[antlr-interest] Lexer confusion

[Monty Zukowski]

On May 26, 2004, at 8:23 PM, FranklinChen at cmu.edu wrote:
> WORD
>     :
>         'A'
>         (
>             HYPHEN
>             'A'
>         )*
>     ;

> the generated code goes into WORD,
> sees HYPHEN, and then wants an 'A' and bombs out because there isn't
> any.

Yes, that is exactly as you have specified the WORD rule.  If you see 
an A followed by a HYPHEN it must be followed by A.

This may be something not so obvious with antlr's approximate lookahead.

Try this:

WORD
     :
         'A'
         ( (HYPHEN 'A')=>
             HYPHEN
             'A'
         )*
     ;

That will give a warning about a superflous syntactic predicate, but it 
should work.


Monty Zukowski

ANTLR & Java Consultant -- http://www.codetransform.com
ANSI C/GCC transformation toolkit -- 
http://www.codetransform.com/gcc.html
Embrace the Decay -- http://www.codetransform.com/EmbraceDecay.html



 
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