[Compiler-sig] AST observations

[Eric C. Newton]

Yes, I did a lot of this, too.

I gave up when I wanted to re-use something like a "find all Name
Nodes" visitor, and then look up the parents later.

I can certainly keep a reverse map.  I'm already keeping a reverse map
from symbol to node, too.

On Thu, Apr 18, 2002 at 09:37:52AM +0000, Finn Bock wrote:
> [Eric C. Newton]
> 
> >I gave up on trying to use recursion to figure out a Node's parents in
> >an AST tree.  Very often I need to know the parents of the Node I'm
> >looking at, and using recursion to hold this information was becoming
> >cumbersome.
> 
> If you only need the ancestry of the current node in the visitXXXX
> methods, then the open_level(), close_level() visitor methods that I
> suggested previously should work nicely:
> 
> class MyVisitor(ASTVisitor):
>     def __init__(self):
>         self.ancestry = []
> 
>     def open_level(self, node):
>         self.ancestry.append(node)
> 
>     def close_level(self, node):
>         self.ancestry.pop()
> 
>     def visitFunctionDef(self, node):
>         print "parent is", self.ancestry[-2]
> 
> 
> regards,
> finn