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| # | |
| # Copyright (c) 2012-2017 The ANTLR Project. All rights reserved. | |
| # Use of this file is governed by the BSD 3-clause license that | |
| # can be found in the LICENSE.txt file in the project root. | |
| from antlr4.atn.ATNState import StarLoopEntryState | |
| from antlr4.atn.ATNConfigSet import ATNConfigSet | |
| from antlr4.atn.ATNState import DecisionState | |
| from antlr4.dfa.DFAState import DFAState | |
| from antlr4.error.Errors import IllegalStateException | |
| class DFA(object): | |
| __slots__ = ('atnStartState', 'decision', '_states', 's0', 'precedenceDfa') | |
| def __init__(self, atnStartState:DecisionState, decision:int=0): | |
| # From which ATN state did we create this DFA? | |
| self.atnStartState = atnStartState | |
| self.decision = decision | |
| # A set of all DFA states. Use {@link Map} so we can get old state back | |
| # ({@link Set} only allows you to see if it's there). | |
| self._states = dict() | |
| self.s0 = None | |
| # {@code true} if this DFA is for a precedence decision; otherwise, | |
| # {@code false}. This is the backing field for {@link #isPrecedenceDfa}, | |
| # {@link #setPrecedenceDfa}. | |
| self.precedenceDfa = False | |
| if isinstance(atnStartState, StarLoopEntryState): | |
| if atnStartState.isPrecedenceDecision: | |
| self.precedenceDfa = True | |
| precedenceState = DFAState(configs=ATNConfigSet()) | |
| precedenceState.edges = [] | |
| precedenceState.isAcceptState = False | |
| precedenceState.requiresFullContext = False | |
| self.s0 = precedenceState | |
| # Get the start state for a specific precedence value. | |
| # | |
| # @param precedence The current precedence. | |
| # @return The start state corresponding to the specified precedence, or | |
| # {@code null} if no start state exists for the specified precedence. | |
| # | |
| # @throws IllegalStateException if this is not a precedence DFA. | |
| # @see #isPrecedenceDfa() | |
| def getPrecedenceStartState(self, precedence:int): | |
| if not self.precedenceDfa: | |
| raise IllegalStateException("Only precedence DFAs may contain a precedence start state.") | |
| # s0.edges is never null for a precedence DFA | |
| if precedence < 0 or precedence >= len(self.s0.edges): | |
| return None | |
| return self.s0.edges[precedence] | |
| # Set the start state for a specific precedence value. | |
| # | |
| # @param precedence The current precedence. | |
| # @param startState The start state corresponding to the specified | |
| # precedence. | |
| # | |
| # @throws IllegalStateException if this is not a precedence DFA. | |
| # @see #isPrecedenceDfa() | |
| # | |
| def setPrecedenceStartState(self, precedence:int, startState:DFAState): | |
| if not self.precedenceDfa: | |
| raise IllegalStateException("Only precedence DFAs may contain a precedence start state.") | |
| if precedence < 0: | |
| return | |
| # synchronization on s0 here is ok. when the DFA is turned into a | |
| # precedence DFA, s0 will be initialized once and not updated again | |
| # s0.edges is never null for a precedence DFA | |
| if precedence >= len(self.s0.edges): | |
| ext = [None] * (precedence + 1 - len(self.s0.edges)) | |
| self.s0.edges.extend(ext) | |
| self.s0.edges[precedence] = startState | |
| # | |
| # Sets whether this is a precedence DFA. If the specified value differs | |
| # from the current DFA configuration, the following actions are taken; | |
| # otherwise no changes are made to the current DFA. | |
| # | |
| # <ul> | |
| # <li>The {@link #states} map is cleared</li> | |
| # <li>If {@code precedenceDfa} is {@code false}, the initial state | |
| # {@link #s0} is set to {@code null}; otherwise, it is initialized to a new | |
| # {@link DFAState} with an empty outgoing {@link DFAState#edges} array to | |
| # store the start states for individual precedence values.</li> | |
| # <li>The {@link #precedenceDfa} field is updated</li> | |
| # </ul> | |
| # | |
| # @param precedenceDfa {@code true} if this is a precedence DFA; otherwise, | |
| # {@code false} | |
| def setPrecedenceDfa(self, precedenceDfa:bool): | |
| if self.precedenceDfa != precedenceDfa: | |
| self._states = dict() | |
| if precedenceDfa: | |
| precedenceState = DFAState(configs=ATNConfigSet()) | |
| precedenceState.edges = [] | |
| precedenceState.isAcceptState = False | |
| precedenceState.requiresFullContext = False | |
| self.s0 = precedenceState | |
| else: | |
| self.s0 = None | |
| self.precedenceDfa = precedenceDfa | |
| def states(self): | |
| return self._states | |
| # Return a list of all states in this DFA, ordered by state number. | |
| def sortedStates(self): | |
| return sorted(self._states.keys(), key=lambda state: state.stateNumber) | |
| def __str__(self): | |
| return self.toString(None) | |
| def toString(self, literalNames:list=None, symbolicNames:list=None): | |
| if self.s0 is None: | |
| return "" | |
| from antlr4.dfa.DFASerializer import DFASerializer | |
| serializer = DFASerializer(self,literalNames,symbolicNames) | |
| return str(serializer) | |
| def toLexerString(self): | |
| if self.s0 is None: | |
| return "" | |
| from antlr4.dfa.DFASerializer import LexerDFASerializer | |
| serializer = LexerDFASerializer(self) | |
| return str(serializer) | |