[antlr-interest] Semantic Predicates and SemanticExceptions
Monty Zukowski
monty at codetransform.com
Mon Aug 2 10:26:20 PDT 2004
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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>
>
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