curds: Add a way to walk the node tree

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

curds/playlist/node.py

@@ -100,3 +100,9 @@ class PlaylistNode:
         for child in self.children:
             del nodes[id(child)]
         self.children.clear()
+
+    def walk(self, root=False):
+        if self.parent != None or root == True:
+            yield self
+        for node in self.children:
+            yield from node.walk()

curds/playlist/test_node.py

@@ -250,3 +250,25 @@ class TestPlaylistNode(unittest.TestCase):
         root.reset()
         self.assertEqual(root.children, [ ])
         self.assertEqual(node.nodes, { id(root) : root })
+
+    def test_node_walk(self):
+        root = node.PlaylistNode()
+        a = node.PlaylistNode("a")
+        b = node.PlaylistNode("b")
+        c = node.PlaylistNode("c")
+        d = node.PlaylistNode("d")
+        vals = [ a, b, d, c ]
+
+        root.append_child(a)
+        a.append_child(b)
+        a.append_child(c)
+        b.append_child(d)
+
+        for i, n in enumerate(root.walk()):
+            self.assertEqual(n, vals[i])
+        self.assertEqual(i, 3)
+
+        vals = [ root ] + vals
+        for i, n in enumerate(root.walk(root=True)):
+            self.assertEqual(n, vals[i])
+        self.assertEqual(i, 4)