[antlr-interest] partial tree rewrites

[Benoit Fouletier]

On Thu, Jul 16, 2009 at 9:53 PM, Gavin Lambert <antlr at mirality.co.nz> wrote:

> At 02:10 17/07/2009, Benoit Fouletier wrote:
>
>> (VAR ID -> VAR ID)
>> (
>> ASSIGN INT
>> ->COLON TYPE["int"] ASSIGN INT
>> |ASSIGN StringValue
>> ->COLON TYPE["string"] ASSIGN StringValue
>> )
>>
>> Do I have the syntax wrong, or are partial rewrites simply not possible?
>>
>
> A rewrite always sets the output of the entire rule.  You cannot use it for
> only part of the rule.  This is important for iterative rules which need to
> build up a nested chain of nodes.
>

Ah, makes sense!


> (A workaround is to move the bit that you want to do a partial rewrite for
> into a subrule.)
>

Thanks I'll do that. It's simple and maybe even more elegant than the syntax
I had in mind.
BTW, should I mark these kind of subrule as fragments? I don't really get
when to use fragment.

Anyway thanks!

        Ben
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