[antlr-interest] Problem using predicates in V3

[Dr. Hartmut Kocher]

The language is fixed :-( And no, I didn't invent it.

Your second solution is also not possible because then "t123a" would parse
OK, but "t 123 a" too, which is not allowed. (Of course there's a whitespace
rule)...

In ANTLR2 I did the following:

tokens {
"abc";
}

IDENT  
   options { 
     testLiterals=true; 
   }
  :     
    ("abc" DIGIT) => "abc"  
  | ('a'..'z') (LD | '_')*;  // LD is letter or digit

This worked quite well. Now I'm trying to accomplish the same with ANTLR 3.
No such luck so far.

Hartmut

-----Ursprüngliche Nachricht-----
Von: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] Im Auftrag von Terence Parr
Gesendet: Sonntag, 11. Februar 2007 21:39
An: ANTLR Interest
Betreff: Re: [antlr-interest] Problem using predicates in V3


On Feb 11, 2007, at 12:26 PM, Dr. Hartmut Kocher wrote:

> I know that this is ambiguous. That's why I tried to solve it with a
> predicate. I need both definitions. In other places in the grammar  
> I have
> identifiers like "t123a". Still 'abc' must always be parsed as  
> 'abc' never
> as identifier. That means 'abc2' must be parsed as 'abc' INT even  
> though it
> matches the definition of the ID token.
>
> So I need to force the lexer to never parse 'abc' as ID.

Oh, you have a context-sensitivity problem.  First thing.  Try not to  
do that.  Either redesign your language or send hate mail to the  
designer. ;)  Now, it might be a simple problem.  Just match ID w/o  
digits and then put back together later using the context from the  
parser.

identifierInSomeCase : IDENT INT? {put backtogether} ;

Ter