[antlr-interest] Bug (difference) in ANTLR 3.2 tree matching.

[Jim Idle]

Are you by any chance constructing those nodes/trees yourself? I have seen behavior differences because people did not call setParent on nodes they constructed their selves and the tree walker then ends up following siblings/children that are not really there. Perhaps you can show the code/grammar you are using to generate the AST? There might be a bug I suppose.

Jim

> -----Original Message-----
> From: Michael Matera [mailto:mike.matera at xilinx.com]
> Sent: Tuesday, December 15, 2009 4:01 PM
> To: Gavin Lambert
> Cc: Jim Idle; antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Bug (difference) in ANTLR 3.2 tree
> matching.
> 
> Hi,
> 
> Sorry to nag, but my test case shows that what you have suggested is
> not
> the problem.  During the test case execution I print out the AST that
> resulted from matching the wildcard and, in both 3.1.1 and 3.2, the
> resulting AST is exactly the same.  The difference in behavior is
> caused
> by running my TreeParser on the resulting AST.  In 3.2 it seems that
> more nodes magically appear when they shouldn't.
> 
> Cheers
> ./m
> 
> 
> Gavin Lambert wrote:
> > At 10:44 10/12/2009, Michael Matera wrote:
> >>It seems that the '.' operator has become more greedy in
> >>the 3.2 release.
> >
> > I haven't tried 3.2 myself yet, but from what I recall of prior
> > discussion on the list:
> >  - in 3.0 and 3.1 the . operator was "match a single token" and did
> not
> > consume an entire subtree.
> >  - in 3.2, the . operator is supposed to be "match a single token or
> > subtree".
> >
> > So 3.2's . should be the equivalent of 3.0 or 3.1's "(. | ^(. .+))".
> > (Whether that's actually the case or not, I don't know.)
> >
> >
> > ie. given a rule:
> >   rule : ^(ROOT a=. b=. c=.) ;
> >
> > under 3.0/3.1 people were reporting:
> >   input = ^(ROOT ID ^(BLOCK ONE TWO) THREE)
> >   a = ID
> >   b = BLOCK
> >   c = DOWN
> > (I think.  c might have been ONE or THREE instead [I don't remember],
> > but b wasn't the whole subtree.)
> >
> > Under 3.2 it's supposed to do what you'd expect.  (Again, whether it
> > does or not...)
> >
> >
> 
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