On Fri, Feb 11, 2011 at 7:04 PM, Olivier Lefevre <lefev...@yahoo.com> wrote:
> Great! Not to abuse but would you know in which section of
> "The Definitive ANTLR Reference" this mentioned? I couldn't
> find it. What is this syntax called?
>
It's called a "validating semantic predicate" which is explained in chapter
12 and 13.
But in my real-world problem it was actually not a choice
> between rule1 and rule2 but a question of whether to allow
> an extra alternative in the z case without too much
> verbatim repetition, i.e. (again in pseudo-code):
>
> rule[boolean z] :
> rule1 | rule2 | ... | rule23 | (z ? rule24 : nothing) ;
>
> That is, allow rule24 if z otherwise stop at rule23.
You can still do that:
rule [boolean z]
: {z}? (rule1 | rule2 | rule3 | ... | rule23 | rule24)
| (rule1 | rule2 | rule3 | ... | rule23)
;
Regards,
Bart.
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