[antlr-interest] How do I skip a subtree walking in a tree grammar?

[Shihwei Li]

Hi,

How do I skip a subtree walking in a tree grammar?

I have a tree grammar to evaluate a boolean expression. What I want to do is
to implement 'conditional' boolean expression:
say the expression is 'A and B', then if the evaluation of A is already
false, I want to skip the evaluation (walking) of B subtree. How do I do
that?

It seems that I can't insert an action like:
       * ^( AND a=bool_exp { if (!a) return false; } b=bool_exp) { $value =
(a && b); },*
because it messes up the token stream for further tree walking.

Here is my original tree grammar:

*bool_exp returns [boolean value]
   throws ConditionExpressionException
   :
       not_bool_exp                  { $value = $not_bool_exp.value; }
   |
       ^( OR a=bool_exp b=bool_exp)  { $value = (a || b); }
   |
       ^( AND a=bool_exp b=bool_exp) { $value = (a && b); }
   ;
*
--peter
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