bpo-40636: PEP 618: add strict parameter to zip() (GH-20921)
zip() now supports PEP 618's strict parameter, which raises a ValueError if the arguments are exhausted at different lengths. Patch by Brandt Bucher. Co-authored-by: Brandt Bucher <brandtbucher@gmail.com> Co-authored-by: Ram Rachum <ram@rachum.com>
This commit is contained in:
Guido van Rossum
GitHub
parent
37bb289556
commit
310f6aa7db
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@ -1521,6 +1521,14 @@ class BuiltinTest(unittest.TestCase):
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self.assertRaises(TypeError, vars, 42)
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self.assertEqual(vars(self.C_get_vars()), {'a':2})
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def iter_error(self, iterable, error):
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"""Collect `iterable` into a list, catching an expected `error`."""
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items = []
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with self.assertRaises(error):
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for item in iterable:
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items.append(item)
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return items
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def test_zip(self):
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a = (1, 2, 3)
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b = (4, 5, 6)
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@ -1573,6 +1581,66 @@ class BuiltinTest(unittest.TestCase):
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z1 = zip(a, b)
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self.check_iter_pickle(z1, t, proto)
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def test_zip_pickle_strict(self):
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a = (1, 2, 3)
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b = (4, 5, 6)
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t = [(1, 4), (2, 5), (3, 6)]
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for proto in range(pickle.HIGHEST_PROTOCOL + 1):
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z1 = zip(a, b, strict=True)
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self.check_iter_pickle(z1, t, proto)
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def test_zip_pickle_strict_fail(self):
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a = (1, 2, 3)
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b = (4, 5, 6, 7)
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t = [(1, 4), (2, 5), (3, 6)]
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for proto in range(pickle.HIGHEST_PROTOCOL + 1):
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z1 = zip(a, b, strict=True)
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z2 = pickle.loads(pickle.dumps(z1, proto))
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self.assertEqual(self.iter_error(z1, ValueError), t)
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self.assertEqual(self.iter_error(z2, ValueError), t)
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def test_zip_pickle_stability(self):
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# Pickles of zip((1, 2, 3), (4, 5, 6)) dumped from 3.9:
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pickles = [
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b'citertools\nizip\np0\n(c__builtin__\niter\np1\n((I1\nI2\nI3\ntp2\ntp3\nRp4\nI0\nbg1\n((I4\nI5\nI6\ntp5\ntp6\nRp7\nI0\nbtp8\nRp9\n.',
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b'citertools\nizip\nq\x00(c__builtin__\niter\nq\x01((K\x01K\x02K\x03tq\x02tq\x03Rq\x04K\x00bh\x01((K\x04K\x05K\x06tq\x05tq\x06Rq\x07K\x00btq\x08Rq\t.',
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b'\x80\x02citertools\nizip\nq\x00c__builtin__\niter\nq\x01K\x01K\x02K\x03\x87q\x02\x85q\x03Rq\x04K\x00bh\x01K\x04K\x05K\x06\x87q\x05\x85q\x06Rq\x07K\x00b\x86q\x08Rq\t.',
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b'\x80\x03cbuiltins\nzip\nq\x00cbuiltins\niter\nq\x01K\x01K\x02K\x03\x87q\x02\x85q\x03Rq\x04K\x00bh\x01K\x04K\x05K\x06\x87q\x05\x85q\x06Rq\x07K\x00b\x86q\x08Rq\t.',
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b'\x80\x04\x95L\x00\x00\x00\x00\x00\x00\x00\x8c\x08builtins\x94\x8c\x03zip\x94\x93\x94\x8c\x08builtins\x94\x8c\x04iter\x94\x93\x94K\x01K\x02K\x03\x87\x94\x85\x94R\x94K\x00bh\x05K\x04K\x05K\x06\x87\x94\x85\x94R\x94K\x00b\x86\x94R\x94.',
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b'\x80\x05\x95L\x00\x00\x00\x00\x00\x00\x00\x8c\x08builtins\x94\x8c\x03zip\x94\x93\x94\x8c\x08builtins\x94\x8c\x04iter\x94\x93\x94K\x01K\x02K\x03\x87\x94\x85\x94R\x94K\x00bh\x05K\x04K\x05K\x06\x87\x94\x85\x94R\x94K\x00b\x86\x94R\x94.',
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]
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for protocol, dump in enumerate(pickles):
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z1 = zip((1, 2, 3), (4, 5, 6))
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z2 = zip((1, 2, 3), (4, 5, 6), strict=False)
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z3 = pickle.loads(dump)
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l3 = list(z3)
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self.assertEqual(type(z3), zip)
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self.assertEqual(pickle.dumps(z1, protocol), dump)
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self.assertEqual(pickle.dumps(z2, protocol), dump)
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self.assertEqual(list(z1), l3)
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self.assertEqual(list(z2), l3)
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def test_zip_pickle_strict_stability(self):
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# Pickles of zip((1, 2, 3), (4, 5), strict=True) dumped from 3.10:
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pickles = [
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b'citertools\nizip\np0\n(c__builtin__\niter\np1\n((I1\nI2\nI3\ntp2\ntp3\nRp4\nI0\nbg1\n((I4\nI5\ntp5\ntp6\nRp7\nI0\nbtp8\nRp9\nI01\nb.',
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b'citertools\nizip\nq\x00(c__builtin__\niter\nq\x01((K\x01K\x02K\x03tq\x02tq\x03Rq\x04K\x00bh\x01((K\x04K\x05tq\x05tq\x06Rq\x07K\x00btq\x08Rq\tI01\nb.',
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b'\x80\x02citertools\nizip\nq\x00c__builtin__\niter\nq\x01K\x01K\x02K\x03\x87q\x02\x85q\x03Rq\x04K\x00bh\x01K\x04K\x05\x86q\x05\x85q\x06Rq\x07K\x00b\x86q\x08Rq\t\x88b.',
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b'\x80\x03cbuiltins\nzip\nq\x00cbuiltins\niter\nq\x01K\x01K\x02K\x03\x87q\x02\x85q\x03Rq\x04K\x00bh\x01K\x04K\x05\x86q\x05\x85q\x06Rq\x07K\x00b\x86q\x08Rq\t\x88b.',
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b'\x80\x04\x95L\x00\x00\x00\x00\x00\x00\x00\x8c\x08builtins\x94\x8c\x03zip\x94\x93\x94\x8c\x08builtins\x94\x8c\x04iter\x94\x93\x94K\x01K\x02K\x03\x87\x94\x85\x94R\x94K\x00bh\x05K\x04K\x05\x86\x94\x85\x94R\x94K\x00b\x86\x94R\x94\x88b.',
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b'\x80\x05\x95L\x00\x00\x00\x00\x00\x00\x00\x8c\x08builtins\x94\x8c\x03zip\x94\x93\x94\x8c\x08builtins\x94\x8c\x04iter\x94\x93\x94K\x01K\x02K\x03\x87\x94\x85\x94R\x94K\x00bh\x05K\x04K\x05\x86\x94\x85\x94R\x94K\x00b\x86\x94R\x94\x88b.',
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]
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a = (1, 2, 3)
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b = (4, 5)
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t = [(1, 4), (2, 5)]
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for protocol, dump in enumerate(pickles):
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z1 = zip(a, b, strict=True)
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z2 = pickle.loads(dump)
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self.assertEqual(pickle.dumps(z1, protocol), dump)
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self.assertEqual(type(z2), zip)
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self.assertEqual(self.iter_error(z1, ValueError), t)
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self.assertEqual(self.iter_error(z2, ValueError), t)
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def test_zip_bad_iterable(self):
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exception = TypeError()
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@ -1585,6 +1653,88 @@ class BuiltinTest(unittest.TestCase):
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self.assertIs(cm.exception, exception)
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def test_zip_strict(self):
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self.assertEqual(tuple(zip((1, 2, 3), 'abc', strict=True)),
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((1, 'a'), (2, 'b'), (3, 'c')))
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self.assertRaises(ValueError, tuple,
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zip((1, 2, 3, 4), 'abc', strict=True))
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self.assertRaises(ValueError, tuple,
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zip((1, 2), 'abc', strict=True))
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self.assertRaises(ValueError, tuple,
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zip((1, 2), (1, 2), 'abc', strict=True))
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def test_zip_strict_iterators(self):
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x = iter(range(5))
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y = [0]
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z = iter(range(5))
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self.assertRaises(ValueError, list,
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(zip(x, y, z, strict=True)))
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self.assertEqual(next(x), 2)
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self.assertEqual(next(z), 1)
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def test_zip_strict_error_handling(self):
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class Error(Exception):
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pass
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class Iter:
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def __init__(self, size):
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self.size = size
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def __iter__(self):
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return self
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def __next__(self):
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self.size -= 1
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if self.size < 0:
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raise Error
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return self.size
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l1 = self.iter_error(zip("AB", Iter(1), strict=True), Error)
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self.assertEqual(l1, [("A", 0)])
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l2 = self.iter_error(zip("AB", Iter(2), "A", strict=True), ValueError)
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self.assertEqual(l2, [("A", 1, "A")])
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l3 = self.iter_error(zip("AB", Iter(2), "ABC", strict=True), Error)
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self.assertEqual(l3, [("A", 1, "A"), ("B", 0, "B")])
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l4 = self.iter_error(zip("AB", Iter(3), strict=True), ValueError)
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self.assertEqual(l4, [("A", 2), ("B", 1)])
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l5 = self.iter_error(zip(Iter(1), "AB", strict=True), Error)
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self.assertEqual(l5, [(0, "A")])
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l6 = self.iter_error(zip(Iter(2), "A", strict=True), ValueError)
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self.assertEqual(l6, [(1, "A")])
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l7 = self.iter_error(zip(Iter(2), "ABC", strict=True), Error)
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self.assertEqual(l7, [(1, "A"), (0, "B")])
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l8 = self.iter_error(zip(Iter(3), "AB", strict=True), ValueError)
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self.assertEqual(l8, [(2, "A"), (1, "B")])
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def test_zip_strict_error_handling_stopiteration(self):
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class Iter:
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def __init__(self, size):
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self.size = size
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def __iter__(self):
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return self
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def __next__(self):
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self.size -= 1
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if self.size < 0:
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raise StopIteration
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return self.size
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l1 = self.iter_error(zip("AB", Iter(1), strict=True), ValueError)
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self.assertEqual(l1, [("A", 0)])
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l2 = self.iter_error(zip("AB", Iter(2), "A", strict=True), ValueError)
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self.assertEqual(l2, [("A", 1, "A")])
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l3 = self.iter_error(zip("AB", Iter(2), "ABC", strict=True), ValueError)
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self.assertEqual(l3, [("A", 1, "A"), ("B", 0, "B")])
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l4 = self.iter_error(zip("AB", Iter(3), strict=True), ValueError)
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self.assertEqual(l4, [("A", 2), ("B", 1)])
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l5 = self.iter_error(zip(Iter(1), "AB", strict=True), ValueError)
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self.assertEqual(l5, [(0, "A")])
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l6 = self.iter_error(zip(Iter(2), "A", strict=True), ValueError)
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self.assertEqual(l6, [(1, "A")])
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l7 = self.iter_error(zip(Iter(2), "ABC", strict=True), ValueError)
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self.assertEqual(l7, [(1, "A"), (0, "B")])
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l8 = self.iter_error(zip(Iter(3), "AB", strict=True), ValueError)
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self.assertEqual(l8, [(2, "A"), (1, "B")])
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def test_format(self):
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# Test the basic machinery of the format() builtin. Don't test
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# the specifics of the various formatters
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@ -0,0 +1,3 @@
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:func:`zip` now supports :pep:`618`'s ``strict`` parameter, which raises a
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:exc:`ValueError` if the arguments are exhausted at different lengths.
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Patch by Brandt Bucher.
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@ -2517,9 +2517,10 @@ builtin_issubclass_impl(PyObject *module, PyObject *cls,
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typedef struct {
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PyObject_HEAD
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Py_ssize_t tuplesize;
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PyObject *ittuple; /* tuple of iterators */
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Py_ssize_t tuplesize;
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PyObject *ittuple; /* tuple of iterators */
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PyObject *result;
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int strict;
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} zipobject;
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static PyObject *
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@ -2530,9 +2531,21 @@ zip_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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PyObject *ittuple; /* tuple of iterators */
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PyObject *result;
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Py_ssize_t tuplesize;
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int strict = 0;
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if (type == &PyZip_Type && !_PyArg_NoKeywords("zip", kwds))
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return NULL;
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if (kwds) {
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PyObject *empty = PyTuple_New(0);
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if (empty == NULL) {
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return NULL;
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}
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static char *kwlist[] = {"strict", NULL};
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int parsed = PyArg_ParseTupleAndKeywords(
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empty, kwds, "|$p:zip", kwlist, &strict);
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Py_DECREF(empty);
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if (!parsed) {
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return NULL;
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}
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}
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/* args must be a tuple */
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assert(PyTuple_Check(args));
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@ -2573,6 +2586,7 @@ zip_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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lz->ittuple = ittuple;
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lz->tuplesize = tuplesize;
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lz->result = result;
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lz->strict = strict;
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return (PyObject *)lz;
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}
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@ -2613,6 +2627,9 @@ zip_next(zipobject *lz)
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item = (*Py_TYPE(it)->tp_iternext)(it);
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if (item == NULL) {
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Py_DECREF(result);
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if (lz->strict) {
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goto check;
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}
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return NULL;
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}
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olditem = PyTuple_GET_ITEM(result, i);
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@ -2628,28 +2645,85 @@ zip_next(zipobject *lz)
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item = (*Py_TYPE(it)->tp_iternext)(it);
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if (item == NULL) {
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Py_DECREF(result);
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if (lz->strict) {
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goto check;
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}
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return NULL;
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}
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PyTuple_SET_ITEM(result, i, item);
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}
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}
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return result;
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check:
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if (PyErr_Occurred()) {
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if (!PyErr_ExceptionMatches(PyExc_StopIteration)) {
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// next() on argument i raised an exception (not StopIteration)
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return NULL;
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}
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PyErr_Clear();
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}
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if (i) {
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// ValueError: zip() argument 2 is shorter than argument 1
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// ValueError: zip() argument 3 is shorter than arguments 1-2
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const char* plural = i == 1 ? " " : "s 1-";
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return PyErr_Format(PyExc_ValueError,
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"zip() argument %d is shorter than argument%s%d",
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i + 1, plural, i);
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}
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for (i = 1; i < tuplesize; i++) {
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it = PyTuple_GET_ITEM(lz->ittuple, i);
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item = (*Py_TYPE(it)->tp_iternext)(it);
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if (item) {
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Py_DECREF(item);
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const char* plural = i == 1 ? " " : "s 1-";
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return PyErr_Format(PyExc_ValueError,
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"zip() argument %d is longer than argument%s%d",
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i + 1, plural, i);
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}
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if (PyErr_Occurred()) {
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if (!PyErr_ExceptionMatches(PyExc_StopIteration)) {
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// next() on argument i raised an exception (not StopIteration)
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return NULL;
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}
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PyErr_Clear();
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}
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// Argument i is exhausted. So far so good...
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}
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// All arguments are exhausted. Success!
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return NULL;
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}
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static PyObject *
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zip_reduce(zipobject *lz, PyObject *Py_UNUSED(ignored))
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{
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/* Just recreate the zip with the internal iterator tuple */
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return Py_BuildValue("OO", Py_TYPE(lz), lz->ittuple);
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if (lz->strict) {
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return PyTuple_Pack(3, Py_TYPE(lz), lz->ittuple, Py_True);
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}
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return PyTuple_Pack(2, Py_TYPE(lz), lz->ittuple);
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}
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PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
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static PyObject *
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zip_setstate(zipobject *lz, PyObject *state)
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{
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int strict = PyObject_IsTrue(state);
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if (strict < 0) {
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return NULL;
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}
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lz->strict = strict;
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Py_RETURN_NONE;
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}
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static PyMethodDef zip_methods[] = {
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{"__reduce__", (PyCFunction)zip_reduce, METH_NOARGS, reduce_doc},
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{NULL, NULL} /* sentinel */
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{"__setstate__", (PyCFunction)zip_setstate, METH_O, setstate_doc},
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{NULL} /* sentinel */
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};
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PyDoc_STRVAR(zip_doc,
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"zip(*iterables) --> A zip object yielding tuples until an input is exhausted.\n\
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"zip(*iterables, strict=False) --> Yield tuples until an input is exhausted.\n\
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\n\
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>>> list(zip('abcdefg', range(3), range(4)))\n\
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[('a', 0, 0), ('b', 1, 1), ('c', 2, 2)]\n\
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@ -2657,7 +2731,10 @@ PyDoc_STRVAR(zip_doc,
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The zip object yields n-length tuples, where n is the number of iterables\n\
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passed as positional arguments to zip(). The i-th element in every tuple\n\
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comes from the i-th iterable argument to zip(). This continues until the\n\
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shortest argument is exhausted.");
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shortest argument is exhausted.\n\
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\n\
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If strict is true and one of the arguments is exhausted before the others,\n\
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raise a ValueError.");
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PyTypeObject PyZip_Type = {
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PyVarObject_HEAD_INIT(&PyType_Type, 0)
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