Implement iterator on nodes by level

skiplist-py/iterators.py

@@ -0,0 +1,11 @@
+class LevelNodeIterator(object):
+    def __init__(self, skip_list, level=0):
+        self.s = skip_list
+        self.l = level
+
+    def __iter__(self):
+        node = self.s.head.next[self.l]
+        while node.next:
+            yield node
+            node = node.next[self.l]
+        raise StopIteration

skiplist-py/tests.py

@@ -1,6 +1,7 @@
 import unittest
 
 from skiplist import Skiplist, NIL
+from iterators import LevelNodeIterator
 
 
 class DataStructTestCase(unittest.TestCase):
@@ -42,5 +43,13 @@ def test_str(self):
         self.assertEqual('skiplist([])', str(sl))
         sl['1'] = 1
         self.assertEqual('skiplist([\'1\'])', str(sl))
+
+
+class LevelIteratorTestCase(unittest.TestCase):
+    def test_iterator_default(self):
+        s = Skiplist(foo=1, bar=2)
+        self.assertListEqual(sorted(['foo', 'bar']), sorted(node.key for node in LevelNodeIterator(s)))
+
+
 if __name__ == '__main__':
     unittest.main()