255 lines
7.1 KiB
Python
255 lines
7.1 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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#
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# The following images show the relation of states and
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# {@link ATNState#transitions} for various grammar constructs.
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#
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# <ul>
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#
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# <li>Solid edges marked with an ε indicate a required
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# {@link EpsilonTransition}.</li>
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#
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# <li>Dashed edges indicate locations where any transition derived from
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# {@link Transition} might appear.</li>
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#
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# <li>Dashed nodes are place holders for either a sequence of linked
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# {@link BasicState} states or the inclusion of a block representing a nested
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# construct in one of the forms below.</li>
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#
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# <li>Nodes showing multiple outgoing alternatives with a {@code ...} support
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# any number of alternatives (one or more). Nodes without the {@code ...} only
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# support the exact number of alternatives shown in the diagram.</li>
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#
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# </ul>
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#
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# <h2>Basic Blocks</h2>
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#
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# <h3>Rule</h3>
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#
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# <embed src="images/Rule.svg" type="image/svg+xml"/>
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#
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# <h3>Block of 1 or more alternatives</h3>
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#
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# <embed src="images/Block.svg" type="image/svg+xml"/>
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#
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# <h2>Greedy Loops</h2>
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#
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# <h3>Greedy Closure: {@code (...)*}</h3>
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#
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# <embed src="images/ClosureGreedy.svg" type="image/svg+xml"/>
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#
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# <h3>Greedy Positive Closure: {@code (...)+}</h3>
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#
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# <embed src="images/PositiveClosureGreedy.svg" type="image/svg+xml"/>
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#
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# <h3>Greedy Optional: {@code (...)?}</h3>
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#
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# <embed src="images/OptionalGreedy.svg" type="image/svg+xml"/>
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#
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# <h2>Non-Greedy Loops</h2>
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#
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# <h3>Non-Greedy Closure: {@code (...)*?}</h3>
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#
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# <embed src="images/ClosureNonGreedy.svg" type="image/svg+xml"/>
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#
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# <h3>Non-Greedy Positive Closure: {@code (...)+?}</h3>
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#
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# <embed src="images/PositiveClosureNonGreedy.svg" type="image/svg+xml"/>
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#
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# <h3>Non-Greedy Optional: {@code (...)??}</h3>
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#
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# <embed src="images/OptionalNonGreedy.svg" type="image/svg+xml"/>
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#
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from antlr4.atn.Transition import Transition
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INITIAL_NUM_TRANSITIONS = 4
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class ATNState(object):
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# constants for serialization
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INVALID_TYPE = 0
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BASIC = 1
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RULE_START = 2
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BLOCK_START = 3
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PLUS_BLOCK_START = 4
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STAR_BLOCK_START = 5
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TOKEN_START = 6
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RULE_STOP = 7
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BLOCK_END = 8
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STAR_LOOP_BACK = 9
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STAR_LOOP_ENTRY = 10
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PLUS_LOOP_BACK = 11
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LOOP_END = 12
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serializationNames = [
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"INVALID",
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"BASIC",
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"RULE_START",
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"BLOCK_START",
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"PLUS_BLOCK_START",
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"STAR_BLOCK_START",
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"TOKEN_START",
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"RULE_STOP",
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"BLOCK_END",
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"STAR_LOOP_BACK",
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"STAR_LOOP_ENTRY",
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"PLUS_LOOP_BACK",
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"LOOP_END" ]
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INVALID_STATE_NUMBER = -1
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def __init__(self):
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# Which ATN are we in?
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self.atn = None
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self.stateNumber = ATNState.INVALID_STATE_NUMBER
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self.stateType = None
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self.ruleIndex = 0 # at runtime, we don't have Rule objects
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self.epsilonOnlyTransitions = False
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# Track the transitions emanating from this ATN state.
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self.transitions = []
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# Used to cache lookahead during parsing, not used during construction
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self.nextTokenWithinRule = None
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def __hash__(self):
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return self.stateNumber
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def __eq__(self, other):
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return isinstance(other, ATNState) and self.stateNumber==other.stateNumber
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def onlyHasEpsilonTransitions(self):
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return self.epsilonOnlyTransitions
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def isNonGreedyExitState(self):
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return False
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def __str__(self):
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return str(self.stateNumber)
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def addTransition(self, trans:Transition, index:int=-1):
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if len(self.transitions)==0:
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self.epsilonOnlyTransitions = trans.isEpsilon
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elif self.epsilonOnlyTransitions != trans.isEpsilon:
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self.epsilonOnlyTransitions = False
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# TODO System.err.format(Locale.getDefault(), "ATN state %d has both epsilon and non-epsilon transitions.\n", stateNumber);
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if index==-1:
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self.transitions.append(trans)
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else:
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self.transitions.insert(index, trans)
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class BasicState(ATNState):
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def __init__(self):
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super().__init__()
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self.stateType = self.BASIC
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class DecisionState(ATNState):
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def __init__(self):
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super().__init__()
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self.decision = -1
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self.nonGreedy = False
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# The start of a regular {@code (...)} block.
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class BlockStartState(DecisionState):
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def __init__(self):
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super().__init__()
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self.endState = None
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class BasicBlockStartState(BlockStartState):
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def __init__(self):
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super().__init__()
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self.stateType = self.BLOCK_START
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# Terminal node of a simple {@code (a|b|c)} block.
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class BlockEndState(ATNState):
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def __init__(self):
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super().__init__()
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self.stateType = self.BLOCK_END
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self.startState = None
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# The last node in the ATN for a rule, unless that rule is the start symbol.
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# In that case, there is one transition to EOF. Later, we might encode
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# references to all calls to this rule to compute FOLLOW sets for
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# error handling.
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#
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class RuleStopState(ATNState):
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def __init__(self):
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super().__init__()
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self.stateType = self.RULE_STOP
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class RuleStartState(ATNState):
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def __init__(self):
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super().__init__()
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self.stateType = self.RULE_START
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self.stopState = None
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self.isPrecedenceRule = False
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# Decision state for {@code A+} and {@code (A|B)+}. It has two transitions:
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# one to the loop back to start of the block and one to exit.
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#
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class PlusLoopbackState(DecisionState):
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def __init__(self):
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super().__init__()
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self.stateType = self.PLUS_LOOP_BACK
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# Start of {@code (A|B|...)+} loop. Technically a decision state, but
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# we don't use for code generation; somebody might need it, so I'm defining
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# it for completeness. In reality, the {@link PlusLoopbackState} node is the
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# real decision-making note for {@code A+}.
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#
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class PlusBlockStartState(BlockStartState):
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def __init__(self):
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super().__init__()
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self.stateType = self.PLUS_BLOCK_START
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self.loopBackState = None
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# The block that begins a closure loop.
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class StarBlockStartState(BlockStartState):
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def __init__(self):
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super().__init__()
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self.stateType = self.STAR_BLOCK_START
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class StarLoopbackState(ATNState):
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def __init__(self):
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super().__init__()
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self.stateType = self.STAR_LOOP_BACK
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class StarLoopEntryState(DecisionState):
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def __init__(self):
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super().__init__()
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self.stateType = self.STAR_LOOP_ENTRY
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self.loopBackState = None
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# Indicates whether this state can benefit from a precedence DFA during SLL decision making.
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self.isPrecedenceDecision = None
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# Mark the end of a * or + loop.
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class LoopEndState(ATNState):
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def __init__(self):
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super().__init__()
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self.stateType = self.LOOP_END
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self.loopBackState = None
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# The Tokens rule start state linking to each lexer rule start state */
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class TokensStartState(DecisionState):
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def __init__(self):
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super().__init__()
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self.stateType = self.TOKEN_START
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