[antlr-interest] Re: Lexer problem
manfredlotz
Manfred.Lotz at web.de
Sat Dec 29 01:09:16 PST 2001
After scanning ".a." the lexer seems to think it has to be ",a,a".
After finding 'b' it says unexpected char.
Can a syntactic predicate help. I have to admit that I didn't
understand exactly what it is and what it can do for me.
Manfred
--- In antlr-interest at y..., mzukowski at b... wrote:
> Take a look at the generated code. Can you see why it doesn't work?
You
> may need to use a syntactic predicate in front of ".a.a".
>
> Monty
>
> > -----Original Message-----
> > From: manfredlotz [mailto:Manfred.Lotz at w...]
> > Sent: Thursday, December 27, 2001 9:41 PM
> > To: antlr-interest at y...
> > Subject: [antlr-interest] Lexer problem
> >
> >
> > Using the definiton shown below the lexer has a problem to
recognize
> > tokens if they arrive in a certain order.
> >
> > E.g., ".a.a.b$" or ".ac$" work fine, however ".a.b$" does not.
> >
> > Any idea what I have to change to make it working. I know it has
to do
> > with the fact that ".a" is a substring of ".a.a" but I don't know
how
> > to improve the t.g file.
> >
> > Manfred
> > _____________________
> >
> > class TLexer extends Lexer;
> > options {
> > k=4;
> > filter=IGNORE;
> > }
> >
> > MYENDTOKEN : '$' ;
> >
> > A : ( ".a" | ".a.a" | ".b" | 'a' | 'c' ) ;
> >
> > protected
> > IGNORE : ( "\r\n" | '\r' | '\n' ) { _ttype = Token.SKIP; };
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
More information about the antlr-interest
mailing list