[antlr-interest] CommonTree & Tree grammar versus DIY

Gerald Rosenberg gerald at certiv.net
Thu Aug 21 14:15:17 PDT 2008


At 01:21 PM 8/21/2008, Gavin Lambert wrote:
>At 14:42 21/08/2008, Gerald Rosenberg wrote:
> >For ad-hoc AST changes, the better approach, at least
> >conceptually, is to implement a low-level structural
> >modification API with methods to "find" a node based on
> >parameter values, and to similarly create, copy, insert and
> >delete nodes.
>
>You can write a tree grammar to do the find (or just do it manually, 
>depending on how flexible your find requirements are), and use the 
>TreeAdaptors for modifying the tree structure afterwards...

Absolutely.  But doing so by hand is a fragile mess.  With tree 
walkers, it is still a mess.  Since a tree grammar will all of the 
rewrites listed in the grammar, you will need to have a separate 
grammar for each node type and for each operation.  Orchestration is clumsy.  



More information about the antlr-interest mailing list