[antlr-interest] Skip subtree with gated semantic predicate in tree parser - need help

[fridi]

Hi all,

I tried to skip a rule in an if-then-else construct using gated symantic 
predicates. 
This works well until the subrule itself is a tree (i.e. a nested 
if-then-else), and this tree should be skipped if the expression returns false.

So it seems, that the '.' does not match the whole subtree? I get this error: 
Eval.g: node from after line 1:21 no viable alternative at input 'DOWN

Thanks for any hint, fridi



ifElse
scope {
   boolean expResult;
} :
    ^(
       IFTHEN b = expression { $ifElse::expResult = b; }
       (
          {$ifElse::expResult == true}?=> actionSequence
          | . // if expResult == false, no action required but eat the token
       )
      )	
    ;


(full grammar see attachments)





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