AntlrWorks 2 output

Question

So i am using Antlrworks 2, working on a rather large grammar. Problem is that in this grammar there are multiple ambiguities that i am trying to work through.

I was wondering if there is a way to interpret which rules were invoked when there was a failure.

For instance, when i run my rule i get following output

[@0,0:1='99',<20>,1:0]
[@1,2:1='<EOF>',<-1>,1:2]
line 1:0 mismatched input '99' expecting Digit2
(dummy 99)

I am wondering what [@0,0:1='99',<20>,1:0] means. Do the @0 or <20> have any relationship to the rule number in my grammar or something ?

Answer 1

Here is a breakdown of the default token formatting.

[@{TokenIndex},{StartIndex}:{StopIndex}={Text},<{TokenType}>,{Line}:{Column}]

The {TokenType} field generally corresponds to a particular lexer rule (the constant will be declared in your generated lexer). However, the -> type(X) command can be used in any lexer rule to reassign tokens produced by that rule to another type. If the value 20 is assigned to the token named Foo, then the first token in your listing was produced by either a lexer rule named Foo or a lexer rule containing the action -> type(foo) or you have a user-defined action which explicitly assigns the type Foo to a token produced by some other rule (this will be code you wrote, not code generated by ANTLR).