From 3f5cb6ff28e3790fcf92f8c0a98efbe2b73567fa Mon Sep 17 00:00:00 2001
From: Ross Lawley <ross.lawley@gmail.com>
Date: Wed, 8 May 2013 10:33:14 +0000
Subject: [PATCH] Fix cursor cloning issue with deepcopy and regex #179

---
 pymongo/cursor.py   | 21 ++++++++++++++++-----
 test/test_cursor.py | 10 ++++++++++
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/pymongo/cursor.py b/pymongo/cursor.py
index 4d11fe0aa..5b42e60a0 100644
--- a/pymongo/cursor.py
+++ b/pymongo/cursor.py
@@ -841,22 +841,33 @@ class Cursor(object):
         return self.__clone(deepcopy=True)
 
     def __deepcopy(self, x, memo=None):
-        """Deepcopy helper for the data dictionary.
+        """Deepcopy helper for the data dictionary or list.
 
         Regular expressions cannot be deep copied but as they are immutable we
         don't have to copy them when cloning.
         """
-        y = {}
+        if not hasattr(x, 'items'):
+            y, is_list, iterator = [], True, enumerate(x)
+        else:
+            y, is_list, iterator = {}, False, x.iteritems()
+
         if memo is None:
             memo = {}
         val_id = id(x)
         if val_id in memo:
             return memo.get(val_id)
         memo[val_id] = y
-        for key, value in x.iteritems():
-            if isinstance(value, dict) and not isinstance(value, SON):
+
+        for key, value in iterator:
+            if isinstance(value, (dict, list)) and not isinstance(value, SON):
                 value = self.__deepcopy(value, memo)
             elif not isinstance(value, RE_TYPE):
                 value = copy.deepcopy(value, memo)
-            y[copy.deepcopy(key, memo)] = value
+
+            if is_list:
+                y.append(value)
+            else:
+                if not isinstance(key, RE_TYPE):
+                    key = copy.deepcopy(key, memo)
+                y[key] = value
         return y
diff --git a/test/test_cursor.py b/test/test_cursor.py
index e1c3b83ae..ef04f9af4 100644
--- a/test/test_cursor.py
+++ b/test/test_cursor.py
@@ -529,6 +529,16 @@ class TestCursor(unittest.TestCase):
         self.assertTrue(isinstance(cursor2._Cursor__hint, SON))
         self.assertEqual(cursor._Cursor__hint, cursor2._Cursor__hint)
 
+    def test_deepcopy_cursor_littered_with_regexes(self):
+
+        cursor = self.db.test.find({"x": re.compile("^hmmm.*"),
+                                    "y": [re.compile("^hmm.*")],
+                                    "z": {"a": [re.compile("^hm.*")]},
+                                    re.compile("^key.*"): {"a": [re.compile("^hm.*")]}})
+
+        cursor2 = copy.deepcopy(cursor)
+        self.assertEqual(cursor._Cursor__spec, cursor2._Cursor__spec)
+
     def test_add_remove_option(self):
         cursor = self.db.test.find()
         self.assertEqual(0, cursor._Cursor__query_options())