Merge branch 'UmanShahzad-master'

tests/test_treelib.py

@@ -10,7 +10,7 @@
     from io import BytesIO
 import unittest
 from treelib import Tree, Node
-from treelib.tree import NodeIDAbsentError
+from treelib.tree import NodeIDAbsentError, LoopError
 
 def encode(value):
     if sys.version_info[0] == 2:
@@ -367,6 +367,17 @@ def test_filter_nodes(self):
         self.assertEqual(tuple(new_tree.filter_nodes(lambda n: not n.is_root())), (nodes[1],))
         self.assertTrue(set(new_tree.filter_nodes(lambda n: True)), set(nodes))
 
+    def test_loop(self):
+        tree = Tree()
+        tree.create_node('a', 'a')
+        tree.create_node('b', 'b', parent='a')
+        tree.create_node('c', 'c', parent='b')
+        tree.create_node('d', 'd', parent='c')
+        try:
+            tree.move_node('b', 'd')
+        except LoopError, e:
+            pass
+
 def suite():
     suites = [NodeCase, TreeCase]
     suite = unittest.TestSuite()

treelib/node.py

@@ -61,7 +61,7 @@ def bpointer(self, nid):
         if nid is not None:
             self._bpointer = nid
         else:
-            # print("WARNNING: the bpointer of node %s " \
+            # print("WARNING: the bpointer of node %s " \
             #      "is set to None" % self._identifier)
             self._bpointer = None
 
@@ -93,7 +93,7 @@ def identifier(self):
     def identifier(self, value):
         """Set the value of `_identifier`."""
         if value is None:
-            print("WARNNING: node ID can not be None")
+            print("WARNING: node ID can not be None")
         else:
             self._set_identifier(value)
 
@@ -133,7 +133,7 @@ def update_fpointer(self, nid, mode=ADD):
             if nid in self._fpointer:
                 self._fpointer.remove(nid)
         elif mode is self.INSERT:  # deprecate to ADD mode
-            print("WARNNING: INSERT is deprecated to ADD mode")
+            print("WARNING: INSERT is deprecated to ADD mode")
             self.update_fpointer(nid)
 
     def __repr__(self):

treelib/tree.py

@@ -27,10 +27,12 @@ class NodeIDAbsentError(Exception):
     """Exception throwed if a node's identifier is unknown"""
     pass
 
+
 class NodePropertyAbsentError(Exception):
     """Exception throwed if a node's data property is not specified"""
     pass
 
+
 class MultipleRootError(Exception):
     """Exception throwed if more than one root exists in a tree."""
     pass
@@ -52,6 +54,15 @@ class LinkPastRootNodeError(Exception):
 class InvalidLevelNumber(Exception):
     pass
 
+
+class LoopError(Exception):
+    """
+    Exception thrown if trying to move node B to node A's position
+    while A is B's ancestor.
+    """
+    pass
+
+
 def python_2_unicode_compatible(klass):
     """
     (slightly modified from :
@@ -463,12 +474,25 @@ def move_node(self, source, destination):
         """
         if not self.contains(source) or not self.contains(destination):
             raise NodeIDAbsentError
+        elif self.is_ancestor(source, destination):
+            raise LoopError
 
         parent = self[source].bpointer
         self.__update_fpointer(parent, source, Node.DELETE)
         self.__update_fpointer(destination, source, Node.ADD)
         self.__update_bpointer(source, destination)
 
+    def is_ancestor(self, ancestor, grandchild):
+        parent = self[grandchild].bpointer
+        child = grandchild
+        while parent is not None:
+            if parent == ancestor:
+                return True
+            else:
+                child = self[child].bpointer
+                parent = self[child].bpointer
+        return False
+
     @property
     def nodes(self):
         """Return a dict form of nodes in a tree: {id: node_instance}"""