[antlr-interest] charVocabulary having no effect

[André Næss]

On Mon, 13 Dec 2004 11:37:03 -0800, Terence Parr <parrt at cs.usfca.edu> wrote:

> > To my Lexer options.
> >
> > But I'm still getting unexpected char errors. I have a fairly simple
> 
> Is it because you have not included a rule to match those chars?
> Saying all ascii in the vocab means you must have a rule to handle any
> ascii char that comes in.  For example,  you have no rule for left
> bracket.  If that comes along, you'll get an unexpected char error.

Well yes, there was no rule to match the character, not until I added
a dummy one anyway. But it was still my understanding that when I use
.*, or in my case:

        (
            options {
                greedy=false;
            }
        :   .
        )*
 
charVocabulary would be used. Useful when you're matching strings for
example. In my case I want to discard that which is matched by the .*,
but what if I wanted to keep it?

> > The error goes away, but then it stops on some other char. This
> > continues until I've added all the chars not listed in some rule in
> > the lexer. So to be sure it seems I will have to explicitly list *all*
> > the ASCII characters.
> 
> Well, yeah.  If you want it to ignore stuff you don't have rules for,
> just set filter=true. :)

What I'm trying to achieve is to match a function prototype but ignore
it's body. Functions are declared using FUNCTION .. END_FUNCTION
pairs, so I use the above non-greedy (.)* construct to match the body.
But filter seems to work and is probably a much better idea, thanks
for the tip!

Regards
André Næss


 
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