[antlr-interest] short circuiting further evaluation

[Jane Eisenstein]

I also don't know how to short circuit further parsing of sub trees when appropriate. I suspect these problems are related. :-)

Jane

On May 28, 2010, at 8:47 AM, Jane Eisenstein wrote:

> I'm working with a simple expression grammar:
> 
> condition:	conditional_expression  EOF
> 	;
> 
> conditional_expression 
> 	:	conditional_term  
> 		(  OR conditional_expression  )?
> 	;
> 
> conditional_term 
> 	:	conditional_factor
> 		( AND conditional_term  )? 
> 	;
> 
> conditional_factor 
> 	:	conditional_primary
> 	|	NOT conditional_primary
> 	;
> 
> conditional_primary 
> 	: ID 
> 	| LEFT_PAREN conditional_expression RIGHT_PAREN 
> 	;
> 
> At runtime, ID tokens evaluate to either true or false. Once it is clear the condition as a whole will evaluate to either true or false, I'd like to stop the evaluation and return the value of the condition. So far, all I've managed to do is short-circuit further ID evaluations once an upper level outcome is know.
> 
> Is there a way to short circuit the entire parse? I'm not sure how to even tell it would be time to do so.
> 
> Jane
> 
> 
> 
> 
> 
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