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Issue #22818: Splitting on a pattern that could match an empty string now

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raises a warning.  Patterns that can only match empty strings are now
rejected.
This commit is contained in:
Serhiy Storchaka 2015-02-03 11:04:19 +02:00
parent 32ca3dcb97
commit 83e802796c
6 changed files with 85 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

39
Lib/test/test_re.py
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@ -251,28 +251,28 @@ class ReTests(unittest.TestCase):
for string in ":a:b::c", S(":a:b::c"):
self.assertTypedEqual(re.split(":", string),
['', 'a', 'b', '', 'c'])
self.assertTypedEqual(re.split(":*", string),
self.assertTypedEqual(re.split(":+", string),
['', 'a', 'b', 'c'])
self.assertTypedEqual(re.split("(:*)", string),
self.assertTypedEqual(re.split("(:+)", string),
['', ':', 'a', ':', 'b', '::', 'c'])
for string in (b":a:b::c", B(b":a:b::c"), bytearray(b":a:b::c"),
memoryview(b":a:b::c")):
self.assertTypedEqual(re.split(b":", string),
[b'', b'a', b'b', b'', b'c'])
self.assertTypedEqual(re.split(b":*", string),
self.assertTypedEqual(re.split(b":+", string),
[b'', b'a', b'b', b'c'])
self.assertTypedEqual(re.split(b"(:*)", string),
self.assertTypedEqual(re.split(b"(:+)", string),
[b'', b':', b'a', b':', b'b', b'::', b'c'])
for a, b, c in ("\xe0\xdf\xe7", "\u0430\u0431\u0432",
"\U0001d49c\U0001d49e\U0001d4b5"):
string = ":%s:%s::%s" % (a, b, c)
self.assertEqual(re.split(":", string), ['', a, b, '', c])
self.assertEqual(re.split(":*", string), ['', a, b, c])
self.assertEqual(re.split("(:*)", string),
self.assertEqual(re.split(":+", string), ['', a, b, c])
self.assertEqual(re.split("(:+)", string),
['', ':', a, ':', b, '::', c])
self.assertEqual(re.split("(?::*)", ":a:b::c"), ['', 'a', 'b', 'c'])
self.assertEqual(re.split("(:)*", ":a:b::c"),
self.assertEqual(re.split("(?::+)", ":a:b::c"), ['', 'a', 'b', 'c'])
self.assertEqual(re.split("(:)+", ":a:b::c"),
['', ':', 'a', ':', 'b', ':', 'c'])
self.assertEqual(re.split("([b:]+)", ":a:b::c"),
['', ':', 'a', ':b::', 'c'])
@ -282,13 +282,34 @@ class ReTests(unittest.TestCase):
self.assertEqual(re.split("(?:b)|(?::+)", ":a:b::c"),
['', 'a', '', '', 'c'])
for sep, expected in [
(':*', ['', 'a', 'b', 'c']),
('(?::*)', ['', 'a', 'b', 'c']),
('(:*)', ['', ':', 'a', ':', 'b', '::', 'c']),
('(:)*', ['', ':', 'a', ':', 'b', ':', 'c']),
]:
with self.subTest(sep=sep), self.assertWarns(FutureWarning):
self.assertTypedEqual(re.split(sep, ':a:b::c'), expected)
for sep, expected in [
('', [':a:b::c']),
(r'\b', [':a:b::c']),
(r'(?=:)', [':a:b::c']),
(r'(?<=:)', [':a:b::c']),
]:
with self.subTest(sep=sep), self.assertRaises(ValueError):
self.assertTypedEqual(re.split(sep, ':a:b::c'), expected)
def test_qualified_re_split(self):
self.assertEqual(re.split(":", ":a:b::c", maxsplit=2), ['', 'a', 'b::c'])
self.assertEqual(re.split(':', 'a:b:c:d', maxsplit=2), ['a', 'b', 'c:d'])
self.assertEqual(re.split("(:)", ":a:b::c", maxsplit=2),
['', ':', 'a', ':', 'b::c'])
self.assertEqual(re.split("(:*)", ":a:b::c", maxsplit=2),
self.assertEqual(re.split("(:+)", ":a:b::c", maxsplit=2),
['', ':', 'a', ':', 'b::c'])
with self.assertWarns(FutureWarning):
self.assertEqual(re.split("(:*)", ":a:b::c", maxsplit=2),
['', ':', 'a', ':', 'b::c'])
def test_re_findall(self):
self.assertEqual(re.findall(":+", "abc"), [])