[antlr-interest] Anyone in the whole world doing multi step tree transformation?

Loring Craymer lgcraymer at yahoo.com
Sun Jan 24 22:25:58 PST 2010


Some key points:
1.)  Capture semantics rather than designing tree structures.  
2.)  Preserve grammar structure--that is, rule a in pass n becomes rule a in pass n+1 unless there is reason to do otherwise.
3.)  Avoid cluttering your grammars with action code.
4.)  Separate analysis passes from transformation passes.

Follow those principles, and you'll find that rippling changes across grammars is tedious, but not a real problem.


----- Original Message ----
> From: Oliver Zeigermann <oliver.zeigermann at gmail.com>
> To: antlr-interest Interest <antlr-interest at antlr.org>
> Sent: Sun, January 24, 2010 1:03:35 AM
> Subject: [antlr-interest] Anyone in the whole world doing multi step tree transformation?
> Folks!
> I was just wondering if anyone except me is actually doing tree
> transformations using ANTLR. I use the tree transformation feature
> introduced in 3.1. While this does work well, it is so very hard to
> refactor or extend my tree structures as I have to change all my
> transformer stages and have no tool support to find out what to change
> and where.
> I started using heterogenous tokens with normalized children to make
> use of compiler type checking which helps, but does not comletely
> solve my issues as I still have an unchecked children list - which I
> need to traverse the tree using tree walkes.
> I was considering skipping the whole grammar driving tree
> transformation step, but what should I replace it with?
> I know of the xtext approach that uses non normalized heterogenous
> tokens generated from a common model shared by all transformation
> parts. Which seems like a good idea, however, does not seem to have a
> means powerful enough to do serious tree transformation.
> Any experiences? Hints?
> Thanks in advance
> - Oliver
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