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A collection of tests for ANTLR 4 Runtime libraries.
#
# [The "BSD license"]
# Copyright (c) 2012 Terence Parr
# Copyright (c) 2012 Sam Harwell
# Copyright (c) 2014 Eric Vergnaud
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#/
# When we hit an accept state in either the DFA or the ATN, we
# have to notify the character stream to start buffering characters
# via {@link IntStream#mark} and record the current state. The current sim state
# includes the current index into the input, the current line,
# and current character position in that line. Note that the Lexer is
# tracking the starting line and characterization of the token. These
# variables track the "state" of the simulator when it hits an accept state.
#
# We track these variables separately for the DFA and ATN simulation
# because the DFA simulation often has to fail over to the ATN
# simulation. If the ATN simulation fails, we need the DFA to fall
# back to its previously accepted state, if any. If the ATN succeeds,
# then the ATN does the accept and the DFA simulator that invoked it
# can simply return the predicted token type.
#/
from antlr4 import Lexer
from antlr4.PredictionContext import SingletonPredictionContext, PredictionContext
from antlr4.Token import Token
from antlr4.atn.ATN import ATN
from antlr4.atn.ATNConfig import LexerATNConfig
from antlr4.atn.ATNSimulator import ATNSimulator
from antlr4.atn.ATNConfigSet import ATNConfigSet, OrderedATNConfigSet
from antlr4.atn.ATNState import RuleStopState, ATNState
from antlr4.atn.LexerActionExecutor import LexerActionExecutor
from antlr4.atn.Transition import Transition
from antlr4.dfa.DFAState import DFAState
from antlr4.error.Errors import LexerNoViableAltException, UnsupportedOperationException
class SimState(object):
def __init__(self):
self.reset()
def reset(self):
self.index = -1
self.line = 0
self.column = -1
self.dfaState = None
class LexerATNSimulator(ATNSimulator):
debug = False
dfa_debug = False
MIN_DFA_EDGE = 0
MAX_DFA_EDGE = 127 # forces unicode to stay in ATN
ERROR = None
match_calls = 0
def __init__(self, recog, atn, decisionToDFA, sharedContextCache):
super(LexerATNSimulator, self).__init__(atn, sharedContextCache)
self.decisionToDFA = decisionToDFA
self.recog = recog
# The current token's starting index into the character stream.
# Shared across DFA to ATN simulation in case the ATN fails and the
# DFA did not have a previous accept state. In this case, we use the
# ATN-generated exception object.
self.startIndex = -1
# line number 1..n within the input#/
self.line = 1
# The index of the character relative to the beginning of the line 0..n-1#/
self.column = 0
from antlr4.Lexer import Lexer
self.mode = Lexer.DEFAULT_MODE
# Used during DFA/ATN exec to record the most recent accept configuration info
self.prevAccept = SimState()
def copyState(self, simulator ):
self.column = simulator.column
self.line = simulator.line
self.mode = simulator.mode
self.startIndex = simulator.startIndex
def match(self, input , mode):
self.match_calls += 1
self.mode = mode
mark = input.mark()
try:
self.startIndex = input.index
self.prevAccept.reset()
dfa = self.decisionToDFA[mode]
if dfa.s0 is None:
return self.matchATN(input)
else:
return self.execATN(input, dfa.s0)
finally:
input.release(mark)
def reset(self):
self.prevAccept.reset()
self.startIndex = -1
self.line = 1
self.column = 0
self.mode = Lexer.DEFAULT_MODE
def matchATN(self, input):
startState = self.atn.modeToStartState[self.mode]
if self.debug:
print("matchATN mode " + str(self.mode) + " start: " + str(startState))
old_mode = self.mode
s0_closure = self.computeStartState(input, startState)
suppressEdge = s0_closure.hasSemanticContext
s0_closure.hasSemanticContext = False
next = self.addDFAState(s0_closure)
if not suppressEdge:
self.decisionToDFA[self.mode].s0 = next
predict = self.execATN(input, next)
if self.debug:
print("DFA after matchATN: " + str(self.decisionToDFA[old_mode].toLexerString()))
return predict
def execATN(self, input, ds0):
if self.debug:
print("start state closure=" + str(ds0.configs))
if ds0.isAcceptState:
# allow zero-length tokens
self.captureSimState(self.prevAccept, input, ds0)
t = input.LA(1)
s = ds0 # s is current/from DFA state
while True: # while more work
if self.debug:
print("execATN loop starting closure: %s\n", s.configs)
# As we move src->trg, src->trg, we keep track of the previous trg to
# avoid looking up the DFA state again, which is expensive.
# If the previous target was already part of the DFA, we might
# be able to avoid doing a reach operation upon t. If s!=null,
# it means that semantic predicates didn't prevent us from
# creating a DFA state. Once we know s!=null, we check to see if
# the DFA state has an edge already for t. If so, we can just reuse
# it's configuration set; there's no point in re-computing it.
# This is kind of like doing DFA simulation within the ATN
# simulation because DFA simulation is really just a way to avoid
# computing reach/closure sets. Technically, once we know that
# we have a previously added DFA state, we could jump over to
# the DFA simulator. But, that would mean popping back and forth
# a lot and making things more complicated algorithmically.
# This optimization makes a lot of sense for loops within DFA.
# A character will take us back to an existing DFA state
# that already has lots of edges out of it. e.g., .* in comments.
# print("Target for:" + str(s) + " and:" + str(t))
target = self.getExistingTargetState(s, t)
# print("Existing:" + str(target))
if target is None:
target = self.computeTargetState(input, s, t)
# print("Computed:" + str(target))
if target == self.ERROR:
break
# If this is a consumable input element, make sure to consume before
# capturing the accept state so the input index, line, and char
# position accurately reflect the state of the interpreter at the
# end of the token.
if t != Token.EOF:
self.consume(input)
if target.isAcceptState:
self.captureSimState(self.prevAccept, input, target)
if t == Token.EOF:
break
t = input.LA(1)
s = target # flip; current DFA target becomes new src/from state
return self.failOrAccept(self.prevAccept, input, s.configs, t)
# Get an existing target state for an edge in the DFA. If the target state
# for the edge has not yet been computed or is otherwise not available,
# this method returns {@code null}.
#
# @param s The current DFA state
# @param t The next input symbol
# @return The existing target DFA state for the given input symbol
# {@code t}, or {@code null} if the target state for this edge is not
# already cached
def getExistingTargetState(self, s, t):
if s.edges is None or t < self.MIN_DFA_EDGE or t > self.MAX_DFA_EDGE:
return None
target = s.edges[t - self.MIN_DFA_EDGE]
if self.debug and target is not None:
print("reuse state "+s.stateNumber+ " edge to "+target.stateNumber)
return target
# Compute a target state for an edge in the DFA, and attempt to add the
# computed state and corresponding edge to the DFA.
#
# @param input The input stream
# @param s The current DFA state
# @param t The next input symbol
#
# @return The computed target DFA state for the given input symbol
# {@code t}. If {@code t} does not lead to a valid DFA state, this method
# returns {@link #ERROR}.
def computeTargetState(self, input, s, t):
reach = OrderedATNConfigSet()
# if we don't find an existing DFA state
# Fill reach starting from closure, following t transitions
self.getReachableConfigSet(input, s.configs, reach, t)
if len(reach)==0: # we got nowhere on t from s
if not reach.hasSemanticContext:
# we got nowhere on t, don't throw out this knowledge; it'd
# cause a failover from DFA later.
self. addDFAEdge(s, t, self.ERROR)
# stop when we can't match any more char
return self.ERROR
# Add an edge from s to target DFA found/created for reach
return self.addDFAEdge(s, t, cfgs=reach)
def failOrAccept(self, prevAccept , input, reach, t):
if self.prevAccept.dfaState is not None:
lexerActionExecutor = prevAccept.dfaState.lexerActionExecutor
self.accept(input, lexerActionExecutor, self.startIndex, prevAccept.index, prevAccept.line, prevAccept.column)
return prevAccept.dfaState.prediction
else:
# if no accept and EOF is first char, return EOF
if t==Token.EOF and input.index==self.startIndex:
return Token.EOF
raise LexerNoViableAltException(self.recog, input, self.startIndex, reach)
# Given a starting configuration set, figure out all ATN configurations
# we can reach upon input {@code t}. Parameter {@code reach} is a return
# parameter.
def getReachableConfigSet(self, input, closure, reach, t):
# this is used to skip processing for configs which have a lower priority
# than a config that already reached an accept state for the same rule
skipAlt = ATN.INVALID_ALT_NUMBER
for cfg in closure:
currentAltReachedAcceptState = ( cfg.alt == skipAlt )
if currentAltReachedAcceptState and cfg.passedThroughNonGreedyDecision:
continue
if self.debug:
print("testing %s at %s\n", self.getTokenName(t), cfg.toString(self.recog, True))
for trans in cfg.state.transitions: # for each transition
target = self.getReachableTarget(trans, t)
if target is not None:
lexerActionExecutor = cfg.lexerActionExecutor
if lexerActionExecutor is not None:
lexerActionExecutor = lexerActionExecutor.fixOffsetBeforeMatch(input.index - self.startIndex)
treatEofAsEpsilon = (t == Token.EOF)
config = LexerATNConfig(state=target, lexerActionExecutor=lexerActionExecutor, config=cfg)
if self.closure(input, config, reach, currentAltReachedAcceptState, True, treatEofAsEpsilon):
# any remaining configs for this alt have a lower priority than
# the one that just reached an accept state.
skipAlt = cfg.alt
def accept(self, input, lexerActionExecutor, startIndex, index, line, charPos):
if self.debug:
print("ACTION %s\n", lexerActionExecutor)
# seek to after last char in token
input.seek(index)
self.line = line
self.column = charPos
if lexerActionExecutor is not None and self.recog is not None:
lexerActionExecutor.execute(self.recog, input, startIndex)
def getReachableTarget(self, trans, t):
if trans.matches(t, 0, 0xFFFE):
return trans.target
else:
return None
def computeStartState(self, input, p):
initialContext = PredictionContext.EMPTY
configs = OrderedATNConfigSet()
for i in range(0,len(p.transitions)):
target = p.transitions[i].target
c = LexerATNConfig(state=target, alt=i+1, context=initialContext)
self.closure(input, c, configs, False, False, False)
return configs
# Since the alternatives within any lexer decision are ordered by
# preference, this method stops pursuing the closure as soon as an accept
# state is reached. After the first accept state is reached by depth-first
# search from {@code config}, all other (potentially reachable) states for
# this rule would have a lower priority.
#
# @return {@code true} if an accept state is reached, otherwise
# {@code false}.
def closure(self, input, config, configs, currentAltReachedAcceptState,
speculative, treatEofAsEpsilon):
if self.debug:
print("closure("+config.toString(self.recog, True)+")")
if isinstance( config.state, RuleStopState ):
if self.debug:
if self.recog is not None:
print("closure at %s rule stop %s\n", self.recog.getRuleNames()[config.state.ruleIndex], config)
else:
print("closure at rule stop %s\n", config)
if config.context is None or config.context.hasEmptyPath():
if config.context is None or config.context.isEmpty():
configs.add(config)
return True
else:
configs.add(LexerATNConfig(state=config.state, config=config, context=PredictionContext.EMPTY))
currentAltReachedAcceptState = True
if config.context is not None and not config.context.isEmpty():
for i in range(0,len(config.context)):
if config.context.getReturnState(i) != PredictionContext.EMPTY_RETURN_STATE:
newContext = config.context.getParent(i) # "pop" return state
returnState = self.atn.states[config.context.getReturnState(i)]
c = LexerATNConfig(state=returnState, config=config, context=newContext)
currentAltReachedAcceptState = self.closure(input, c, configs,
currentAltReachedAcceptState, speculative, treatEofAsEpsilon)
return currentAltReachedAcceptState
# optimization
if not config.state.epsilonOnlyTransitions:
if not currentAltReachedAcceptState or not config.passedThroughNonGreedyDecision:
configs.add(config)
for t in config.state.transitions:
c = self.getEpsilonTarget(input, config, t, configs, speculative, treatEofAsEpsilon)
if c is not None:
currentAltReachedAcceptState = self.closure(input, c, configs, currentAltReachedAcceptState, speculative, treatEofAsEpsilon)
return currentAltReachedAcceptState
# side-effect: can alter configs.hasSemanticContext
def getEpsilonTarget(self, input, config, t, configs, speculative, treatEofAsEpsilon):
c = None
if t.serializationType==Transition.RULE:
newContext = SingletonPredictionContext.create(config.context, t.followState.stateNumber)
c = LexerATNConfig(state=t.target, config=config, context=newContext)
elif t.serializationType==Transition.PRECEDENCE:
raise UnsupportedOperationException("Precedence predicates are not supported in lexers.")
elif t.serializationType==Transition.PREDICATE:
# Track traversing semantic predicates. If we traverse,
# we cannot add a DFA state for this "reach" computation
# because the DFA would not test the predicate again in the
# future. Rather than creating collections of semantic predicates
# like v3 and testing them on prediction, v4 will test them on the
# fly all the time using the ATN not the DFA. This is slower but
# semantically it's not used that often. One of the key elements to
# this predicate mechanism is not adding DFA states that see
# predicates immediately afterwards in the ATN. For example,
# a : ID {p1}? | ID {p2}? ;
# should create the start state for rule 'a' (to save start state
# competition), but should not create target of ID state. The
# collection of ATN states the following ID references includes
# states reached by traversing predicates. Since this is when we
# test them, we cannot cash the DFA state target of ID.
if self.debug:
print("EVAL rule "+ str(t.ruleIndex) + ":" + str(t.predIndex))
configs.hasSemanticContext = True
if self.evaluatePredicate(input, t.ruleIndex, t.predIndex, speculative):
c = LexerATNConfig(state=t.target, config=config)
elif t.serializationType==Transition.ACTION:
if config.context is None or config.context.hasEmptyPath():
# execute actions anywhere in the start rule for a token.
#
# TODO: if the entry rule is invoked recursively, some
# actions may be executed during the recursive call. The
# problem can appear when hasEmptyPath() is true but
# isEmpty() is false. In this case, the config needs to be
# split into two contexts - one with just the empty path
# and another with everything but the empty path.
# Unfortunately, the current algorithm does not allow
# getEpsilonTarget to return two configurations, so
# additional modifications are needed before we can support
# the split operation.
lexerActionExecutor = LexerActionExecutor.append(config.lexerActionExecutor,
self.atn.lexerActions[t.actionIndex])
c = LexerATNConfig(state=t.target, config=config, lexerActionExecutor=lexerActionExecutor)
else:
# ignore actions in referenced rules
c = LexerATNConfig(state=t.target, config=config)
elif t.serializationType==Transition.EPSILON:
c = LexerATNConfig(state=t.target, config=config)
elif t.serializationType in [ Transition.ATOM, Transition.RANGE, Transition.SET ]:
if treatEofAsEpsilon:
if t.matches(Token.EOF, 0, 0xFFFF):
c = LexerATNConfig(state=t.target, config=config)
return c
# Evaluate a predicate specified in the lexer.
#
# If {@code speculative} is {@code true}, this method was called before
# {@link #consume} for the matched character. This method should call
# {@link #consume} before evaluating the predicate to ensure position
# sensitive values, including {@link Lexer#getText}, {@link Lexer#getLine},
# and {@link Lexer#getcolumn}, properly reflect the current
# lexer state. This method should restore {@code input} and the simulator
# to the original state before returning (i.e. undo the actions made by the
# call to {@link #consume}.
#
# @param input The input stream.
# @param ruleIndex The rule containing the predicate.
# @param predIndex The index of the predicate within the rule.
# @param speculative {@code true} if the current index in {@code input} is
# one character before the predicate's location.
#
# @return {@code true} if the specified predicate evaluates to
# {@code true}.
#/
def evaluatePredicate(self, input, ruleIndex, predIndex, speculative):
# assume true if no recognizer was provided
if self.recog is None:
return True
if not speculative:
return self.recog.sempred(None, ruleIndex, predIndex)
savedcolumn = self.column
savedLine = self.line
index = input.index
marker = input.mark()
try:
self.consume(input)
return self.recog.sempred(None, ruleIndex, predIndex)
finally:
self.column = savedcolumn
self.line = savedLine
input.seek(index)
input.release(marker)
def captureSimState(self, settings, input, dfaState):
settings.index = input.index
settings.line = self.line
settings.column = self.column
settings.dfaState = dfaState
def addDFAEdge(self, from_, tk, to=None, cfgs=None):
if to is None and cfgs is not None:
# leading to this call, ATNConfigSet.hasSemanticContext is used as a
# marker indicating dynamic predicate evaluation makes this edge
# dependent on the specific input sequence, so the static edge in the
# DFA should be omitted. The target DFAState is still created since
# execATN has the ability to resynchronize with the DFA state cache
# following the predicate evaluation step.
#
# TJP notes: next time through the DFA, we see a pred again and eval.
# If that gets us to a previously created (but dangling) DFA
# state, we can continue in pure DFA mode from there.
#/
suppressEdge = cfgs.hasSemanticContext
cfgs.hasSemanticContext = False
to = self.addDFAState(cfgs)
if suppressEdge:
return to
# add the edge
if tk < self.MIN_DFA_EDGE or tk > self.MAX_DFA_EDGE:
# Only track edges within the DFA bounds
return to
if self.debug:
print("EDGE " + str(from_) + " -> " + str(to) + " upon "+ chr(tk))
if from_.edges is None:
# make room for tokens 1..n and -1 masquerading as index 0
from_.edges = [ None ] * (self.MAX_DFA_EDGE - self.MIN_DFA_EDGE + 1)
from_.edges[tk - self.MIN_DFA_EDGE] = to # connect
return to
# Add a new DFA state if there isn't one with this set of
# configurations already. This method also detects the first
# configuration containing an ATN rule stop state. Later, when
# traversing the DFA, we will know which rule to accept.
def addDFAState(self, configs):
proposed = DFAState(configs=configs)
firstConfigWithRuleStopState = None
for c in configs:
if isinstance(c.state, RuleStopState):
firstConfigWithRuleStopState = c
break
if firstConfigWithRuleStopState is not None:
proposed.isAcceptState = True
proposed.lexerActionExecutor = firstConfigWithRuleStopState.lexerActionExecutor
proposed.prediction = self.atn.ruleToTokenType[firstConfigWithRuleStopState.state.ruleIndex]
dfa = self.decisionToDFA[self.mode]
existing = dfa.states.get(proposed, None)
if existing is not None:
return existing
newState = proposed
newState.stateNumber = len(dfa.states)
configs.setReadonly(True)
newState.configs = configs
dfa.states[newState] = newState
return newState
def getDFA(self, mode):
return self.decisionToDFA[mode]
# Get the text matched so far for the current token.
def getText(self, input):
# index is first lookahead char, don't include.
return input.getText(self.startIndex, input.index-1)
def consume(self, input):
curChar = input.LA(1)
if curChar==ord('\n'):
self.line += 1
self.column = 0
else:
self.column += 1
input.consume()
def getTokenName(self, t):
if t==-1:
return "EOF"
else:
return "'" + chr(t) + "'"
LexerATNSimulator.ERROR = DFAState(0x7FFFFFFF, ATNConfigSet())
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