[antlr-interest] accessing parent node in order to replace

[Jim Idle]

Make the return value of production)_b the tree. In production-a, test
this for null. If null then rewrite with the production_a  else rewrite
with the tree returned by _b.

 

 

{retTre == null}? -> ...

-> 

 

However, you should be able to find a way to do this without all that.
Perhaps you have factored things into production_b too much.

 

Have you considered dividing the things that cause a rewrite in one
rule, and those that don't in another., then rewriteing in _a accoreding
to which branch is taken:

 

p_a: token (

                                   prod_c
-> ^(prod_c)

                                | prod_d                              ->
^(token balh)

                )

                ;

 

prod_b : prod_c | prod_d ;   // Only if you need a rule for them all at
once

 

prod_c  : blah ;

prod_d : blah ;

 

Jim

 

From: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] On Behalf Of Pam L Sampson
Sent: Thursday, May 31, 2007 1:16 PM
To: antlr-interest at antlr.org
Subject: [antlr-interest] accessing parent node in order to replace

 

I would like to build a tree where in some cases I want the parent node
removed and replaced with a different tree. My question is how do I
access the parent node of the tree I am currently building. For example:

production_a
    : token production_b
    //tree built here
    ;
production_b
    : token 
    //now here I would like to replace the tree built in production_a
    //with a new tree for production_b but only in some cases
    //how do I replace the previous subtree with the new one?
    ;



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