[antlr-interest] lexer problem

Robert Soule robert.soule at gmail.com
Mon Nov 3 14:17:51 PST 2008


Thank you! My problem was that I was testing the solution with the
interpreter.

thanks again for your help,
Robert

On Mon, Nov 3, 2008 at 3:00 PM, Gavin Lambert <antlr at mirality.co.nz> wrote:
> At 04:59 4/11/2008, Robert Soule wrote:
>>start
>>       : LSQUARE AB RSQUARE
>>       | A
>>       ;
>>AB     :       ('a'|'b')+;
>>
>>fragment A: '[a]';
>>LSQUARE
>> :  (A) => A { $type = A; }
>> |  '['
>> ;
>>
>>RSQUARE        :       ']';
>>
>>
>>When I test with inputs "[ba]" I pass, but "[ab]" fails.
>
> It works for me (ANTLR 3.0.1).  You are using a real compiled parser,
> though, right (or ANTLRworks' debugger)?  Not the interpreter?  Because the
> interpreter doesn't execute predicates (so it almost never works properly).
>
> If I change the start rule given above to this:
>
> start : (LSQUARE AB RSQUARE | A)+ ;
>
> then it'll successfully match the input "[ba][a][ab]".
>
>


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