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No need to fully evaluate predicates when called from execDFA because ambiguous alts aren't reported anyway.

This commit is contained in:
Sam Harwell 2012-03-10 16:32:10 -06:00
parent 2cc39c2f9b
commit 04cd48e88d
1 changed files with 13 additions and 5 deletions
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18
runtime/Java/src/org/antlr/v4/runtime/atn/ParserATNSimulator.java
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@ -417,7 +417,8 @@ public class ParserATNSimulator<Symbol extends Token> extends ATNSimulator {
if ( s.predicates!=null ) {
// rewind input so pred's LT(i) calls make sense
input.seek(startIndex);
IntervalSet alts = evalSemanticContext(s.predicates, outerContext);
// since we don't report ambiguities in execDFA, we never need to use complete predicate evaluation here
IntervalSet alts = evalSemanticContext(s.predicates, outerContext, false);
if (alts.isNil()) {
throw noViableAlt(input, outerContext, s.configset, startIndex);
}
@ -569,7 +570,7 @@ public class ParserATNSimulator<Symbol extends Token> extends ATNSimulator {
if ( predPredictions!=null ) {
int stopIndex = input.index();
input.seek(startIndex);
IntervalSet alts = evalSemanticContext(predPredictions, outerContext);
IntervalSet alts = evalSemanticContext(predPredictions, outerContext, true);
D.prediction = ATN.INVALID_ALT_NUMBER;
switch (alts.size()) {
case 0:
@ -641,7 +642,7 @@ public class ParserATNSimulator<Symbol extends Token> extends ATNSimulator {
// we have a validating predicate; test it
predPredictions = getPredicatePredictions(reach.conflictingAlts, altToPred);
input.seek(startIndex);
IntervalSet alts = evalSemanticContext(predPredictions, outerContext);
IntervalSet alts = evalSemanticContext(predPredictions, outerContext, true);
reach.uniqueAlt = ATN.INVALID_ALT_NUMBER;
switch (alts.size()) {
case 0:
@ -831,12 +832,17 @@ public class ParserATNSimulator<Symbol extends Token> extends ATNSimulator {
* unpredicated config which behaves as "always true."
*/
public IntervalSet evalSemanticContext(List<DFAState.PredPrediction> predPredictions,
ParserRuleContext<?> outerContext)
ParserRuleContext<?> outerContext,
boolean complete)
{
IntervalSet predictions = new IntervalSet();
for (DFAState.PredPrediction pair : predPredictions) {
if ( pair.pred==null ) {
predictions.add(pair.alt);
if (!complete) {
break;
}
continue;
}
@ -848,7 +854,9 @@ public class ParserATNSimulator<Symbol extends Token> extends ATNSimulator {
if ( evaluatedResult ) {
if ( debug || dfa_debug ) System.out.println("PREDICT "+pair.alt);
predictions.add(pair.alt);
continue;
if (!complete) {
break;
}
}
}