Hi, I have a question regarding the possibility of messing with the compiler in the area of lexical tie-ins.
Basically, I am working on LilyPond, a language with a rather free-form syntax. The problem area I am with is the area of function calls: a function call token is recognized in the lexer, and the lexer looks at the required argument list and types and produces appropriate tokens causing the parser to collect the function arguments. Now since the language is basically free-form, quite a few arguments are undelimited and are recognized as being complete once the lookahead token can no longer become part of the argument. Now here is the problem: after the argument list is collected, I might have a lookahead token already. The function is called, and only after the call the _syntactic_ category of the call is determinable, so I need to inject an appropriate token into the stream. The question now is at what point of time it is too late to swap out the lookahead token because its state is irretrievably part of the parser state? Can I still swap it out as long as it has not been shifted and has only caused reductions? Or may that be too late? It would seem to me that the basic definition of LALR(1) which makes the lookahead token not be part in the reduction rules itself would make it somewhat plausible that an algorithm working on LALR(1) efficiently might fully reconsider the lookahead token after every reduction. But that's just guessing. Are there any hard or soft criteria about when it may or may not be allowed to pull the lookahead token out from under Bison and put something else there? Thanks -- David Kastrup _______________________________________________ help-bison@gnu.org https://lists.gnu.org/mailman/listinfo/help-bison
