Lib/site-packages/antlr4/atn/Transition.py

#
# 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.
#

#  An ATN transition between any two ATN states.  Subclasses define
#  atom, set, epsilon, action, predicate, rule transitions.
#
#  <p>This is a one way link.  It emanates from a state (usually via a list of
#  transitions) and has a target state.</p>
#
#  <p>Since we never have to change the ATN transitions once we construct it,
#  we can fix these transitions as specific classes. The DFA transitions
#  on the other hand need to update the labels as it adds transitions to
#  the states. We'll use the term Edge for the DFA to distinguish them from
#  ATN transitions.</p>
#
from antlr4.IntervalSet import IntervalSet
from antlr4.Token import Token

# need forward declarations
from antlr4.atn.SemanticContext import Predicate, PrecedencePredicate

ATNState = None
RuleStartState = None

class Transition (object):
    __slots__ = ('target','isEpsilon','label')

    # constants for serialization
    EPSILON			= 1
    RANGE			= 2
    RULE			= 3
    PREDICATE		= 4 # e.g., {isType(input.LT(1))}?
    ATOM			= 5
    ACTION			= 6
    SET				= 7 # ~(A|B) or ~atom, wildcard, which convert to next 2
    NOT_SET			= 8
    WILDCARD		= 9
    PRECEDENCE		= 10

    serializationNames = [
            "INVALID",
            "EPSILON",
            "RANGE",
            "RULE",
            "PREDICATE",
            "ATOM",
            "ACTION",
            "SET",
            "NOT_SET",
            "WILDCARD",
            "PRECEDENCE"
        ]

    serializationTypes = dict()

    def __init__(self, target:ATNState):
        # The target of this transition.
        if target is None:
            raise Exception("target cannot be null.")
        self.target = target
        # Are we epsilon, action, sempred?
        self.isEpsilon = False
        self.label = None


# TODO: make all transitions sets? no, should remove set edges
class AtomTransition(Transition):
    __slots__ = ('label_', 'serializationType')

    def __init__(self, target:ATNState, label:int):
        super().__init__(target)
        self.label_ = label # The token type or character value; or, signifies special label.
        self.label = self.makeLabel()
        self.serializationType = self.ATOM

    def makeLabel(self):
        s = IntervalSet()
        s.addOne(self.label_)
        return s

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return self.label_ == symbol

    def __str__(self):
        return str(self.label_)

class RuleTransition(Transition):
    __slots__ = ('ruleIndex', 'precedence', 'followState', 'serializationType')

    def __init__(self, ruleStart:RuleStartState, ruleIndex:int, precedence:int, followState:ATNState):
        super().__init__(ruleStart)
        self.ruleIndex = ruleIndex # ptr to the rule definition object for this rule ref
        self.precedence = precedence
        self.followState = followState # what node to begin computations following ref to rule
        self.serializationType = self.RULE
        self.isEpsilon = True

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return False


class EpsilonTransition(Transition):
    __slots__ = ('serializationType', 'outermostPrecedenceReturn')

    def __init__(self, target, outermostPrecedenceReturn=-1):
        super(EpsilonTransition, self).__init__(target)
        self.serializationType = self.EPSILON
        self.isEpsilon = True
        self.outermostPrecedenceReturn = outermostPrecedenceReturn

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return False

    def __str__(self):
        return "epsilon"

class RangeTransition(Transition):
    __slots__ = ('serializationType', 'start', 'stop')

    def __init__(self, target:ATNState, start:int, stop:int):
        super().__init__(target)
        self.serializationType = self.RANGE
        self.start = start
        self.stop = stop
        self.label = self.makeLabel()

    def makeLabel(self):
        s = IntervalSet()
        s.addRange(range(self.start, self.stop + 1))
        return s

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return symbol >= self.start and symbol <= self.stop

    def __str__(self):
        return "'" + chr(self.start) + "'..'" + chr(self.stop) + "'"

class AbstractPredicateTransition(Transition):

    def __init__(self, target:ATNState):
        super().__init__(target)


class PredicateTransition(AbstractPredicateTransition):
    __slots__ = ('serializationType', 'ruleIndex', 'predIndex', 'isCtxDependent')

    def __init__(self, target:ATNState, ruleIndex:int, predIndex:int, isCtxDependent:bool):
        super().__init__(target)
        self.serializationType = self.PREDICATE
        self.ruleIndex = ruleIndex
        self.predIndex = predIndex
        self.isCtxDependent = isCtxDependent # e.g., $i ref in pred
        self.isEpsilon = True

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return False

    def getPredicate(self):
        return Predicate(self.ruleIndex, self.predIndex, self.isCtxDependent)

    def __str__(self):
        return "pred_" + str(self.ruleIndex) + ":" + str(self.predIndex)

class ActionTransition(Transition):
    __slots__ = ('serializationType', 'ruleIndex', 'actionIndex', 'isCtxDependent')

    def __init__(self, target:ATNState, ruleIndex:int, actionIndex:int=-1, isCtxDependent:bool=False):
        super().__init__(target)
        self.serializationType = self.ACTION
        self.ruleIndex = ruleIndex
        self.actionIndex = actionIndex
        self.isCtxDependent = isCtxDependent # e.g., $i ref in pred
        self.isEpsilon = True

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return False

    def __str__(self):
        return "action_"+self.ruleIndex+":"+self.actionIndex

# A transition containing a set of values.
class SetTransition(Transition):
    __slots__ = 'serializationType'

    def __init__(self, target:ATNState, set:IntervalSet):
        super().__init__(target)
        self.serializationType = self.SET
        if set is not None:
            self.label = set
        else:
            self.label = IntervalSet()
            self.label.addRange(range(Token.INVALID_TYPE, Token.INVALID_TYPE + 1))

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return symbol in self.label

    def __str__(self):
        return str(self.label)

class NotSetTransition(SetTransition):

    def __init__(self, target:ATNState, set:IntervalSet):
        super().__init__(target, set)
        self.serializationType = self.NOT_SET

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return symbol >= minVocabSymbol \
            and symbol <= maxVocabSymbol \
            and not super(type(self), self).matches(symbol, minVocabSymbol, maxVocabSymbol)

    def __str__(self):
        return '~' + super(type(self), self).__str__()


class WildcardTransition(Transition):
    __slots__ = 'serializationType'

    def __init__(self, target:ATNState):
        super().__init__(target)
        self.serializationType = self.WILDCARD

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return symbol >= minVocabSymbol and symbol <= maxVocabSymbol

    def __str__(self):
        return "."


class PrecedencePredicateTransition(AbstractPredicateTransition):
    __slots__ = ('serializationType', 'precedence')

    def __init__(self, target:ATNState, precedence:int):
        super().__init__(target)
        self.serializationType = self.PRECEDENCE
        self.precedence = precedence
        self.isEpsilon = True

    def matches( self, symbol:int, minVocabSymbol:int,  maxVocabSymbol:int):
        return False


    def getPredicate(self):
        return PrecedencePredicate(self.precedence)

    def __str__(self):
        return self.precedence + " >= _p"


Transition.serializationTypes = {
             EpsilonTransition: Transition.EPSILON,
             RangeTransition: Transition.RANGE,
             RuleTransition: Transition.RULE,
             PredicateTransition: Transition.PREDICATE,
             AtomTransition: Transition.ATOM,
             ActionTransition: Transition.ACTION,
             SetTransition: Transition.SET,
             NotSetTransition: Transition.NOT_SET,
             WildcardTransition: Transition.WILDCARD,
             PrecedencePredicateTransition: Transition.PRECEDENCE
         }

del ATNState
del RuleStartState

from antlr4.atn.ATNState import *