jasder
/
antlr
1
0
Fork 1
Code Issues Pull Requests Releases 1 Wiki Activity

If there is no syntactically and semantically valid alternative that reaches the end of the decision entry rule upon no viable alt, choose the first alternative that is syntactically valid but semantically invalid. Refactor into separate method for clarity.

This commit is contained in:
Terence Parr 2014-04-02 09:38:26 -07:00
parent 9652d0059c
commit 8f000d273d
1 changed files with 41 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
runtime/Java/src/org/antlr/v4/runtime/atn/ParserATNSimulator.java
View File

@ -46,6 +46,7 @@ import org.antlr.v4.runtime.misc.Interval;
import org.antlr.v4.runtime.misc.IntervalSet;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.runtime.misc.Nullable;
import org.antlr.v4.runtime.misc.Pair;
import java.util.ArrayList;
import java.util.Arrays;
@ -326,7 +327,7 @@ public class ParserATNSimulator extends ATNSimulator {
@NotNull DFA[] decisionToDFA,
@NotNull PredictionContextCache sharedContextCache)
{
super(atn,sharedContextCache);
super(atn, sharedContextCache);
this.parser = parser;
this.decisionToDFA = decisionToDFA;
// DOTGenerator dot = new DOTGenerator(null);
@ -486,14 +487,10 @@ public class ParserATNSimulator extends ATNSimulator {
// will get error no matter what.
NoViableAltException e = noViableAlt(input, outerContext, previousD.configs, startIndex);
input.seek(startIndex);
ATNConfigSet filtered =
filterForTruePredicates(previousD.configs, outerContext);
int alt = getAltThatFinishedDecisionEntryRule(filtered);
int alt = getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule(previousD.configs, outerContext);
if ( alt!=ATN.INVALID_ALT_NUMBER ) {
// return w/o altering DFA
return alt;
}
throw e;
}
@ -700,9 +697,7 @@ public class ParserATNSimulator extends ATNSimulator {
// will get error no matter what.
NoViableAltException e = noViableAlt(input, outerContext, previous, startIndex);
input.seek(startIndex);
ATNConfigSet filtered =
filterForTruePredicates(previous, outerContext);
int alt = getAltThatFinishedDecisionEntryRule(filtered);
int alt = getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule(previous, outerContext);
if ( alt!=ATN.INVALID_ALT_NUMBER ) {
return alt;
}
@ -1224,6 +1219,27 @@ public class ParserATNSimulator extends ATNSimulator {
* {@link ATN#INVALID_ALT_NUMBER} if a suitable alternative was not
* identified and {@link #adaptivePredict} should report an error instead.
*/
protected int getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule(ATNConfigSet configs,
ParserRuleContext outerContext)
{
Pair<ATNConfigSet,ATNConfigSet> sets =
splitAccordingToSemanticValidity(configs, outerContext);
ATNConfigSet semValidConfigs = sets.a;
ATNConfigSet semInvalidConfigs = sets.b;
int alt = 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.size()>0 ) {
alt = getAltThatFinishedDecisionEntryRule(semInvalidConfigs);
if ( alt!=ATN.INVALID_ALT_NUMBER ) { // syntactically viable path exists
return alt;
}
}
return ATN.INVALID_ALT_NUMBER;
}
protected int getAltThatFinishedDecisionEntryRule(ATNConfigSet configs) {
IntervalSet alts = new IntervalSet();
for (ATNConfig c : configs) {
@ -1235,31 +1251,36 @@ public class ParserATNSimulator extends ATNSimulator {
return alts.getMinElement();
}
/** Walk the list of configurations and strip out any that have predicates,
* that evaluate to false. Create a new set so as not to alter the
* incoming parameter.
/** 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.
*/
protected ATNConfigSet filterForTruePredicates(ATNConfigSet configs,
ParserRuleContext outerContext)
protected Pair<ATNConfigSet,ATNConfigSet> splitAccordingToSemanticValidity(
ATNConfigSet configs,
ParserRuleContext outerContext)
{
ATNConfigSet filtered = new ATNConfigSet(configs.fullCtx);
ATNConfigSet succeeded = new ATNConfigSet(configs.fullCtx);
ATNConfigSet failed = new ATNConfigSet(configs.fullCtx);
for (ATNConfig c : configs) {
if ( c.semanticContext!=SemanticContext.NONE ) {
// TODO: @Sam: do we need to examine pred.isCtxDependent?
// i.e., what do we do if the predicate examines $label?
boolean predicateEvaluationResult = c.semanticContext.eval(parser, outerContext);
if ( predicateEvaluationResult ) {
filtered.add(c);
succeeded.add(c);
}
else {
failed.add(c);
}
}
else {
filtered.add(c);
succeeded.add(c);
}
}
return filtered;
return new Pair(succeeded,failed);
}
/** Look through a list of predicate/alt pairs, returning alts for the