added __len__ to PriorityQueue/Stack, and changed __iter__ implementation to return (item, priority) tuples, added more test cases

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40713

scrapy/trunk/scrapy/tests/test_utils_datatypes.py

@@ -10,11 +10,15 @@ class DatatypesTestCase(unittest.TestCase):
         output = [('one', 1), ('three-1', 3), ('three-2', 3), ('five', 5), ('six', 6)]
 
         pq = PriorityQueue()
+        assert not bool(pq)
         for item, prio in input:
             pq.push(item, prio)
         out = []
+        assert bool(pq)
+        self.assertEqual(len(pq), len(input))
         while pq:
             out.append(pq.pop())
+        self.assertEqual(len(pq), 0)
         self.assertEqual(out, output)
 
     def test_priority_stack(self):
@@ -23,11 +27,15 @@ class DatatypesTestCase(unittest.TestCase):
         output = [('one', 1), ('three-2', 3), ('three-1', 3), ('five', 5), ('six', 6)]
 
         pq = PriorityStack()
+        assert not bool(pq)
         for item, prio in input:
             pq.push(item, prio)
+        assert bool(pq)
         out = []
+        self.assertEqual(len(pq), len(input))
         while pq:
             out.append(pq.pop())
+        self.assertEqual(len(pq), 0)
         self.assertEqual(out, output)
 
 if __name__ == "__main__":

scrapy/trunk/scrapy/utils/datatypes.py

@@ -420,8 +420,11 @@ class PriorityQueue(object):
         priority, _, item = heappop(self.items)
         return item, priority
 
+    def __len__(self):
+        return len(self.items)
+
     def __iter__(self):
-        return ((priority, item) for priority, _, item in self.items)
+        return ((item, priority) for priority, _, item in self.items)
 
     def __nonzero__(self):
         return bool(self.items)