preprocessor

Jul 23, 2010 at 11:03 PM
I'm implementing a language which has a c-like preprocessor- #define, #undef, #include, etc. At the moment I don't really care about expanding them in the AST, I'd just like them to be appropriately parsed. The trick is that they can be anywhere. My guess is that I should create a new Terminal and add it the to the NonGrammarTerminals list. Would it be appropriate to derive from CompoundTerminalBase, say with a prefix like "#define" and a suffix of a newline? Or would that fail on a multiline #define (with trailing backslash), and I should look at CommentTerminal instead? And if I wanted to store the #define text (for providing tooltips in Visual Studio), what would be a good way to go about that? Any direction would be appreciated.
Coordinator
Jul 26, 2010 at 5:10 PM
I think it should be a custom terminal, with a highly specialized matching function. You would also need some special facility to do actual substitution to recognize macro reference (probably hook it into Identifier terminal) and to perform actual substitution - token filter I guess, that would push-back the expanded macro definition back into scanner source - or (alternatively) inject a set of tokens into the token stream. Still I don't have a ready to use solution or recipe for this, still thinking how to support this in Irony. I've been long asked about supporting c-style macros, but did not get to this yet. Try playing with a token filter