[antlr-interest] Exception tests eat performance?

[Karl Meissner]

--- Terence Parr <parrt at cs.usfca.edu> wrote:
> Hi gang, my only additional comment would be that using return values 
> makes it pretty hard to have other return values from a rule, which are 
> arguably very handy.

Which is why I used in my  psuedo code ;-)

But fine, I used returned values in my rules all the time too. 
The traditional alternatives to a return value are

1) reference parameters

void Rule123( .... , ref ResultInfo result) { 

   result = null; // assume success;


   if( someproblem) result = new ResultInfo();    
    
}


2) Sticking the result into some globally accessable place such as a member.  Results could even
be held in a stack, equivlent to inputState.guessing.  

    ....
    Rule456( ); 
    if(  globalResultState != null )  break; 





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