[antlr-interest] Beginner questions

Kay Röpke kroepke at classdump.org
Tue Jan 8 08:57:41 PST 2008


Hi!

On Jan 7, 2008, at 5:25 PM, Damien wrote:

> 1) My grammar runs fine on the input "d+f(-2)" but the interpreter  
> fails with "FailedPredicateException". Is "backtrack=true"  
> impossible in interpreted mode?

Currently not, no. I don't remember the exact problems with it, but it  
isn't implemented. You can use the debugger to attach to an external  
driver class, though. That should work.

>
> 2) Using the debugger on the input "d+f(-2)", the part of the parse  
> tree from atom > functionExpr > .. appears in double, the one on the  
> left being green. I can't find what that means.

That's a skipped parse tree when backtracking, IIRC. The last one in  
green is the one that matched.

>
> 3) I'm using java as the target language. I can't find how the  
> access the parse tree, only the AST with the option output=AST.


See http://www.antlr.org/wiki/pages/viewpage.action?pageId=1760

cheers,
-k
-- 
Kay Röpke
http://classdump.org/








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