None of those suggestion will help with the actual grammar unfortunately. It is indeed ambiguous, that is the warning I get if I turn backtracking off, but I can't refactor the rules (or the actual, large grammar) w/o ending with a completely meaningless AST.
I still don't understand why antlr won't backtrack there, I suspect this is a limitation of the implementation strategy that uses predicates; or maybe I am expecting too much and the kind of backtracking required here would be too hard or expensive to implement? Basically I have an ambiguous but valid non left-recursive grammar, and I don't see why antlr after failing on one branch doesn't backtrack to try the other branch of the ambiguity. I do use the debugger, and it shows that the (automatically generated) syntactic predicate for expr passed ( DOT ^( EXPR "c" ) ) and that b.c was accepted as an expr, and the next node in the parse tree is the MissingTokenExpression at = (the parser expects a separator at that point). Replacing the '.' literal by an explicit DOT token doesn't make any difference. -- View this message in context: http://antlr.1301665.n2.nabble.com/Confused-about-backtracking-tp7033712p7039721.html Sent from the ANTLR mailing list archive at Nabble.com. List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to il-antlr-inter...@googlegroups.com. To unsubscribe from this group, send email to il-antlr-interest+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
