[antlr-interest] difference in tree parser..

[pady]

I have a simple if-else grammar ( attached Gwf.g and GwfWalker.g ). When I
run this, I get issues around even handling simple if-else. I debugged
through the generated code and found that one of the generated tree parser
code was looking for an UP token when deciding on the predicate. So I wrote
a very similar simplified grammar ( attached X.g and XW.g ) which has
similar logic for the if-else rule alone. This one works as expected ( and
the generated java code is exactly as expected ).

Can anybody take a quick look at why this difference is there below ? ( the
"ifStatement" rule in Gwf*.g and the "ifRule" rule in X*.g ).

Gwf.g ( grammar )

ifStatement
  : 'if' boolExpression s1=statement (options {k=1;}: 'else' s2=statement)?
  -> ^('if' boolExpression ^(TRUE_COND $s1 ) (^(FALSE_COND $s2 ))?)
  ;

GwfWalker.g ( tree grammar )


ifStatement
   : ^('if' b=boolExpression
       ^(TRUE_COND ({$b.result}? => statement | .))
       (^(FALSE_COND ({!$b.result}? => statement | .)))?)
   ;


X.g ( grammar )

ifRule
 : 'if' boolExpr r1 r2? -> ^(R1_TOK r1) (^(R2_TOK r2))?
 ;

XW.g ( tree grammar )

ifRule
 : ^('if' b=boolExpr ^(R1_TOK ({$b.res}?=> r1 | .)) (^(R2_TOK ({!$b.res}?=>
r2 | .)))?)
 ;




Thanks

-- pady
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