[antlr-interest] optional node in tree parser...

[Oliver Zeigermann]

rule
: {$p}=> ^(A B) (^(C .))?
;

2009/1/2 Pady Srinivasan <padysrini at hotmail.com>:
>
> Can I have some rule as follows ?
>
> rule
> : {$p}=> ^(A B) ^(C .)?
> ;
>
> When I do this, I get an error about "unexpected token '?'". How do I
> indicate that the second subtree might not exist ?
>
>
> Thanks
>
> -- pady
>
>
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