Right now this only breaks tree parsers. However, the fundamental semantics of the mark/rewind operation indicate they should come in pairs.
There is a matched mark/rewind inside each of the semantic predicate evaluation functions. I'm not even sure this rewind is needed, but I also don't have proof that it's not. Sam -----Original Message----- From: Terence Parr [mailto:[email protected]] Sent: Tuesday, March 03, 2009 7:43 PM To: Sam Harwell Cc: [email protected] Subject: Re: [antlr-dev] cyclicDFAState template incompatible with unbuffered tree node streams On Mar 3, 2009, at 4:06 PM, Sam Harwell wrote: > Taken from Java.stg, we end up with a mismatched mark/rewind, which > causes the temporary stream buffer (FastQueue) to flush during a > predict operation that encounters predicates. oh right! that used to work because we buffered up the entire thing. thanks for catching this Sam! > > /** A state in a cyclic DFA; it's a special state and part of a big > switch on > * state. > */ > cyclicDFAState > (decisionNumber,stateNumber,edges,needErrorClause,semPredState) ::= << > int LA<decisionNumber>_<stateNumber> = input.LA(1);<\n> > <if(semPredState)> <! get next lookahead symbol to test edges, then > rewind !> > int index<decisionNumber>_<stateNumber> = input.index(); > input.rewind();<\n> > <endif> > s = -1; > <edges; separator="\nelse "> > <if(semPredState)> <! return input cursor to state before we > rewound !> > input.seek(index<decisionNumber>_<stateNumber>);<\n> > <endif> > if ( s>=0 ) return s; > break; > >> > > For now I noticed it "works" to simply add a call input.mark() right > after the call to input.rewind(), but I don't think that's the > proper solution. Hmm...now I have to remember what the hell I meant the stuff to do. I assume this is for a tree parser since the parser is not yet using the fast queue? Ter _______________________________________________ antlr-dev mailing list [email protected] http://www.antlr.org/mailman/listinfo/antlr-dev
