Add count from 2.7 to 2.6

The future.types.newrange already has a _count method which is now moved to the
backports to allow make this public.

src/future/backports/misc.py

@@ -22,6 +22,16 @@ def ceil(x):
     return int(oldceil(x))
 
 
+if PY26:
+    # itertools.count in Py 2.6 doesn't accept a step parameter
+    def count(start=0, step=1):
+        while True:
+            yield start
+            start += step
+else:
+    from itertools import count
+
+
 # OrderedDict Shim from  Raymond Hettinger, python core dev
 # http://code.activestate.com/recipes/576693-ordered-dictionary-for-py24/
 # here to support version 2.6.

src/future/types/newrange.py

@@ -21,6 +21,7 @@
 from collections import Sequence, Iterator
 from itertools import islice
 
+from future.backports.misc import count
 
 class newrange(Sequence):
     """
@@ -141,7 +142,7 @@ class range_iterator(Iterator):
     """An iterator for a :class:`range`.
     """
     def __init__(self, range_):
-        self._stepper = islice(_count(range_.start, range_.step), len(range_))
+        self._stepper = islice(count(range_.start, range_.step), len(range_))
 
     def __iter__(self):
         return self
@@ -150,11 +151,4 @@ def next(self):
         return next(self._stepper)
 
 
-# itertools.count in Py 2.6 doesn't accept a step parameter
-def _count(start=0, step=1):
-    while True:
-        yield start
-        start += step
-
-
 __all__ = ['newrange']

tests/test_future/test_count.py

@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+"""
+Tests for the backported class:`range` class.
+"""
+from itertools import count as it_count
+
+from future.backports.misc import count
+from future.tests.base import unittest, skip26
+
+
+class CountTest(unittest.TestCase):
+
+    """Test the count function."""
+
+    def _test_count_func(self, func):
+        self.assertEqual(next(func(1)), 1)
+        self.assertEqual(next(func(start=1)), 1)
+
+        c = func()
+        self.assertEqual(next(c), 0)
+        self.assertEqual(next(c), 1)
+        self.assertEqual(next(c), 2)
+        c = func(1, 1)
+        self.assertEqual(next(c), 1)
+        self.assertEqual(next(c), 2)
+        c = func(step=1)
+        self.assertEqual(next(c), 0)
+        self.assertEqual(next(c), 1)
+        c = func(start=1, step=1)
+        self.assertEqual(next(c), 1)
+        self.assertEqual(next(c), 2)
+
+        c = func(-1)
+        self.assertEqual(next(c), -1)
+        self.assertEqual(next(c), 0)
+        self.assertEqual(next(c), 1)
+        c = func(1, -1)
+        self.assertEqual(next(c), 1)
+        self.assertEqual(next(c), 0)
+        self.assertEqual(next(c), -1)
+        c = func(-1, -1)
+        self.assertEqual(next(c), -1)
+        self.assertEqual(next(c), -2)
+        self.assertEqual(next(c), -3)
+
+    def test_count(self):
+        """Test the count function."""
+        self._test_count_func(count)
+
+    @skip26
+    def test_own_count(self):
+        """Test own count implementation."""
+        self._test_count_func(it_count)
+
+
+if __name__ == '__main__':
+    unittest.main()