[antlr-interest] Newbie Question

[Jim Idle]

Behdad Forghani wrote:
> Hello,
>
> I am trying to built AST from a rule with an optional part.
> The rule is:
>
> type :
> 	builtinType  constraint?;
>
>
> I want the constraint node to be the child of builtinType. So, I add:
>
> type :
>    builtinType  constraint?->^(builtinType constraint?);
>   
That should be fine, unless the constraint has more than one node 
itself, which I am guessing is your issue. You probably really want an 
imaginary token here:

tokens {
BUILTINTYPE;
}

type :
   builtinType  constraint?->^(BUILTINTYPE builtinType constraint?);

;

Jim