[antlr-interest] Semantic Predicates and SemanticExceptions

[Monty Zukowski]

By the way you need to keep your semantic predicates in place so the 
exception is thrown that the syntactic predicate catches.

Monty

On Aug 2, 2004, at 10:04 AM, Monty Zukowski wrote:

> On Aug 2, 2004, at 9:38 AM, johnj1984 wrote:
>
>>    Essentially I need to tell the parser that when my semantic check
>> fails, it should backtrack from the failed evaluation only,
>> successfully exit the rules its matched so far, and reparse the
>> failed text from somewhere higher in its rule hierarchy.
>
> To achieve backtracking you need to use syntactic predicates, up at the
> point where you want to backtrack to.  Something like this:
>
>     ruleClassDeclaration
>     	: ((ruleProcedureDeclarationPart)=>ruleProcedureDeclarationPart) *
>     	;
>
> Ignore the warning about a superfluous syntactic predicate, it's wrong.
>
> Monty
>
> 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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