Implement and apply PEP 322, reverse iteration
diff --git a/Lib/heapq.py b/Lib/heapq.py
index 2c30b12..2223a97 100644
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -165,7 +165,7 @@
# or i < (n-1)/2. If n is even = 2*j, this is (2*j-1)/2 = j-1/2 so
# j-1 is the largest, which is n//2 - 1. If n is odd = 2*j+1, this is
# (2*j+1-1)/2 = j so j-1 is the largest, and that's again n//2-1.
- for i in xrange(n//2 - 1, -1, -1):
+ for i in reversed(xrange(n//2)):
_siftup(x, i)
# 'heap' is a heap at all indices >= startpos, except possibly for pos. pos
diff --git a/Lib/mhlib.py b/Lib/mhlib.py
index 5520f82..899939a 100644
--- a/Lib/mhlib.py
+++ b/Lib/mhlib.py
@@ -975,8 +975,7 @@
print seqs
f.putsequences(seqs)
do('f.getsequences()')
- testfolders.reverse()
- for t in testfolders: do('mh.deletefolder(%s)' % `t`)
+ for t in reversed(testfolders): do('mh.deletefolder(%s)' % `t`)
do('mh.getcontext()')
context = mh.getcontext()
f = mh.openfolder(context)
diff --git a/Lib/platform.py b/Lib/platform.py
index 31c47b4..389e50c 100755
--- a/Lib/platform.py
+++ b/Lib/platform.py
@@ -201,7 +201,7 @@
if os.path.isdir('/usr/lib/setup'):
# Check for slackware verson tag file (thanks to Greg Andruk)
verfiles = os.listdir('/usr/lib/setup')
- for n in range(len(verfiles)-1, -1, -1):
+ for n in reversed(xrange(len(verfiles))):
if verfiles[n][:14] != 'slack-version-':
del verfiles[n]
if verfiles:
diff --git a/Lib/random.py b/Lib/random.py
index 16b667a..1f279bb 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -253,7 +253,7 @@
if random is None:
random = self.random
- for i in xrange(len(x)-1, 0, -1):
+ for i in reversed(xrange(1, len(x))):
# pick an element in x[:i+1] with which to exchange x[i]
j = int(random() * (i+1))
x[i], x[j] = x[j], x[i]
diff --git a/Lib/rfc822.py b/Lib/rfc822.py
index 4f69b22..9a52a90 100644
--- a/Lib/rfc822.py
+++ b/Lib/rfc822.py
@@ -421,8 +421,7 @@
hit = 0
if hit:
list.append(i)
- list.reverse()
- for i in list:
+ for i in reversed(list):
del self.headers[i]
def setdefault(self, name, default=""):
diff --git a/Lib/test/test_enumerate.py b/Lib/test/test_enumerate.py
index 88e24e8..b073606 100644
--- a/Lib/test/test_enumerate.py
+++ b/Lib/test/test_enumerate.py
@@ -124,9 +124,27 @@
seq = range(10,20000,2)
res = zip(range(20000), seq)
+class TestReversed(unittest.TestCase):
+
+ def test_simple(self):
+ class A:
+ def __getitem__(self, i):
+ if i < 5:
+ return str(i)
+ raise StopIteration
+ def __len__(self):
+ return 5
+ for data in 'abc', range(5), tuple(enumerate('abc')), A(), xrange(1,17,5):
+ self.assertEqual(list(data)[::-1], list(reversed(data)))
+ self.assertRaises(TypeError, reversed, {})
+
+ def test_xrange_optimization(self):
+ x = xrange(1)
+ self.assertEqual(type(reversed(x)), type(iter(x)))
def test_main(verbose=None):
- testclasses = (EnumerateTestCase, SubclassTestCase, TestEmpty, TestBig)
+ testclasses = (EnumerateTestCase, SubclassTestCase, TestEmpty, TestBig,
+ TestReversed)
test_support.run_unittest(*testclasses)
# verify reference counting