pos;
        binaryExpr.opKind = OperatorKind.BITWISE_XOR;
        binaryExpr.lhsExpr = unaryExpr.expr;
        if (TypeTags.BYTE == unaryExpr.type.tag) {
            binaryExpr.type = symTable.byteType;
            binaryExpr.rhsExpr = ASTBuilderUtil.createLiteral(pos, symTable.byteType, 0xffL);
            binaryExpr.opSymbol = (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.BITWISE_XOR,
                    symTable.byteType, symTable.byteType);
        } else {
            binaryExpr.type = symTable.intType;
            binaryExpr.rhsExpr = ASTBuilderUtil.createLiteral(pos, symTable.intType, -1L);
            binaryExpr.opSymbol = (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.BITWISE_XOR,
                    symTable.intType, symTable.intType);
        }
        result = rewriteExpr(binaryExpr);
    }

    @Override
    public void visit(BLangTypeConversionExpr conversionExpr) {
        
        
        
        

        
        if (conversionExpr.typeNode == null && !conversionExpr.annAttachments.isEmpty()) {
            result = rewriteExpr(conversionExpr.expr);
            return;
        }
        conversionExpr.typeNode = rewrite(conversionExpr.typeNode, env);
        conversionExpr.expr = rewriteExpr(conversionExpr.expr);
        result = conversionExpr;
    }

    @Override
    public void visit(BLangLambdaFunction bLangLambdaFunction) {
        
        env.enclPkg.lambdaFunctions.add(bLangLambdaFunction);
        result = bLangLambdaFunction;
    }

    @Override
    public void visit(BLangArrowFunction bLangArrowFunction) {
        BLangFunction bLangFunction = (BLangFunction) TreeBuilder.createFunctionNode();
        bLangFunction.setName(bLangArrowFunction.functionName);

        BLangLambdaFunction lambdaFunction = (BLangLambdaFunction) TreeBuilder.createLambdaFunctionNode();
        lambdaFunction.pos = bLangArrowFunction.pos;
        bLangFunction.addFlag(Flag.LAMBDA);
        lambdaFunction.function = bLangFunction;

        
        BLangValueType returnType = (BLangValueType) TreeBuilder.createValueTypeNode();
        returnType.type = bLangArrowFunction.body.expr.type;
        bLangFunction.setReturnTypeNode(returnType);
        bLangFunction.setBody(populateArrowExprBodyBlock(bLangArrowFunction));

        bLangArrowFunction.params.forEach(bLangFunction::addParameter);
        lambdaFunction.parent = bLangArrowFunction.parent;
        lambdaFunction.type = bLangArrowFunction.funcType;

        
        BLangFunction funcNode = lambdaFunction.function;
        BInvokableSymbol funcSymbol = Symbols.createFunctionSymbol(Flags.asMask(funcNode.flagSet),
                new Name(funcNode.name.value), env.enclPkg.symbol.pkgID, bLangArrowFunction.funcType,
                env.enclEnv.enclVarSym, true);
        SymbolEnv invokableEnv = SymbolEnv.createFunctionEnv(funcNode, funcSymbol.scope, env);
        defineInvokableSymbol(funcNode, funcSymbol, invokableEnv);

        List<BVarSymbol> paramSymbols = funcNode.requiredParams.stream().peek(varNode -> {
            Scope enclScope = invokableEnv.scope;
            varNode.symbol.kind = SymbolKind.FUNCTION;
            varNode.symbol.owner = invokableEnv.scope.owner;
            enclScope.define(varNode.symbol.name, varNode.symbol);
        }).map(varNode -> varNode.symbol).collect(Collectors.toList());

        funcSymbol.params = paramSymbols;
        funcSymbol.restParam = getRestSymbol(funcNode);
        funcSymbol.retType = funcNode.returnTypeNode.type;

        
        List<BType> paramTypes = paramSymbols.stream().map(paramSym -> paramSym.type).collect(Collectors.toList());
        funcNode.type = new BInvokableType(paramTypes, getRestType(funcSymbol), funcNode.returnTypeNode.type, null);

        lambdaFunction.function.pos = bLangArrowFunction.pos;
        lambdaFunction.function.body.pos = bLangArrowFunction.pos;
        
        lambdaFunction.capturedClosureEnv = env;
        rewrite(lambdaFunction.function, env);
        env.enclPkg.addFunction(lambdaFunction.function);
        bLangArrowFunction.function = lambdaFunction.function;
        result = rewriteExpr(lambdaFunction);
    }

    private void defineInvokableSymbol(BLangInvokableNode invokableNode, BInvokableSymbol funcSymbol,
                                       SymbolEnv invokableEnv) {
        invokableNode.symbol = funcSymbol;
        funcSymbol.scope = new Scope(funcSymbol);
        invokableEnv.scope = funcSymbol.scope;
    }

    @Override
    public void visit(BLangXMLQName xmlQName) {
        result = xmlQName;
    }

    @Override
    public void visit(BLangXMLAttribute xmlAttribute) {
        xmlAttribute.name = rewriteExpr(xmlAttribute.name);
        xmlAttribute.value = rewriteExpr(xmlAttribute.value);
        result = xmlAttribute;
    }

    @Override
    public void visit(BLangXMLElementLiteral xmlElementLiteral) {
        xmlElementLiteral.startTagName = rewriteExpr(xmlElementLiteral.startTagName);
        xmlElementLiteral.endTagName = rewriteExpr(xmlElementLiteral.endTagName);
        xmlElementLiteral.modifiedChildren = rewriteExprs(xmlElementLiteral.modifiedChildren);
        xmlElementLiteral.attributes = rewriteExprs(xmlElementLiteral.attributes);

        
        Iterator<BLangXMLAttribute> attributesItr = xmlElementLiteral.attributes.iterator();
        while (attributesItr.hasNext()) {
            BLangXMLAttribute attribute = attributesItr.next();
            if (!attribute.isNamespaceDeclr) {
                continue;
            }

            
            BLangXMLNS xmlns;
            if ((xmlElementLiteral.scope.owner.tag & SymTag.PACKAGE) == SymTag.PACKAGE) {
                xmlns = new BLangPackageXMLNS();
            } else {
                xmlns = new BLangLocalXMLNS();
            }
            xmlns.namespaceURI = attribute.value.concatExpr;
            xmlns.prefix = ((BLangXMLQName) attribute.name).localname;
            xmlns.symbol = attribute.symbol;

            xmlElementLiteral.inlineNamespaces.add(xmlns);
        }

        result = xmlElementLiteral;
    }

    @Override
    public void visit(BLangXMLTextLiteral xmlTextLiteral) {
        xmlTextLiteral.concatExpr = rewriteExpr(constructStringTemplateConcatExpression(xmlTextLiteral.textFragments));
        result = xmlTextLiteral;
    }

    @Override
    public void visit(BLangXMLCommentLiteral xmlCommentLiteral) {
        xmlCommentLiteral.concatExpr = rewriteExpr(
                constructStringTemplateConcatExpression(xmlCommentLiteral.textFragments));
        result = xmlCommentLiteral;
    }

    @Override
    public void visit(BLangXMLProcInsLiteral xmlProcInsLiteral) {
        xmlProcInsLiteral.target = rewriteExpr(xmlProcInsLiteral.target);
        xmlProcInsLiteral.dataConcatExpr =
                rewriteExpr(constructStringTemplateConcatExpression(xmlProcInsLiteral.dataFragments));
        result = xmlProcInsLiteral;
    }

    @Override
    public void visit(BLangXMLQuotedString xmlQuotedString) {
        xmlQuotedString.concatExpr = rewriteExpr(
                constructStringTemplateConcatExpression(xmlQuotedString.textFragments));
        result = xmlQuotedString;
    }

    @Override
    public void visit(BLangStringTemplateLiteral stringTemplateLiteral) {
        result = rewriteExpr(constructStringTemplateConcatExpression(stringTemplateLiteral.exprs));
    }

    @Override
    public void visit(BLangWorkerSend workerSendNode) {
        workerSendNode.expr = visitCloneInvocation(rewriteExpr(workerSendNode.expr), workerSendNode.expr.type);
        if (workerSendNode.keyExpr != null) {
            workerSendNode.keyExpr = rewriteExpr(workerSendNode.keyExpr);
        }
        result = workerSendNode;
    }

    @Override
    public void visit(BLangWorkerSyncSendExpr syncSendExpr) {
        syncSendExpr.expr = visitCloneInvocation(rewriteExpr(syncSendExpr.expr), syncSendExpr.expr.type);
        result = syncSendExpr;
    }

    @Override
    public void visit(BLangWorkerReceive workerReceiveNode) {
        if (workerReceiveNode.keyExpr != null) {
            workerReceiveNode.keyExpr = rewriteExpr(workerReceiveNode.keyExpr);
        }
        result = workerReceiveNode;
    }

    @Override
    public void visit(BLangWorkerFlushExpr workerFlushExpr) {
        workerFlushExpr.workerIdentifierList = workerFlushExpr.cachedWorkerSendStmts
                .stream().map(send -> send.workerIdentifier).distinct().collect(Collectors.toList());
        result = workerFlushExpr;
    }

    @Override
    public void visit(BLangXMLAttributeAccess xmlAttributeAccessExpr) {
        xmlAttributeAccessExpr.indexExpr = rewriteExpr(xmlAttributeAccessExpr.indexExpr);
        xmlAttributeAccessExpr.expr = rewriteExpr(xmlAttributeAccessExpr.expr);

        if (xmlAttributeAccessExpr.indexExpr != null
                && xmlAttributeAccessExpr.indexExpr.getKind() == NodeKind.XML_QNAME) {
            ((BLangXMLQName) xmlAttributeAccessExpr.indexExpr).isUsedInXML = true;
        }

        xmlAttributeAccessExpr.desugared = true;

        
        
        if (xmlAttributeAccessExpr.lhsVar || xmlAttributeAccessExpr.indexExpr != null) {
            result = xmlAttributeAccessExpr;
        } else {
            result = rewriteExpr(xmlAttributeAccessExpr);
        }
    }

    
    

    @Override
    public void visit(BLangLocalVarRef localVarRef) {
        result = localVarRef;
    }

    @Override
    public void visit(BLangFieldVarRef fieldVarRef) {
        result = fieldVarRef;
    }

    @Override
    public void visit(BLangPackageVarRef packageVarRef) {
        result = packageVarRef;
    }

    @Override
    public void visit(BLangFunctionVarRef functionVarRef) {
        result = functionVarRef;
    }

    @Override
    public void visit(BLangStructFieldAccessExpr fieldAccessExpr) {
        result = fieldAccessExpr;
    }

    @Override
    public void visit(BLangStructFunctionVarRef functionVarRef) {
        result = functionVarRef;
    }

    @Override
    public void visit(BLangMapAccessExpr mapKeyAccessExpr) {
        result = mapKeyAccessExpr;
    }

    @Override
    public void visit(BLangArrayAccessExpr arrayIndexAccessExpr) {
        result = arrayIndexAccessExpr;
    }

    @Override
    public void visit(BLangTupleAccessExpr arrayIndexAccessExpr) {
        result = arrayIndexAccessExpr;
    }

    @Override
    public void visit(BLangMapLiteral mapLiteral) {
        result = mapLiteral;
    }

    @Override
    public void visit(BLangStructLiteral structLiteral) {
        result = structLiteral;
    }

    @Override
    public void visit(BLangWaitForAllExpr.BLangWaitLiteral waitLiteral) {
        result = waitLiteral;
    }

    @Override
    public void visit(BLangXMLElementAccess xmlElementAccess) {
        
        
        xmlElementAccess.expr = rewriteExpr(xmlElementAccess.expr);

        ArrayList<BLangExpression> filters = expandFilters(xmlElementAccess.filters);

        BLangInvocation invocationNode = createLanglibXMLInvocation(xmlElementAccess.pos, XML_INTERNAL_GET_ELEMENTS,
                xmlElementAccess.expr, new ArrayList<>(), filters);
        result = rewriteExpr(invocationNode);
    }

    private ArrayList<BLangExpression> expandFilters(List<BLangXMLElementFilter> filters) {
        Map<Name, BXMLNSSymbol> nameBXMLNSSymbolMap = symResolver.resolveAllNamespaces(env);
        BXMLNSSymbol defaultNSSymbol = nameBXMLNSSymbolMap.get(names.fromString(XMLConstants.DEFAULT_NS_PREFIX));
        String defaultNS = defaultNSSymbol != null ? defaultNSSymbol.namespaceURI : null;

        ArrayList<BLangExpression> args = new ArrayList<>();
        for (BLangXMLElementFilter filter : filters) {
            BSymbol nsSymbol = symResolver.lookupSymbolInPrefixSpace(env, names.fromString(filter.namespace));
            if (nsSymbol == symTable.notFoundSymbol) {
                if (defaultNS != null && !filter.name.equals("*")) {
                    String expandedName = createExpandedQName(defaultNS, filter.name);
                    args.add(createStringLiteral(filter.elemNamePos, expandedName));
                } else {
                    args.add(createStringLiteral(filter.elemNamePos, filter.name));
                }
            } else {
                BXMLNSSymbol bxmlnsSymbol = (BXMLNSSymbol) nsSymbol;
                String expandedName = createExpandedQName(bxmlnsSymbol.namespaceURI, filter.name);
                BLangLiteral stringLiteral = createStringLiteral(filter.elemNamePos, expandedName);
                args.add(stringLiteral);
            }
        }
        return args;
    }

    private BLangInvocation createLanglibXMLInvocation(DiagnosticPos pos, String functionName,
                                                       BLangExpression invokeOnExpr,
                                                       ArrayList<BLangExpression> args,
                                                       ArrayList<BLangExpression> restArgs) {
        invokeOnExpr = rewriteExpr(invokeOnExpr);

        BLangInvocation invocationNode = (BLangInvocation) TreeBuilder.createInvocationNode();
        invocationNode.pos = pos;
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue(functionName);
        name.pos = pos;
        invocationNode.name = name;
        invocationNode.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        invocationNode.expr = invokeOnExpr;

        invocationNode.symbol = symResolver.lookupLangLibMethod(symTable.xmlType, names.fromString(functionName));

        ArrayList<BLangExpression> requiredArgs = new ArrayList<>();
        requiredArgs.add(invokeOnExpr);
        requiredArgs.addAll(args);
        invocationNode.requiredArgs = requiredArgs;
        invocationNode.restArgs = rewriteExprs(restArgs);

        invocationNode.type = ((BInvokableType) invocationNode.symbol.type).getReturnType();
        invocationNode.langLibInvocation = true;
        return invocationNode;
    }

    @Override
    public void visit(BLangXMLNavigationAccess xmlNavigation) {
        xmlNavigation.expr = rewriteExpr(xmlNavigation.expr);
        xmlNavigation.childIndex = rewriteExpr(xmlNavigation.childIndex);

        ArrayList<BLangExpression> filters = expandFilters(xmlNavigation.filters);

        
        if (xmlNavigation.navAccessType == XMLNavigationAccess.NavAccessType.DESCENDANTS) {
            BLangInvocation invocationNode = createLanglibXMLInvocation(xmlNavigation.pos,
                    XML_INTERNAL_SELECT_DESCENDANTS, xmlNavigation.expr, new ArrayList<>(), filters);
            result = rewriteExpr(invocationNode);
        } else if (xmlNavigation.navAccessType == XMLNavigationAccess.NavAccessType.CHILDREN) {
            
            BLangInvocation invocationNode = createLanglibXMLInvocation(xmlNavigation.pos, XML_INTERNAL_CHILDREN,
                    xmlNavigation.expr, new ArrayList<>(), new ArrayList<>());
            result = rewriteExpr(invocationNode);
        } else {
            BLangExpression childIndexExpr;
            
            if (xmlNavigation.childIndex == null) {
                childIndexExpr = new BLangLiteral(Long.valueOf(-1), symTable.intType);
            } else {
                
                childIndexExpr = xmlNavigation.childIndex;
            }
            ArrayList<BLangExpression> args = new ArrayList<>();
            args.add(rewriteExpr(childIndexExpr));

            BLangInvocation invocationNode = createLanglibXMLInvocation(xmlNavigation.pos,
                    XML_INTERNAL_GET_FILTERED_CHILDREN_FLAT, xmlNavigation.expr, args, filters);
            result = rewriteExpr(invocationNode);
        }
    }

    @Override
    public void visit(BLangIsAssignableExpr assignableExpr) {
        assignableExpr.lhsExpr = rewriteExpr(assignableExpr.lhsExpr);
        result = assignableExpr;
    }

    @Override
    public void visit(BFunctionPointerInvocation fpInvocation) {
        result = fpInvocation;
    }

    @Override
    public void visit(BLangTypedescExpr typedescExpr) {
        typedescExpr.typeNode = rewrite(typedescExpr.typeNode, env);
        result = typedescExpr;
    }

    @Override
    public void visit(BLangIntRangeExpression intRangeExpression) {
        if (!intRangeExpression.includeStart) {
            intRangeExpression.startExpr = getModifiedIntRangeStartExpr(intRangeExpression.startExpr);
        }
        if (!intRangeExpression.includeEnd) {
            intRangeExpression.endExpr = getModifiedIntRangeEndExpr(intRangeExpression.endExpr);
        }

        intRangeExpression.startExpr = rewriteExpr(intRangeExpression.startExpr);
        intRangeExpression.endExpr = rewriteExpr(intRangeExpression.endExpr);
        result = intRangeExpression;
    }

    @Override
    public void visit(BLangRestArgsExpression bLangVarArgsExpression) {
        result = rewriteExpr(bLangVarArgsExpression.expr);
    }

    @Override
    public void visit(BLangNamedArgsExpression bLangNamedArgsExpression) {
        bLangNamedArgsExpression.expr = rewriteExpr(bLangNamedArgsExpression.expr);
        result = bLangNamedArgsExpression.expr;
    }

    @Override
    public void visit(BLangMatchExpression bLangMatchExpression) {
        
        addMatchExprDefaultCase(bLangMatchExpression);

        
        
        String matchTempResultVarName = GEN_VAR_PREFIX.value + "temp_result";
        BLangSimpleVariable tempResultVar = ASTBuilderUtil.createVariable(bLangMatchExpression.pos,
                matchTempResultVarName, bLangMatchExpression.type, null,
                new BVarSymbol(0, names.fromString(matchTempResultVarName), this.env.scope.owner.pkgID,
                        bLangMatchExpression.type, this.env.scope.owner));

        BLangSimpleVariableDef tempResultVarDef =
                ASTBuilderUtil.createVariableDef(bLangMatchExpression.pos, tempResultVar);
        tempResultVarDef.desugared = true;

        BLangBlockStmt stmts = ASTBuilderUtil.createBlockStmt(bLangMatchExpression.pos, Lists.of(tempResultVarDef));
        List<BLangMatchTypedBindingPatternClause> patternClauses = new ArrayList<>();

        for (int i = 0; i < bLangMatchExpression.patternClauses.size(); i++) {
            BLangMatchExprPatternClause pattern = bLangMatchExpression.patternClauses.get(i);
            pattern.expr = rewriteExpr(pattern.expr);

            
            
            BLangVariableReference tempResultVarRef =
                    ASTBuilderUtil.createVariableRef(bLangMatchExpression.pos, tempResultVar.symbol);

            
            pattern.expr = addConversionExprIfRequired(pattern.expr, tempResultVarRef.type);
            BLangAssignment assignmentStmt =
                    ASTBuilderUtil.createAssignmentStmt(pattern.pos, tempResultVarRef, pattern.expr);
            BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(pattern.pos, Lists.of(assignmentStmt));

            
            
            patternClauses.add(ASTBuilderUtil.createMatchStatementPattern(pattern.pos, pattern.variable, patternBody));
        }

        stmts.addStatement(ASTBuilderUtil.createMatchStatement(bLangMatchExpression.pos, bLangMatchExpression.expr,
                patternClauses));
        BLangVariableReference tempResultVarRef =
                ASTBuilderUtil.createVariableRef(bLangMatchExpression.pos, tempResultVar.symbol);
        BLangStatementExpression statementExpr = createStatementExpression(stmts, tempResultVarRef);
        statementExpr.type = bLangMatchExpression.type;
        result = rewriteExpr(statementExpr);
    }

    @Override
    public void visit(BLangCheckedExpr checkedExpr) {
        visitCheckAndCheckPanicExpr(checkedExpr, false);
    }

    @Override
    public void visit(BLangCheckPanickedExpr checkedExpr) {
        visitCheckAndCheckPanicExpr(checkedExpr, true);
    }

    private void visitCheckAndCheckPanicExpr(BLangCheckedExpr checkedExpr, boolean isCheckPanic) {
        
        
        
        
        
        
        
        
        
        
        

        
        String checkedExprVarName = GEN_VAR_PREFIX.value;
        BLangSimpleVariable checkedExprVar = ASTBuilderUtil.createVariable(checkedExpr.pos,
                checkedExprVarName, checkedExpr.type, null, new BVarSymbol(0,
                        names.fromString(checkedExprVarName),
                        this.env.scope.owner.pkgID, checkedExpr.type, this.env.scope.owner));
        BLangSimpleVariableDef checkedExprVarDef = ASTBuilderUtil.createVariableDef(checkedExpr.pos, checkedExprVar);
        checkedExprVarDef.desugared = true;

        
        BLangMatchTypedBindingPatternClause patternSuccessCase =
                getSafeAssignSuccessPattern(checkedExprVar.pos, checkedExprVar.symbol.type, true,
                        checkedExprVar.symbol, null);
        BLangMatchTypedBindingPatternClause patternErrorCase = getSafeAssignErrorPattern(checkedExpr.pos,
                this.env.scope.owner, checkedExpr.equivalentErrorTypeList, isCheckPanic);

        
        BLangMatch matchStmt = ASTBuilderUtil.createMatchStatement(checkedExpr.pos, checkedExpr.expr,
                new ArrayList<BLangMatchTypedBindingPatternClause>() {{
                    add(patternSuccessCase);
                    add(patternErrorCase);
                }});

        
        BLangBlockStmt generatedStmtBlock = ASTBuilderUtil.createBlockStmt(checkedExpr.pos,
                new ArrayList<BLangStatement>() {{
                    add(checkedExprVarDef);
                    add(matchStmt);
                }});

        
        BLangSimpleVarRef tempCheckedExprVarRef = ASTBuilderUtil.createVariableRef(
                checkedExpr.pos, checkedExprVar.symbol);

        BLangStatementExpression statementExpr = createStatementExpression(
                generatedStmtBlock, tempCheckedExprVarRef);
        statementExpr.type = checkedExpr.type;
        result = rewriteExpr(statementExpr);
    }

    @Override
    public void visit(BLangServiceConstructorExpr serviceConstructorExpr) {
        final BLangTypeInit typeInit = ASTBuilderUtil.createEmptyTypeInit(serviceConstructorExpr.pos,
                serviceConstructorExpr.serviceNode.serviceTypeDefinition.symbol.type);
        serviceConstructorExpr.serviceNode.annAttachments.forEach(attachment ->  rewrite(attachment, env));
        result = rewriteExpr(typeInit);
    }

    @Override
    public void visit(BLangTypeTestExpr typeTestExpr) {
        BLangExpression expr = typeTestExpr.expr;
        if (types.isValueType(expr.type)) {
            addConversionExprIfRequired(expr, symTable.anyType);
        }
        typeTestExpr.expr = rewriteExpr(expr);
        typeTestExpr.typeNode = rewrite(typeTestExpr.typeNode, env);
        result = typeTestExpr;
    }

    @Override
    public void visit(BLangAnnotAccessExpr annotAccessExpr) {
        BLangBinaryExpr binaryExpr = (BLangBinaryExpr) TreeBuilder.createBinaryExpressionNode();
        binaryExpr.pos = annotAccessExpr.pos;
        binaryExpr.opKind = OperatorKind.ANNOT_ACCESS;
        binaryExpr.lhsExpr = annotAccessExpr.expr;
        binaryExpr.rhsExpr = ASTBuilderUtil.createLiteral(annotAccessExpr.pkgAlias.pos, symTable.stringType,
                                                          annotAccessExpr.annotationSymbol.bvmAlias());
        binaryExpr.type = annotAccessExpr.type;
        binaryExpr.opSymbol = new BOperatorSymbol(names.fromString(OperatorKind.ANNOT_ACCESS.value()), null,
                                                  new BInvokableType(Lists.of(binaryExpr.lhsExpr.type,
                                                                              binaryExpr.rhsExpr.type),
                                                          annotAccessExpr.type, null), null);
        result = rewriteExpr(binaryExpr);
    }

    @Override
    public void visit(BLangIsLikeExpr isLikeExpr) {
        isLikeExpr.expr = rewriteExpr(isLikeExpr.expr);
        result = isLikeExpr;
    }

    @Override
    public void visit(BLangStatementExpression bLangStatementExpression) {
        bLangStatementExpression.expr = rewriteExpr(bLangStatementExpression.expr);
        bLangStatementExpression.stmt = rewrite(bLangStatementExpression.stmt, env);
        result = bLangStatementExpression;
    }

    @Override
    public void visit(BLangQueryExpr queryExpr) {
        BLangStatementExpression stmtExpr = queryDesugar.desugarQueryExpr(queryExpr, env);
        result = rewrite(stmtExpr, env);
    }

    @Override
    public void visit(BLangQueryAction queryAction) {
        BLangStatementExpression stmtExpr = queryDesugar.desugarQueryAction(queryAction, env);
        result = rewrite(stmtExpr, env);
    }

    @Override
    public void visit(BLangJSONArrayLiteral jsonArrayLiteral) {
        jsonArrayLiteral.exprs = rewriteExprs(jsonArrayLiteral.exprs);
        result = jsonArrayLiteral;
    }

    @Override
    public void visit(BLangConstant constant) {

        BConstantSymbol constSymbol = constant.symbol;
        if (constSymbol.literalType.tag <= TypeTags.BOOLEAN || constSymbol.literalType.tag == TypeTags.NIL) {
            if (constSymbol.literalType.tag != TypeTags.NIL && constSymbol.value.value == null) {
                throw new IllegalStateException();
            }
            BLangLiteral literal = ASTBuilderUtil.createLiteral(constant.expr.pos, constSymbol.literalType,
                    constSymbol.value.value);
            constant.expr = rewriteExpr(literal);
        } else {
            constant.expr = rewriteExpr(constant.expr);
        }
        constant.annAttachments.forEach(attachment ->  rewrite(attachment, env));
        result = constant;
    }

    @Override
    public void visit(BLangIgnoreExpr ignoreExpr) {
        result = ignoreExpr;
    }

    @Override
    public void visit(BLangConstRef constantRef) {
        result = ASTBuilderUtil.createLiteral(constantRef.pos, constantRef.type, constantRef.value);
    }

    

    
    BLangSimpleVariableDef getIteratorVariableDefinition(DiagnosticPos pos, BVarSymbol collectionSymbol,
                                                                 BInvokableSymbol iteratorInvokableSymbol,
                                                                 boolean isIteratorFuncFromLangLib) {


        BLangSimpleVarRef dataReference = ASTBuilderUtil.createVariableRef(pos, collectionSymbol);
        BLangInvocation iteratorInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
        iteratorInvocation.pos = pos;
        iteratorInvocation.expr = dataReference;
        iteratorInvocation.symbol = iteratorInvokableSymbol;
        iteratorInvocation.type = iteratorInvokableSymbol.retType;
        iteratorInvocation.argExprs = Lists.of(dataReference);
        iteratorInvocation.requiredArgs = iteratorInvocation.argExprs;
        iteratorInvocation.langLibInvocation = isIteratorFuncFromLangLib;
        BVarSymbol iteratorSymbol = new BVarSymbol(0, names.fromString("$iterator$"), this.env.scope.owner.pkgID,
                iteratorInvokableSymbol.retType, this.env.scope.owner);

        
        BLangSimpleVariable iteratorVariable = ASTBuilderUtil.createVariable(pos, "$iterator$",
                iteratorInvokableSymbol.retType, iteratorInvocation, iteratorSymbol);
        return ASTBuilderUtil.createVariableDef(pos, iteratorVariable);
    }

    
    BLangSimpleVariableDef getIteratorNextVariableDefinition(DiagnosticPos pos, BType nillableResultType,
                                                                     BVarSymbol iteratorSymbol,
                                                                     BVarSymbol resultSymbol) {
        BLangInvocation nextInvocation = createIteratorNextInvocation(pos, iteratorSymbol);
        BLangSimpleVariable resultVariable = ASTBuilderUtil.createVariable(pos, "$result$",
                nillableResultType, nextInvocation, resultSymbol);
        return ASTBuilderUtil.createVariableDef(pos, resultVariable);
    }

    
    BLangAssignment getIteratorNextAssignment(DiagnosticPos pos,
                                                      BVarSymbol iteratorSymbol, BVarSymbol resultSymbol) {
        BLangSimpleVarRef resultReferenceInAssignment = ASTBuilderUtil.createVariableRef(pos, resultSymbol);

        
        BLangInvocation nextInvocation = createIteratorNextInvocation(pos, iteratorSymbol);

        
        nextInvocation.expr.type = types.getSafeType(nextInvocation.expr.type, true, false);

        return ASTBuilderUtil.createAssignmentStmt(pos, resultReferenceInAssignment, nextInvocation, false);
    }

    BLangInvocation createIteratorNextInvocation(DiagnosticPos pos, BVarSymbol iteratorSymbol) {
        BLangIdentifier nextIdentifier = ASTBuilderUtil.createIdentifier(pos, "next");
        BLangSimpleVarRef iteratorReferenceInNext = ASTBuilderUtil.createVariableRef(pos, iteratorSymbol);
        BInvokableSymbol nextFuncSymbol = getNextFunc((BObjectType) iteratorSymbol.type).symbol;
        BLangInvocation nextInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
        nextInvocation.pos = pos;
        nextInvocation.name = nextIdentifier;
        nextInvocation.expr = iteratorReferenceInNext;
        nextInvocation.requiredArgs = Lists.of(ASTBuilderUtil.createVariableRef(pos, iteratorSymbol));
        nextInvocation.argExprs = nextInvocation.requiredArgs;
        nextInvocation.symbol = nextFuncSymbol;
        nextInvocation.type = nextFuncSymbol.retType;
        return nextInvocation;
    }

    private BAttachedFunction getNextFunc(BObjectType iteratorType) {
        BObjectTypeSymbol iteratorSymbol = (BObjectTypeSymbol) iteratorType.tsymbol;
        for (BAttachedFunction bAttachedFunction : iteratorSymbol.attachedFuncs) {
            if (bAttachedFunction.funcName.value.equals("next")) {
                return bAttachedFunction;
            }
        }
        return null;
    }

    
    BLangFieldBasedAccess getValueAccessExpression(DiagnosticPos pos, BType varType, BVarSymbol resultSymbol) {
        BLangSimpleVarRef resultReferenceInVariableDef = ASTBuilderUtil.createVariableRef(pos, resultSymbol);
        BLangIdentifier valueIdentifier = ASTBuilderUtil.createIdentifier(pos, "value");

        BLangFieldBasedAccess fieldBasedAccessExpression =
                ASTBuilderUtil.createFieldAccessExpr(resultReferenceInVariableDef, valueIdentifier);
        fieldBasedAccessExpression.pos = pos;
        fieldBasedAccessExpression.type = varType;
        fieldBasedAccessExpression.originalType = fieldBasedAccessExpression.type;
        return fieldBasedAccessExpression;
    }

    private BlockFunctionBodyNode populateArrowExprBodyBlock(BLangArrowFunction bLangArrowFunction) {
        BlockFunctionBodyNode blockNode = TreeBuilder.createBlockFunctionBodyNode();
        BLangReturn returnNode = (BLangReturn) TreeBuilder.createReturnNode();
        returnNode.pos = bLangArrowFunction.body.expr.pos;
        returnNode.setExpression(bLangArrowFunction.body.expr);
        blockNode.addStatement(returnNode);
        return blockNode;
    }

    private BLangInvocation createInvocationNode(String functionName, List<BLangExpression> args, BType retType) {
        BLangInvocation invocationNode = (BLangInvocation) TreeBuilder.createInvocationNode();
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue(functionName);
        invocationNode.name = name;
        invocationNode.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        
        invocationNode.symbol = symTable.rootScope.lookup(new Name(functionName)).symbol;
        invocationNode.type = retType;
        invocationNode.requiredArgs = args;
        return invocationNode;
    }

    private BLangInvocation createLangLibInvocationNode(String functionName,
                                                        BLangExpression onExpr,
                                                        List<BLangExpression> args,
                                                        BType retType,
                                                        DiagnosticPos pos) {
        BLangInvocation invocationNode = (BLangInvocation) TreeBuilder.createInvocationNode();
        invocationNode.pos = pos;
        BLangIdentifier name = (BLangIdentifier) TreeBuilder.createIdentifierNode();
        name.setLiteral(false);
        name.setValue(functionName);
        name.pos = pos;
        invocationNode.name = name;
        invocationNode.pkgAlias = (BLangIdentifier) TreeBuilder.createIdentifierNode();

        invocationNode.expr = onExpr;



        invocationNode.symbol = symResolver.lookupLangLibMethod(onExpr.type, names.fromString(functionName));

        ArrayList<BLangExpression> requiredArgs = new ArrayList<>();
        requiredArgs.add(onExpr);
        requiredArgs.addAll(args);
        invocationNode.requiredArgs = requiredArgs;

        invocationNode.type = retType != null ? retType : ((BInvokableSymbol) invocationNode.symbol).retType;
        invocationNode.langLibInvocation = true;
        return invocationNode;
    }

    private BLangArrayLiteral createArrayLiteralExprNode() {
        BLangArrayLiteral expr = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
        expr.exprs = new ArrayList<>();
        expr.type = new BArrayType(symTable.anyType);
        return expr;
    }

    private void visitFunctionPointerInvocation(BLangInvocation iExpr) {
        BLangVariableReference expr;
        if (iExpr.expr == null) {
            expr = new BLangSimpleVarRef();
        } else {
            BLangFieldBasedAccess fieldBasedAccess = new BLangFieldBasedAccess();
            fieldBasedAccess.expr = iExpr.expr;
            fieldBasedAccess.field = iExpr.name;
            expr = fieldBasedAccess;
        }
        expr.symbol = iExpr.symbol;
        expr.type = iExpr.symbol.type;

        BLangExpression rewritten = rewriteExpr(expr);
        result = new BFunctionPointerInvocation(iExpr, rewritten);
    }

    private BLangExpression visitCloneInvocation(BLangExpression expr, BType lhsType) {
        if (types.isValueType(expr.type)) {
            return expr;
        }
        if (expr.type.tag == TypeTags.ERROR) {
            return expr;
        }
        BLangInvocation cloneInvok = createLangLibInvocationNode("clone", expr, new ArrayList<>(), expr.type, expr.pos);
        return addConversionExprIfRequired(cloneInvok, lhsType);
    }

    private BLangExpression visitCloneReadonly(BLangExpression expr, BType lhsType) {
        if (types.isValueType(expr.type)) {
            return expr;
        }
        if (expr.type.tag == TypeTags.ERROR) {
            return expr;
        }
        BLangInvocation cloneInvok = createLangLibInvocationNode("cloneReadOnly", expr, new ArrayList<>(), expr.type,
                expr.pos);
        return addConversionExprIfRequired(cloneInvok, lhsType);
    }

    @SuppressWarnings("unchecked")
    <E extends BLangNode> E rewrite(E node, SymbolEnv env) {
        if (node == null) {
            return null;
        }

        if (node.desugared) {
            return node;
        }

        SymbolEnv previousEnv = this.env;
        this.env = env;

        node.accept(this);
        BLangNode resultNode = this.result;
        this.result = null;
        resultNode.desugared = true;

        this.env = previousEnv;
        return (E) resultNode;
    }

    @SuppressWarnings("unchecked")
    <E extends BLangExpression> E rewriteExpr(E node) {
        if (node == null) {
            return null;
        }

        if (node.desugared) {
            return node;
        }

        BLangExpression expr = node;
        if (node.impConversionExpr != null) {
            expr = node.impConversionExpr;
            node.impConversionExpr = null;
        }

        expr.accept(this);
        BLangNode resultNode = this.result;
        this.result = null;
        resultNode.desugared = true;

        return (E) resultNode;
    }

    @SuppressWarnings("unchecked")
    <E extends BLangStatement> E rewrite(E statement, SymbolEnv env) {
        if (statement == null) {
            return null;
        }
        BLangStatementLink link = new BLangStatementLink();
        link.parent = currentLink;
        currentLink = link;
        BLangStatement stmt = (BLangStatement) rewrite((BLangNode) statement, env);
        
        link.statement = stmt;
        stmt.statementLink = link;
        currentLink = link.parent;
        return (E) stmt;
    }

    private <E extends BLangStatement> List<E> rewriteStmt(List<E> nodeList, SymbolEnv env) {
        for (int i = 0; i < nodeList.size(); i++) {
            nodeList.set(i, rewrite(nodeList.get(i), env));
        }
        return nodeList;
    }

    private <E extends BLangNode> List<E> rewrite(List<E> nodeList, SymbolEnv env) {
        for (int i = 0; i < nodeList.size(); i++) {
            nodeList.set(i, rewrite(nodeList.get(i), env));
        }
        return nodeList;
    }

    private <E extends BLangExpression> List<E> rewriteExprs(List<E> nodeList) {
        for (int i = 0; i < nodeList.size(); i++) {
            nodeList.set(i, rewriteExpr(nodeList.get(i)));
        }
        return nodeList;
    }

    private BLangLiteral createStringLiteral(DiagnosticPos pos, String value) {
        BLangLiteral stringLit = new BLangLiteral(value, symTable.stringType);
        stringLit.pos = pos;
        return stringLit;
    }

    private BLangLiteral createIntLiteral(long value) {
        BLangLiteral literal = (BLangLiteral) TreeBuilder.createLiteralExpression();
        literal.value = value;
        literal.type = symTable.intType;
        return literal;
    }

    private BLangLiteral createByteLiteral(DiagnosticPos pos, Byte value) {
        BLangLiteral byteLiteral = new BLangLiteral(Byte.toUnsignedInt(value), symTable.byteType);
        byteLiteral.pos = pos;
        return byteLiteral;
    }

    private BLangExpression createTypeCastExpr(BLangExpression expr, BType targetType) {
        BLangTypeConversionExpr conversionExpr = (BLangTypeConversionExpr) TreeBuilder.createTypeConversionNode();
        conversionExpr.pos = expr.pos;
        conversionExpr.expr = expr;
        conversionExpr.type = targetType;
        conversionExpr.targetType = targetType;
        return conversionExpr;
    }

    private BType getElementType(BType type) {
        if (type.tag != TypeTags.ARRAY) {
            return type;
        }

        return getElementType(((BArrayType) type).getElementType());
    }

    
    private void addReturnIfNotPresent(BLangInvokableNode invokableNode) {
        if (Symbols.isNative(invokableNode.symbol) ||
                (invokableNode.hasBody() && invokableNode.body.getKind() != NodeKind.BLOCK_FUNCTION_BODY)) {
            return;
        }
        
        
        BLangBlockFunctionBody funcBody = (BLangBlockFunctionBody) invokableNode.body;
        if (invokableNode.workers.size() == 0 && invokableNode.symbol.type.getReturnType().isNullable()
                && (funcBody.stmts.size() < 1
                || funcBody.stmts.get(funcBody.stmts.size() - 1).getKind() != NodeKind.RETURN)) {
            DiagnosticPos invPos = invokableNode.pos;
            DiagnosticPos returnStmtPos = new DiagnosticPos(invPos.src, invPos.eLine, invPos.eLine, invPos.sCol,
                                                            invPos.sCol);
            BLangReturn returnStmt = ASTBuilderUtil.createNilReturnStmt(returnStmtPos, symTable.nilType);
            funcBody.addStatement(returnStmt);
        }
    }

    /**
     * Reorder the invocation arguments to match the original function signature.
     *
     * @param iExpr Function invocation expressions to reorder the arguments
     */
    private void reorderArguments(BLangInvocation iExpr) {
        BSymbol symbol = iExpr.symbol;

        if (symbol == null || symbol.type.tag != TypeTags.INVOKABLE) {
            return;
        }

        BInvokableSymbol invokableSymbol = (BInvokableSymbol) symbol;

        List<BLangExpression> restArgs = iExpr.restArgs;
        int originalRequiredArgCount = iExpr.requiredArgs.size();

        
        BLangExpression varargRef = null;
        BLangBlockStmt blockStmt = null;

        int restArgCount = restArgs.size();

        if (restArgCount > 0 &&
                restArgs.get(restArgCount - 1).getKind() == NodeKind.REST_ARGS_EXPR &&
                originalRequiredArgCount < invokableSymbol.params.size()) {
            
            
            
            BLangExpression expr = ((BLangRestArgsExpression) restArgs.get(restArgCount - 1)).expr;
            DiagnosticPos varargExpPos = expr.pos;
            BType varargVarType = expr.type;
            String varargVarName = DESUGARED_VARARG_KEY + this.varargCount++;

            BVarSymbol varargVarSymbol = new BVarSymbol(0, names.fromString(varargVarName), this.env.scope.owner.pkgID,
                                                        varargVarType, this.env.scope.owner);
            varargRef = ASTBuilderUtil.createVariableRef(varargExpPos, varargVarSymbol);

            BLangSimpleVariable var = createVariable(varargExpPos, varargVarName, varargVarType, expr, varargVarSymbol);

            BLangSimpleVariableDef varDef = ASTBuilderUtil.createVariableDef(varargExpPos);
            varDef.var = var;
            varDef.type = varargVarType;

            blockStmt = createBlockStmt(varargExpPos);
            blockStmt.stmts.add(varDef);
        }

        if (!invokableSymbol.params.isEmpty()) {
            
            reorderNamedArgs(iExpr, invokableSymbol, varargRef);
        }

        
        if (restArgCount == 0 || restArgs.get(restArgCount - 1).getKind() != NodeKind.REST_ARGS_EXPR) {
            if (invokableSymbol.restParam == null) {
                return;
            }

            BLangArrayLiteral arrayLiteral = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
            List<BLangExpression> exprs = new ArrayList<>();

            BArrayType arrayType = (BArrayType) invokableSymbol.restParam.type;
            BType elemType = arrayType.eType;

            for (BLangExpression restArg : restArgs) {
                exprs.add(addConversionExprIfRequired(restArg, elemType));
            }

            arrayLiteral.exprs = exprs;
            arrayLiteral.type = arrayType;

            if (restArgCount != 0) {
                iExpr.restArgs = new ArrayList<>();
            }

            iExpr.restArgs.add(arrayLiteral);
            return;
        }

        
        if (restArgCount == 1 && restArgs.get(0).getKind() == NodeKind.REST_ARGS_EXPR) {

            
            
            if (iExpr.requiredArgs.size() == originalRequiredArgCount) {
                return;
            }

            
            
            
            
            BLangExpression firstNonRestArg = iExpr.requiredArgs.remove(0);
            BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, firstNonRestArg);
            stmtExpression.type = firstNonRestArg.type;
            iExpr.requiredArgs.add(0, stmtExpression);

            
            
            if (invokableSymbol.restParam == null) {
                return;
            }

            BLangLiteral startIndex = createIntLiteral(invokableSymbol.params.size() - originalRequiredArgCount);
            BLangInvocation sliceInvocation =
                    createLangLibInvocationNode(SLICE_LANGLIB_METHOD, varargRef,
                                                new ArrayList<BLangExpression>() {{
                                                    add(startIndex);
                                                }},
                                                varargRef.type, varargRef.pos);
            restArgs.remove(0);
            restArgs.add(addConversionExprIfRequired(sliceInvocation, invokableSymbol.restParam.type));
            return;
        }

        
        
        BArrayType restParamType = (BArrayType) invokableSymbol.restParam.type;

        BLangArrayLiteral arrayLiteral = (BLangArrayLiteral) TreeBuilder.createArrayLiteralExpressionNode();
        arrayLiteral.type = restParamType;

        BType elemType = restParamType.eType;
        DiagnosticPos pos = restArgs.get(0).pos;

        List<BLangExpression> exprs = new ArrayList<>();

        for (int i = 0; i < restArgCount - 1; i++) {
            exprs.add(addConversionExprIfRequired(restArgs.get(i), elemType));
        }
        arrayLiteral.exprs = exprs;

        BLangRestArgsExpression pushRestArgsExpr = (BLangRestArgsExpression) TreeBuilder.createVarArgsNode();
        pushRestArgsExpr.pos = pos;
        pushRestArgsExpr.expr = restArgs.remove(restArgCount - 1);

        String name = DESUGARED_VARARG_KEY + this.varargCount++;
        BVarSymbol varSymbol = new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, restParamType,
                                              this.env.scope.owner);
        BLangSimpleVarRef arrayVarRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        BLangSimpleVariable var = createVariable(pos, name, restParamType, arrayLiteral, varSymbol);
        BLangSimpleVariableDef varDef = ASTBuilderUtil.createVariableDef(pos);
        varDef.var = var;
        varDef.type = restParamType;

        BLangBlockStmt pushBlockStmt = createBlockStmt(pos);
        pushBlockStmt.stmts.add(varDef);

        BLangExpressionStmt expressionStmt = createExpressionStmt(pos, pushBlockStmt);
        BLangInvocation pushInvocation = createLangLibInvocationNode(PUSH_LANGLIB_METHOD, arrayVarRef,
                                                                     new ArrayList<BLangExpression>() {{
                                                                         add(pushRestArgsExpr);
                                                                     }}, restParamType, pos);
        pushInvocation.restArgs.add(pushInvocation.requiredArgs.remove(1));
        expressionStmt.expr = pushInvocation;

        BLangStatementExpression stmtExpression = createStatementExpression(pushBlockStmt, arrayVarRef);
        stmtExpression.type = restParamType;

        iExpr.restArgs = new ArrayList<BLangExpression>(1) {{ add(stmtExpression); }};
    }

    private void reorderNamedArgs(BLangInvocation iExpr, BInvokableSymbol invokableSymbol, BLangExpression varargRef) {
        List<BLangExpression> args = new ArrayList<>();
        Map<String, BLangExpression> namedArgs = new HashMap<>();
        iExpr.requiredArgs.stream()
                .filter(expr -> expr.getKind() == NodeKind.NAMED_ARGS_EXPR)
                .forEach(expr -> namedArgs.put(((NamedArgNode) expr).getName().value, expr));

        List<BVarSymbol> params = invokableSymbol.params;

        int varargIndex = 0;

        BType varargType = null;
        boolean tupleTypedVararg = false;

        if (varargRef != null) {
            varargType = varargRef.type;
            tupleTypedVararg = varargType.tag == TypeTags.TUPLE;
        }

        
        for (int i = 0; i < params.size(); i++) {
            BVarSymbol param = params.get(i);
            if (iExpr.requiredArgs.size() > i && iExpr.requiredArgs.get(i).getKind() != NodeKind.NAMED_ARGS_EXPR) {
                
                args.add(iExpr.requiredArgs.get(i));
            } else if (namedArgs.containsKey(param.name.value)) {
                
                args.add(namedArgs.get(param.name.value));
            } else if (varargRef == null) {
                
                BLangExpression expr = new BLangIgnoreExpr();
                expr.type = param.type;
                args.add(expr);
            } else {
                
                
                BLangIndexBasedAccess memberAccessExpr =
                        (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
                memberAccessExpr.pos = varargRef.pos;
                memberAccessExpr.expr = varargRef;
                memberAccessExpr.indexExpr = rewriteExpr(createIntLiteral(varargIndex));
                memberAccessExpr.type = tupleTypedVararg ? ((BTupleType) varargType).tupleTypes.get(varargIndex) :
                        ((BArrayType) varargType).eType;
                varargIndex++;
                args.add(addConversionExprIfRequired(memberAccessExpr, param.type));
            }
        }
        iExpr.requiredArgs = args;
    }

    private BLangMatchTypedBindingPatternClause getSafeAssignErrorPattern(
            DiagnosticPos pos, BSymbol invokableSymbol, List<BType> equivalentErrorTypes, boolean isCheckPanicExpr) {
        
        
        BType enclosingFuncReturnType = ((BInvokableType) invokableSymbol.type).retType;
        Set<BType> returnTypeSet = enclosingFuncReturnType.tag == TypeTags.UNION ?
                ((BUnionType) enclosingFuncReturnType).getMemberTypes() :
                new LinkedHashSet<BType>() {{
                    add(enclosingFuncReturnType);
                }};

        
        boolean returnOnError = equivalentErrorTypes.stream()
                .allMatch(errorType -> returnTypeSet.stream()
                        .anyMatch(retType -> types.isAssignable(errorType, retType)));

        
        
        String patternFailureCaseVarName = GEN_VAR_PREFIX.value + "t_failure";
        BLangSimpleVariable patternFailureCaseVar = ASTBuilderUtil.createVariable(pos,
                patternFailureCaseVarName, symTable.errorType, null, new BVarSymbol(0,
                        names.fromString(patternFailureCaseVarName),
                        this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner));

        
        BLangVariableReference patternFailureCaseVarRef = ASTBuilderUtil.createVariableRef(pos,
                patternFailureCaseVar.symbol);

        BLangBlockStmt patternBlockFailureCase = (BLangBlockStmt) TreeBuilder.createBlockNode();
        patternBlockFailureCase.pos = pos;
        if (!isCheckPanicExpr && returnOnError) {
            
            BLangReturn returnStmt = (BLangReturn) TreeBuilder.createReturnNode();
            returnStmt.pos = pos;
            returnStmt.expr = patternFailureCaseVarRef;
            patternBlockFailureCase.stmts.add(returnStmt);
        } else {
            
            BLangPanic panicNode = (BLangPanic) TreeBuilder.createPanicNode();
            panicNode.pos = pos;
            panicNode.expr = patternFailureCaseVarRef;
            patternBlockFailureCase.stmts.add(panicNode);
        }

        return ASTBuilderUtil.createMatchStatementPattern(pos, patternFailureCaseVar, patternBlockFailureCase);
    }

    private BLangMatchTypedBindingPatternClause getSafeAssignSuccessPattern(DiagnosticPos pos, BType lhsType,
            boolean isVarDef, BVarSymbol varSymbol, BLangExpression lhsExpr) {
        
        
        String patternSuccessCaseVarName = GEN_VAR_PREFIX.value + "t_match";
        BLangSimpleVariable patternSuccessCaseVar = ASTBuilderUtil.createVariable(pos,
                patternSuccessCaseVarName, lhsType, null, new BVarSymbol(0,
                        names.fromString(patternSuccessCaseVarName),
                        this.env.scope.owner.pkgID, lhsType, this.env.scope.owner));

        
        BLangExpression varRefExpr;
        if (isVarDef) {
            varRefExpr = ASTBuilderUtil.createVariableRef(pos, varSymbol);
        } else {
            varRefExpr = lhsExpr;
        }

        BLangVariableReference patternSuccessCaseVarRef = ASTBuilderUtil.createVariableRef(pos,
                patternSuccessCaseVar.symbol);
        BLangAssignment assignmentStmtSuccessCase = ASTBuilderUtil.createAssignmentStmt(pos,
                varRefExpr, patternSuccessCaseVarRef, false);

        BLangBlockStmt patternBlockSuccessCase = ASTBuilderUtil.createBlockStmt(pos,
                new ArrayList<BLangStatement>() {{
                    add(assignmentStmtSuccessCase);
                }});
        return ASTBuilderUtil.createMatchStatementPattern(pos,
                patternSuccessCaseVar, patternBlockSuccessCase);
    }

    private BLangStatement generateIfElseStmt(BLangMatch matchStmt, BLangSimpleVariable matchExprVar) {
        List<BLangMatchBindingPatternClause> patterns = matchStmt.patternClauses;

        BLangIf parentIfNode = generateIfElseStmt(patterns.get(0), matchExprVar);
        BLangIf currentIfNode = parentIfNode;
        for (int i = 1; i < patterns.size(); i++) {
            BLangMatchBindingPatternClause patternClause = patterns.get(i);
            if (i == patterns.size() - 1 && patternClause.isLastPattern) { 
                currentIfNode.elseStmt = getMatchPatternElseBody(patternClause, matchExprVar);
            } else {
                currentIfNode.elseStmt = generateIfElseStmt(patternClause, matchExprVar);
                currentIfNode = (BLangIf) currentIfNode.elseStmt;
            }
        }

        
        
        
        
        
        return parentIfNode;
    }


    /**
     * Generate an if-else statement from the given match statement.
     *
     * @param pattern match pattern statement node
     * @param matchExprVar  variable node of the match expression
     * @return if else statement node
     */
    private BLangIf generateIfElseStmt(BLangMatchBindingPatternClause pattern, BLangSimpleVariable matchExprVar) {
        BLangExpression ifCondition = createPatternIfCondition(pattern, matchExprVar.symbol);
        if (NodeKind.MATCH_TYPED_PATTERN_CLAUSE == pattern.getKind()) {
            BLangBlockStmt patternBody = getMatchPatternBody(pattern, matchExprVar);
            return ASTBuilderUtil.createIfElseStmt(pattern.pos, ifCondition, patternBody, null);
        }

        
        BType expectedType = matchExprVar.type;
        if (pattern.getKind() == NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE) {
            BLangMatchStructuredBindingPatternClause matchPattern = (BLangMatchStructuredBindingPatternClause) pattern;
            expectedType = getStructuredBindingPatternType(matchPattern.bindingPatternVariable);
        }

        if (NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE == pattern.getKind()) { 
            BLangMatchStructuredBindingPatternClause structuredPattern =
                    (BLangMatchStructuredBindingPatternClause) pattern;
            BLangSimpleVariableDef varDef = forceCastIfApplicable(matchExprVar.symbol, pattern.pos, expectedType);

            
            BLangSimpleVarRef matchExprVarRef = ASTBuilderUtil.createVariableRef(pattern.pos, varDef.var.symbol);
            structuredPattern.bindingPatternVariable.expr = matchExprVarRef;

            BLangStatement varDefStmt;
            if (NodeKind.TUPLE_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createTupleVariableDef(pattern.pos,
                        (BLangTupleVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.RECORD_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createRecordVariableDef(pattern.pos,
                        (BLangRecordVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.ERROR_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createErrorVariableDef(pattern.pos,
                        (BLangErrorVariable) structuredPattern.bindingPatternVariable);
            } else {
                varDefStmt = ASTBuilderUtil
                        .createVariableDef(pattern.pos, (BLangSimpleVariable) structuredPattern.bindingPatternVariable);
            }

            if (structuredPattern.typeGuardExpr != null) {
                BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(structuredPattern.pos);
                blockStmt.addStatement(varDef);
                blockStmt.addStatement(varDefStmt);
                BLangStatementExpression stmtExpr = createStatementExpression(blockStmt,
                                                                              structuredPattern.typeGuardExpr);
                stmtExpr.type = symTable.booleanType;

                ifCondition = ASTBuilderUtil
                        .createBinaryExpr(pattern.pos, ifCondition, stmtExpr, symTable.booleanType, OperatorKind.AND,
                                (BOperatorSymbol) symResolver
                                        .resolveBinaryOperator(OperatorKind.AND, symTable.booleanType,
                                                symTable.booleanType));
            } else {
                structuredPattern.body.stmts.add(0, varDef);
                structuredPattern.body.stmts.add(1, varDefStmt);
            }
        }

        return ASTBuilderUtil.createIfElseStmt(pattern.pos, ifCondition, pattern.body, null);
    }

    private BLangBlockStmt getMatchPatternBody(BLangMatchBindingPatternClause pattern,
                                               BLangSimpleVariable matchExprVar) {

        BLangBlockStmt body;

        BLangMatchTypedBindingPatternClause patternClause = (BLangMatchTypedBindingPatternClause) pattern;
        
        if (patternClause.variable.name.value.equals(Names.IGNORE.value)) {
            return patternClause.body;
        }

        
        
        BLangSimpleVarRef matchExprVarRef = ASTBuilderUtil.createVariableRef(patternClause.pos,
                matchExprVar.symbol);
        BLangExpression patternVarExpr = addConversionExprIfRequired(matchExprVarRef, patternClause.variable.type);

        
        BLangSimpleVariable patternVar = ASTBuilderUtil.createVariable(patternClause.pos, "",
                patternClause.variable.type, patternVarExpr, patternClause.variable.symbol);
        BLangSimpleVariableDef patternVarDef = ASTBuilderUtil.createVariableDef(patternVar.pos, patternVar);
        patternClause.body.stmts.add(0, patternVarDef);
        body = patternClause.body;

        return body;
    }

    private BLangBlockStmt getMatchPatternElseBody(BLangMatchBindingPatternClause pattern,
            BLangSimpleVariable matchExprVar) {

        BLangBlockStmt body = pattern.body;

        if (NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE == pattern.getKind()) { 

            
            BLangSimpleVarRef matchExprVarRef = ASTBuilderUtil.createVariableRef(pattern.pos, matchExprVar.symbol);

            BLangMatchStructuredBindingPatternClause structuredPattern =
                    (BLangMatchStructuredBindingPatternClause) pattern;

            structuredPattern.bindingPatternVariable.expr = matchExprVarRef;

            BLangStatement varDefStmt;
            if (NodeKind.TUPLE_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createTupleVariableDef(pattern.pos,
                        (BLangTupleVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.RECORD_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createRecordVariableDef(pattern.pos,
                        (BLangRecordVariable) structuredPattern.bindingPatternVariable);
            } else if (NodeKind.ERROR_VARIABLE == structuredPattern.bindingPatternVariable.getKind()) {
                varDefStmt = ASTBuilderUtil.createErrorVariableDef(pattern.pos,
                        (BLangErrorVariable) structuredPattern.bindingPatternVariable);
            } else {
                varDefStmt = ASTBuilderUtil
                        .createVariableDef(pattern.pos, (BLangSimpleVariable) structuredPattern.bindingPatternVariable);
            }
            structuredPattern.body.stmts.add(0, varDefStmt);
            body = structuredPattern.body;
        }

        return body;
    }

    BLangExpression addConversionExprIfRequired(BLangExpression expr, BType lhsType) {
        if (lhsType.tag == TypeTags.NONE) {
            return expr;
        }

        BType rhsType = expr.type;
        if (types.isSameType(rhsType, lhsType)) {
            return expr;
        }

        types.setImplicitCastExpr(expr, rhsType, lhsType);
        if (expr.impConversionExpr != null) {
            return expr;
        }

        if (lhsType.tag == TypeTags.JSON && rhsType.tag == TypeTags.NIL) {
            return expr;
        }

        if (lhsType.tag == TypeTags.NIL && rhsType.isNullable()) {
            return expr;
        }

        if (lhsType.tag == TypeTags.ARRAY && rhsType.tag == TypeTags.TUPLE) {
            return expr;
        }

        
        BLangTypeConversionExpr conversionExpr = (BLangTypeConversionExpr)
                TreeBuilder.createTypeConversionNode();
        conversionExpr.expr = expr;
        conversionExpr.targetType = lhsType;
        conversionExpr.type = lhsType;
        conversionExpr.pos = expr.pos;
        conversionExpr.checkTypes = false;
        return conversionExpr;
    }

    private BLangExpression createPatternIfCondition(BLangMatchBindingPatternClause patternClause,
                                                     BVarSymbol varSymbol) {
        BType patternType;

        switch (patternClause.getKind()) {
            case MATCH_STATIC_PATTERN_CLAUSE:
                BLangMatchStaticBindingPatternClause staticPattern =
                        (BLangMatchStaticBindingPatternClause) patternClause;
                patternType = staticPattern.literal.type;
                break;
            case MATCH_STRUCTURED_PATTERN_CLAUSE:
                BLangMatchStructuredBindingPatternClause structuredPattern =
                        (BLangMatchStructuredBindingPatternClause) patternClause;
                patternType = getStructuredBindingPatternType(structuredPattern.bindingPatternVariable);
                break;
            default:
                BLangMatchTypedBindingPatternClause simplePattern = (BLangMatchTypedBindingPatternClause) patternClause;
                patternType = simplePattern.variable.type;
                break;
        }

        BLangExpression binaryExpr;
        BType[] memberTypes;
        if (patternType.tag == TypeTags.UNION) {
            BUnionType unionType = (BUnionType) patternType;
            memberTypes = unionType.getMemberTypes().toArray(new BType[0]);
        } else {
            memberTypes = new BType[1];
            memberTypes[0] = patternType;
        }

        if (memberTypes.length == 1) {
            binaryExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[0]);
        } else {
            BLangExpression lhsExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[0]);
            BLangExpression rhsExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[1]);
            binaryExpr = ASTBuilderUtil.createBinaryExpr(patternClause.pos, lhsExpr, rhsExpr,
                    symTable.booleanType, OperatorKind.OR,
                    (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.OR,
                            lhsExpr.type, rhsExpr.type));
            for (int i = 2; i < memberTypes.length; i++) {
                lhsExpr = createPatternMatchBinaryExpr(patternClause, varSymbol, memberTypes[i]);
                rhsExpr = binaryExpr;
                binaryExpr = ASTBuilderUtil.createBinaryExpr(patternClause.pos, lhsExpr, rhsExpr,
                        symTable.booleanType, OperatorKind.OR,
                        (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.OR,
                                lhsExpr.type, rhsExpr.type));
            }
        }
        return binaryExpr;
    }

    private BType getStructuredBindingPatternType(BLangVariable bindingPatternVariable) {
        if (NodeKind.TUPLE_VARIABLE == bindingPatternVariable.getKind()) {
            BLangTupleVariable tupleVariable = (BLangTupleVariable) bindingPatternVariable;
            List<BType> memberTypes = new ArrayList<>();
            for (int i = 0; i < tupleVariable.memberVariables.size(); i++) {
                memberTypes.add(getStructuredBindingPatternType(tupleVariable.memberVariables.get(i)));
            }
            BTupleType tupleType = new BTupleType(memberTypes);
            if (tupleVariable.restVariable != null) {
                BArrayType restArrayType = (BArrayType) getStructuredBindingPatternType(tupleVariable.restVariable);
                tupleType.restType = restArrayType.eType;
            }
            return tupleType;
        }

        if (NodeKind.RECORD_VARIABLE == bindingPatternVariable.getKind()) {
            BLangRecordVariable recordVariable = (BLangRecordVariable) bindingPatternVariable;

            BRecordTypeSymbol recordSymbol =
                    Symbols.createRecordSymbol(0, names.fromString("$anonRecordType$" + recordCount++),
                                               env.enclPkg.symbol.pkgID, null, env.scope.owner);
            recordSymbol.initializerFunc = createRecordInitFunc();
            recordSymbol.scope = new Scope(recordSymbol);
            recordSymbol.scope.define(
                    names.fromString(recordSymbol.name.value + "." + recordSymbol.initializerFunc.funcName.value),
                    recordSymbol.initializerFunc.symbol);

            List<BField> fields = new ArrayList<>();
            List<BLangSimpleVariable> typeDefFields = new ArrayList<>();

            for (int i = 0; i < recordVariable.variableList.size(); i++) {
                String fieldNameStr = recordVariable.variableList.get(i).key.value;
                Name fieldName = names.fromString(fieldNameStr);
                BType fieldType = getStructuredBindingPatternType(
                        recordVariable.variableList.get(i).valueBindingPattern);
                BVarSymbol fieldSymbol = new BVarSymbol(Flags.REQUIRED, fieldName,
                        env.enclPkg.symbol.pkgID, fieldType, recordSymbol);

                
                fields.add(new BField(fieldName, bindingPatternVariable.pos, fieldSymbol));
                typeDefFields.add(ASTBuilderUtil.createVariable(null, fieldNameStr, fieldType, null, fieldSymbol));
                recordSymbol.scope.define(fieldName, fieldSymbol);
            }

            BRecordType recordVarType = new BRecordType(recordSymbol);
            recordVarType.fields = fields;

            
            recordVarType.restFieldType = recordVariable.restParam != null ?
                        ((BMapType) ((BLangSimpleVariable) recordVariable.restParam).type).constraint :
                    symTable.anydataType;
            recordSymbol.type = recordVarType;
            recordVarType.tsymbol = recordSymbol;

            BLangRecordTypeNode recordTypeNode = TypeDefBuilderHelper.createRecordTypeNode(typeDefFields,
                                                                                           recordVarType,
                                                                                           bindingPatternVariable.pos);
            recordTypeNode.initFunction =
                    rewrite(TypeDefBuilderHelper.createInitFunctionForRecordType(recordTypeNode, env, names, symTable),
                            env);
            TypeDefBuilderHelper.addTypeDefinition(recordVarType, recordSymbol, recordTypeNode, env);

            return recordVarType;
        }

        if (NodeKind.ERROR_VARIABLE == bindingPatternVariable.getKind()) {
            BLangErrorVariable errorVariable = (BLangErrorVariable) bindingPatternVariable;
            BErrorTypeSymbol errorTypeSymbol = new BErrorTypeSymbol(
                    SymTag.ERROR,
                    Flags.PUBLIC,
                    names.fromString("$anonErrorType$" + errorCount++),
                    env.enclPkg.symbol.pkgID,
                    null, null);
            BType detailType;
            if ((errorVariable.detail == null || errorVariable.detail.isEmpty()) && errorVariable.restDetail != null) {
                detailType = symTable.detailType;
            } else {
                detailType = createDetailType(errorVariable.detail, errorVariable.restDetail, errorCount++);

                BLangRecordTypeNode recordTypeNode = createRecordTypeNode(errorVariable, (BRecordType) detailType);
                TypeDefBuilderHelper.addTypeDefinition(detailType, detailType.tsymbol, recordTypeNode, env);
            }
            BErrorType errorType = new BErrorType(errorTypeSymbol,
                    ((BErrorType) errorVariable.type).reasonType,
                    detailType);
            errorTypeSymbol.type = errorType;

            TypeDefBuilderHelper.addTypeDefinition(errorType, errorTypeSymbol, createErrorTypeNode(errorType), env);
            return errorType;
        }

        return bindingPatternVariable.type;
    }

    private BLangRecordTypeNode createRecordTypeNode(BLangErrorVariable errorVariable, BRecordType detailType) {
        List<BLangSimpleVariable> fieldList = new ArrayList<>();
        for (BLangErrorVariable.BLangErrorDetailEntry field : errorVariable.detail) {
            BVarSymbol symbol = field.valueBindingPattern.symbol;
            if (symbol == null) {
                symbol = new BVarSymbol(
                        Flags.PUBLIC,
                        names.fromString(field.key.value + "$"),
                        this.env.enclPkg.packageID,
                        symTable.pureType,
                        null);
            }
            BLangSimpleVariable fieldVar = ASTBuilderUtil.createVariable(
                    field.valueBindingPattern.pos,
                    symbol.name.value,
                    field.valueBindingPattern.type,
                    field.valueBindingPattern.expr,
                    symbol);
            fieldList.add(fieldVar);
        }
        return TypeDefBuilderHelper.createRecordTypeNode(fieldList, detailType, errorVariable.pos);
    }

    private BType createDetailType(List<BLangErrorVariable.BLangErrorDetailEntry> detail,
                                   BLangSimpleVariable restDetail, int errorNo) {
        BRecordTypeSymbol detailRecordTypeSymbol = new BRecordTypeSymbol(
                SymTag.RECORD,
                Flags.PUBLIC,
                names.fromString("$anonErrorType$" + errorNo + "$detailType"),
                env.enclPkg.symbol.pkgID, null, null);

        detailRecordTypeSymbol.initializerFunc = createRecordInitFunc();
        detailRecordTypeSymbol.scope = new Scope(detailRecordTypeSymbol);
        detailRecordTypeSymbol.scope.define(
                names.fromString(detailRecordTypeSymbol.name.value + "." +
                        detailRecordTypeSymbol.initializerFunc.funcName.value),
                detailRecordTypeSymbol.initializerFunc.symbol);

        BRecordType detailRecordType = new BRecordType(detailRecordTypeSymbol);
        detailRecordType.restFieldType = symTable.anydataType;

        if (restDetail == null) {
            detailRecordType.sealed = true;
        }

        for (BLangErrorVariable.BLangErrorDetailEntry detailEntry : detail) {
            Name fieldName = names.fromIdNode(detailEntry.key);
            BType fieldType = getStructuredBindingPatternType(detailEntry.valueBindingPattern);
            BVarSymbol fieldSym = new BVarSymbol(
                        Flags.PUBLIC, fieldName, detailRecordTypeSymbol.pkgID, fieldType, detailRecordTypeSymbol);
            detailRecordType.fields.add(new BField(fieldName, detailEntry.key.pos, fieldSym));
            detailRecordTypeSymbol.scope.define(fieldName, fieldSym);
        }

        return detailRecordType;
    }

    private BAttachedFunction createRecordInitFunc() {
        BInvokableType bInvokableType = new BInvokableType(new ArrayList<>(), symTable.nilType, null);
        BInvokableSymbol initFuncSymbol = Symbols.createFunctionSymbol(
                Flags.PUBLIC, Names.EMPTY, env.enclPkg.symbol.pkgID, bInvokableType, env.scope.owner, false);
        initFuncSymbol.retType = symTable.nilType;
        return new BAttachedFunction(Names.INIT_FUNCTION_SUFFIX, initFuncSymbol, bInvokableType);
    }

    BLangErrorType createErrorTypeNode(BErrorType errorType) {
        BLangErrorType errorTypeNode = (BLangErrorType) TreeBuilder.createErrorTypeNode();
        errorTypeNode.type = errorType;
        return errorTypeNode;
    }

    private BLangExpression createPatternMatchBinaryExpr(BLangMatchBindingPatternClause patternClause,
                                                         BVarSymbol varSymbol, BType patternType) {
        DiagnosticPos pos = patternClause.pos;

        BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        if (NodeKind.MATCH_STATIC_PATTERN_CLAUSE == patternClause.getKind()) {
            BLangMatchStaticBindingPatternClause pattern = (BLangMatchStaticBindingPatternClause) patternClause;
            return createBinaryExpression(pos, varRef, pattern.literal);
        }

        if (NodeKind.MATCH_STRUCTURED_PATTERN_CLAUSE == patternClause.getKind()) {
            return createIsLikeExpression(pos, ASTBuilderUtil.createVariableRef(pos, varSymbol), patternType);
        }

        if (patternType == symTable.nilType) {
            BLangLiteral bLangLiteral = ASTBuilderUtil.createLiteral(pos, symTable.nilType, null);
            return ASTBuilderUtil.createBinaryExpr(pos, varRef, bLangLiteral, symTable.booleanType,
                    OperatorKind.EQUAL, (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.EQUAL,
                            symTable.anyType, symTable.nilType));
        } else {
            return createIsAssignableExpression(pos, varSymbol, patternType);
        }
    }

    private BLangExpression createBinaryExpression(DiagnosticPos pos, BLangSimpleVarRef varRef,
            BLangExpression expression) {

        BLangBinaryExpr binaryExpr;
        if (NodeKind.GROUP_EXPR == expression.getKind()) {
            return createBinaryExpression(pos, varRef, ((BLangGroupExpr) expression).expression);
        }

        if (NodeKind.BINARY_EXPR == expression.getKind()) {
            binaryExpr = (BLangBinaryExpr) expression;
            BLangExpression lhsExpr = createBinaryExpression(pos, varRef, binaryExpr.lhsExpr);
            BLangExpression rhsExpr = createBinaryExpression(pos, varRef, binaryExpr.rhsExpr);

            binaryExpr = ASTBuilderUtil.createBinaryExpr(pos, lhsExpr, rhsExpr, symTable.booleanType, OperatorKind.OR,
                    (BOperatorSymbol) symResolver
                            .resolveBinaryOperator(OperatorKind.OR, symTable.booleanType, symTable.booleanType));
        } else if (expression.getKind() == NodeKind.SIMPLE_VARIABLE_REF
                && ((BLangSimpleVarRef) expression).variableName.value.equals(IGNORE.value)) {
            BLangValueType anyType = (BLangValueType) TreeBuilder.createValueTypeNode();
            anyType.type = symTable.anyType;
            anyType.typeKind = TypeKind.ANY;
            return ASTBuilderUtil.createTypeTestExpr(pos, varRef, anyType);
        } else {
            binaryExpr = ASTBuilderUtil
                    .createBinaryExpr(pos, varRef, expression, symTable.booleanType, OperatorKind.EQUAL, null);

            BSymbol opSymbol = symResolver.resolveBinaryOperator(OperatorKind.EQUAL, varRef.type, expression.type);
            if (opSymbol == symTable.notFoundSymbol) {
                opSymbol = symResolver
                        .getBinaryEqualityForTypeSets(OperatorKind.EQUAL, symTable.anydataType, expression.type,
                                binaryExpr);
            }
            binaryExpr.opSymbol = (BOperatorSymbol) opSymbol;
        }
        return binaryExpr;
    }

    private BLangIsAssignableExpr createIsAssignableExpression(DiagnosticPos pos,
                                                               BVarSymbol varSymbol,
                                                               BType patternType) {
        
        
        BLangSimpleVarRef varRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        
        return ASTBuilderUtil.createIsAssignableExpr(pos, varRef, patternType, symTable.booleanType, names);
    }

    private BLangIsLikeExpr createIsLikeExpression(DiagnosticPos pos, BLangExpression expr, BType type) {
        return ASTBuilderUtil.createIsLikeExpr(pos, expr, ASTBuilderUtil.createTypeNode(type), symTable.booleanType);
    }

    private BLangAssignment createAssignmentStmt(BLangSimpleVariable variable) {
        BLangSimpleVarRef varRef = (BLangSimpleVarRef) TreeBuilder.createSimpleVariableReferenceNode();
        varRef.pos = variable.pos;
        varRef.variableName = variable.name;
        varRef.symbol = variable.symbol;
        varRef.type = variable.type;

        BLangAssignment assignmentStmt = (BLangAssignment) TreeBuilder.createAssignmentNode();
        assignmentStmt.expr = variable.expr;
        assignmentStmt.pos = variable.pos;
        assignmentStmt.setVariable(varRef);
        return assignmentStmt;
    }

    private BLangAssignment createStructFieldUpdate(BLangFunction function, BLangSimpleVariable variable,
                                                    BVarSymbol symbol) {
        BLangSimpleVarRef selfVarRef = ASTBuilderUtil.createVariableRef(variable.pos, symbol);
        BLangFieldBasedAccess fieldAccess = ASTBuilderUtil.createFieldAccessExpr(selfVarRef, variable.name);
        fieldAccess.symbol = variable.symbol;
        fieldAccess.type = variable.type;

        BLangAssignment assignmentStmt = (BLangAssignment) TreeBuilder.createAssignmentNode();
        assignmentStmt.expr = variable.expr;
        assignmentStmt.pos = variable.pos;
        assignmentStmt.setVariable(fieldAccess);

        SymbolEnv initFuncEnv = SymbolEnv.createFunctionEnv(function, function.symbol.scope, env);
        return rewrite(assignmentStmt, initFuncEnv);
    }

    private void addMatchExprDefaultCase(BLangMatchExpression bLangMatchExpression) {
        List<BType> exprTypes;
        List<BType> unmatchedTypes = new ArrayList<>();

        if (bLangMatchExpression.expr.type.tag == TypeTags.UNION) {
            BUnionType unionType = (BUnionType) bLangMatchExpression.expr.type;
            exprTypes = new ArrayList<>(unionType.getMemberTypes());
        } else {
            exprTypes = Lists.of(bLangMatchExpression.type);
        }

        
        for (BType type : exprTypes) {
            boolean assignable = false;
            for (BLangMatchExprPatternClause pattern : bLangMatchExpression.patternClauses) {
                if (this.types.isAssignable(type, pattern.variable.type)) {
                    assignable = true;
                    break;
                }
            }

            if (!assignable) {
                unmatchedTypes.add(type);
            }
        }

        if (unmatchedTypes.isEmpty()) {
            return;
        }

        BType defaultPatternType;
        if (unmatchedTypes.size() == 1) {
            defaultPatternType = unmatchedTypes.get(0);
        } else {
            defaultPatternType = BUnionType.create(null, new LinkedHashSet<>(unmatchedTypes));
        }

        String patternCaseVarName = GEN_VAR_PREFIX.value + "t_match_default";
        BLangSimpleVariable patternMatchCaseVar = ASTBuilderUtil.createVariable(bLangMatchExpression.pos,
                patternCaseVarName, defaultPatternType, null, new BVarSymbol(0, names.fromString(patternCaseVarName),
                        this.env.scope.owner.pkgID, defaultPatternType, this.env.scope.owner));

        BLangMatchExprPatternClause defaultPattern =
                (BLangMatchExprPatternClause) TreeBuilder.createMatchExpressionPattern();
        defaultPattern.variable = patternMatchCaseVar;
        defaultPattern.expr = ASTBuilderUtil.createVariableRef(bLangMatchExpression.pos, patternMatchCaseVar.symbol);
        defaultPattern.pos = bLangMatchExpression.pos;
        bLangMatchExpression.patternClauses.add(defaultPattern);
    }

    private boolean safeNavigate(BLangAccessExpression accessExpr) {
        if (accessExpr.lhsVar || accessExpr.expr == null) {
            return false;
        }

        if (accessExpr.errorSafeNavigation || accessExpr.nilSafeNavigation) {
            return true;
        }

        NodeKind kind = accessExpr.expr.getKind();
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR ||
                kind == NodeKind.INDEX_BASED_ACCESS_EXPR) {
            return safeNavigate((BLangAccessExpression) accessExpr.expr);
        }

        return false;
    }

    private BLangExpression rewriteSafeNavigationExpr(BLangAccessExpression accessExpr) {
        BType originalExprType = accessExpr.type;
        
        String matchTempResultVarName = GEN_VAR_PREFIX.value + "temp_result";
        BLangSimpleVariable tempResultVar = ASTBuilderUtil.createVariable(accessExpr.pos, matchTempResultVarName,
                accessExpr.type, null, new BVarSymbol(0, names.fromString(matchTempResultVarName),
                        this.env.scope.owner.pkgID, accessExpr.type, this.env.scope.owner));
        BLangSimpleVariableDef tempResultVarDef = ASTBuilderUtil.createVariableDef(accessExpr.pos, tempResultVar);
        BLangVariableReference tempResultVarRef =
                ASTBuilderUtil.createVariableRef(accessExpr.pos, tempResultVar.symbol);

        
        handleSafeNavigation(accessExpr, accessExpr.type, tempResultVar);

        
        BLangMatch matcEXpr = this.matchStmtStack.firstElement();
        BLangBlockStmt blockStmt =
                ASTBuilderUtil.createBlockStmt(accessExpr.pos, Lists.of(tempResultVarDef, matcEXpr));
        BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, tempResultVarRef);
        stmtExpression.type = originalExprType;

        
        this.matchStmtStack = new Stack<>();
        this.accessExprStack = new Stack<>();
        this.successPattern = null;
        this.safeNavigationAssignment = null;
        return stmtExpression;
    }

    private void handleSafeNavigation(BLangAccessExpression accessExpr, BType type, BLangSimpleVariable tempResultVar) {
        if (accessExpr.expr == null) {
            return;
        }

        
        NodeKind kind = accessExpr.expr.getKind();
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR ||
                kind == NodeKind.INDEX_BASED_ACCESS_EXPR ||
                kind == NodeKind.INVOCATION) {
            handleSafeNavigation((BLangAccessExpression) accessExpr.expr, type, tempResultVar);
        }

        if (!(accessExpr.errorSafeNavigation || accessExpr.nilSafeNavigation)) {
            BType originalType = accessExpr.originalType;
            if (TypeTags.isXMLTypeTag(originalType.tag)) {
                accessExpr.type = BUnionType.create(null, originalType, symTable.errorType);
            } else {
                accessExpr.type = originalType;
            }
            if (this.safeNavigationAssignment != null) {
                this.safeNavigationAssignment.expr = addConversionExprIfRequired(accessExpr, tempResultVar.type);
            }
            return;
        }

        /*
         * If the field access is a safe navigation, create a match expression.
         * Then chain the current expression as the success-pattern of the parent
         * match expr, if available.
         * eg:
         * x but {              <--- parent match expr
         *   error e => e,
         *   T t => t.y but {   <--- current expr
         *      error e => e,
         *      R r => r.z
         *   }
         * }
         */

        BLangMatch matchStmt = ASTBuilderUtil.createMatchStatement(accessExpr.pos, accessExpr.expr, new ArrayList<>());

        
        if (accessExpr.nilSafeNavigation) {
            matchStmt.patternClauses.add(getMatchNullPattern(accessExpr, tempResultVar));
            matchStmt.type = type;
        }

        
        if (accessExpr.errorSafeNavigation) {
            matchStmt.patternClauses.add(getMatchErrorPattern(accessExpr, tempResultVar));
            matchStmt.type = type;
            matchStmt.pos = accessExpr.pos;

        }

        
        BLangMatchTypedBindingPatternClause successPattern =
                getSuccessPattern(accessExpr, tempResultVar, accessExpr.errorSafeNavigation);
        matchStmt.patternClauses.add(successPattern);
        this.matchStmtStack.push(matchStmt);
        if (this.successPattern != null) {
            this.successPattern.body = ASTBuilderUtil.createBlockStmt(accessExpr.pos, Lists.of(matchStmt));
        }
        this.successPattern = successPattern;
    }

    private BLangMatchTypedBindingPatternClause getMatchErrorPattern(BLangExpression expr,
                                                                         BLangSimpleVariable tempResultVar) {
        String errorPatternVarName = GEN_VAR_PREFIX.value + "t_match_error";
        BLangSimpleVariable errorPatternVar = ASTBuilderUtil.createVariable(expr.pos, errorPatternVarName,
                symTable.errorType, null, new BVarSymbol(0, names.fromString(errorPatternVarName),
                        this.env.scope.owner.pkgID, symTable.errorType, this.env.scope.owner));

        
        BLangSimpleVarRef assignmentRhsExpr = ASTBuilderUtil.createVariableRef(expr.pos, errorPatternVar.symbol);
        BLangVariableReference tempResultVarRef = ASTBuilderUtil.createVariableRef(expr.pos, tempResultVar.symbol);
        BLangAssignment assignmentStmt =
                ASTBuilderUtil.createAssignmentStmt(expr.pos, tempResultVarRef, assignmentRhsExpr, false);
        BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(expr.pos, Lists.of(assignmentStmt));

        
        
        BLangMatchTypedBindingPatternClause errorPattern = ASTBuilderUtil
                .createMatchStatementPattern(expr.pos, errorPatternVar, patternBody);
        return errorPattern;
    }

    private BLangMatchExprPatternClause getMatchNullPatternGivenExpression(DiagnosticPos pos,
                                                                           BLangExpression expr) {
        String nullPatternVarName = IGNORE.toString();
        BLangSimpleVariable errorPatternVar = ASTBuilderUtil.createVariable(pos, nullPatternVarName, symTable.nilType,
                null, new BVarSymbol(0, names.fromString(nullPatternVarName),
                        this.env.scope.owner.pkgID, symTable.nilType, this.env.scope.owner));

        BLangMatchExprPatternClause nullPattern =
                (BLangMatchExprPatternClause) TreeBuilder.createMatchExpressionPattern();
        nullPattern.variable = errorPatternVar;
        nullPattern.expr = expr;
        nullPattern.pos = pos;
        return nullPattern;
    }

    private BLangMatchTypedBindingPatternClause getMatchNullPattern(BLangExpression expr,
            BLangSimpleVariable tempResultVar) {
        
        String nullPatternVarName = GEN_VAR_PREFIX.value + "t_match_null";
        BLangSimpleVariable nullPatternVar = ASTBuilderUtil.createVariable(expr.pos, nullPatternVarName,
                symTable.nilType, null, new BVarSymbol(0, names.fromString(nullPatternVarName),
                        this.env.scope.owner.pkgID, symTable.nilType, this.env.scope.owner));

        
        BLangSimpleVarRef assignmentRhsExpr = ASTBuilderUtil.createVariableRef(expr.pos, nullPatternVar.symbol);
        BLangVariableReference tempResultVarRef = ASTBuilderUtil.createVariableRef(expr.pos, tempResultVar.symbol);
        BLangAssignment assignmentStmt =
                ASTBuilderUtil.createAssignmentStmt(expr.pos, tempResultVarRef, assignmentRhsExpr, false);
        BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(expr.pos, Lists.of(assignmentStmt));

        
        
        BLangMatchTypedBindingPatternClause nullPattern = ASTBuilderUtil
                .createMatchStatementPattern(expr.pos, nullPatternVar, patternBody);
        return nullPattern;
    }

    private BLangMatchTypedBindingPatternClause getSuccessPattern(BLangAccessExpression accessExpr,
            BLangSimpleVariable tempResultVar, boolean liftError) {
        BType type = types.getSafeType(accessExpr.expr.type, true, liftError);
        String successPatternVarName = GEN_VAR_PREFIX.value + "t_match_success";

        BVarSymbol  successPatternSymbol;
        if (type.tag == TypeTags.INVOKABLE) {
            successPatternSymbol = new BInvokableSymbol(SymTag.VARIABLE, 0, names.fromString(successPatternVarName),
                    this.env.scope.owner.pkgID, type, this.env.scope.owner);
        } else {
            successPatternSymbol = new BVarSymbol(0, names.fromString(successPatternVarName),
                    this.env.scope.owner.pkgID, type, this.env.scope.owner);
        }

        BLangSimpleVariable successPatternVar = ASTBuilderUtil.createVariable(accessExpr.pos, successPatternVarName,
                type, null, successPatternSymbol);

        
        accessExpr.expr = ASTBuilderUtil.createVariableRef(accessExpr.pos, successPatternVar.symbol);
        accessExpr.errorSafeNavigation = false;
        accessExpr.nilSafeNavigation = false;

        
        
        
        if (TypeTags.isXMLTypeTag(accessExpr.expr.type.tag)) {
            
            accessExpr.type = BUnionType.create(null, accessExpr.originalType, symTable.errorType, symTable.nilType);
        } else {
            accessExpr.type = accessExpr.originalType;
        }

        BLangVariableReference tempResultVarRef =
                ASTBuilderUtil.createVariableRef(accessExpr.pos, tempResultVar.symbol);

        BLangExpression assignmentRhsExpr = addConversionExprIfRequired(accessExpr, tempResultVarRef.type);
        BLangAssignment assignmentStmt =
                ASTBuilderUtil.createAssignmentStmt(accessExpr.pos, tempResultVarRef, assignmentRhsExpr, false);
        BLangBlockStmt patternBody = ASTBuilderUtil.createBlockStmt(accessExpr.pos, Lists.of(assignmentStmt));

        
        
        BLangMatchTypedBindingPatternClause successPattern =
                ASTBuilderUtil.createMatchStatementPattern(accessExpr.pos, successPatternVar, patternBody);
        this.safeNavigationAssignment = assignmentStmt;
        return successPattern;
    }

    private boolean safeNavigateLHS(BLangExpression expr) {
        if (expr.getKind() != NodeKind.FIELD_BASED_ACCESS_EXPR && expr.getKind() != NodeKind.INDEX_BASED_ACCESS_EXPR) {
            return false;
        }

        BLangExpression varRef = ((BLangAccessExpression) expr).expr;
        if (varRef.type.isNullable()) {
            return true;
        }

        return safeNavigateLHS(varRef);
    }

    private BLangStatement rewriteSafeNavigationAssignment(BLangAccessExpression accessExpr, BLangExpression rhsExpr,
                                                           boolean safeAssignment) {
        
        
        
        
        
        
        
        
        
        
        
        
        this.accessExprStack = new Stack<>();
        List<BLangStatement> stmts = new ArrayList<>();
        createLHSSafeNavigation(stmts, accessExpr.expr);
        BLangAssignment assignment = ASTBuilderUtil.createAssignmentStmt(accessExpr.pos,
                cloneExpression(accessExpr), rhsExpr);
        stmts.add(assignment);
        return ASTBuilderUtil.createBlockStmt(accessExpr.pos, stmts);
    }

    private void createLHSSafeNavigation(List<BLangStatement> stmts, BLangExpression expr) {
        NodeKind kind = expr.getKind();
        boolean root = false;
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR || kind == NodeKind.INDEX_BASED_ACCESS_EXPR ||
                kind == NodeKind.INVOCATION) {
            BLangAccessExpression accessExpr = (BLangAccessExpression) expr;
            createLHSSafeNavigation(stmts, accessExpr.expr);
            accessExpr.expr = accessExprStack.pop();
        } else {
            root = true;
        }

        
        
        if (expr.getKind() == NodeKind.INVOCATION) {
            BLangInvocation invocation = (BLangInvocation) expr;
            BVarSymbol interMediateSymbol = new BVarSymbol(0, names.fromString(GEN_VAR_PREFIX.value
                    + "i_intermediate"), this.env.scope.owner.pkgID, invocation.type, this.env.scope.owner);
            BLangSimpleVariable intermediateVariable = ASTBuilderUtil.createVariable(expr.pos,
                    interMediateSymbol.name.value, invocation.type, invocation, interMediateSymbol);
            BLangSimpleVariableDef intermediateVariableDefinition = ASTBuilderUtil.createVariableDef(invocation.pos,
                    intermediateVariable);
            stmts.add(intermediateVariableDefinition);

            expr = ASTBuilderUtil.createVariableRef(invocation.pos, interMediateSymbol);
        }

        if (expr.type.isNullable()) {
            BLangTypeTestExpr isNillTest = ASTBuilderUtil.createTypeTestExpr(expr.pos, expr, getNillTypeNode());
            isNillTest.type = symTable.booleanType;

            BLangBlockStmt thenStmt = ASTBuilderUtil.createBlockStmt(expr.pos);

            
            expr = cloneExpression(expr);
            expr.type = types.getSafeType(expr.type, true, false);

            if (isDefaultableMappingType(expr.type) && !root) { 
                
                BLangRecordLiteral jsonLiteral = (BLangRecordLiteral) TreeBuilder.createRecordLiteralNode();
                jsonLiteral.type = expr.type;
                jsonLiteral.pos = expr.pos;
                BLangAssignment assignment = ASTBuilderUtil.createAssignmentStmt(expr.pos,
                        expr, jsonLiteral);
                thenStmt.addStatement(assignment);
            } else {
                BLangLiteral literal = (BLangLiteral) TreeBuilder.createLiteralExpression();
                literal.value = ERROR_REASON_NULL_REFERENCE_ERROR;
                literal.type = symTable.stringType;

                BLangInvocation errorCtorInvocation = (BLangInvocation) TreeBuilder.createInvocationNode();
                errorCtorInvocation.pos = expr.pos;
                errorCtorInvocation.argExprs.add(literal);
                errorCtorInvocation.requiredArgs.add(literal);
                errorCtorInvocation.type = symTable.errorType;
                errorCtorInvocation.symbol = symTable.errorConstructor;

                BLangPanic panicNode = (BLangPanic) TreeBuilder.createPanicNode();
                panicNode.expr = errorCtorInvocation;
                panicNode.pos = expr.pos;
                thenStmt.addStatement(panicNode);
            }

            BLangIf ifelse = ASTBuilderUtil.createIfElseStmt(expr.pos, isNillTest, thenStmt, null);
            stmts.add(ifelse);
        }

        accessExprStack.push(expr);
    }

    BLangValueType getNillTypeNode() {
        BLangValueType nillTypeNode = (BLangValueType) TreeBuilder.createValueTypeNode();
        nillTypeNode.typeKind = TypeKind.NIL;
        nillTypeNode.type = symTable.nilType;
        return nillTypeNode;
    }

    private BLangVariableReference cloneExpression(BLangExpression expr) {
        switch (expr.getKind()) {
            case SIMPLE_VARIABLE_REF:
                return ASTBuilderUtil.createVariableRef(expr.pos, ((BLangSimpleVarRef) expr).symbol);
            case FIELD_BASED_ACCESS_EXPR:
            case INDEX_BASED_ACCESS_EXPR:
            case INVOCATION:
                return cloneAccessExpr((BLangAccessExpression) expr);
            default:
                throw new IllegalStateException();
        }
    }

    private BLangAccessExpression cloneAccessExpr(BLangAccessExpression originalAccessExpr) {
        if (originalAccessExpr.expr == null) {
            return originalAccessExpr;
        }

        BLangVariableReference varRef;
        NodeKind kind = originalAccessExpr.expr.getKind();
        if (kind == NodeKind.FIELD_BASED_ACCESS_EXPR || kind == NodeKind.INDEX_BASED_ACCESS_EXPR ||
                kind == NodeKind.INVOCATION) {
            varRef = cloneAccessExpr((BLangAccessExpression) originalAccessExpr.expr);
        } else {
            varRef = cloneExpression(originalAccessExpr.expr);
        }
        varRef.type = types.getSafeType(originalAccessExpr.expr.type, true, false);

        BLangAccessExpression accessExpr;
        switch (originalAccessExpr.getKind()) {
            case FIELD_BASED_ACCESS_EXPR:
                accessExpr = ASTBuilderUtil.createFieldAccessExpr(varRef,
                        ((BLangFieldBasedAccess) originalAccessExpr).field);
                break;
            case INDEX_BASED_ACCESS_EXPR:
                accessExpr = ASTBuilderUtil.createIndexAccessExpr(varRef,
                        ((BLangIndexBasedAccess) originalAccessExpr).indexExpr);
                break;
            case INVOCATION:
                
                accessExpr = null;
                break;
            default:
                throw new IllegalStateException();
        }

        accessExpr.originalType = originalAccessExpr.originalType;
        accessExpr.pos = originalAccessExpr.pos;
        accessExpr.lhsVar = originalAccessExpr.lhsVar;
        accessExpr.symbol = originalAccessExpr.symbol;
        accessExpr.errorSafeNavigation = false;
        accessExpr.nilSafeNavigation = false;

        
        
        
        accessExpr.type = originalAccessExpr.originalType;
        return accessExpr;
    }

    private BLangBinaryExpr getModifiedIntRangeStartExpr(BLangExpression expr) {
        BLangLiteral constOneLiteral = ASTBuilderUtil.createLiteral(expr.pos, symTable.intType, 1L);
        return ASTBuilderUtil.createBinaryExpr(expr.pos, expr, constOneLiteral, symTable.intType, OperatorKind.ADD,
                (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.ADD,
                        symTable.intType,
                        symTable.intType));
    }

    private BLangBinaryExpr getModifiedIntRangeEndExpr(BLangExpression expr) {
        BLangLiteral constOneLiteral = ASTBuilderUtil.createLiteral(expr.pos, symTable.intType, 1L);
        return ASTBuilderUtil.createBinaryExpr(expr.pos, expr, constOneLiteral, symTable.intType, OperatorKind.SUB,
                (BOperatorSymbol) symResolver.resolveBinaryOperator(OperatorKind.SUB,
                        symTable.intType,
                        symTable.intType));
    }

    private BLangLiteral getBooleanLiteral(boolean value) {
        BLangLiteral literal = (BLangLiteral) TreeBuilder.createLiteralExpression();
        literal.value = value;
        literal.type = symTable.booleanType;
        return literal;
    }

    private boolean isDefaultableMappingType(BType type) {
        switch (types.getSafeType(type, true, false).tag) {
            case TypeTags.JSON:
            case TypeTags.MAP:
            case TypeTags.RECORD:
                return true;
            default:
                return false;
        }
    }

    private BLangFunction createInitFunctionForObjectType(BLangObjectTypeNode structureTypeNode, SymbolEnv env) {
        BLangFunction initFunction =
                TypeDefBuilderHelper.createInitFunctionForStructureType(structureTypeNode, env,
                                                                        Names.GENERATED_INIT_SUFFIX, names, symTable);
        BObjectTypeSymbol typeSymbol = ((BObjectTypeSymbol) structureTypeNode.type.tsymbol);
        typeSymbol.generatedInitializerFunc = new BAttachedFunction(Names.GENERATED_INIT_SUFFIX, initFunction.symbol,
                (BInvokableType) initFunction.type);
        structureTypeNode.generatedInitFunction = initFunction;
        initFunction.returnTypeNode.type = symTable.nilType;
        return rewrite(initFunction, env);
    }

    private void visitBinaryLogicalExpr(BLangBinaryExpr binaryExpr) {
        /*
         * Desugar (lhsExpr && rhsExpr) to following if-else:
         * 
         * logical AND:
         * -------------
         * T $result$;
         * if (lhsExpr) {
         *    $result$ = rhsExpr;
         * } else {
         *    $result$ = false;
         * }
         * 
         * logical OR:
         * -------------
         * T $result$;
         * if (lhsExpr) {
         *    $result$ = true;
         * } else {
         *    $result$ = rhsExpr;
         * }
         * 
         */
        BLangSimpleVariableDef resultVarDef = createVarDef("$result$", binaryExpr.type, null, binaryExpr.pos);
        BLangBlockStmt thenBody = ASTBuilderUtil.createBlockStmt(binaryExpr.pos);
        BLangBlockStmt elseBody = ASTBuilderUtil.createBlockStmt(binaryExpr.pos);

        
        BLangSimpleVarRef thenResultVarRef = ASTBuilderUtil.createVariableRef(binaryExpr.pos, resultVarDef.var.symbol);
        BLangExpression thenResult;
        if (binaryExpr.opKind == OperatorKind.AND) {
            thenResult = binaryExpr.rhsExpr;
        } else {
            thenResult = getBooleanLiteral(true);
        }
        BLangAssignment thenAssignment =
                ASTBuilderUtil.createAssignmentStmt(binaryExpr.pos, thenResultVarRef, thenResult);
        thenBody.addStatement(thenAssignment);

        
        BLangExpression elseResult;
        BLangSimpleVarRef elseResultVarRef = ASTBuilderUtil.createVariableRef(binaryExpr.pos, resultVarDef.var.symbol);
        if (binaryExpr.opKind == OperatorKind.AND) {
            elseResult = getBooleanLiteral(false);
        } else {
            elseResult = binaryExpr.rhsExpr;
        }
        BLangAssignment elseAssignment =
                ASTBuilderUtil.createAssignmentStmt(binaryExpr.pos, elseResultVarRef, elseResult);
        elseBody.addStatement(elseAssignment);

        
        BLangSimpleVarRef resultVarRef = ASTBuilderUtil.createVariableRef(binaryExpr.pos, resultVarDef.var.symbol);
        BLangIf ifElse = ASTBuilderUtil.createIfElseStmt(binaryExpr.pos, binaryExpr.lhsExpr, thenBody, elseBody);

        BLangBlockStmt blockStmt = ASTBuilderUtil.createBlockStmt(binaryExpr.pos, Lists.of(resultVarDef, ifElse));
        BLangStatementExpression stmtExpr = createStatementExpression(blockStmt, resultVarRef);
        stmtExpr.type = binaryExpr.type;

        result = rewriteExpr(stmtExpr);
    }

    /**
     * Split packahe init function into several smaller functions.
     *
     * @param packageNode package node
     * @param env symbol environment
     * @return initial init function but trimmed in size
     */
    private BLangFunction splitInitFunction(BLangPackage packageNode, SymbolEnv env) {
        int methodSize = INIT_METHOD_SPLIT_SIZE;
        BLangBlockFunctionBody funcBody = (BLangBlockFunctionBody) packageNode.initFunction.body;
        if (funcBody.stmts.size() < methodSize || !isJvmTarget) {
            return packageNode.initFunction;
        }
        BLangFunction initFunction = packageNode.initFunction;

        List<BLangFunction> generatedFunctions = new ArrayList<>();
        List<BLangStatement> stmts = new ArrayList<>(funcBody.stmts);
        funcBody.stmts.clear();
        BLangFunction newFunc = initFunction;
        BLangBlockFunctionBody newFuncBody = (BLangBlockFunctionBody) newFunc.body;

        
        int varDefIndex = 0;
        for (int i = 0; i < stmts.size(); i++) {
            if (stmts.get(i).getKind() == NodeKind.VARIABLE_DEF) {
                break;
            }
            varDefIndex++;
            if (i > 0 && i % methodSize == 0) {
                generatedFunctions.add(newFunc);
                newFunc = createIntermediateInitFunction(packageNode, env);
                newFuncBody = (BLangBlockFunctionBody) newFunc.body;
                symTable.rootScope.define(names.fromIdNode(newFunc.name), newFunc.symbol);
            }

            newFuncBody.stmts.add(stmts.get(i));
        }

        
        List<BLangStatement> chunkStmts = new ArrayList<>();
        for (int i = varDefIndex; i < stmts.size(); i++) {
            BLangStatement stmt = stmts.get(i);
            chunkStmts.add(stmt);
            varDefIndex++;
            if ((stmt.getKind() == NodeKind.ASSIGNMENT) &&
                    (((BLangAssignment) stmt).expr.getKind() == NodeKind.SERVICE_CONSTRUCTOR) &&
                    (newFuncBody.stmts.size() + chunkStmts.size() > methodSize)) {
                
                if (newFuncBody.stmts.size() + chunkStmts.size() > methodSize) {
                    generatedFunctions.add(newFunc);
                    newFunc = createIntermediateInitFunction(packageNode, env);
                    newFuncBody = (BLangBlockFunctionBody) newFunc.body;
                    symTable.rootScope.define(names.fromIdNode(newFunc.name), newFunc.symbol);
                }
                newFuncBody.stmts.addAll(chunkStmts);
                chunkStmts.clear();
            } else if ((stmt.getKind() == NodeKind.ASSIGNMENT) &&
                    (((BLangAssignment) stmt).varRef instanceof BLangPackageVarRef) &&
                    Symbols.isFlagOn(((BLangPackageVarRef) ((BLangAssignment) stmt).varRef).varSymbol.flags,
                            Flags.LISTENER)
            ) {
                
                break;
            }
        }
        newFuncBody.stmts.addAll(chunkStmts);

        
        for (int i = varDefIndex; i < stmts.size(); i++) {
            if (i > 0 && i % methodSize == 0) {
                generatedFunctions.add(newFunc);
                newFunc = createIntermediateInitFunction(packageNode, env);
                newFuncBody = (BLangBlockFunctionBody) newFunc.body;
                symTable.rootScope.define(names.fromIdNode(newFunc.name), newFunc.symbol);
            }
            newFuncBody.stmts.add(stmts.get(i));
        }

        generatedFunctions.add(newFunc);

        for (int j = 0; j < generatedFunctions.size() - 1; j++) {
            BLangFunction thisFunction = generatedFunctions.get(j);

            BLangCheckedExpr checkedExpr =
                    ASTBuilderUtil.createCheckExpr(initFunction.pos,
                                                   createInvocationNode(generatedFunctions.get(j + 1).name.value,
                                                                        new ArrayList<>(), symTable.errorOrNilType),
                                                   symTable.nilType);
            checkedExpr.equivalentErrorTypeList.add(symTable.errorType);

            BLangExpressionStmt expressionStmt = ASTBuilderUtil
                    .createExpressionStmt(thisFunction.pos, (BLangBlockFunctionBody) thisFunction.body);
            expressionStmt.expr = checkedExpr;
            expressionStmt.expr.pos = initFunction.pos;

            if (j > 0) { 
                thisFunction = rewrite(thisFunction, env);
                packageNode.functions.add(thisFunction);
                packageNode.topLevelNodes.add(thisFunction);
            }
        }

        if (generatedFunctions.size() > 1) {
            
            BLangFunction lastFunc = generatedFunctions.get(generatedFunctions.size() - 1);
            lastFunc = rewrite(lastFunc, env);
            packageNode.functions.add(lastFunc);
            packageNode.topLevelNodes.add(lastFunc);
        }

        return generatedFunctions.get(0);
    }

    /**
     * Create an intermediate package init function.
     *
     * @param pkgNode package node
     * @param env     symbol environment of package
     */
    private BLangFunction createIntermediateInitFunction(BLangPackage pkgNode, SymbolEnv env) {
        String alias = pkgNode.symbol.pkgID.toString();
        BLangFunction initFunction = ASTBuilderUtil
                .createInitFunctionWithErrorOrNilReturn(pkgNode.pos, alias,
                                                        new Name(Names.INIT_FUNCTION_SUFFIX.value
                                                                + this.initFuncIndex++), symTable);
        
        createInvokableSymbol(initFunction, env);
        return initFunction;
    }

    private BType getRestType(BInvokableSymbol invokableSymbol) {
        if (invokableSymbol != null && invokableSymbol.restParam != null) {
            return invokableSymbol.restParam.type;
        }
        return null;
    }

    private BType getRestType(BLangFunction function) {
        if (function != null && function.restParam != null) {
            return function.restParam.type;
        }
        return null;
    }

    private BVarSymbol getRestSymbol(BLangFunction function) {
        if (function != null && function.restParam != null) {
            return function.restParam.symbol;
        }
        return null;
    }

    private boolean isComputedKey(RecordLiteralNode.RecordField field) {
        if (!field.isKeyValueField()) {
            return false;
        }
        return ((BLangRecordLiteral.BLangRecordKeyValueField) field).key.computedKey;
    }

    private BLangStatementExpression rewriteMappingConstructor(BLangRecordLiteral mappingConstructorExpr) {
        List<RecordLiteralNode.RecordField> fields = mappingConstructorExpr.fields;

        BType type = mappingConstructorExpr.type;
        DiagnosticPos pos = mappingConstructorExpr.pos;

        BLangRecordLiteral recordLiteral = type.tag == TypeTags.RECORD ? new BLangStructLiteral(pos, type) :
                new BLangMapLiteral(pos, type);

        String name = DESUGARED_MAPPING_CONSTR_KEY + this.annonVarCount++;

        BVarSymbol varSymbol = new BVarSymbol(0, names.fromString(name), this.env.scope.owner.pkgID, type,
                                              this.env.scope.owner);
        BLangSimpleVariable var = createVariable(pos, name, type, recordLiteral, varSymbol);
        BLangSimpleVariableDef varDef = ASTBuilderUtil.createVariableDef(pos);
        varDef.var = var;
        varDef.type = type;

        BLangBlockStmt blockStmt = createBlockStmt(pos);
        blockStmt.stmts.add(varDef);

        BLangSimpleVarRef mappingVarRef = ASTBuilderUtil.createVariableRef(pos, varSymbol);

        for (RecordLiteralNode.RecordField field : fields) {
            if (field.isKeyValueField()) {
                BLangRecordLiteral.BLangRecordKeyValueField keyValueField =
                        (BLangRecordLiteral.BLangRecordKeyValueField) field;

                BLangRecordLiteral.BLangRecordKey key = keyValueField.key;
                BLangExpression keyExpr = key.expr;
                BLangExpression indexExpr = key.computedKey ? keyExpr :
                        keyExpr.getKind() == NodeKind.SIMPLE_VARIABLE_REF ?
                                createStringLiteral(pos, ((BLangSimpleVarRef) keyExpr).variableName.value) :
                                ((BLangLiteral) keyExpr);;
                addMemberStoreForKeyValuePair(pos, blockStmt, mappingVarRef, indexExpr, keyValueField.valueExpr);
            } else if (field.getKind() == NodeKind.SIMPLE_VARIABLE_REF) {
                BLangSimpleVarRef varRefField = (BLangSimpleVarRef) field;
                addMemberStoreForKeyValuePair(pos, blockStmt, mappingVarRef,
                                              createStringLiteral(pos, varRefField.variableName.value),
                                              varRefField);
            } else {
                BLangRecordLiteral.BLangRecordSpreadOperatorField spreadOpField =
                        (BLangRecordLiteral.BLangRecordSpreadOperatorField) field;

                BLangForeach foreach = (BLangForeach) TreeBuilder.createForeachNode();
                foreach.pos = pos;

                foreach.collection = generateMapEntriesInvocation(spreadOpField.expr, spreadOpField.expr.type);
                types.setForeachTypedBindingPatternType(foreach);

                BLangSimpleVariable foreachVariable = ASTBuilderUtil.createVariable(pos, "$foreach$i", foreach.varType);
                foreachVariable.symbol = new BVarSymbol(0, names.fromIdNode(foreachVariable.name),
                                                        this.env.scope.owner.pkgID, foreachVariable.type,
                                                        this.env.scope.owner);
                BLangSimpleVarRef foreachVarRef = ASTBuilderUtil.createVariableRef(pos, foreachVariable.symbol);
                foreach.variableDefinitionNode = ASTBuilderUtil.createVariableDef(pos, foreachVariable);
                foreach.isDeclaredWithVar = true;
                BLangBlockStmt foreachBodyBlock = ASTBuilderUtil.createBlockStmt(pos);

                BTupleType foreachVarRefType = (BTupleType) foreachVarRef.type;

                BLangIndexBasedAccess indexExpr = (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
                indexExpr.pos = pos;
                indexExpr.expr = foreachVarRef;
                indexExpr.indexExpr = rewriteExpr(createIntLiteral(0));
                indexExpr.type = foreachVarRefType.tupleTypes.get(0);

                BLangIndexBasedAccess valueExpr = (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
                valueExpr.pos = pos;
                valueExpr.expr = foreachVarRef;
                valueExpr.indexExpr = rewriteExpr(createIntLiteral(1));
                valueExpr.type = foreachVarRefType.tupleTypes.get(1);

                addMemberStoreForKeyValuePair(pos, foreachBodyBlock, mappingVarRef, indexExpr, valueExpr);

                foreach.body = foreachBodyBlock;
                blockStmt.addStatement(foreach);
            }
        }

        BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, mappingVarRef);
        stmtExpression.type = type;
        return stmtExpression;
    }

    private void addMemberStoreForKeyValuePair(DiagnosticPos pos, BLangBlockStmt blockStmt,
                                               BLangExpression mappingVarRef, BLangExpression indexExpr,
                                               BLangExpression value) {
        BLangAssignment assignmentStmt = ASTBuilderUtil.createAssignmentStmt(pos, blockStmt);
        assignmentStmt.expr = rewriteExpr(value);

        BLangIndexBasedAccess indexAccessNode = (BLangIndexBasedAccess) TreeBuilder.createIndexBasedAccessNode();
        indexAccessNode.pos = pos;
        indexAccessNode.expr = mappingVarRef;
        indexAccessNode.indexExpr = rewriteExpr(indexExpr);
        indexAccessNode.type = value.type;
        assignmentStmt.varRef = indexAccessNode;
    }

    private Map<String, BLangExpression> getKeyValuePairs(BLangStatementExpression desugaredMappingConst) {
        List<BLangStatement> stmts = ((BLangBlockStmt) desugaredMappingConst.stmt).stmts;

        Map<String, BLangExpression> keyValuePairs = new HashMap<>();

        for (int i = 1; i < stmts.size(); i++) {
            BLangAssignment assignmentStmt = (BLangAssignment) stmts.get(i);

            BLangExpression indexExpr = ((BLangIndexBasedAccess) assignmentStmt.varRef).indexExpr;
            if (indexExpr.getKind() != NodeKind.LITERAL) {
                continue;
            }

            keyValuePairs.put((String) ((BLangLiteral) indexExpr).value, assignmentStmt.expr);
        }
        return keyValuePairs;
    }
}