[Compiler-sig] AST observations

[Finn Bock]

[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