[antlr-interest] Parsing comments

[Jim Idle]

fragment WRAPPER : ;
COMMENT : '//' SPACE*
      ( ('@')=> '@' (~WSCHARS)* { $type = WRAPPER; }
         |  ' (~WSCHARS)*
       )
;

Always left factor and change the token type dynamically.

Jim

On Sep 17, 2009, at 7:55 AM, Soren Holstebroe <holstebroe at gmail.com>  
wrote:

> Hi,
>
> I have this project where C++ templates are being unfolded and  
> wrapped in .NET. This wrapping is performed by some perl-scripts  
> which over time have become quite messy, so I wanted to rewrite the  
> wrapper using ANTLR.
>
> The way the current template wrapper works is by parsing simple  
> template expressions defined in the comments preceding a function  
> definition. This is similar to documentation frameworks like  
> doxygen, where the documentation is embedded in the comments above  
> functions, classes, etc.
> The simple syntax contains elements like this:
> // @TEMPLATE <int, float>
> which tells the wrapper to unfold the template using an int for the  
> first template type and a float for the second.
>
> My problem is that I am already stuck in defining the lexer.
> Since all wrapper expressions start with '@' I tried to define a  
> token like:
> WRAPPERSTART : SLASHSLASH SPACE* '@'
> and some grammar rules based on that token.
> However that doesn't work since the lexer will always choose the  
> longest matching rule, which would always be the normal single line  
> comment rule.
>
> I can imagine that there are many approaches to tackle this problem  
> and some hints would be greatly appreciated.
>
> Soren
>
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