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