Gokulakannan Somasundaram wrote: > Hi, > I have a requirement, where in before starting the parsing, i > need to tell the parser whether the first token is T_FUNCTION / > T_TRIGGER(say callType). (i.e) this token is not available as part of > the text to be parsed. In Bison, it is just declared with %token > T_FUNCTION and %token T_TRIGGER. The scanner makes sure that it emits > the callType token before it emits the tokens to be parsed. Although, > i am able to come up with some ways to do this, they are too ugly. > Can someone provide me a clean way of passing information > into the parser and make the scanner emit that as the first token, > even before the actual tokens are emitted? I am trying to do this in > C-Language target. I think that it is unlikely that you need to do this as some of the reasons that you would do this in bison are not limitations in ANTLR. For parsing you only need a token type and then access to the text that this represents, then you may or may not require a custom token type for an AST node for your tree.
So, you can change token types in the lexer by looking ahead in the character stream and making decisions on what you see (which is sometimes required), or more likely, just return something generic like ID, and let the parser work out what this represents. You can emit() multiple tokens if you really need to, but the chances are fairly slim that you really need to I think. Gavin pointed out where you start, but the code needed to implement this is fairly involved and I bet if you just rethink your lexer/parser in an 'ANTLR' way, you will find you don't need to do it. Jim 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-interest@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 -~----------~----~----~----~------~----~------~--~---
