[antlr-interest] Simple question, Hard answer?

[Thomas Brandon]

On Wed, Sep 3, 2008 at 7:13 PM, Bill Mayfield <antlrinterest at gmail.com> wrote:
> Hi,
>
> Suppose I want to recognize each pattern 'okko' in a random string of
> characters. Some examples:
>
> aaaaaoookoooookkooooaaa -> should yield one match of 'okko'
> aaaokkookko -> should yield two matches of 'okko'
>
>
>
> Here is a grammar that won't work ;o)
>
> grammar test;
>
> start   :       .* pattern .*;
>
> pattern :       T1 T2 T2 T1;
>
>
> T1      :       'o';
> T2      :       'k';
>
Wildcards in parser rules match any token, not any character. As your
lexer only matches 'o'|'k' anything else will cause a lexer error. Try
adding a lexer rule to match any other input after your other lexer
rules, like:
OTHER: .;
Or you may want to look at filtering lexers as they may be better
suited to your task.

Tom.
>
> No matter what grammar I try. I can't get it to work... how hard can it be?
>
>
> Thanks for any input you may provide,
> Bill
>
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