[antlr-interest] Grammar refuses to compile (Simple ANTLR gotcha)

[Ilia Kantor]

Thanks, David, 

You were right, actually I put predicates one level lower then they should be =)
Works fine with suggested fix.

> On Tue, Apr 24, 2007 at 04:40:51PM +0400, Ilia Kantor wrote:
> > This grammar doesn't compile (ambiguitiy)
> > 
> > I want "rule_call" to match "#a.b.c" from arbitrary text
> > 
> > Could you please explain what's the reason of error I have here and how to fix it ?
> > 
> > warning(200): My.g:8:24: Decision can match input such as "DOT WORD" using multiple alternatives: 1, 2
> > As a result, alternative(s) 2 were disabled for that input
> > warning(200): My.g:8:24: Decision can match input such as "MINUS GT WORD" using multiple alternatives: 1, 2
> > As a result, alternative(s) 2 were disabled for that input
> > 
> > 
> > -----------------------------------------
> > 
> > document:
> > 	(text | rule_call)+;
> >         
> > rule_call: 
> > 		GET_SCOPE_VALUE WORD rule_long_def_part+;
> > 	
> > rule_long_def_part
> > 	:	
> > 	(MINUS GT WORD) => MINUS GT WORD | 
> > 	(DOT WORD) => DOT WORD;
> > 	
> > 
> > text:
> > 	DOT | MINUS | WORD | WS| GT | SPECIAL_CHAR ;
> 
> I'd try adding,
> 
>   ((rule_long_def_part)=> rule_long_def_part)+
> 
> to make ANTLR match that content 'now', rather than exiting rule_call
> and matching the tokens with text+ in the document rule.  I guess you
> don't need the predicates in rule_long_def_part itself?
> 
> [I didn't test that though.]
> 
> dave
> 
> -- 
> http://david.holroyd.me.uk/
>