[antlr-interest] Help: What does this mean?

[Jim Idle]

I would suggest that you replace your uses of 'literal' with LEXER 
specified tokens, then analyze this grammar with ANTLRWorks. This will 
give you a visual representation of your issue. 

However it looks like this is part of an expression tree and that you 
have mis-constructed it. Take a look at any of the expression trees in 
the example grammars such as Java and this may help you get your 
expression tree in order. This rule looks likely to be not quite what 
you think it is ;-)

Jim

-----Original Message-----
From: Austin Hastings [mailto:Austin_Hastings at Yahoo.com] 
Sent: Friday, November 16, 2007 10:26 PM
To: antlr-interest
Subject: [antlr-interest] Help: What does this mean?

I get this warning:

   [antlr3] warning(200): 
/home/austin/gunit/sources/org/antlr/gunit/TestSuite.g:504:51: Decision 
can match input such as "'&&'" using multiple alternatives: 1, 2
   [antlr3] As a result, alternative(s) 2 were disabled for that input


For this code:

outputExpr_and returns [Assertion assertion]
    : op1=outputExpr_primary ('&&' op2=outputExpr_and)*
      {
        if (op2 == null)
        {
            $assertion = $op1.assertion;
        }
        else
        {
            $assertion = new Conjunction($op1.start, $op2.stop);
            $assertion.addClauses($op1.assertion, $op2.assertion);
        }
      }
    ;

I don't see two alternatives, unless the * is considered an alternative 
somehow. The 'outputExpr_primary' production is always something 
concrete, either a parenthesized subexpression or a list of keywords - 
never empty. So (1) what are "alternatives 1,2" for this case; and (2) 
how could I display them - is there a "painfully verbose" antlr switch I 

don't know about?

Thanks,

=Austin