[antlr-interest] CommonTree & Tree grammar versus DIY

[Terence Parr]

On Aug 15, 2008, at 8:12 AM, Andy Tripp wrote:

> Marc,
> This "writing by hand" article is referring to walking a tree-like  
> data structure (the AST).
> Pretty much every programmer already knows how to do this by hand:
>
> void walk(Tree t) {
> doSomething(t);
> for (Tree child: t.children()) {
>    walk(child);
> }
> }

But empirically, people don't know how to do language stuff so that  
must not be enough as you clearly know from your very complicated and  
nice stuff :)

> By contrast, there are only a handful of people who know how to do  
> that same thing
> with an ANTLR treewalker.

Coincidental with the people that have built language stuff ;)

> The "manipulating an AST" work of building a translator is quite a  
> different
> job than the "build a lexer/parser" part of it.

Yep.  i'm mostly a fan of walking not rewriting ASts by the way...that  
gets WAY too hard.  Further, Andy has a nice approach of rewriting.   
Expect ANTLRMorph, by Leon Su, this Fall!

Ter