Issue #16991: Add a C implementation of collections.OrderedDict.

1 files changed, 19 insertions, 2 deletions

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index fc60e13..6794de1 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -7,7 +7,6 @@ from _collections_abc import *
 import _collections_abc
 __all__ += _collections_abc.__all__
 
-from _collections import deque, defaultdict
 from operator import itemgetter as _itemgetter, eq as _eq
 from keyword import iskeyword as _iskeyword
 import sys as _sys
@@ -16,7 +15,18 @@ from _weakref import proxy as _proxy
 from itertools import repeat as _repeat, chain as _chain, starmap as _starmap
 from reprlib import recursive_repr as _recursive_repr
 
-MutableSequence.register(deque)
+try:
+    from _collections import deque
+except ImportError:
+    pass
+else:
+    MutableSequence.register(deque)
+
+try:
+    from _collections import defaultdict
+except ImportError:
+    pass
+
 
 ################################################################################
 ### OrderedDict
@@ -264,6 +274,13 @@ class OrderedDict(dict):
         return dict.__eq__(self, other)
 
 
+try:
+    from _collections import OrderedDict
+except ImportError:
+    # Leave the pure Python version in place.
+    pass
+
+
 ################################################################################
 ### namedtuple
 ################################################################################