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Fix ParserATNSimulator.execDFA adding incorrect error edges in the DFA

This commit is contained in:
Sam Harwell 2012-02-10 00:52:24 -06:00
parent 30c58bf8eb
commit cd3adb140d
1 changed files with 17 additions and 22 deletions
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39
runtime/Java/src/org/antlr/v4/runtime/atn/ParserATNSimulator.java
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@ -372,31 +372,26 @@ public class ParserATNSimulator<Symbol extends Token> extends ATNSimulator {
parser.getInputString(startIndex) +
" at DFA state "+s.stateNumber);
}
try {
alt = execATN(dfa, s, input, startIndex, outerContext);
// this adds edge even if next state is accept for
// same alt; e.g., s0-A->:s1=>2-B->:s2=>2
// TODO: This next stuff kills edge, but extra states remain. :(
if ( s.isAcceptState && alt!=-1 ) {
DFAState d = s.edges[input.LA(1)+1];
if ( d.isAcceptState && d.prediction==s.prediction ) {
// we can carve it out.
s.edges[input.LA(1)+1] = ERROR; // IGNORE really not error
}
alt = execATN(dfa, s, input, startIndex, outerContext);
// this adds edge even if next state is accept for
// same alt; e.g., s0-A->:s1=>2-B->:s2=>2
// TODO: This next stuff kills edge, but extra states remain. :(
if ( s.isAcceptState && alt!=-1 ) {
DFAState d = s.edges[input.LA(1)+1];
if ( d.isAcceptState && d.prediction==s.prediction ) {
// we can carve it out.
s.edges[input.LA(1)+1] = ERROR; // IGNORE really not error
}
if ( dfa_debug ) {
System.out.println("back from DFA update, alt="+alt+", dfa=\n"+dfa.toString(parser.getTokenNames()));
//dump(dfa);
}
// action already executed
if ( dfa_debug ) System.out.println("DFA decision "+dfa.decision+
" predicts "+alt);
return alt; // we've updated DFA, exec'd action, and have our deepest answer
}
catch (NoViableAltException nvae) {
addDFAEdge(s, t, ERROR);
throw nvae;
if ( dfa_debug ) {
System.out.println("back from DFA update, alt="+alt+", dfa=\n"+dfa.toString(parser.getTokenNames()));
//dump(dfa);
}
// action already executed
if ( dfa_debug ) System.out.println("DFA decision "+dfa.decision+
" predicts "+alt);
return alt; // we've updated DFA, exec'd action, and have our deepest answer
}
DFAState target = s.edges[t+1];
if ( target == ERROR ) {