[antlr-interest] AST tree output from Tree Parser

Gavin Lambert antlr at mirality.co.nz
Tue Nov 27 22:51:07 PST 2007


At 12:41 28/11/2007, Surinder Jain wrote:
>I remember (vaiguly since it was many years ago) that ANTLR2 tree 
>walker (or its equivalent) could read a tree, transform it (as 
>per tree grammar rewrite rules) and produce a new different 
>output tree.  This allowed multiple passes making translation job 
>into many simple steps rather than one complex one.
>
>It appears that this ability has been taken away in ANTLR3.
>
>Is my understanding correct or am I missing something that is not 
>in the defintive book.  If I am correct then is there any plan to 
>add tree transformation feature in near future?

AST output for tree walkers was intentionally left out of 3.0 (to 
make things simpler), but AFAIK it's planned to be added in a 
future release.  (I think it was going to be in 3.1, but I'm not 
sure if that's still true or not.)
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