Question

I’m trying to get the feel for antlr3, and i pasted the Expression evaluator into an ANTLRWorks window (latest version) and compiled it. It compiled successfully and started, but two problems:

• Attempting to use a input of 1+2*4/3; resulted in the actual input for the parser being 1+2*43.
• One of the errors it shows in it’s graphical parser tree is MissingTokenException(0!=0).

As i’m new to antlr, can someone help?

Answer 1

The example you linked to doesn’t support division (just look at the code, you’ll notice there’s no division here:

expr returns [int value]
    :   e=multExpr {$value = $e.value;}
        (   '+' e=multExpr {$value += $e.value;}
        |   '-' e=multExpr {$value -= $e.value;}
        )*