Sync widgets demo

packages/jinja/package.json

@@ -1,7 +1,7 @@
 {
 	"name": "@huggingface/jinja",
 	"packageManager": "pnpm@8.10.5",
-	"version": "0.1.3",
+	"version": "0.2.0",
 	"description": "A minimalistic JavaScript implementation of the Jinja templating engine, specifically designed for parsing and rendering ML chat templates.",
 	"repository": "https://github.com/huggingface/huggingface.js.git",
 	"publishConfig": {

packages/jinja/src/ast.ts

@@ -165,6 +165,21 @@ export class FilterExpression extends Expression {
 	}
 }
 
+/**
+ * An operation with two sides, separated by the "is" operator.
+ */
+export class TestExpression extends Expression {
+	override type = "TestExpression";
+
+	constructor(
+		public operand: Expression,
+		public negate: boolean,
+		public test: Identifier // TODO: Add support for non-identifier tests
+	) {
+		super();
+	}
+}
+
 /**
  * An operation with one side (operator on the left).
  */
@@ -201,3 +216,14 @@ export class SliceExpression extends Expression {
 		super();
 	}
 }
+
+export class KeywordArgumentExpression extends Expression {
+	override type = "KeywordArgumentExpression";
+
+	constructor(
+		public key: Identifier,
+		public value: Expression
+	) {
+		super();
+	}
+}

packages/jinja/src/index.ts

@@ -10,11 +10,12 @@
  *
  * @module index
  */
-import type { Program } from "./ast";
 import { tokenize } from "./lexer";
 import { parse } from "./parser";
-import type { StringValue } from "./runtime";
 import { Environment, Interpreter } from "./runtime";
+import type { Program } from "./ast";
+import type { StringValue } from "./runtime";
+import { range } from "./utils";
 
 export class Template {
 	parsed: Program;
@@ -23,11 +24,10 @@ export class Template {
 	 * @param {string} template The template string
 	 */
 	constructor(template: string) {
-		// Since `lstrip_blocks` is enabled, we strip tabs and spaces from the beginning of a line to the start of a block.
-		// We can achieve the same effect by replacing all instances of `%}\s+{%` with `%}{%` (as a pre-processing step).
-		template = template.replace(/%}\s+{%/g, "%}{%");
-
-		const tokens = tokenize(template);
+		const tokens = tokenize(template, {
+			lstrip_blocks: true,
+			trim_blocks: true,
+		});
 		this.parsed = parse(tokens);
 	}
 
@@ -41,6 +41,7 @@ export class Template {
 		env.set("raise_exception", (args: string) => {
 			throw new Error(args);
 		});
+		env.set("range", range);
 
 		// Add user-defined variables
 		for (const [key, value] of Object.entries(items)) {

packages/jinja/src/lexer.ts

@@ -33,6 +33,7 @@ export const TOKEN_TYPES = Object.freeze({
 	If: "If",
 	For: "For",
 	In: "In",
+	Is: "Is",
 	NotIn: "NotIn",
 	Else: "Else",
 	EndIf: "EndIf",
@@ -52,6 +53,7 @@ const KEYWORDS = Object.freeze({
 	set: TOKEN_TYPES.Set,
 	for: TOKEN_TYPES.For,
 	in: TOKEN_TYPES.In,
+	is: TOKEN_TYPES.Is,
 	if: TOKEN_TYPES.If,
 	else: TOKEN_TYPES.Else,
 	endif: TOKEN_TYPES.EndIf,
@@ -137,12 +139,46 @@ const ESCAPE_CHARACTERS = new Map([
 	["\\", "\\"], // Backslash
 ]);
 
+export interface PreprocessOptions {
+	trim_blocks?: boolean;
+	lstrip_blocks?: boolean;
+}
+
+function preprocess(template: string, options: PreprocessOptions = {}): string {
+	// According to https://jinja.palletsprojects.com/en/3.0.x/templates/#whitespace-control
+
+	// In the default configuration:
+	//  - a single trailing newline is stripped if present
+	//  - other whitespace (spaces, tabs, newlines etc.) is returned unchanged
+	if (template.endsWith("\n")) {
+		template = template.slice(0, -1);
+	}
+
+	if (options.trim_blocks) {
+		// If an application configures Jinja to trim_blocks, the first newline after
+		// a template tag is removed automatically (like in PHP).
+		template = template.replace(/%}\n/g, "%}");
+	}
+	if (options.lstrip_blocks) {
+		// The lstrip_blocks option can also be set to strip tabs and spaces from the
+		// beginning of a line to the start of a block. (Nothing will be stripped if
+		// there are other characters before the start of the block.)
+		template = template.replace(/^[ \t]*{%/gm, "{%");
+	}
+
+	return template
+		.replace(/-%}\s*/g, "%}")
+		.replace(/\s*{%-/g, "{%")
+		.replace(/-}}\s*/g, "}}")
+		.replace(/\s*{{-/g, "{{");
+}
+
 /**
  * Generate a list of tokens from a source string.
  */
-export function tokenize(source: string): Token[] {
+export function tokenize(source: string, options: PreprocessOptions = {}): Token[] {
 	const tokens: Token[] = [];
-	const src: string = source;
+	const src: string = preprocess(source, options);
 
 	let cursorPosition = 0;
 

packages/jinja/src/parser.ts

@@ -14,8 +14,10 @@ import {
 	BooleanLiteral,
 	BinaryExpression,
 	FilterExpression,
+	TestExpression,
 	UnaryExpression,
 	SliceExpression,
+	KeywordArgumentExpression,
 } from "./ast";
 
 /**
@@ -26,6 +28,12 @@ export function parse(tokens: Token[]): Program {
 	const program = new Program([]);
 	let current = 0;
 
+	/**
+	 * Consume the next token if it matches the expected type, otherwise throw an error.
+	 * @param type The expected token type
+	 * @param error The error message to throw if the token does not match the expected type
+	 * @returns The consumed token
+	 */
 	function expect(type: string, error: string): Token {
 		const prev = tokens[current++];
 		if (!prev || prev.type !== type) {
@@ -191,6 +199,7 @@ export function parse(tokens: Token[]): Program {
 		// Choose parse function with lowest precedence
 		return parseLogicalOrExpression();
 	}
+
 	function parseLogicalOrExpression(): Statement {
 		let left = parseLogicalAndExpression();
 		while (is(TOKEN_TYPES.Or)) {
@@ -278,21 +287,36 @@ export function parse(tokens: Token[]): Program {
 		// add (x + 5, foo())
 		expect(TOKEN_TYPES.OpenParen, "Expected opening parenthesis for arguments list");
 
-		const args = is(TOKEN_TYPES.CloseParen) ? [] : parseArgumentsList();
+		const args = parseArgumentsList();
 
 		expect(TOKEN_TYPES.CloseParen, "Expected closing parenthesis for arguments list");
 		return args;
 	}
 	function parseArgumentsList(): Statement[] {
 		// comma-separated arguments list
-		const args = [parseExpression()]; // Update when we allow assignment expressions
 
-		while (is(TOKEN_TYPES.Comma)) {
-			++current; // consume comma
-			args.push(parseExpression());
+		const args = [];
+		while (!is(TOKEN_TYPES.CloseParen)) {
+			let argument = parseExpression();
+
+			if (is(TOKEN_TYPES.Equals)) {
+				// keyword argument
+				// e.g., func(x = 5, y = a or b)
+				++current; // consume equals
+				if (!(argument instanceof Identifier)) {
+					throw new SyntaxError(`Expected identifier for keyword argument`);
+				}
+				const value = parseExpression();
+				argument = new KeywordArgumentExpression(argument, value);
+			}
+			args.push(argument);
+			if (is(TOKEN_TYPES.Comma)) {
+				++current; // consume comma
+			}
 		}
 		return args;
 	}
+
 	function parseMemberExpressionArgumentsList(): Statement {
 		// NOTE: This also handles slice expressions colon-separated arguments list
 		// e.g., ['test'], [0], [:2], [1:], [1:2], [1:2:3]
@@ -354,17 +378,45 @@ export function parse(tokens: Token[]): Program {
 	}
 
 	function parseMultiplicativeExpression(): Statement {
-		let left = parseFilterExpression();
+		let left = parseTestExpression();
+
+		// Multiplicative operators have higher precedence than test expressions
+		// e.g., (4 * 4 is divisibleby(2)) evaluates as (4 * (4 is divisibleby(2)))
 
 		while (is(TOKEN_TYPES.MultiplicativeBinaryOperator)) {
 			const operator = tokens[current];
 			++current;
-			const right = parseFilterExpression();
+			const right = parseTestExpression();
 			left = new BinaryExpression(operator, left, right);
 		}
 		return left;
 	}
 
+	function parseTestExpression(): Statement {
+		let operand = parseFilterExpression();
+
+		while (is(TOKEN_TYPES.Is)) {
+			// Support chaining tests
+			++current; // consume is
+			const negate = is(TOKEN_TYPES.Not);
+			if (negate) {
+				++current; // consume not
+			}
+
+			let filter = parsePrimaryExpression();
+			if (filter instanceof BooleanLiteral) {
+				// Special case: treat boolean literals as identifiers
+				filter = new Identifier(filter.value.toString());
+			}
+			if (!(filter instanceof Identifier)) {
+				throw new SyntaxError(`Expected identifier for the test`);
+			}
+			// TODO: Add support for non-identifier tests
+			operand = new TestExpression(operand, negate, filter);
+		}
+		return operand;
+	}
+
 	function parseFilterExpression(): Statement {
 		let operand = parseCallMemberExpression();
 

packages/jinja/src/runtime.ts

@@ -12,10 +12,12 @@ import type {
 	Identifier,
 	BinaryExpression,
 	FilterExpression,
+	TestExpression,
 	UnaryExpression,
 	SliceExpression,
+	KeywordArgumentExpression,
 } from "./ast";
-import { slice } from "./utils";
+import { slice, titleCase } from "./utils";
 
 export type AnyRuntimeValue =
 	| NumericValue
@@ -89,6 +91,12 @@ export class StringValue extends RuntimeValue<string> {
 				return new StringValue(this.value.trim());
 			}),
 		],
+		[
+			"title",
+			new FunctionValue(() => {
+				return new StringValue(titleCase(this.value));
+			}),
+		],
 		["length", new NumericValue(this.value.length)],
 	]);
 }
@@ -167,7 +175,20 @@ export class Environment {
 	/**
 	 * The variables declared in this environment.
 	 */
-	variables: Map<string, AnyRuntimeValue> = new Map();
+	variables: Map<string, AnyRuntimeValue> = new Map([
+		[
+			"namespace",
+			new FunctionValue((args) => {
+				if (args.length === 0) {
+					return new ObjectValue(new Map());
+				}
+				if (args.length !== 1 || !(args[0] instanceof ObjectValue)) {
+					throw new Error("`namespace` expects either zero arguments or a single object argument");
+				}
+				return args[0];
+			}),
+		],
+	]);
 
 	constructor(public parent?: Environment) {}
 
@@ -245,25 +266,27 @@ export class Interpreter {
 	}
 
 	/**
-	 * Evaulates expressions following the binary operation type.
+	 * Evaluates expressions following the binary operation type.
 	 */
 	private evaluateBinaryExpression(node: BinaryExpression, environment: Environment): AnyRuntimeValue {
 		const left = this.evaluate(node.left, environment);
-		const right = this.evaluate(node.right, environment);
 
-		// Arbitrary operands
+		// Logical operators
+		// NOTE: Short-circuiting is handled by the `evaluate` function
+		switch (node.operator.value) {
+			case "and":
+				return left.__bool__().value ? this.evaluate(node.right, environment) : left;
+			case "or":
+				return left.__bool__().value ? left : this.evaluate(node.right, environment);
+		}
+
+		// Equality operators
+		const right = this.evaluate(node.right, environment);
 		switch (node.operator.value) {
-			// Equality operators
 			case "==":
 				return new BooleanValue(left.value == right.value);
 			case "!=":
 				return new BooleanValue(left.value != right.value);
-
-			// Logical operators
-			case "and":
-				return left.__bool__().value ? right : left;
-			case "or":
-				return left.__bool__().value ? left : right;
 		}
 
 		if (left instanceof UndefinedValue || right instanceof UndefinedValue) {
@@ -326,7 +349,7 @@ export class Interpreter {
 	}
 
 	/**
-	 * Evaulates expressions following the filter operation type.
+	 * Evaluates expressions following the filter operation type.
 	 */
 	private evaluateFilterExpression(node: FilterExpression, environment: Environment): AnyRuntimeValue {
 		const operand = this.evaluate(node.operand, environment);
@@ -380,7 +403,7 @@ export class Interpreter {
 				case "lower":
 					return new StringValue(operand.value.toLowerCase());
 				case "title":
-					return new StringValue(operand.value.replace(/\b\w/g, (c) => c.toUpperCase()));
+					return new StringValue(titleCase(operand.value));
 				case "capitalize":
 					return new StringValue(operand.value.charAt(0).toUpperCase() + operand.value.slice(1));
 				case "trim":
@@ -401,7 +424,77 @@ export class Interpreter {
 	}
 
 	/**
-	 * Evaulates expressions following the unary operation type.
+	 * Evaluates expressions following the test operation type.
+	 */
+	private evaluateTestExpression(node: TestExpression, environment: Environment): BooleanValue {
+		// For now, we only support the built-in tests
+		// https://jinja.palletsprojects.com/en/3.0.x/templates/#list-of-builtin-tests
+		//
+		// TODO: Add support for non-identifier tests. e.g., divisibleby(number)
+
+		const result: boolean = (() => {
+			try {
+				const operand = this.evaluate(node.operand, environment);
+
+				switch (node.test.value) {
+					case "boolean":
+						return operand.type === "BooleanValue";
+					case "callable":
+						return operand instanceof FunctionValue;
+					case "odd":
+						if (operand.type !== "NumericValue") {
+							throw new Error(`Cannot apply test "odd" to type: ${operand.type}`);
+						}
+						return (operand as NumericValue).value % 2 !== 0;
+					case "even":
+						if (operand.type !== "NumericValue") {
+							throw new Error(`Cannot apply test "even" to type: ${operand.type}`);
+						}
+						return (operand as NumericValue).value % 2 === 0;
+					case "false":
+						return operand.type === "BooleanValue" && !(operand as BooleanValue).value;
+					case "true":
+						return operand.type === "BooleanValue" && (operand as BooleanValue).value;
+					case "number":
+						return operand.type === "NumericValue";
+					case "integer":
+						return operand.type === "NumericValue" && Number.isInteger((operand as NumericValue).value);
+					case "iterable":
+						return operand instanceof ArrayValue || operand instanceof StringValue;
+					case "lower": {
+						const str = (operand as StringValue).value;
+						return operand.type === "StringValue" && str === str.toLowerCase();
+					}
+					case "upper": {
+						const str = (operand as StringValue).value;
+						return operand.type === "StringValue" && str === str.toUpperCase();
+					}
+					case "none":
+						return operand.type === "NullValue";
+					case "defined":
+						return true;
+					case "undefined":
+						return false;
+				}
+				throw new Error(`Unknown test: ${node.test.value}`);
+			} catch (e) {
+				if (node.operand.type === "Identifier") {
+					// Special cases where we want to check if a variable is defined
+					if (node.test.value === "defined") {
+						return false;
+					} else if (node.test.value === "undefined") {
+						return true;
+					}
+				}
+				throw e;
+			}
+		})();
+
+		return new BooleanValue(node.negate ? !result : result);
+	}
+
+	/**
+	 * Evaluates expressions following the unary operation type.
 	 */
 	private evaluateUnaryExpression(node: UnaryExpression, environment: Environment): AnyRuntimeValue {
 		const argument = this.evaluate(node.argument, environment);
@@ -414,7 +507,7 @@ export class Interpreter {
 		}
 	}
 
-	private evalProgram(program: Program, environment: Environment): AnyRuntimeValue {
+	private evalProgram(program: Program, environment: Environment): StringValue {
 		return this.evaluateBlock(program.body, environment);
 	}
 
@@ -431,9 +524,6 @@ export class Interpreter {
 			}
 		}
 
-		// Since `trim_blocks` is enabled, we remove the first newline after the template tag
-		result = result.replace(/^\n/, "");
-
 		return new StringValue(result);
 	}
 
@@ -442,7 +532,22 @@ export class Interpreter {
 	}
 
 	private evaluateCallExpression(expr: CallExpression, environment: Environment): AnyRuntimeValue {
-		const args = expr.args.map((arg) => this.evaluate(arg, environment) as AnyRuntimeValue);
+		// Accumulate all keyword arguments into a single object, which will be
+		// used as the final argument in the call function.
+		const args: AnyRuntimeValue[] = [];
+		const kwargs = new Map();
+		for (const argument of expr.args) {
+			if (argument.type === "KeywordArgumentExpression") {
+				const kwarg = argument as KeywordArgumentExpression;
+				kwargs.set(kwarg.key.value, this.evaluate(kwarg.value, environment));
+			} else {
+				args.push(this.evaluate(argument, environment));
+			}
+		}
+		if (kwargs.size > 0) {
+			args.push(new ObjectValue(kwargs));
+		}
+
 		const fn = this.evaluate(expr.callee, environment);
 		if (fn.type !== "FunctionValue") {
 			throw new Error(`Cannot call something that is not a function: got ${fn.type}`);
@@ -525,12 +630,25 @@ export class Interpreter {
 	}
 
 	private evaluateSet(node: SetStatement, environment: Environment): NullValue {
-		if (node.assignee.type !== "Identifier") {
+		const rhs = this.evaluate(node.value, environment);
+		if (node.assignee.type === "Identifier") {
+			const variableName = (node.assignee as Identifier).value;
+			environment.setVariable(variableName, rhs);
+		} else if (node.assignee.type === "MemberExpression") {
+			const member = node.assignee as MemberExpression;
+
+			const object = this.evaluate(member.object, environment);
+			if (!(object instanceof ObjectValue)) {
+				throw new Error("Cannot assign to member of non-object");
+			}
+			if (member.property.type !== "Identifier") {
+				throw new Error("Cannot assign to member with non-identifier property");
+			}
+			object.value.set((member.property as Identifier).value, rhs);
+		} else {
 			throw new Error(`Invalid LHS inside assignment expression: ${JSON.stringify(node.assignee)}`);
 		}
 
-		const variableName = (node.assignee as Identifier).value;
-		environment.setVariable(variableName, this.evaluate(node.value, environment));
 		return new NullValue();
 	}
 
@@ -553,22 +671,19 @@ export class Interpreter {
 		for (let i = 0; i < iterable.value.length; ++i) {
 			// Update the loop variable
 			// TODO: Only create object once, then update value?
-			scope.setVariable(
-				"loop",
-				new ObjectValue(
-					new Map(
-						(
-							[
-								["index", new NumericValue(i + 1)],
-								["index0", new NumericValue(i)],
-								["first", new BooleanValue(i === 0)],
-								["last", new BooleanValue(i === iterable.value.length - 1)],
-								["length", new NumericValue(iterable.value.length)],
-							] as [string, AnyRuntimeValue][]
-						).map(([key, value]) => [key, value])
-					)
-				)
-			);
+			const loop = new Map([
+				["index", new NumericValue(i + 1)],
+				["index0", new NumericValue(i)],
+				["revindex", new NumericValue(iterable.value.length - i)],
+				["revindex0", new NumericValue(iterable.value.length - i - 1)],
+				["first", new BooleanValue(i === 0)],
+				["last", new BooleanValue(i === iterable.value.length - 1)],
+				["length", new NumericValue(iterable.value.length)],
+				["previtem", i > 0 ? iterable.value[i - 1] : new UndefinedValue()],
+				["nextitem", i < iterable.value.length - 1 ? iterable.value[i + 1] : new UndefinedValue()],
+			] as [string, AnyRuntimeValue][]);
+
+			scope.setVariable("loop", new ObjectValue(loop));
 
 			// For this iteration, set the loop variable to the current element
 			scope.setVariable(node.loopvar.value, iterable.value[i]);
@@ -617,6 +732,8 @@ export class Interpreter {
 				return this.evaluateBinaryExpression(statement as BinaryExpression, environment);
 			case "FilterExpression":
 				return this.evaluateFilterExpression(statement as FilterExpression, environment);
+			case "TestExpression":
+				return this.evaluateTestExpression(statement as TestExpression, environment);
 
 			default:
 				throw new SyntaxError(`Unknown node type: ${statement.type}`);

packages/jinja/src/utils.ts

@@ -1,3 +1,23 @@
+/**
+ * Function that mimics Python's range() function.
+ * @param start The start value of the range.
+ * @param stop The stop value of the range. If not provided, start will be 0 and stop will be the provided start value.
+ * @param step The step value of the range. Defaults to 1.
+ * @returns The range of numbers.
+ */
+export function range(start: number, stop?: number, step = 1): number[] {
+	if (stop === undefined) {
+		stop = start;
+		start = 0;
+	}
+
+	const result: number[] = [];
+	for (let i = start; i < stop; i += step) {
+		result.push(i);
+	}
+	return result;
+}
+
 /**
  * Function that mimics Python's array slicing.
  * @param array The array to slice.
@@ -23,3 +43,12 @@ export function slice<T>(array: T[], start?: number, stop?: number, step = 1): T
 	}
 	return result;
 }
+
+/**
+ * Function that mimics Python's string.title() function.
+ * @param value The string to title case.
+ * @returns The title cased string.
+ */
+export function titleCase(value: string): string {
+	return value.replace(/\b\w/g, (c) => c.toUpperCase());
+}

packages/jinja/test/e2e.test.js

@@ -10,7 +10,7 @@ const EXAMPLE_CHAT = [
 	{ role: "user", content: "I'd like to show off how chat templating works!" },
 ];
 
-const EXAMPLE_CHAT_WITH_SYTEM = [
+const EXAMPLE_CHAT_WITH_SYSTEM = [
 	{
 		role: "system",
 		content: "You are a friendly chatbot who always responds in the style of a pirate",
@@ -80,7 +80,7 @@ const TEST_DEFAULT_TEMPLATES = Object.freeze({
 		// hf-internal-testing/llama-tokenizer
 		chat_template: `{% if messages[0]['role'] == 'system' %}{% set loop_messages = messages[1:] %}{% set system_message = messages[0]['content'] %}{% elif USE_DEFAULT_PROMPT == true and not '<<SYS>>' in messages[0]['content'] %}{% set loop_messages = messages %}{% set system_message = 'DEFAULT_SYSTEM_MESSAGE' %}{% else %}{% set loop_messages = messages %}{% set system_message = false %}{% endif %}{% for message in loop_messages %}{% if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if loop.index0 == 0 and system_message != false %}{% set content = '<<SYS>>\\n' + system_message + '\\n<</SYS>>\\n\\n' + message['content'] %}{% else %}{% set content = message['content'] %}{% endif %}{% if message['role'] == 'user' %}{{ bos_token + '[INST] ' + content.strip() + ' [/INST]' }}{% elif message['role'] == 'system' %}{{ '<<SYS>>\\n' + content.strip() + '\\n<</SYS>>\\n\\n' }}{% elif message['role'] == 'assistant' %}{{ ' ' + content.strip() + ' ' + eos_token }}{% endif %}{% endfor %}`,
 		data: {
-			messages: EXAMPLE_CHAT_WITH_SYTEM,
+			messages: EXAMPLE_CHAT_WITH_SYSTEM,
 			bos_token: "<s>",
 			eos_token: "</s>",
 			USE_DEFAULT_PROMPT: true,
@@ -106,7 +106,7 @@ const TEST_CUSTOM_TEMPLATES = Object.freeze({
 	"HuggingFaceH4/zephyr-7b-beta (add_generation_prompt=false)": {
 		chat_template: `{% for message in messages %}\n{% if message['role'] == 'user' %}\n{{ '<|user|>\n' + message['content'] + eos_token }}\n{% elif message['role'] == 'system' %}\n{{ '<|system|>\n' + message['content'] + eos_token }}\n{% elif message['role'] == 'assistant' %}\n{{ '<|assistant|>\n'  + message['content'] + eos_token }}\n{% endif %}\n{% if loop.last and add_generation_prompt %}\n{{ '<|assistant|>' }}\n{% endif %}\n{% endfor %}`,
 		data: {
-			messages: EXAMPLE_CHAT_WITH_SYTEM,
+			messages: EXAMPLE_CHAT_WITH_SYSTEM,
 			eos_token: "</s>",
 			add_generation_prompt: false,
 		},
@@ -124,6 +124,16 @@ const TEST_CUSTOM_TEMPLATES = Object.freeze({
 		},
 		target: `<|system|>\nYou are a friendly chatbot who always responds in the style of a pirate</s>\n<|user|>\nHow many helicopters can a human eat in one sitting?</s>\n<|assistant|>\n`,
 	},
+	"HuggingFaceH4/zephyr-7b-gemma-v0.1": {
+		chat_template: `{% if messages[0]['role'] == 'user' or messages[0]['role'] == 'system' %}{{ bos_token }}{% endif %}{% for message in messages %}{{ '<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n' }}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% elif messages[-1]['role'] == 'assistant' %}{{ eos_token }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<bos>",
+			eos_token: "<eos>",
+			add_generation_prompt: false,
+		},
+		target: `<bos><|im_start|>user\nHello, how are you?<|im_end|>\n<|im_start|>assistant\nI'm doing great. How can I help you today?<|im_end|>\n<|im_start|>user\nI'd like to show off how chat templating works!<|im_end|>\n`,
+	},
 	"mistralai/Mistral-7B-Instruct-v0.1": {
 		chat_template: `{{ bos_token }}{% for message in messages %}{% if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if message['role'] == 'user' %}{{ '[INST] ' + message['content'] + ' [/INST]' }}{% elif message['role'] == 'assistant' %}{{ message['content'] + eos_token + ' ' }}{% else %}{{ raise_exception('Only user and assistant roles are supported!') }}{% endif %}{% endfor %}`,
 		data: {
@@ -133,6 +143,149 @@ const TEST_CUSTOM_TEMPLATES = Object.freeze({
 		},
 		target: `<s>[INST] Hello, how are you? [/INST]I'm doing great. How can I help you today?</s> [INST] I'd like to show off how chat templating works! [/INST]`,
 	},
+	"mistralai/Mixtral-8x7B-Instruct-v0.1": {
+		chat_template: `{{ bos_token }}{% for message in messages %}{% if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if message['role'] == 'user' %}{{ '[INST] ' + message['content'] + ' [/INST]' }}{% elif message['role'] == 'assistant' %}{{ message['content'] + eos_token}}{% else %}{{ raise_exception('Only user and assistant roles are supported!') }}{% endif %}{% endfor %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+		},
+		target: `<s>[INST] Hello, how are you? [/INST]I'm doing great. How can I help you today?</s>[INST] I'd like to show off how chat templating works! [/INST]`,
+	},
+	"cognitivecomputations/dolphin-2.5-mixtral-8x7b": {
+		chat_template: `{% if not add_generation_prompt is defined %}{% set add_generation_prompt = false %}{% endif %}{% for message in messages %}{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+		},
+		target: `<|im_start|>user\nHello, how are you?<|im_end|>\n<|im_start|>assistant\nI'm doing great. How can I help you today?<|im_end|>\n<|im_start|>user\nI'd like to show off how chat templating works!<|im_end|>\n`,
+	},
+	"openchat/openchat-3.5-0106": {
+		chat_template: `{{ bos_token }}{% for message in messages %}{{ 'GPT4 Correct ' + message['role'].title() + ': ' + message['content'] + '<|end_of_turn|>'}}{% endfor %}{% if add_generation_prompt %}{{ 'GPT4 Correct Assistant:' }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `<s>GPT4 Correct User: Hello, how are you?<|end_of_turn|>GPT4 Correct Assistant: I'm doing great. How can I help you today?<|end_of_turn|>GPT4 Correct User: I'd like to show off how chat templating works!<|end_of_turn|>`,
+	},
+	"upstage/SOLAR-10.7B-Instruct-v1.0": {
+		chat_template: `{% for message in messages %}{% if message['role'] == 'system' %}{% if message['content']%}{{'### System:\n' + message['content']+'\n\n'}}{% endif %}{% elif message['role'] == 'user' %}{{'### User:\n' + message['content']+'\n\n'}}{% elif message['role'] == 'assistant' %}{{'### Assistant:\n'  + message['content']}}{% endif %}{% if loop.last and add_generation_prompt %}{{ '### Assistant:\n' }}{% endif %}{% endfor %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `### User:\nHello, how are you?\n\n### Assistant:\nI'm doing great. How can I help you today?### User:\nI'd like to show off how chat templating works!\n\n`,
+	},
+	"codellama/CodeLlama-70b-Instruct-hf": {
+		chat_template: `{% if messages[0]['role'] == 'system' %}{% set user_index = 1 %}{% else %}{% set user_index = 0 %}{% endif %}{% for message in messages %}{% if (message['role'] == 'user') != ((loop.index0 + user_index) % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if loop.index0 == 0 %}{{ '<s>' }}{% endif %}{% set content = 'Source: ' + message['role'] + '\n\n ' + message['content'] | trim %}{{ content + ' <step> ' }}{% endfor %}{{'Source: assistant\nDestination: user\n\n '}}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+		},
+		target: `<s>Source: user\n\n Hello, how are you? <step> Source: assistant\n\n I'm doing great. How can I help you today? <step> Source: user\n\n I'd like to show off how chat templating works! <step> Source: assistant\nDestination: user\n\n `,
+	},
+	"Deci/DeciLM-7B-instruct": {
+		chat_template: `{% for message in messages %}\n{% if message['role'] == 'user' %}\n{{ '### User:\n' + message['content'] }}\n{% elif message['role'] == 'system' %}\n{{ '### System:\n' + message['content'] }}\n{% elif message['role'] == 'assistant' %}\n{{ '### Assistant:\n'  + message['content'] }}\n{% endif %}\n{% if loop.last and add_generation_prompt %}\n{{ '### Assistant:' }}\n{% endif %}\n{% endfor %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `### User:\nHello, how are you?\n### Assistant:\nI'm doing great. How can I help you today?\n### User:\nI'd like to show off how chat templating works!\n`,
+	},
+	"Qwen/Qwen1.5-72B-Chat": {
+		chat_template: `{% for message in messages %}{% if loop.first and messages[0]['role'] != 'system' %}{{ '<|im_start|>system\nYou are a helpful assistant<|im_end|>\n' }}{% endif %}{{'<|im_start|>' + message['role'] + '\n' + message['content']}}{% if (loop.last and add_generation_prompt) or not loop.last %}{{ '<|im_end|>' + '\n'}}{% endif %}{% endfor %}{% if add_generation_prompt and messages[-1]['role'] != 'assistant' %}{{ '<|im_start|>assistant\n' }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `<|im_start|>system\nYou are a helpful assistant<|im_end|>\n<|im_start|>user\nHello, how are you?<|im_end|>\n<|im_start|>assistant\nI'm doing great. How can I help you today?<|im_end|>\n<|im_start|>user\nI'd like to show off how chat templating works!`,
+	},
+	"deepseek-ai/deepseek-llm-7b-chat": {
+		chat_template: `{% if not add_generation_prompt is defined %}{% set add_generation_prompt = false %}{% endif %}{{ bos_token }}{% for message in messages %}{% if message['role'] == 'user' %}{{ 'User: ' + message['content'] + '\n\n' }}{% elif message['role'] == 'assistant' %}{{ 'Assistant: ' + message['content'] + eos_token }}{% elif message['role'] == 'system' %}{{ message['content'] + '\n\n' }}{% endif %}{% endfor %}{% if add_generation_prompt %}{{ 'Assistant:' }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<｜begin▁of▁sentence｜>",
+			eos_token: "<｜end▁of▁sentence｜>",
+		},
+		target: `<｜begin▁of▁sentence｜>User: Hello, how are you?\n\nAssistant: I'm doing great. How can I help you today?<｜end▁of▁sentence｜>User: I'd like to show off how chat templating works!\n\n`,
+	},
+	"h2oai/h2o-danube-1.8b-chat": {
+		chat_template: `{% for message in messages %}{% if message['role'] == 'user' %}{{ '<|prompt|>' + message['content'] + eos_token }}{% elif message['role'] == 'system' %}{{ '<|system|>' + message['content'] + eos_token }}{% elif message['role'] == 'assistant' %}{{ '<|answer|>'  + message['content'] + eos_token }}{% endif %}{% if loop.last and add_generation_prompt %}{{ '<|answer|>' }}{% endif %}{% endfor %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `<|prompt|>Hello, how are you?</s><|answer|>I'm doing great. How can I help you today?</s><|prompt|>I'd like to show off how chat templating works!</s>`,
+	},
+	"internlm/internlm2-chat-7b": {
+		chat_template: `{% if messages[0]['role'] == 'user' or messages[0]['role'] == 'system' %}{{ bos_token }}{% endif %}{% for message in messages %}{{ '<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n' }}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% elif messages[-1]['role'] == 'assistant' %}{{ eos_token }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `<s><|im_start|>user\nHello, how are you?<|im_end|>\n<|im_start|>assistant\nI'm doing great. How can I help you today?<|im_end|>\n<|im_start|>user\nI'd like to show off how chat templating works!<|im_end|>\n`,
+	},
+	"TheBloke/deepseek-coder-33B-instruct-AWQ": {
+		chat_template: `{%- set found_item = false -%}\n{%- for message in messages -%}\n    {%- if message['role'] == 'system' -%}\n        {%- set found_item = true -%}\n    {%- endif -%}\n{%- endfor -%}\n{%- if not found_item -%}\n{{'You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer.\\n'}}\n{%- endif %}\n{%- for message in messages %}\n    {%- if message['role'] == 'system' %}\n{{ message['content'] }}\n    {%- else %}\n        {%- if message['role'] == 'user' %}\n{{'### Instruction:\\n' + message['content'] + '\\n'}}\n        {%- else %}\n{{'### Response:\\n' + message['content'] + '\\n<|EOT|>\\n'}}\n        {%- endif %}\n    {%- endif %}\n{%- endfor %}\n{{'### Response:\\n'}}\n`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<｜begin▁of▁sentence｜>",
+			eos_token: "<|EOT|>",
+		},
+		target: `You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer.\n### Instruction:\nHello, how are you?\n### Response:\nI'm doing great. How can I help you today?\n<|EOT|>\n### Instruction:\nI'd like to show off how chat templating works!\n### Response:\n`,
+	},
+	"ericzzz/falcon-rw-1b-chat": {
+		chat_template: `{% for message in messages %}{% if loop.index > 1 and loop.previtem['role'] != 'assistant' %}{{ ' ' }}{% endif %}{% if message['role'] == 'system' %}{{ '[SYS] ' + message['content'].strip() }}{% elif message['role'] == 'user' %}{{ '[INST] ' + message['content'].strip() }}{% elif message['role'] == 'assistant' %}{{ '[RESP] '  + message['content'] + eos_token }}{% endif %}{% endfor %}{% if add_generation_prompt %}{{ ' [RESP] ' }}{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<|endoftext|>",
+			eos_token: "<|endoftext|>",
+			add_generation_prompt: false,
+		},
+		target: `[INST] Hello, how are you? [RESP] I'm doing great. How can I help you today?<|endoftext|>[INST] I'd like to show off how chat templating works!`,
+	},
+	"abacusai/Smaug-34B-v0.1": {
+		chat_template: `{%- for idx in range(0, messages|length) -%}\n{%- if messages[idx]['role'] == 'user' -%}\n{%- if idx > 1 -%}\n{{- bos_token + '[INST] ' + messages[idx]['content'] + ' [/INST]' -}}\n{%- else -%}\n{{- messages[idx]['content'] + ' [/INST]' -}}\n{%- endif -%}\n{% elif messages[idx]['role'] == 'system' %}\n{{- '[INST] <<SYS>>\\n' + messages[idx]['content'] + '\\n<</SYS>>\\n\\n' -}}\n{%- elif messages[idx]['role'] == 'assistant' -%}\n{{- ' '  + messages[idx]['content'] + ' ' + eos_token -}}\n{% endif %}\n{% endfor %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+		},
+		target: `Hello, how are you? [/INST] I'm doing great. How can I help you today? </s><s>[INST] I'd like to show off how chat templating works! [/INST]`,
+	},
+	"maywell/Synatra-Mixtral-8x7B": {
+		chat_template: `Below is an instruction that describes a task. Write a response that appropriately completes the request.\n\n{% for message in messages %}{% if message['role'] == 'user' %}### Instruction:\n{{ message['content']|trim -}}{% if not loop.last %}{% endif %}\n{% elif message['role'] == 'assistant' %}### Response:\n{{ message['content']|trim -}}{% if not loop.last %}{% endif %}\n{% elif message['role'] == 'system' %}{{ message['content']|trim -}}{% if not loop.last %}{% endif %}\n{% endif %}\n{% endfor %}\n{% if add_generation_prompt and messages[-1]['role'] != 'assistant' %}\n### Response:\n{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<s>",
+			eos_token: "</s>",
+			add_generation_prompt: false,
+		},
+		target: `Below is an instruction that describes a task. Write a response that appropriately completes the request.\n\n### Instruction:\nHello, how are you?### Response:\nI'm doing great. How can I help you today?### Instruction:\nI'd like to show off how chat templating works!`,
+	},
+	"deepseek-ai/deepseek-coder-33b-instruct": {
+		chat_template: `{% if not add_generation_prompt is defined %}\n{% set add_generation_prompt = false %}\n{% endif %}\n{%- set ns = namespace(found=false) -%}\n{%- for message in messages -%}\n    {%- if message['role'] == 'system' -%}\n        {%- set ns.found = true -%}\n    {%- endif -%}\n{%- endfor -%}\n{{bos_token}}{%- if not ns.found -%}\n{{'You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer\\n'}}\n{%- endif %}\n{%- for message in messages %}\n    {%- if message['role'] == 'system' %}\n{{ message['content'] }}\n    {%- else %}\n        {%- if message['role'] == 'user' %}\n{{'### Instruction:\\n' + message['content'] + '\\n'}}\n        {%- else %}\n{{'### Response:\\n' + message['content'] + '\\n<|EOT|>\\n'}}\n        {%- endif %}\n    {%- endif %}\n{%- endfor %}\n{% if add_generation_prompt %}\n{{'### Response:'}}\n{% endif %}`,
+		data: {
+			messages: EXAMPLE_CHAT,
+			bos_token: "<｜begin▁of▁sentence｜>",
+			eos_token: "<|EOT|>",
+		},
+		target: `<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer\n### Instruction:\nHello, how are you?\n### Response:\nI'm doing great. How can I help you today?\n<|EOT|>\n### Instruction:\nI'd like to show off how chat templating works!\n`,
+	},
 });
 
 describe("End-to-end tests", () => {

packages/jinja/test/interpreter.test.js

@@ -0,0 +1,118 @@
+import { describe, it, expect } from "vitest";
+
+import { Environment, Interpreter } from "../src/runtime";
+import { tokenize } from "../src/lexer";
+import { parse } from "../src/parser";
+
+describe("Test interpreter options", () => {
+	// https://jinja.palletsprojects.com/en/3.0.x/templates/#whitespace-control
+	it("should handle whitespace control", () => {
+		const EXAMPLE_IF_TEMPLATE = `<div>\n    {% if True %}\n        yay\n    {% endif %}\n</div>`;
+		const EXAMPLE_FOR_TEMPLATE = `{% for item in seq %}\n    {{ item }}\n{% endfor %}`;
+		const EXAMPLE_FOR_TEMPLATE_2 = `{% for item in seq -%}\n    {{ item }}\n{% endfor %}`;
+		const EXAMPLE_FOR_TEMPLATE_3 = `{% for item in seq %}\n    {{ item }}\n{%- endfor %}`;
+		const EXAMPLE_FOR_TEMPLATE_4 = `{% for item in seq -%}\n    {{ item }}\n{%- endfor %}`;
+
+		const seq = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+		const TESTS = [
+			// If tests
+			{
+				template: EXAMPLE_IF_TEMPLATE,
+				data: {},
+				options: {},
+				target: `<div>\n    \n        yay\n    \n</div>`,
+			},
+			{
+				template: EXAMPLE_IF_TEMPLATE,
+				data: {},
+				options: {
+					lstrip_blocks: true,
+				},
+				target: `<div>\n\n        yay\n\n</div>`,
+			},
+			{
+				template: EXAMPLE_IF_TEMPLATE,
+				data: {},
+				options: {
+					trim_blocks: true,
+				},
+				target: `<div>\n            yay\n    </div>`,
+			},
+			{
+				template: EXAMPLE_IF_TEMPLATE,
+				data: {},
+				options: {
+					lstrip_blocks: true,
+					trim_blocks: true,
+				},
+				target: `<div>\n        yay\n</div>`,
+			},
+
+			// For tests
+			{
+				template: EXAMPLE_FOR_TEMPLATE,
+				data: { seq },
+				options: {},
+				target: `\n    1\n\n    2\n\n    3\n\n    4\n\n    5\n\n    6\n\n    7\n\n    8\n\n    9\n`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE,
+				data: { seq },
+				options: { lstrip_blocks: true },
+				target: `\n    1\n\n    2\n\n    3\n\n    4\n\n    5\n\n    6\n\n    7\n\n    8\n\n    9\n`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE,
+				data: { seq },
+				options: { trim_blocks: true },
+				target: `    1\n    2\n    3\n    4\n    5\n    6\n    7\n    8\n    9\n`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE,
+				data: { seq },
+				options: { lstrip_blocks: true, trim_blocks: true },
+				target: `    1\n    2\n    3\n    4\n    5\n    6\n    7\n    8\n    9\n`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE_2,
+				data: { seq },
+				options: {},
+				target: `1\n2\n3\n4\n5\n6\n7\n8\n9\n`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE_3,
+				data: { seq },
+				options: {},
+				target: `\n    1\n    2\n    3\n    4\n    5\n    6\n    7\n    8\n    9`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE_3,
+				data: { seq },
+				options: { trim_blocks: true },
+				target: `    1    2    3    4    5    6    7    8    9`,
+			},
+			{
+				template: EXAMPLE_FOR_TEMPLATE_4,
+				data: { seq },
+				options: {},
+				target: `123456789`,
+			},
+		];
+
+		for (const test of TESTS) {
+			const env = new Environment();
+			env.set("True", true);
+			for (const [key, value] of Object.entries(test.data)) {
+				env.set(key, value);
+			}
+
+			const tokens = tokenize(test.template, test.options);
+			const parsed = parse(tokens);
+
+			const interpreter = new Interpreter(env);
+			const result = interpreter.run(parsed);
+			expect(result.value).toEqual(test.target);
+		}
+	});
+});

packages/jinja/test/templates.test.js

@@ -49,6 +49,7 @@ const TEST_STRINGS = {
 	// Object methods
 	OBJ_METHODS: `{{ obj.x(x, y) }}{{ ' ' + obj.x() + ' ' }}{{ obj.z[x](x, y) }}`,
 	STRING_METHODS: `{{ '  A  '.strip() }}{% set x = '  B  ' %}{{ x.strip() }}{% set y = ' aBcD ' %}{{ y.upper() }}{{ y.lower() }}`,
+	STRING_METHODS_2: `{{ 'test test'.title() }}`,
 
 	// String indexing and slicing
 	STRING_SLICING: `|{{ x[0] }}|{{ x[:] }}|{{ x[:3] }}|{{ x[1:4] }}|{{ x[1:-1] }}|{{ x[1::2] }}|{{ x[5::-1] }}|`,
@@ -78,6 +79,22 @@ const TEST_STRINGS = {
 	BOOLEAN_MIXED: `|{{ true and 1 }}|{{ true and 0 }}|{{ false and 1 }}|{{ false and 0 }}|{{ true or 1 }}|{{ true or 0 }}|{{ false or 1 }}|{{ false or 0 }}|`,
 	BOOLEAN_MIXED_2: `|{{ true and '' }}|{{ true and 'a' }}|{{ false or '' }}|{{ false or 'a' }}|{{ '' and true }}|{{ 'a' and true }}|{{ '' or false }}|{{ 'a' or false }}|`,
 	BOOLEAN_MIXED_IF: `{% if '' %}{{ 'A' }}{% endif %}{% if 'a' %}{{ 'B' }}{% endif %}{% if true and '' %}{{ 'C' }}{% endif %}{% if true and 'a' %}{{ 'D' }}{% endif %}`,
+
+	// Tests (is operator)
+	IS_OPERATOR: `|{{ unknown_var is defined }}|{{ unknown_var is not defined }}|{{ known_var is defined }}|{{ known_var is not defined }}|`,
+	IS_OPERATOR_2: `|{{ true is true }}|{{ true is not true }}|{{ true is false }}|{{ true is not false }}|{{ true is boolean }}|{{ 1 is boolean }}|`,
+	IS_OPERATOR_3: `|{{ 1 is odd }}|{{ 2 is odd }}|{{ 1 is even }}|{{ 2 is even }}|{{ 2 is number }}|{{ '2' is number }}|{{ 2 is integer }}|{{ '2' is integer }}|`,
+	IS_OPERATOR_4: `|{{ func is callable }}|{{ 2 is callable }}|{{ 1 is iterable }}|{{ 'hello' is iterable }}|`,
+	IS_OPERATOR_5: `|{{ 'a' is lower }}|{{ 'A' is lower }}|{{ 'a' is upper }}|{{ 'A' is upper }}|`,
+
+	// Short-circuit evaluation
+	SHORT_CIRCUIT: `{{ false and raise_exception('This should not be printed') }}`,
+	SHORT_CIRCUIT_1: `{{ true or raise_exception('This should not be printed') }}`,
+
+	// Namespaces
+	NAMESPACE: `{% set ns = namespace() %}{% set ns.foo = 'bar' %}{{ ns.foo }}`,
+	NAMESPACE_1: `{% set ns = namespace(default=false) %}{{ ns.default }}`,
+	NAMESPACE_2: `{% set ns = namespace(default=false, number=1+1) %}|{{ ns.default }}|{{ ns.number }}|`,
 };
 
 const TEST_PARSED = {
@@ -728,6 +745,15 @@ const TEST_PARSED = {
 		{ value: ")", type: "CloseParen" },
 		{ value: "}}", type: "CloseExpression" },
 	],
+	STRING_METHODS_2: [
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "test test", type: "StringLiteral" },
+		{ value: ".", type: "Dot" },
+		{ value: "title", type: "Identifier" },
+		{ value: "(", type: "OpenParen" },
+		{ value: ")", type: "CloseParen" },
+		{ value: "}}", type: "CloseExpression" },
+	],
 
 	// String indexing and slicing
 	STRING_SLICING: [
@@ -1477,6 +1503,280 @@ const TEST_PARSED = {
 		{ value: "endif", type: "EndIf" },
 		{ value: "%}", type: "CloseStatement" },
 	],
+
+	// Tests (is operator)
+	IS_OPERATOR: [
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "unknown_var", type: "Identifier" },
+		{ value: "is", type: "Is" },
+		{ value: "defined", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "unknown_var", type: "Identifier" },
+		{ value: "is", type: "Is" },
+		{ value: "not", type: "UnaryOperator" },
+		{ value: "defined", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "known_var", type: "Identifier" },
+		{ value: "is", type: "Is" },
+		{ value: "defined", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "known_var", type: "Identifier" },
+		{ value: "is", type: "Is" },
+		{ value: "not", type: "UnaryOperator" },
+		{ value: "defined", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+	],
+	IS_OPERATOR_2: [
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "not", type: "UnaryOperator" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "false", type: "BooleanLiteral" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "not", type: "UnaryOperator" },
+		{ value: "false", type: "BooleanLiteral" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "boolean", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "1", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "boolean", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+	],
+	IS_OPERATOR_3: [
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "1", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "odd", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "odd", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "1", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "even", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "even", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "number", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "number", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "integer", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "integer", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+	],
+	IS_OPERATOR_4: [
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "func", type: "Identifier" },
+		{ value: "is", type: "Is" },
+		{ value: "callable", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "2", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "callable", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "1", type: "NumericLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "iterable", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "hello", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "iterable", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+	],
+	IS_OPERATOR_5: [
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "a", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "lower", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "A", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "lower", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "a", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "upper", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "A", type: "StringLiteral" },
+		{ value: "is", type: "Is" },
+		{ value: "upper", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+	],
+
+	// Short-circuit evaluation
+	SHORT_CIRCUIT: [
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "false", type: "BooleanLiteral" },
+		{ value: "and", type: "And" },
+		{ value: "raise_exception", type: "Identifier" },
+		{ value: "(", type: "OpenParen" },
+		{ value: "This should not be printed", type: "StringLiteral" },
+		{ value: ")", type: "CloseParen" },
+		{ value: "}}", type: "CloseExpression" },
+	],
+	SHORT_CIRCUIT_1: [
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "true", type: "BooleanLiteral" },
+		{ value: "or", type: "Or" },
+		{ value: "raise_exception", type: "Identifier" },
+		{ value: "(", type: "OpenParen" },
+		{ value: "This should not be printed", type: "StringLiteral" },
+		{ value: ")", type: "CloseParen" },
+		{ value: "}}", type: "CloseExpression" },
+	],
+
+	// Namespaces
+	NAMESPACE: [
+		{ value: "{%", type: "OpenStatement" },
+		{ value: "set", type: "Set" },
+		{ value: "ns", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "namespace", type: "Identifier" },
+		{ value: "(", type: "OpenParen" },
+		{ value: ")", type: "CloseParen" },
+		{ value: "%}", type: "CloseStatement" },
+		{ value: "{%", type: "OpenStatement" },
+		{ value: "set", type: "Set" },
+		{ value: "ns", type: "Identifier" },
+		{ value: ".", type: "Dot" },
+		{ value: "foo", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "bar", type: "StringLiteral" },
+		{ value: "%}", type: "CloseStatement" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "ns", type: "Identifier" },
+		{ value: ".", type: "Dot" },
+		{ value: "foo", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+	],
+	NAMESPACE_1: [
+		{ value: "{%", type: "OpenStatement" },
+		{ value: "set", type: "Set" },
+		{ value: "ns", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "namespace", type: "Identifier" },
+		{ value: "(", type: "OpenParen" },
+		{ value: "default", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "false", type: "BooleanLiteral" },
+		{ value: ")", type: "CloseParen" },
+		{ value: "%}", type: "CloseStatement" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "ns", type: "Identifier" },
+		{ value: ".", type: "Dot" },
+		{ value: "default", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+	],
+	NAMESPACE_2: [
+		{ value: "{%", type: "OpenStatement" },
+		{ value: "set", type: "Set" },
+		{ value: "ns", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "namespace", type: "Identifier" },
+		{ value: "(", type: "OpenParen" },
+		{ value: "default", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "false", type: "BooleanLiteral" },
+		{ value: ",", type: "Comma" },
+		{ value: "number", type: "Identifier" },
+		{ value: "=", type: "Equals" },
+		{ value: "1", type: "NumericLiteral" },
+		{ value: "+", type: "AdditiveBinaryOperator" },
+		{ value: "1", type: "NumericLiteral" },
+		{ value: ")", type: "CloseParen" },
+		{ value: "%}", type: "CloseStatement" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "ns", type: "Identifier" },
+		{ value: ".", type: "Dot" },
+		{ value: "default", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+		{ value: "{{", type: "OpenExpression" },
+		{ value: "ns", type: "Identifier" },
+		{ value: ".", type: "Dot" },
+		{ value: "number", type: "Identifier" },
+		{ value: "}}", type: "CloseExpression" },
+		{ value: "|", type: "Text" },
+	],
 };
 
 const TEST_CONTEXT = {
@@ -1552,6 +1852,7 @@ const TEST_CONTEXT = {
 
 	// String methods
 	STRING_METHODS: {},
+	STRING_METHODS_2: {},
 
 	// String indexing and slicing
 	STRING_SLICING: {
@@ -1593,6 +1894,26 @@ const TEST_CONTEXT = {
 	BOOLEAN_MIXED: {},
 	BOOLEAN_MIXED_2: {},
 	BOOLEAN_MIXED_IF: {},
+
+	// Tests (is operator)
+	IS_OPERATOR: {
+		known_var: "Hello World",
+	},
+	IS_OPERATOR_2: {},
+	IS_OPERATOR_3: {},
+	IS_OPERATOR_4: {
+		func: () => {},
+	},
+	IS_OPERATOR_5: {},
+
+	// Short-circuit evaluation
+	SHORT_CIRCUIT: {},
+	SHORT_CIRCUIT_1: {},
+
+	// Namespaces
+	NAMESPACE: {},
+	NAMESPACE_1: {},
+	NAMESPACE_2: {},
 };
 
 const EXPECTED_OUTPUTS = {
@@ -1640,6 +1961,7 @@ const EXPECTED_OUTPUTS = {
 	// Object methods
 	OBJ_METHODS: "AB  A_B",
 	STRING_METHODS: "AB ABCD  abcd ",
+	STRING_METHODS_2: "Test Test",
 
 	// String indexing and slicing
 	STRING_SLICING: "|0|0123456789|012|123|12345678|13579|543210|",
@@ -1653,9 +1975,7 @@ const EXPECTED_OUTPUTS = {
 	MEMBERSHIP_NEGATION_2: "|false|true|false|true|false|true|",
 
 	// Escaped characters
-	// NOTE: Since `trim_blocks` is enabled, we remove the first newline after the template tag,
-	// meaning the first newline in the output is not present
-	ESCAPED_CHARS: `\t'"\\|\n|\t|'|"|\\|`,
+	ESCAPED_CHARS: `\n\t'"\\|\n|\t|'|"|\\|`,
 
 	// Substring inclusion
 	SUBSTRING_INCLUSION: `|true|true|false|true|false|true|false|`,
@@ -1671,6 +1991,22 @@ const EXPECTED_OUTPUTS = {
 	BOOLEAN_MIXED: `|1|0|false|false|true|true|1|0|`,
 	BOOLEAN_MIXED_2: `||a||a||true|false|a|`,
 	BOOLEAN_MIXED_IF: `BD`,
+
+	// Tests (is operator)
+	IS_OPERATOR: `|false|true|true|false|`,
+	IS_OPERATOR_2: `|true|false|false|true|true|false|`,
+	IS_OPERATOR_3: `|true|false|false|true|true|false|true|false|`,
+	IS_OPERATOR_4: `|true|false|false|true|`,
+	IS_OPERATOR_5: `|true|false|false|true|`,
+
+	// Short-circuit evaluation
+	SHORT_CIRCUIT: `false`,
+	SHORT_CIRCUIT_1: `true`,
+
+	// Namespaces
+	NAMESPACE: `bar`,
+	NAMESPACE_1: `false`,
+	NAMESPACE_2: `|false|2|`,
 };
 
 describe("Templates", () => {

packages/tasks/package.json

@@ -1,7 +1,7 @@
 {
 	"name": "@huggingface/tasks",
 	"packageManager": "pnpm@8.10.5",
-	"version": "0.5.1",
+	"version": "0.5.2",
 	"description": "List of ML tasks for huggingface.co/tasks",
 	"repository": "https://github.com/huggingface/huggingface.js.git",
 	"publishConfig": {