Added libbe.tree.Tree.has_descendant().

Tree equality is now based on instance id.  It had previously used the
default list "equal if all elements are equal", which meant that all
the leaves matched each other.

1 files changed, 19 insertions, 0 deletions

diff --git a/libbe/tree.py b/libbe/tree.py
index 0256407..45ae085 100644
--- a/libbe/tree.py
+++ b/libbe/tree.py
@@ -68,7 +68,18 @@ class Tree(list):
     f
     h
     i
+    >>> a.has_descendant(g)
+    True
+    >>> c.has_descendant(g)
+    False
+    >>> a.has_descendant(a)
+    False
+    >>> a.has_descendant(a, match_self=True)
+    True
     """
+    def __eq__(self, other):
+        return id(self) == id(other)
+
     def branch_len(self):
         """
         Exhaustive search every time == SLOW.
@@ -157,4 +168,12 @@ class Tree(list):
             yield (depth,node)
             stack.append(node)
 
+    def has_descendant(self, descendant, depth_first=True, match_self=False):
+        if descendant == self:
+            return match_self
+        for d in self.traverse(depth_first):
+            if descendant == d:
+                return True
+        return False
+
 suite = doctest.DocTestSuite()