[antlr-interest] getParent() function on ANTLR3_BASE_TREE_struct

[Richard Connon]

I've been trying to use the getParent() function on 
ANTLR3_BASE_TREE_struct but it seems that it's returning invalid values.

It was my understanding that this function would either return the 
address of the parent node in the tree (iff the node isn't the root) or 
NULL (iff the node is).

Is this the case?