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Improve robustness and correctness of two functions used by intellij antlr4 plugin to show ambig and lookahead parse trees.

This commit is contained in:
parrt 2016-11-19 13:06:49 -08:00
parent 201925b2da
commit f5d3e4cfe6
1 changed files with 36 additions and 25 deletions
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61
tool/src/org/antlr/v4/tool/GrammarParserInterpreter.java
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@ -48,6 +48,7 @@ import org.antlr.v4.runtime.atn.DecisionState;
import org.antlr.v4.runtime.atn.PredictionMode;
import org.antlr.v4.runtime.atn.RuleStartState;
import org.antlr.v4.runtime.atn.StarLoopEntryState;
import org.antlr.v4.runtime.misc.Interval;
import org.antlr.v4.runtime.tree.Trees;
import java.lang.reflect.Constructor;
@ -292,22 +293,26 @@ public class GrammarParserInterpreter extends ParserInterpreter {
* ambig input.
*/
public static List<ParserRuleContext> getAllPossibleParseTrees(Grammar g,
Parser originalParser,
TokenStream tokens,
int decision,
BitSet alts,
int startIndex,
int stopIndex,
int startRuleIndex)
throws RecognitionException
{
Parser originalParser,
TokenStream tokens,
int decision,
BitSet alts,
int startIndex,
int stopIndex,
int startRuleIndex)
throws RecognitionException {
List<ParserRuleContext> trees = new ArrayList<ParserRuleContext>();
// Create a new parser interpreter to parse the ambiguous subphrase
ParserInterpreter parser = deriveTempParserInterpreter(g, originalParser, tokens);
if ( stopIndex>=(tokens.size()-1) ) { // if we are pointing at EOF token
// EOF is not in tree, so must be 1 less than last non-EOF token
stopIndex = tokens.size()-2;
}
// get ambig trees
int alt = alts.nextSetBit(0);
while (alt >= 0) {
while ( alt>=0 ) {
// re-parse entire input for all ambiguous alternatives
// (don't have to do first as it's been parsed, but do again for simplicity
// using this temp parser.)
@ -318,16 +323,15 @@ public class GrammarParserInterpreter extends ParserInterpreter {
(GrammarInterpreterRuleContext) Trees.getRootOfSubtreeEnclosingRegion(t, startIndex, stopIndex);
// Use higher of overridden decision tree or tree enclosing all tokens
if ( Trees.isAncestorOf(parser.getOverrideDecisionRoot(), ambigSubTree) ) {
ambigSubTree = (GrammarInterpreterRuleContext)parser.getOverrideDecisionRoot();
ambigSubTree = (GrammarInterpreterRuleContext) parser.getOverrideDecisionRoot();
}
trees.add(ambigSubTree);
alt = alts.nextSetBit(alt + 1);
alt = alts.nextSetBit(alt+1);
}
return trees;
}
/** Return a list of parse trees, one for each alternative in a decision
* given the same input.
*
@ -355,25 +359,25 @@ public class GrammarParserInterpreter extends ParserInterpreter {
* @since 4.5.1
*/
public static List<ParserRuleContext> getLookaheadParseTrees(Grammar g,
ParserInterpreter originalParser,
TokenStream tokens,
int startRuleIndex,
int decision,
int startIndex,
int stopIndex)
{
ParserInterpreter originalParser,
TokenStream tokens,
int startRuleIndex,
int decision,
int startIndex,
int stopIndex) {
List<ParserRuleContext> trees = new ArrayList<ParserRuleContext>();
// Create a new parser interpreter to parse the ambiguous subphrase
ParserInterpreter parser = deriveTempParserInterpreter(g, originalParser, tokens);
BailButConsumeErrorStrategy errorHandler = new BailButConsumeErrorStrategy();
parser.setErrorHandler(errorHandler);
DecisionState decisionState = originalParser.getATN().decisionToState.get(decision);
for (int alt=1; alt<=decisionState.getTransitions().length; alt++) {
for (int alt = 1; alt<=decisionState.getTransitions().length; alt++) {
// re-parse entire input for all ambiguous alternatives
// (don't have to do first as it's been parsed, but do again for simplicity
// using this temp parser.)
GrammarParserInterpreter.BailButConsumeErrorStrategy errorHandler =
new GrammarParserInterpreter.BailButConsumeErrorStrategy();
parser.setErrorHandler(errorHandler);
parser.reset();
parser.addDecisionOverride(decision, startIndex, alt);
ParserRuleContext tt = parser.parse(startRuleIndex);
@ -381,10 +385,17 @@ public class GrammarParserInterpreter extends ParserInterpreter {
if ( errorHandler.firstErrorTokenIndex>=0 ) {
stopTreeAt = errorHandler.firstErrorTokenIndex; // cut off rest at first error
}
Interval overallRange = tt.getSourceInterval();
if ( stopTreeAt>overallRange.b ) {
// If we try to look beyond range of tree, stopTreeAt must be EOF
// for which there is no EOF ref in grammar. That means tree
// will not have node for stopTreeAt; limit to overallRange.b
stopTreeAt = overallRange.b;
}
ParserRuleContext subtree =
Trees.getRootOfSubtreeEnclosingRegion(tt,
startIndex,
stopTreeAt);
startIndex,
stopTreeAt);
// Use higher of overridden decision tree or tree enclosing all tokens
if ( Trees.isAncestorOf(parser.getOverrideDecisionRoot(), subtree) ) {
subtree = parser.getOverrideDecisionRoot();