[antlr-interest] Question on aborting rule based on pattern

[Rajeev Bharadhwaj]

I tried inserting the semantic predicate, it fires
alright but it throws a SemanticException. This looks
more like a mechanism to find syntax errors and abort
the parsing. In my case, I want to catch the exception
and stop matching ddd and continue parsing.

Rajeev

--- Stanimir Stamenkov <stanio at myrealbox.com> wrote:

> /Rajeev Bharadhwaj/:
> 
> > How do I stop matching so it can reduce the rule?
> > 
> > aaa : "AAAA" SPACE bbb ccc ;
> > 
> > bbb : ( ddd )+ ;
> > 
> > ddd : ha:ATOM ":" SPACE eee SPACE ; // Rule 1
> > 
> > eee : hva:ATOM (":" hvap:ATOM)* ;
> > 
> > ccc : "XXX" ":" SPACE ((cccentry)+ ; // Rule 2
> > 
> > I would like Rule 1 to stop matching when
> > ha.getText()==XXX, so aaa can shift to Rule 2
> (ccc).
> > 
> > ATOM matches alphabets and numbers to create
> strings.
> 
> Do semantic predicates [1] work for you?
> 
> ddd : ha:ATOM { !"XXX".equals(ha.getText()) }? ...
> 
> [1]
>
http://www.antlr.org/doc/metalang.html#SemanticPredicates
> 
> -- 
> Stanimir
> 


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