Sven Van Echelpoel wrote:
> Hi,
>
> I have observed that the pairing of @init/@after seems to be lost once
> backtracking is introduced, at least in a tree grammar. Most of my rules
> look like this:
>
> some_rule
> @init { enterParserRule( SomeRule ); }
> @after { leaveParserRule( SomeRule ); }
>
@after is not supported in the C target. While it can be hacked in,
there are ramification for all the combinations of backtracking,
predicates, exceptions and so on. I do intend to give this a thorough
going over before the next release though.
You can generally do what you need though like this:
s : {start();} ( alt1 | alt2 | alt3) { end(); } ;
I also recommend that you do not use backtracking for a production parser.
> Would it be correct to say that during backtracking the 'stack' is not
> properly unwound,
Sort of ;-) It is complicated to get all of this to work exactly like
try {} catch {} finally {}. I think I can probably do it, but it needs
some effort in the templates. I'll 'rule' on this for the next release.
Jim
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