JavaScript.src.antlr4.atn.ParserATNSimulator.js Maven / Gradle / Ivy
Show all versions of antlr4-runtime-testsuite Show documentation
//
// [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.
//
//
// The embodiment of the adaptive LL(*), ALL(*), parsing strategy.
//
//
// The basic complexity of the adaptive strategy makes it harder to understand.
// We begin with ATN simulation to build paths in a DFA. Subsequent prediction
// requests go through the DFA first. If they reach a state without an edge for
// the current symbol, the algorithm fails over to the ATN simulation to
// complete the DFA path for the current input (until it finds a conflict state
// or uniquely predicting state).
//
//
// All of that is done without using the outer context because we want to create
// a DFA that is not dependent upon the rule invocation stack when we do a
// prediction. One DFA works in all contexts. We avoid using context not
// necessarily because it's slower, although it can be, but because of the DFA
// caching problem. The closure routine only considers the rule invocation stack
// created during prediction beginning in the decision rule. For example, if
// prediction occurs without invoking another rule's ATN, there are no context
// stacks in the configurations. When lack of context leads to a conflict, we
// don't know if it's an ambiguity or a weakness in the strong LL(*) parsing
// strategy (versus full LL(*)).
//
//
// When SLL yields a configuration set with conflict, we rewind the input and
// retry the ATN simulation, this time using full outer context without adding
// to the DFA. Configuration context stacks will be the full invocation stacks
// from the start rule. If we get a conflict using full context, then we can
// definitively say we have a true ambiguity for that input sequence. If we
// don't get a conflict, it implies that the decision is sensitive to the outer
// context. (It is not context-sensitive in the sense of context-sensitive
// grammars.)
//
//
// The next time we reach this DFA state with an SLL conflict, through DFA
// simulation, we will again retry the ATN simulation using full context mode.
// This is slow because we can't save the results and have to "interpret" the
// ATN each time we get that input.
//
//
// CACHING FULL CONTEXT PREDICTIONS
//
//
// We could cache results from full context to predicted alternative easily and
// that saves a lot of time but doesn't work in presence of predicates. The set
// of visible predicates from the ATN start state changes depending on the
// context, because closure can fall off the end of a rule. I tried to cache
// tuples (stack context, semantic context, predicted alt) but it was slower
// than interpreting and much more complicated. Also required a huge amount of
// memory. The goal is not to create the world's fastest parser anyway. I'd like
// to keep this algorithm simple. By launching multiple threads, we can improve
// the speed of parsing across a large number of files.
//
//
// There is no strict ordering between the amount of input used by SLL vs LL,
// which makes it really hard to build a cache for full context. Let's say that
// we have input A B C that leads to an SLL conflict with full context X. That
// implies that using X we might only use A B but we could also use A B C D to
// resolve conflict. Input A B C D could predict alternative 1 in one position
// in the input and A B C E could predict alternative 2 in another position in
// input. The conflicting SLL configurations could still be non-unique in the
// full context prediction, which would lead us to requiring more input than the
// original A B C. To make a prediction cache work, we have to track the exact
// input used during the previous prediction. That amounts to a cache that maps
// X to a specific DFA for that context.
//
//
// Something should be done for left-recursive expression predictions. They are
// likely LL(1) + pred eval. Easier to do the whole SLL unless error and retry
// with full LL thing Sam does.
//
//
// AVOIDING FULL CONTEXT PREDICTION
//
//
// We avoid doing full context retry when the outer context is empty, we did not
// dip into the outer context by falling off the end of the decision state rule,
// or when we force SLL mode.
//
//
// As an example of the not dip into outer context case, consider as super
// constructor calls versus function calls. One grammar might look like
// this:
//
//
// ctorBody
// : '{' superCall? stat* '}'
// ;
//
//
//
// Or, you might see something like
//
//
// stat
// : superCall ';'
// | expression ';'
// | ...
// ;
//
//
//
// In both cases I believe that no closure operations will dip into the outer
// context. In the first case ctorBody in the worst case will stop at the '}'.
// In the 2nd case it should stop at the ';'. Both cases should stay within the
// entry rule and not dip into the outer context.
//
//
// PREDICATES
//
//
// Predicates are always evaluated if present in either SLL or LL both. SLL and
// LL simulation deals with predicates differently. SLL collects predicates as
// it performs closure operations like ANTLR v3 did. It delays predicate
// evaluation until it reaches and accept state. This allows us to cache the SLL
// ATN simulation whereas, if we had evaluated predicates on-the-fly during
// closure, the DFA state configuration sets would be different and we couldn't
// build up a suitable DFA.
//
//
// When building a DFA accept state during ATN simulation, we evaluate any
// predicates and return the sole semantically valid alternative. If there is
// more than 1 alternative, we report an ambiguity. If there are 0 alternatives,
// we throw an exception. Alternatives without predicates act like they have
// true predicates. The simple way to think about it is to strip away all
// alternatives with false predicates and choose the minimum alternative that
// remains.
//
//
// When we start in the DFA and reach an accept state that's predicated, we test
// those and return the minimum semantically viable alternative. If no
// alternatives are viable, we throw an exception.
//
//
// During full LL ATN simulation, closure always evaluates predicates and
// on-the-fly. This is crucial to reducing the configuration set size during
// closure. It hits a landmine when parsing with the Java grammar, for example,
// without this on-the-fly evaluation.
//
//
// SHARING DFA
//
//
// All instances of the same parser share the same decision DFAs through a
// static field. Each instance gets its own ATN simulator but they share the
// same {@link //decisionToDFA} field. They also share a
// {@link PredictionContextCache} object that makes sure that all
// {@link PredictionContext} objects are shared among the DFA states. This makes
// a big size difference.
//
//
// THREAD SAFETY
//
//
// The {@link ParserATNSimulator} locks on the {@link //decisionToDFA} field when
// it adds a new DFA object to that array. {@link //addDFAEdge}
// locks on the DFA for the current decision when setting the
// {@link DFAState//edges} field. {@link //addDFAState} locks on
// the DFA for the current decision when looking up a DFA state to see if it
// already exists. We must make sure that all requests to add DFA states that
// are equivalent result in the same shared DFA object. This is because lots of
// threads will be trying to update the DFA at once. The
// {@link //addDFAState} method also locks inside the DFA lock
// but this time on the shared context cache when it rebuilds the
// configurations' {@link PredictionContext} objects using cached
// subgraphs/nodes. No other locking occurs, even during DFA simulation. This is
// safe as long as we can guarantee that all threads referencing
// {@code s.edge[t]} get the same physical target {@link DFAState}, or
// {@code null}. Once into the DFA, the DFA simulation does not reference the
// {@link DFA//states} map. It follows the {@link DFAState//edges} field to new
// targets. The DFA simulator will either find {@link DFAState//edges} to be
// {@code null}, to be non-{@code null} and {@code dfa.edges[t]} null, or
// {@code dfa.edges[t]} to be non-null. The
// {@link //addDFAEdge} method could be racing to set the field
// but in either case the DFA simulator works; if {@code null}, and requests ATN
// simulation. It could also race trying to get {@code dfa.edges[t]}, but either
// way it will work because it's not doing a test and set operation.
//
//
// Starting with SLL then failing to combined SLL/LL (Two-Stage
// Parsing)
//
//
// Sam pointed out that if SLL does not give a syntax error, then there is no
// point in doing full LL, which is slower. We only have to try LL if we get a
// syntax error. For maximum speed, Sam starts the parser set to pure SLL
// mode with the {@link BailErrorStrategy}:
//
//
// parser.{@link Parser//getInterpreter() getInterpreter()}.{@link //setPredictionMode setPredictionMode}{@code (}{@link PredictionMode//SLL}{@code )};
// parser.{@link Parser//setErrorHandler setErrorHandler}(new {@link BailErrorStrategy}());
//
//
//
// If it does not get a syntax error, then we're done. If it does get a syntax
// error, we need to retry with the combined SLL/LL strategy.
//
//
// The reason this works is as follows. If there are no SLL conflicts, then the
// grammar is SLL (at least for that input set). If there is an SLL conflict,
// the full LL analysis must yield a set of viable alternatives which is a
// subset of the alternatives reported by SLL. If the LL set is a singleton,
// then the grammar is LL but not SLL. If the LL set is the same size as the SLL
// set, the decision is SLL. If the LL set has size > 1, then that decision
// is truly ambiguous on the current input. If the LL set is smaller, then the
// SLL conflict resolution might choose an alternative that the full LL would
// rule out as a possibility based upon better context information. If that's
// the case, then the SLL parse will definitely get an error because the full LL
// analysis says it's not viable. If SLL conflict resolution chooses an
// alternative within the LL set, them both SLL and LL would choose the same
// alternative because they both choose the minimum of multiple conflicting
// alternatives.
//
//
// Let's say we have a set of SLL conflicting alternatives {@code {1, 2, 3}} and
// a smaller LL set called s. If s is {@code {2, 3}}, then SLL
// parsing will get an error because SLL will pursue alternative 1. If
// s is {@code {1, 2}} or {@code {1, 3}} then both SLL and LL will
// choose the same alternative because alternative one is the minimum of either
// set. If s is {@code {2}} or {@code {3}} then SLL will get a syntax
// error. If s is {@code {1}} then SLL will succeed.
//
//
// Of course, if the input is invalid, then we will get an error for sure in
// both SLL and LL parsing. Erroneous input will therefore require 2 passes over
// the input.
//
var Utils = require('./../Utils');
var Set = Utils.Set;
var BitSet = Utils.BitSet;
var DoubleDict = Utils.DoubleDict;
var ATN = require('./ATN').ATN;
var ATNConfig = require('./ATNConfig').ATNConfig;
var ATNConfigSet = require('./ATNConfigSet').ATNConfigSet;
var Token = require('./../Token').Token;
var DFAState = require('./../dfa/DFAState').DFAState;
var PredPrediction = require('./../dfa/DFAState').PredPrediction;
var ATNSimulator = require('./ATNSimulator').ATNSimulator;
var PredictionMode = require('./PredictionMode').PredictionMode;
var RuleContext = require('./../RuleContext').RuleContext;
var ParserRuleContext = require('./../ParserRuleContext').ParserRuleContext;
var SemanticContext = require('./SemanticContext').SemanticContext;
var StarLoopEntryState = require('./ATNState').StarLoopEntryState;
var RuleStopState = require('./ATNState').RuleStopState;
var PredictionContext = require('./../PredictionContext').PredictionContext;
var Interval = require('./../IntervalSet').Interval;
var Transitions = require('./Transition');
var Transition = Transitions.Transition;
var SetTransition = Transitions.SetTransition;
var NotSetTransition = Transitions.NotSetTransition;
var RuleTransition = Transitions.RuleTransition;
var ActionTransition = Transitions.ActionTransition;
var NoViableAltException = require('./../error/Errors').NoViableAltException;
var SingletonPredictionContext = require('./../PredictionContext').SingletonPredictionContext;
var predictionContextFromRuleContext = require('./../PredictionContext').predictionContextFromRuleContext;
function ParserATNSimulator(parser, atn, decisionToDFA, sharedContextCache) {
ATNSimulator.call(this, atn, sharedContextCache);
this.parser = parser;
this.decisionToDFA = decisionToDFA;
// SLL, LL, or LL + exact ambig detection?//
this.predictionMode = PredictionMode.LL;
// LAME globals to avoid parameters!!!!! I need these down deep in predTransition
this._input = null;
this._startIndex = 0;
this._outerContext = null;
this._dfa = null;
// Each prediction operation uses a cache for merge of prediction contexts.
// Don't keep around as it wastes huge amounts of memory. DoubleKeyMap
// isn't synchronized but we're ok since two threads shouldn't reuse same
// parser/atnsim object because it can only handle one input at a time.
// This maps graphs a and b to merged result c. (a,b)→c. We can avoid
// the merge if we ever see a and b again. Note that (b,a)→c should
// also be examined during cache lookup.
//
this.mergeCache = null;
return this;
}
ParserATNSimulator.prototype = Object.create(ATNSimulator.prototype);
ParserATNSimulator.prototype.constructor = ParserATNSimulator;
ParserATNSimulator.prototype.debug = false;
ParserATNSimulator.prototype.debug_list_atn_decisions = false;
ParserATNSimulator.prototype.dfa_debug = false;
ParserATNSimulator.prototype.retry_debug = false;
ParserATNSimulator.prototype.reset = function() {
};
ParserATNSimulator.prototype.adaptivePredict = function(input, decision, outerContext) {
if (this.debug || this.debug_list_atn_decisions) {
console.log("adaptivePredict decision " + decision +
" exec LA(1)==" + this.getLookaheadName(input) +
" line " + input.LT(1).line + ":" +
input.LT(1).column);
}
this._input = input;
this._startIndex = input.index;
this._outerContext = outerContext;
var dfa = this.decisionToDFA[decision];
this._dfa = dfa;
var m = input.mark();
var index = input.index;
// Now we are certain to have a specific decision's DFA
// But, do we still need an initial state?
try {
var s0;
if (dfa.precedenceDfa) {
// the start state for a precedence DFA depends on the current
// parser precedence, and is provided by a DFA method.
s0 = dfa.getPrecedenceStartState(this.parser.getPrecedence());
} else {
// the start state for a "regular" DFA is just s0
s0 = dfa.s0;
}
if (s0===null) {
if (outerContext===null) {
outerContext = RuleContext.EMPTY;
}
if (this.debug || this.debug_list_atn_decisions) {
console.log("predictATN decision " + dfa.decision +
" exec LA(1)==" + this.getLookaheadName(input) +
", outerContext=" + outerContext.toString(this.parser.ruleNames));
}
// If this is not a precedence DFA, we check the ATN start state
// to determine if this ATN start state is the decision for the
// closure block that determines whether a precedence rule
// should continue or complete.
//
if (!dfa.precedenceDfa && (dfa.atnStartState instanceof StarLoopEntryState)) {
if (dfa.atnStartState.precedenceRuleDecision) {
dfa.setPrecedenceDfa(true);
}
}
var fullCtx = false;
var s0_closure = this.computeStartState(dfa.atnStartState, RuleContext.EMPTY, fullCtx);
if( dfa.precedenceDfa) {
// If this is a precedence DFA, we use applyPrecedenceFilter
// to convert the computed start state to a precedence start
// state. We then use DFA.setPrecedenceStartState to set the
// appropriate start state for the precedence level rather
// than simply setting DFA.s0.
//
s0_closure = this.applyPrecedenceFilter(s0_closure);
s0 = this.addDFAState(dfa, new DFAState(null, s0_closure));
dfa.setPrecedenceStartState(this.parser.getPrecedence(), s0);
} else {
s0 = this.addDFAState(dfa, new DFAState(null, s0_closure));
dfa.s0 = s0;
}
}
var alt = this.execATN(dfa, s0, input, index, outerContext);
if (this.debug) {
console.log("DFA after predictATN: " + dfa.toString(this.parser.literalNames));
}
return alt;
} finally {
this._dfa = null;
this.mergeCache = null; // wack cache after each prediction
input.seek(index);
input.release(m);
}
};
// Performs ATN simulation to compute a predicted alternative based
// upon the remaining input, but also updates the DFA cache to avoid
// having to traverse the ATN again for the same input sequence.
// There are some key conditions we're looking for after computing a new
// set of ATN configs (proposed DFA state):
// if the set is empty, there is no viable alternative for current symbol
// does the state uniquely predict an alternative?
// does the state have a conflict that would prevent us from
// putting it on the work list?
// We also have some key operations to do:
// add an edge from previous DFA state to potentially new DFA state, D,
// upon current symbol but only if adding to work list, which means in all
// cases except no viable alternative (and possibly non-greedy decisions?)
// collecting predicates and adding semantic context to DFA accept states
// adding rule context to context-sensitive DFA accept states
// consuming an input symbol
// reporting a conflict
// reporting an ambiguity
// reporting a context sensitivity
// reporting insufficient predicates
// cover these cases:
// dead end
// single alt
// single alt + preds
// conflict
// conflict + preds
//
ParserATNSimulator.prototype.execATN = function(dfa, s0, input, startIndex, outerContext ) {
if (this.debug || this.debug_list_atn_decisions) {
console.log("execATN decision " + dfa.decision +
" exec LA(1)==" + this.getLookaheadName(input) +
" line " + input.LT(1).line + ":" + input.LT(1).column);
}
var alt;
var previousD = s0;
if (this.debug) {
console.log("s0 = " + s0);
}
var t = input.LA(1);
while(true) { // while more work
var D = this.getExistingTargetState(previousD, t);
if(D===null) {
D = this.computeTargetState(dfa, previousD, t);
}
if(D===ATNSimulator.ERROR) {
// if any configs in previous dipped into outer context, that
// means that input up to t actually finished entry rule
// at least for SLL decision. Full LL doesn't dip into outer
// so don't need special case.
// We will get an error no matter what so delay until after
// decision; better error message. Also, no reachable target
// ATN states in SLL implies LL will also get nowhere.
// If conflict in states that dip out, choose min since we
// will get error no matter what.
var e = this.noViableAlt(input, outerContext, previousD.configs, startIndex);
input.seek(startIndex);
alt = this.getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule(previousD.configs, outerContext);
if(alt!==ATN.INVALID_ALT_NUMBER) {
return alt;
} else {
throw e;
}
}
if(D.requiresFullContext && this.predictionMode !== PredictionMode.SLL) {
// IF PREDS, MIGHT RESOLVE TO SINGLE ALT => SLL (or syntax error)
var conflictingAlts = null;
if (D.predicates!==null) {
if (this.debug) {
console.log("DFA state has preds in DFA sim LL failover");
}
var conflictIndex = input.index;
if(conflictIndex !== startIndex) {
input.seek(startIndex);
}
conflictingAlts = this.evalSemanticContext(D.predicates, outerContext, true);
if (conflictingAlts.length===1) {
if(this.debug) {
console.log("Full LL avoided");
}
return conflictingAlts.minValue();
}
if (conflictIndex !== startIndex) {
// restore the index so reporting the fallback to full
// context occurs with the index at the correct spot
input.seek(conflictIndex);
}
}
if (this.dfa_debug) {
console.log("ctx sensitive state " + outerContext +" in " + D);
}
var fullCtx = true;
var s0_closure = this.computeStartState(dfa.atnStartState, outerContext, fullCtx);
this.reportAttemptingFullContext(dfa, conflictingAlts, D.configs, startIndex, input.index);
alt = this.execATNWithFullContext(dfa, D, s0_closure, input, startIndex, outerContext);
return alt;
}
if (D.isAcceptState) {
if (D.predicates===null) {
return D.prediction;
}
var stopIndex = input.index;
input.seek(startIndex);
var alts = this.evalSemanticContext(D.predicates, outerContext, true);
if (alts.length===0) {
throw this.noViableAlt(input, outerContext, D.configs, startIndex);
} else if (alts.length===1) {
return alts.minValue();
} else {
// report ambiguity after predicate evaluation to make sure the correct set of ambig alts is reported.
this.reportAmbiguity(dfa, D, startIndex, stopIndex, false, alts, D.configs);
return alts.minValue();
}
}
previousD = D;
if (t !== Token.EOF) {
input.consume();
t = input.LA(1);
}
}
};
//
// 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 previousD 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
//
ParserATNSimulator.prototype.getExistingTargetState = function(previousD, t) {
var edges = previousD.edges;
if (edges===null) {
return null;
} else {
return edges[t + 1] || null;
}
};
//
// Compute a target state for an edge in the DFA, and attempt to add the
// computed state and corresponding edge to the DFA.
//
// @param dfa The DFA
// @param previousD 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}.
//
ParserATNSimulator.prototype.computeTargetState = function(dfa, previousD, t) {
var reach = this.computeReachSet(previousD.configs, t, false);
if(reach===null) {
this.addDFAEdge(dfa, previousD, t, ATNSimulator.ERROR);
return ATNSimulator.ERROR;
}
// create new target state; we'll add to DFA after it's complete
var D = new DFAState(null, reach);
var predictedAlt = this.getUniqueAlt(reach);
if (this.debug) {
var altSubSets = PredictionMode.getConflictingAltSubsets(reach);
console.log("SLL altSubSets=" + Utils.arrayToString(altSubSets) +
", previous=" + previousD.configs +
", configs=" + reach +
", predict=" + predictedAlt +
", allSubsetsConflict=" +
PredictionMode.allSubsetsConflict(altSubSets) + ", conflictingAlts=" +
this.getConflictingAlts(reach));
}
if (predictedAlt!==ATN.INVALID_ALT_NUMBER) {
// NO CONFLICT, UNIQUELY PREDICTED ALT
D.isAcceptState = true;
D.configs.uniqueAlt = predictedAlt;
D.prediction = predictedAlt;
} else if (PredictionMode.hasSLLConflictTerminatingPrediction(this.predictionMode, reach)) {
// MORE THAN ONE VIABLE ALTERNATIVE
D.configs.conflictingAlts = this.getConflictingAlts(reach);
D.requiresFullContext = true;
// in SLL-only mode, we will stop at this state and return the minimum alt
D.isAcceptState = true;
D.prediction = D.configs.conflictingAlts.minValue();
}
if (D.isAcceptState && D.configs.hasSemanticContext) {
this.predicateDFAState(D, this.atn.getDecisionState(dfa.decision));
if( D.predicates!==null) {
D.prediction = ATN.INVALID_ALT_NUMBER;
}
}
// all adds to dfa are done after we've created full D state
D = this.addDFAEdge(dfa, previousD, t, D);
return D;
};
ParserATNSimulator.prototype.predicateDFAState = function(dfaState, decisionState) {
// We need to test all predicates, even in DFA states that
// uniquely predict alternative.
var nalts = decisionState.transitions.length;
// Update DFA so reach becomes accept state with (predicate,alt)
// pairs if preds found for conflicting alts
var altsToCollectPredsFrom = this.getConflictingAltsOrUniqueAlt(dfaState.configs);
var altToPred = this.getPredsForAmbigAlts(altsToCollectPredsFrom, dfaState.configs, nalts);
if (altToPred!==null) {
dfaState.predicates = this.getPredicatePredictions(altsToCollectPredsFrom, altToPred);
dfaState.prediction = ATN.INVALID_ALT_NUMBER; // make sure we use preds
} else {
// There are preds in configs but they might go away
// when OR'd together like {p}? || NONE == NONE. If neither
// alt has preds, resolve to min alt
dfaState.prediction = altsToCollectPredsFrom.minValue();
}
};
// comes back with reach.uniqueAlt set to a valid alt
ParserATNSimulator.prototype.execATNWithFullContext = function(dfa, D, // how far we got before failing over
s0,
input,
startIndex,
outerContext) {
if (this.debug || this.debug_list_atn_decisions) {
console.log("execATNWithFullContext "+s0);
}
var fullCtx = true;
var foundExactAmbig = false;
var reach = null;
var previous = s0;
input.seek(startIndex);
var t = input.LA(1);
var predictedAlt = -1;
while (true) { // while more work
reach = this.computeReachSet(previous, t, fullCtx);
if (reach===null) {
// if any configs in previous dipped into outer context, that
// means that input up to t actually finished entry rule
// at least for LL decision. Full LL doesn't dip into outer
// so don't need special case.
// We will get an error no matter what so delay until after
// decision; better error message. Also, no reachable target
// ATN states in SLL implies LL will also get nowhere.
// If conflict in states that dip out, choose min since we
// will get error no matter what.
var e = this.noViableAlt(input, outerContext, previous, startIndex);
input.seek(startIndex);
var alt = this.getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule(previous, outerContext);
if(alt!==ATN.INVALID_ALT_NUMBER) {
return alt;
} else {
throw e;
}
}
var altSubSets = PredictionMode.getConflictingAltSubsets(reach);
if(this.debug) {
console.log("LL altSubSets=" + altSubSets + ", predict=" +
PredictionMode.getUniqueAlt(altSubSets) + ", resolvesToJustOneViableAlt=" +
PredictionMode.resolvesToJustOneViableAlt(altSubSets));
}
reach.uniqueAlt = this.getUniqueAlt(reach);
// unique prediction?
if(reach.uniqueAlt!==ATN.INVALID_ALT_NUMBER) {
predictedAlt = reach.uniqueAlt;
break;
} else if (this.predictionMode !== PredictionMode.LL_EXACT_AMBIG_DETECTION) {
predictedAlt = PredictionMode.resolvesToJustOneViableAlt(altSubSets);
if(predictedAlt !== ATN.INVALID_ALT_NUMBER) {
break;
}
} else {
// In exact ambiguity mode, we never try to terminate early.
// Just keeps scarfing until we know what the conflict is
if (PredictionMode.allSubsetsConflict(altSubSets) && PredictionMode.allSubsetsEqual(altSubSets)) {
foundExactAmbig = true;
predictedAlt = PredictionMode.getSingleViableAlt(altSubSets);
break;
}
// else there are multiple non-conflicting subsets or
// we're not sure what the ambiguity is yet.
// So, keep going.
}
previous = reach;
if( t !== Token.EOF) {
input.consume();
t = input.LA(1);
}
}
// If the configuration set uniquely predicts an alternative,
// without conflict, then we know that it's a full LL decision
// not SLL.
if (reach.uniqueAlt !== ATN.INVALID_ALT_NUMBER ) {
this.reportContextSensitivity(dfa, predictedAlt, reach, startIndex, input.index);
return predictedAlt;
}
// We do not check predicates here because we have checked them
// on-the-fly when doing full context prediction.
//
// In non-exact ambiguity detection mode, we might actually be able to
// detect an exact ambiguity, but I'm not going to spend the cycles
// needed to check. We only emit ambiguity warnings in exact ambiguity
// mode.
//
// For example, we might know that we have conflicting configurations.
// But, that does not mean that there is no way forward without a
// conflict. It's possible to have nonconflicting alt subsets as in:
// altSubSets=[{1, 2}, {1, 2}, {1}, {1, 2}]
// from
//
// [(17,1,[5 $]), (13,1,[5 10 $]), (21,1,[5 10 $]), (11,1,[$]),
// (13,2,[5 10 $]), (21,2,[5 10 $]), (11,2,[$])]
//
// In this case, (17,1,[5 $]) indicates there is some next sequence that
// would resolve this without conflict to alternative 1. Any other viable
// next sequence, however, is associated with a conflict. We stop
// looking for input because no amount of further lookahead will alter
// the fact that we should predict alternative 1. We just can't say for
// sure that there is an ambiguity without looking further.
this.reportAmbiguity(dfa, D, startIndex, input.index, foundExactAmbig, null, reach);
return predictedAlt;
};
ParserATNSimulator.prototype.computeReachSet = function(closure, t, fullCtx) {
if (this.debug) {
console.log("in computeReachSet, starting closure: " + closure);
}
if( this.mergeCache===null) {
this.mergeCache = new DoubleDict();
}
var intermediate = new ATNConfigSet(fullCtx);
// Configurations already in a rule stop state indicate reaching the end
// of the decision rule (local context) or end of the start rule (full
// context). Once reached, these configurations are never updated by a
// closure operation, so they are handled separately for the performance
// advantage of having a smaller intermediate set when calling closure.
//
// For full-context reach operations, separate handling is required to
// ensure that the alternative matching the longest overall sequence is
// chosen when multiple such configurations can match the input.
var skippedStopStates = null;
// First figure out where we can reach on input t
for (var i=0; iWhen {@code lookToEndOfRule} is true, this method uses
// {@link ATN//nextTokens} for each configuration in {@code configs} which is
// not already in a rule stop state to see if a rule stop state is reachable
// from the configuration via epsilon-only transitions.
//
// @param configs the configuration set to update
// @param lookToEndOfRule when true, this method checks for rule stop states
// reachable by epsilon-only transitions from each configuration in
// {@code configs}.
//
// @return {@code configs} if all configurations in {@code configs} are in a
// rule stop state, otherwise return a new configuration set containing only
// the configurations from {@code configs} which are in a rule stop state
//
ParserATNSimulator.prototype.removeAllConfigsNotInRuleStopState = function(configs, lookToEndOfRule) {
if (PredictionMode.allConfigsInRuleStopStates(configs)) {
return configs;
}
var result = new ATNConfigSet(configs.fullCtx);
for(var i=0; i
// Evaluate the precedence predicates for each configuration using
// {@link SemanticContext//evalPrecedence}.
// Remove all configurations which predict an alternative greater than
// 1, for which another configuration that predicts alternative 1 is in the
// same ATN state with the same prediction context. This transformation is
// valid for the following reasons:
//
// - The closure block cannot contain any epsilon transitions which bypass
// the body of the closure, so all states reachable via alternative 1 are
// part of the precedence alternatives of the transformed left-recursive
// rule.
// - The "primary" portion of a left recursive rule cannot contain an
// epsilon transition, so the only way an alternative other than 1 can exist
// in a state that is also reachable via alternative 1 is by nesting calls
// to the left-recursive rule, with the outer calls not being at the
// preferred precedence level.
//
//
//
//
//
// The prediction context must be considered by this filter to address
// situations like the following.
//
//
//
// grammar TA;
// prog: statement* EOF;
// statement: letterA | statement letterA 'b' ;
// letterA: 'a';
//
//
//
// If the above grammar, the ATN state immediately before the token
// reference {@code 'a'} in {@code letterA} is reachable from the left edge
// of both the primary and closure blocks of the left-recursive rule
// {@code statement}. The prediction context associated with each of these
// configurations distinguishes between them, and prevents the alternative
// which stepped out to {@code prog} (and then back in to {@code statement}
// from being eliminated by the filter.
//
//
// @param configs The configuration set computed by
// {@link //computeStartState} as the start state for the DFA.
// @return The transformed configuration set representing the start state
// for a precedence DFA at a particular precedence level (determined by
// calling {@link Parser//getPrecedence}).
//
ParserATNSimulator.prototype.applyPrecedenceFilter = function(configs) {
var config;
var statesFromAlt1 = [];
var configSet = new ATNConfigSet(configs.fullCtx);
for(var i=0; i1
// (basically a graph subtraction algorithm).
if (!config.precedenceFilterSuppressed) {
var context = statesFromAlt1[config.state.stateNumber] || null;
if (context!==null && context.equals(config.context)) {
// eliminated
continue;
}
}
configSet.add(config, this.mergeCache);
}
return configSet;
};
ParserATNSimulator.prototype.getReachableTarget = function(trans, ttype) {
if (trans.matches(ttype, 0, this.atn.maxTokenType)) {
return trans.target;
} else {
return null;
}
};
ParserATNSimulator.prototype.getPredsForAmbigAlts = function(ambigAlts, configs, nalts) {
// REACH=[1|1|[]|0:0, 1|2|[]|0:1]
// altToPred starts as an array of all null contexts. The entry at index i
// corresponds to alternative i. altToPred[i] may have one of three values:
// 1. null: no ATNConfig c is found such that c.alt==i
// 2. SemanticContext.NONE: At least one ATNConfig c exists such that
// c.alt==i and c.semanticContext==SemanticContext.NONE. In other words,
// alt i has at least one unpredicated config.
// 3. Non-NONE Semantic Context: There exists at least one, and for all
// ATNConfig c such that c.alt==i, c.semanticContext!=SemanticContext.NONE.
//
// From this, it is clear that NONE||anything==NONE.
//
var altToPred = [];
for(var i=0;i
// The default implementation of this method uses the following
// algorithm to identify an ATN configuration which successfully parsed the
// decision entry rule. Choosing such an alternative ensures that the
// {@link ParserRuleContext} returned by the calling rule will be complete
// and valid, and the syntax error will be reported later at a more
// localized location.
//
//
// - If a syntactically valid path or paths reach the end of the decision rule and
// they are semantically valid if predicated, return the min associated alt.
// - Else, if a semantically invalid but syntactically valid path exist
// or paths exist, return the minimum associated alt.
//
// - Otherwise, return {@link ATN//INVALID_ALT_NUMBER}.
//
//
//
// In some scenarios, the algorithm described above could predict an
// alternative which will result in a {@link FailedPredicateException} in
// the parser. Specifically, this could occur if the only configuration
// capable of successfully parsing to the end of the decision rule is
// blocked by a semantic predicate. By choosing this alternative within
// {@link //adaptivePredict} instead of throwing a
// {@link NoViableAltException}, the resulting
// {@link FailedPredicateException} in the parser will identify the specific
// predicate which is preventing the parser from successfully parsing the
// decision rule, which helps developers identify and correct logic errors
// in semantic predicates.
//
//
// @param configs The ATN configurations which were valid immediately before
// the {@link //ERROR} state was reached
// @param outerContext The is the \gamma_0 initial parser context from the paper
// or the parser stack at the instant before prediction commences.
//
// @return The value to return from {@link //adaptivePredict}, or
// {@link ATN//INVALID_ALT_NUMBER} if a suitable alternative was not
// identified and {@link //adaptivePredict} should report an error instead.
//
ParserATNSimulator.prototype.getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule = function(configs, outerContext) {
var cfgs = this.splitAccordingToSemanticValidity(configs, outerContext);
var semValidConfigs = cfgs[0];
var semInvalidConfigs = cfgs[1];
var alt = this.getAltThatFinishedDecisionEntryRule(semValidConfigs);
if (alt!==ATN.INVALID_ALT_NUMBER) { // semantically/syntactically viable path exists
return alt;
}
// Is there a syntactically valid path with a failed pred?
if (semInvalidConfigs.items.length>0) {
alt = this.getAltThatFinishedDecisionEntryRule(semInvalidConfigs);
if (alt!==ATN.INVALID_ALT_NUMBER) { // syntactically viable path exists
return alt;
}
}
return ATN.INVALID_ALT_NUMBER;
};
ParserATNSimulator.prototype.getAltThatFinishedDecisionEntryRule = function(configs) {
var alts = [];
for(var i=0;i0 || ((c.state instanceof RuleStopState) && c.context.hasEmptyPath())) {
if(alts.indexOf(c.alt)<0) {
alts.push(c.alt);
}
}
}
if (alts.length===0) {
return ATN.INVALID_ALT_NUMBER;
} else {
return Math.min.apply(null, alts);
}
};
// Walk the list of configurations and split them according to
// those that have preds evaluating to true/false. If no pred, assume
// true pred and include in succeeded set. Returns Pair of sets.
//
// Create a new set so as not to alter the incoming parameter.
//
// Assumption: the input stream has been restored to the starting point
// prediction, which is where predicates need to evaluate.
//
ParserATNSimulator.prototype.splitAccordingToSemanticValidity = function( configs, outerContext) {
var succeeded = new ATNConfigSet(configs.fullCtx);
var failed = new ATNConfigSet(configs.fullCtx);
for(var i=0;i50) {
throw "problem";
}
}
if (config.state instanceof RuleStopState) {
// We hit rule end. If we have context info, use it
// run thru all possible stack tops in ctx
if (! config.context.isEmpty()) {
for ( var i =0; i 0.
if (closureBusy.add(c)!==c) {
// avoid infinite recursion for right-recursive rules
continue;
}
if (this._dfa !== null && this._dfa.precedenceDfa) {
if (t.outermostPrecedenceReturn === this._dfa.atnStartState.ruleIndex) {
c.precedenceFilterSuppressed = true;
}
}
c.reachesIntoOuterContext += 1;
configs.dipsIntoOuterContext = true; // TODO: can remove? only care when we add to set per middle of this method
newDepth -= 1;
if (this.debug) {
console.log("dips into outer ctx: " + c);
}
} else if (t instanceof RuleTransition) {
// latch when newDepth goes negative - once we step out of the entry context we can't return
if (newDepth >= 0) {
newDepth += 1;
}
}
this.closureCheckingStopState(c, configs, closureBusy, continueCollecting, fullCtx, newDepth, treatEofAsEpsilon);
}
}
};
ParserATNSimulator.prototype.getRuleName = function( index) {
if (this.parser!==null && index>=0) {
return this.parser.ruleNames[index];
} else {
return "";
}
};
ParserATNSimulator.prototype.getEpsilonTarget = function(config, t, collectPredicates, inContext, fullCtx, treatEofAsEpsilon) {
switch(t.serializationType) {
case Transition.RULE:
return this.ruleTransition(config, t);
case Transition.PRECEDENCE:
return this.precedenceTransition(config, t, collectPredicates, inContext, fullCtx);
case Transition.PREDICATE:
return this.predTransition(config, t, collectPredicates, inContext, fullCtx);
case Transition.ACTION:
return this.actionTransition(config, t);
case Transition.EPSILON:
return new ATNConfig({state:t.target}, config);
case Transition.ATOM:
case Transition.RANGE:
case Transition.SET:
// EOF transitions act like epsilon transitions after the first EOF
// transition is traversed
if (treatEofAsEpsilon) {
if (t.matches(Token.EOF, 0, 1)) {
return new ATNConfig({state: t.target}, config);
}
}
return null;
default:
return null;
}
};
ParserATNSimulator.prototype.actionTransition = function(config, t) {
if (this.debug) {
console.log("ACTION edge " + t.ruleIndex + ":" + t.actionIndex);
}
return new ATNConfig({state:t.target}, config);
};
ParserATNSimulator.prototype.precedenceTransition = function(config, pt, collectPredicates, inContext, fullCtx) {
if (this.debug) {
console.log("PRED (collectPredicates=" + collectPredicates + ") " +
pt.precedence + ">=_p, ctx dependent=true");
if (this.parser!==null) {
console.log("context surrounding pred is " + Utils.arrayToString(this.parser.getRuleInvocationStack()));
}
}
var c = null;
if (collectPredicates && inContext) {
if (fullCtx) {
// In full context mode, we can evaluate predicates on-the-fly
// during closure, which dramatically reduces the size of
// the config sets. It also obviates the need to test predicates
// later during conflict resolution.
var currentPosition = this._input.index;
this._input.seek(this._startIndex);
var predSucceeds = pt.getPredicate().evaluate(this.parser, this._outerContext);
this._input.seek(currentPosition);
if (predSucceeds) {
c = new ATNConfig({state:pt.target}, config); // no pred context
}
} else {
newSemCtx = SemanticContext.andContext(config.semanticContext, pt.getPredicate());
c = new ATNConfig({state:pt.target, semanticContext:newSemCtx}, config);
}
} else {
c = new ATNConfig({state:pt.target}, config);
}
if (this.debug) {
console.log("config from pred transition=" + c);
}
return c;
};
ParserATNSimulator.prototype.predTransition = function(config, pt, collectPredicates, inContext, fullCtx) {
if (this.debug) {
console.log("PRED (collectPredicates=" + collectPredicates + ") " + pt.ruleIndex +
":" + pt.predIndex + ", ctx dependent=" + pt.isCtxDependent);
if (this.parser!==null) {
console.log("context surrounding pred is " + Utils.arrayToString(this.parser.getRuleInvocationStack()));
}
}
var c = null;
if (collectPredicates && ((pt.isCtxDependent && inContext) || ! pt.isCtxDependent)) {
if (fullCtx) {
// In full context mode, we can evaluate predicates on-the-fly
// during closure, which dramatically reduces the size of
// the config sets. It also obviates the need to test predicates
// later during conflict resolution.
var currentPosition = this._input.index;
this._input.seek(this._startIndex);
var predSucceeds = pt.getPredicate().evaluate(this.parser, this._outerContext);
this._input.seek(currentPosition);
if (predSucceeds) {
c = new ATNConfig({state:pt.target}, config); // no pred context
}
} else {
var newSemCtx = SemanticContext.andContext(config.semanticContext, pt.getPredicate());
c = new ATNConfig({state:pt.target, semanticContext:newSemCtx}, config);
}
} else {
c = new ATNConfig({state:pt.target}, config);
}
if (this.debug) {
console.log("config from pred transition=" + c);
}
return c;
};
ParserATNSimulator.prototype.ruleTransition = function(config, t) {
if (this.debug) {
console.log("CALL rule " + this.getRuleName(t.target.ruleIndex) + ", ctx=" + config.context);
}
var returnState = t.followState;
var newContext = SingletonPredictionContext.create(config.context, returnState.stateNumber);
return new ATNConfig({state:t.target, context:newContext}, config );
};
ParserATNSimulator.prototype.getConflictingAlts = function(configs) {
var altsets = PredictionMode.getConflictingAltSubsets(configs);
return PredictionMode.getAlts(altsets);
};
// Sam pointed out a problem with the previous definition, v3, of
// ambiguous states. If we have another state associated with conflicting
// alternatives, we should keep going. For example, the following grammar
//
// s : (ID | ID ID?) ';' ;
//
// When the ATN simulation reaches the state before ';', it has a DFA
// state that looks like: [12|1|[], 6|2|[], 12|2|[]]. Naturally
// 12|1|[] and 12|2|[] conflict, but we cannot stop processing this node
// because alternative to has another way to continue, via [6|2|[]].
// The key is that we have a single state that has config's only associated
// with a single alternative, 2, and crucially the state transitions
// among the configurations are all non-epsilon transitions. That means
// we don't consider any conflicts that include alternative 2. So, we
// ignore the conflict between alts 1 and 2. We ignore a set of
// conflicting alts when there is an intersection with an alternative
// associated with a single alt state in the state→config-list map.
//
// It's also the case that we might have two conflicting configurations but
// also a 3rd nonconflicting configuration for a different alternative:
// [1|1|[], 1|2|[], 8|3|[]]. This can come about from grammar:
//
// a : A | A | A B ;
//
// After matching input A, we reach the stop state for rule A, state 1.
// State 8 is the state right before B. Clearly alternatives 1 and 2
// conflict and no amount of further lookahead will separate the two.
// However, alternative 3 will be able to continue and so we do not
// stop working on this state. In the previous example, we're concerned
// with states associated with the conflicting alternatives. Here alt
// 3 is not associated with the conflicting configs, but since we can continue
// looking for input reasonably, I don't declare the state done. We
// ignore a set of conflicting alts when we have an alternative
// that we still need to pursue.
//
ParserATNSimulator.prototype.getConflictingAltsOrUniqueAlt = function(configs) {
var conflictingAlts = null;
if (configs.uniqueAlt!== ATN.INVALID_ALT_NUMBER) {
conflictingAlts = new BitSet();
conflictingAlts.add(configs.uniqueAlt);
} else {
conflictingAlts = configs.conflictingAlts;
}
return conflictingAlts;
};
ParserATNSimulator.prototype.getTokenName = function( t) {
if (t===Token.EOF) {
return "EOF";
}
if( this.parser!==null && this.parser.literalNames!==null) {
if (t >= this.parser.literalNames.length) {
console.log("" + t + " ttype out of range: " + this.parser.literalNames);
console.log("" + this.parser.getInputStream().getTokens());
} else {
return this.parser.literalNames[t] + "<" + t + ">";
}
}
return "" + t;
};
ParserATNSimulator.prototype.getLookaheadName = function(input) {
return this.getTokenName(input.LA(1));
};
// Used for debugging in adaptivePredict around execATN but I cut
// it out for clarity now that alg. works well. We can leave this
// "dead" code for a bit.
//
ParserATNSimulator.prototype.dumpDeadEndConfigs = function(nvae) {
console.log("dead end configs: ");
var decs = nvae.getDeadEndConfigs();
for(var i=0; i0) {
var t = c.state.transitions[0];
if (t instanceof AtomTransition) {
trans = "Atom "+ this.getTokenName(t.label);
} else if (t instanceof SetTransition) {
var neg = (t instanceof NotSetTransition);
trans = (neg ? "~" : "") + "Set " + t.set;
}
}
console.error(c.toString(this.parser, true) + ":" + trans);
}
};
ParserATNSimulator.prototype.noViableAlt = function(input, outerContext, configs, startIndex) {
return new NoViableAltException(this.parser, input, input.get(startIndex), input.LT(1), configs, outerContext);
};
ParserATNSimulator.prototype.getUniqueAlt = function(configs) {
var alt = ATN.INVALID_ALT_NUMBER;
for(var i=0;iIf {@code to} is {@code null}, this method returns {@code null}.
// Otherwise, this method returns the {@link DFAState} returned by calling
// {@link //addDFAState} for the {@code to} state.
//
// @param dfa The DFA
// @param from The source state for the edge
// @param t The input symbol
// @param to The target state for the edge
//
// @return If {@code to} is {@code null}, this method returns {@code null};
// otherwise this method returns the result of calling {@link //addDFAState}
// on {@code to}
//
ParserATNSimulator.prototype.addDFAEdge = function(dfa, from_, t, to) {
if( this.debug) {
console.log("EDGE " + from_ + " -> " + to + " upon " + this.getTokenName(t));
}
if (to===null) {
return null;
}
to = this.addDFAState(dfa, to); // used existing if possible not incoming
if (from_===null || t < -1 || t > this.atn.maxTokenType) {
return to;
}
if (from_.edges===null) {
from_.edges = [];
}
from_.edges[t+1] = to; // connect
if (this.debug) {
var names = this.parser===null ? null : this.parser.literalNames;
console.log("DFA=\n" + dfa.toString(names));
}
return to;
};
//
// Add state {@code D} to the DFA if it is not already present, and return
// the actual instance stored in the DFA. If a state equivalent to {@code D}
// is already in the DFA, the existing state is returned. Otherwise this
// method returns {@code D} after adding it to the DFA.
//
// If {@code D} is {@link //ERROR}, this method returns {@link //ERROR} and
// does not change the DFA.
//
// @param dfa The dfa
// @param D The DFA state to add
// @return The state stored in the DFA. This will be either the existing
// state if {@code D} is already in the DFA, or {@code D} itself if the
// state was not already present.
//
ParserATNSimulator.prototype.addDFAState = function(dfa, D) {
if (D == ATNSimulator.ERROR) {
return D;
}
var hash = D.hashString();
var existing = dfa.states[hash] || null;
if(existing!==null) {
return existing;
}
D.stateNumber = dfa.states.length;
if (! D.configs.readOnly) {
D.configs.optimizeConfigs(this);
D.configs.setReadonly(true);
}
dfa.states[hash] = D;
if (this.debug) {
console.log("adding new DFA state: " + D);
}
return D;
};
ParserATNSimulator.prototype.reportAttemptingFullContext = function(dfa, conflictingAlts, configs, startIndex, stopIndex) {
if (this.debug || this.retry_debug) {
var interval = new Interval(startIndex, stopIndex + 1);
console.log("reportAttemptingFullContext decision=" + dfa.decision + ":" + configs +
", input=" + this.parser.getTokenStream().getText(interval));
}
if (this.parser!==null) {
this.parser.getErrorListenerDispatch().reportAttemptingFullContext(this.parser, dfa, startIndex, stopIndex, conflictingAlts, configs);
}
};
ParserATNSimulator.prototype.reportContextSensitivity = function(dfa, prediction, configs, startIndex, stopIndex) {
if (this.debug || this.retry_debug) {
var interval = new Interval(startIndex, stopIndex + 1);
console.log("reportContextSensitivity decision=" + dfa.decision + ":" + configs +
", input=" + this.parser.getTokenStream().getText(interval));
}
if (this.parser!==null) {
this.parser.getErrorListenerDispatch().reportContextSensitivity(this.parser, dfa, startIndex, stopIndex, prediction, configs);
}
};
// If context sensitive parsing, we know it's ambiguity not conflict//
ParserATNSimulator.prototype.reportAmbiguity = function(dfa, D, startIndex, stopIndex,
exact, ambigAlts, configs ) {
if (this.debug || this.retry_debug) {
var interval = new Interval(startIndex, stopIndex + 1);
console.log("reportAmbiguity " + ambigAlts + ":" + configs +
", input=" + this.parser.getTokenStream().getText(interval));
}
if (this.parser!==null) {
this.parser.getErrorListenerDispatch().reportAmbiguity(this.parser, dfa, startIndex, stopIndex, exact, ambigAlts, configs);
}
};
exports.ParserATNSimulator = ParserATNSimulator;