[antlr-interest] Whitespace is significant sometimes
Daniel Lidström
daniel.lidstrom at gpsgate.com
Tue Sep 28 02:46:55 PDT 2010
From: "Loring Craymer" <lgcraymer at yahoo.com>
> This is the sort of problem that can be solved with lexer modes. ANTLR 3
> does
> not support lexer modes, however, so the usual approach is two phase
> parsing,
> where the first pass would parse text outside of [ ] but recognizes [
> ... ]
> constructs as single tokens. The second pass processes the text inside of
> braces. Not pretty, but it works. Trying to implement something which
> requires
> feedback between parser and lexer is a bad idea, even if you can get it to
> work:
> the resulting grammars will be very fragile.
>
> --Loring
Hello Loring. I was just about to implement my scheme when I realized just
what
you are saying. The approach you suggest does seem a lot easier. I figured I
can
use semantic actions at each rule to build an expression tree of my own
classes.
Then I can build a special node that handles the "inner" grammar of variable
rules ([xxx]).
Sounds reasonable to me, at the moment anyway.
Thank you for your suggestion!
Daniel
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