curds: Add a way to get a node from its path

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

curds/playlist/node.py

@@ -29,6 +29,15 @@ class PlaylistNode:
         self.__link_children__(prev, child)
         return self.children.index(child)
 
+    def get_node(self, path):
+        if len(path) == 1:
+            return self.nth_child(path[0])
+        elif len(path) > 1:
+            if path[0] < self.n_children():
+                node = self.nth_child(path[0])
+                return node.get_node(path[1:])
+        return None
+
     def get_path(self):
         if self.parent == None:
             return [ ]

curds/playlist/test_node.py

@@ -139,3 +139,26 @@ class TestPlaylistNode(unittest.TestCase):
         self.assertEqual(a.get_path(),    [ 0 ])
         self.assertEqual(b.get_path(),    [ 0, 0 ])
         self.assertEqual(c.get_path(),    [ 0, 0, 0 ])
+
+    def test_node_get_node(self):
+        root = node.PlaylistNode()
+        a = node.PlaylistNode("a")
+        b = node.PlaylistNode("b")
+        c = node.PlaylistNode("c")
+
+        root.append_child(a)
+        a.append_child(b)
+        b.append_child(c)
+
+        self.assertIsNone(root.get_node([ ]))
+        self.assertEqual( root.get_node([ 0 ]), a)
+        self.assertIsNone(root.get_node([ 1 ]))
+
+        self.assertEqual( root.get_node([ 0, 0 ]), b)
+        self.assertIsNone(root.get_node([ 0, 1 ]))
+        self.assertIsNone(root.get_node([ 1, 0 ]))
+
+        self.assertEqual( root.get_node([ 0, 0, 0 ]), c)
+        self.assertIsNone(root.get_node([ 0, 0, 1 ]))
+        self.assertIsNone(root.get_node([ 0, 1, 0 ]))
+        self.assertIsNone(root.get_node([ 1, 0, 0 ]))