[antlr-interest] What tool[s] do you use when debugging ANTLR grammars?

Greg Lindholm glindholm at yahoo.com
Thu Jun 20 21:04:49 PDT 2002


The two things I've found helpful is:

1) In the parser override reportError() so that it prints type (name)
of the token and prints a stack trace. The default reportError() only
prints the text of the token which is often not enough if you have a
bug in your lexer.

{
    // Override default error reporting
    public void reportError(RecognitionException ex) {
        if (ex instanceof NoViableAltException) {
            NoViableAltException e = (NoViableAltException) ex;
            System.err.println(
                 "("+ MyParser._tokenNames[e.token.getType()]+")");
        }
        ex.printStackTrace();
    }
}

2) When things get really tough I build with the "-T" option to print
trace info.

Greg

--- micheal_jor <open.zone at virgin.net> wrote:
> Following on from my grammar debugging issues and recent ParseView 
> post, I'd like to know what tools others rely on for debugging 
> grammars.
> 
> I've re-written my grammar many times already due to a number of 
> seemingly intractable warnings/errors. I am just about to rewrite 
> again but this time I am starting off by designing an heterogenous 
> AST structure and working my way back from that to the grammar.
> 
> So what tools do you use for grammar debugging and, what tips can you
> 
> offer an ANTLR newbie on grammar creation and debugging?
> 
> Micheal
> 
> 
> 
>  
> 
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/ 
> 
> 


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