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Issue #23622: Unknown escapes in regular expressions that consist of ``'\'`` 

and ASCII letter now raise a deprecation warning and will be forbidden in
Python 3.6.
This commit is contained in:
Serhiy Storchaka 2015-03-24 22:58:14 +02:00
parent 793c14ea29
commit a54aae0683
6 changed files with 60 additions and 19 deletions
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2
Doc/howto/regex.rst
View File

@ -1138,7 +1138,7 @@ Empty matches are replaced only when they're not adjacent to a previous match.
If *replacement* is a string, any backslash escapes in it are processed. That
is, ``\n`` is converted to a single newline character, ``\r`` is converted to a
carriage return, and so forth. Unknown escapes such as ``\j`` are left alone.
carriage return, and so forth. Unknown escapes such as ``\&`` are left alone.
Backreferences, such as ``\6``, are replaced with the substring matched by the
corresponding group in the RE. This lets you incorporate portions of the
original text in the resulting replacement string.

10
Doc/library/re.rst
View File

@ -438,6 +438,10 @@ three digits in length.
.. versionchanged:: 3.3
The ``'\u'`` and ``'\U'`` escape sequences have been added.
.. deprecated-removed:: 3.5 3.6
Unknown escapes consist of ``'\'`` and ASCII letter now raise a
deprecation warning and will be forbidden in Python 3.6.
.. seealso::
@ -687,7 +691,7 @@ form.
*string* is returned unchanged. *repl* can be a string or a function; if it is
a string, any backslash escapes in it are processed. That is, ``\n`` is
converted to a single newline character, ``\r`` is converted to a carriage return, and
so forth. Unknown escapes such as ``\j`` are left alone. Backreferences, such
so forth. Unknown escapes such as ``\&`` are left alone. Backreferences, such
as ``\6``, are replaced with the substring matched by group 6 in the pattern.
For example:
@ -732,6 +736,10 @@ form.
.. versionchanged:: 3.5
Unmatched groups are replaced with an empty string.
.. deprecated-removed:: 3.5 3.6
Unknown escapes consist of ``'\'`` and ASCII letter now raise a
deprecation warning and will be forbidden in Python 3.6.
.. function:: subn(pattern, repl, string, count=0, flags=0)

14
Lib/sre_parse.py
View File

@ -21,6 +21,7 @@ DIGITS = frozenset("0123456789")
OCTDIGITS = frozenset("01234567")
HEXDIGITS = frozenset("0123456789abcdefABCDEF")
ASCIILETTERS = frozenset("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
WHITESPACE = frozenset(" \t\n\r\v\f")
@ -344,6 +345,10 @@ def _class_escape(source, escape):
elif c in DIGITS:
raise ValueError
if len(escape) == 2:
if c in ASCIILETTERS:
import warnings
warnings.warn('bad escape %s' % escape,
DeprecationWarning, stacklevel=8)
return LITERAL, ord(escape[1])
except ValueError:
pass
@ -407,6 +412,10 @@ def _escape(source, escape, state):
return GROUPREF, group
raise ValueError
if len(escape) == 2:
if c in ASCIILETTERS:
import warnings
warnings.warn('bad escape %s' % escape,
DeprecationWarning, stacklevel=8)
return LITERAL, ord(escape[1])
except ValueError:
pass
@ -903,7 +912,10 @@ def parse_template(source, pattern):
try:
this = chr(ESCAPES[this][1])
except KeyError:
pass
if c in ASCIILETTERS:
import warnings
warnings.warn('bad escape %s' % this,
DeprecationWarning, stacklevel=5)
lappend(this)
else:
lappend(this)

6
Lib/test/re_tests.py
View File

@ -87,7 +87,7 @@ tests = [
(r'[\a][\b][\f][\n][\r][\t][\v]', '\a\b\f\n\r\t\v', SUCCEED, 'found', '\a\b\f\n\r\t\v'),
# NOTE: not an error under PCRE/PRE:
(r'\u', '', SYNTAX_ERROR), # A Perl escape
(r'\c\e\g\h\i\j\k\m\o\p\q\y\z', 'ceghijkmopqyz', SUCCEED, 'found', 'ceghijkmopqyz'),
# (r'\c\e\g\h\i\j\k\m\o\p\q\y\z', 'ceghijkmopqyz', SUCCEED, 'found', 'ceghijkmopqyz'),
(r'\xff', '\377', SUCCEED, 'found', chr(255)),
# new \x semantics
(r'\x00ffffffffffffff', '\377', FAIL, 'found', chr(255)),
@ -607,8 +607,8 @@ xyzabc
# new \x semantics
(r'\x00ff', '\377', FAIL),
# (r'\x00ff', '\377', SUCCEED, 'found', chr(255)),
(r'\t\n\v\r\f\a\g', '\t\n\v\r\f\ag', SUCCEED, 'found', '\t\n\v\r\f\ag'),
('\t\n\v\r\f\a\g', '\t\n\v\r\f\ag', SUCCEED, 'found', '\t\n\v\r\f\ag'),
(r'\t\n\v\r\f\a', '\t\n\v\r\f\a', SUCCEED, 'found', '\t\n\v\r\f\a'),
('\t\n\v\r\f\a', '\t\n\v\r\f\a', SUCCEED, 'found', '\t\n\v\r\f\a'),
(r'\t\n\v\r\f\a', '\t\n\v\r\f\a', SUCCEED, 'found', chr(9)+chr(10)+chr(11)+chr(13)+chr(12)+chr(7)),
(r'[\t][\n][\v][\r][\f][\b]', '\t\n\v\r\f\b', SUCCEED, 'found', '\t\n\v\r\f\b'),

39
Lib/test/test_re.py
View File

@ -100,11 +100,14 @@ class ReTests(unittest.TestCase):
self.assertEqual(re.sub('(?P<unk>x)', '\g<unk>\g<unk>', 'xx'), 'xxxx')
self.assertEqual(re.sub('(?P<unk>x)', '\g<1>\g<1>', 'xx'), 'xxxx')
self.assertEqual(re.sub('a',r'\t\n\v\r\f\a\b\B\Z\a\A\w\W\s\S\d\D','a'),
'\t\n\v\r\f\a\b\\B\\Z\a\\A\\w\\W\\s\\S\\d\\D')
self.assertEqual(re.sub('a', '\t\n\v\r\f\a', 'a'), '\t\n\v\r\f\a')
self.assertEqual(re.sub('a', '\t\n\v\r\f\a', 'a'),
(chr(9)+chr(10)+chr(11)+chr(13)+chr(12)+chr(7)))
self.assertEqual(re.sub('a', r'\t\n\v\r\f\a\b', 'a'), '\t\n\v\r\f\a\b')
self.assertEqual(re.sub('a', '\t\n\v\r\f\a\b', 'a'), '\t\n\v\r\f\a\b')
self.assertEqual(re.sub('a', '\t\n\v\r\f\a\b', 'a'),
(chr(9)+chr(10)+chr(11)+chr(13)+chr(12)+chr(7)+chr(8)))
for c in 'cdehijklmopqsuwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ':
with self.subTest(c):
with self.assertWarns(DeprecationWarning):
self.assertEqual(re.sub('a', '\\' + c, 'a'), '\\' + c)
self.assertEqual(re.sub('^\s*', 'X', 'test'), 'Xtest')
@ -551,14 +554,23 @@ class ReTests(unittest.TestCase):
self.assertEqual(re.match(r"\(", '(').group(), '(')
self.assertIsNone(re.match(r"\(", ')'))
self.assertEqual(re.match(r"\\", '\\').group(), '\\')
self.assertEqual(re.match(r"\y", 'y').group(), 'y')
self.assertIsNone(re.match(r"\y", 'z'))
self.assertEqual(re.match(r"[\]]", ']').group(), ']')
self.assertIsNone(re.match(r"[\]]", '['))
self.assertEqual(re.match(r"[a\-c]", '-').group(), '-')
self.assertIsNone(re.match(r"[a\-c]", 'b'))
self.assertEqual(re.match(r"[\^a]+", 'a^').group(), 'a^')
self.assertIsNone(re.match(r"[\^a]+", 'b'))
re.purge() # for warnings
for c in 'ceghijklmopqyzCEFGHIJKLMNOPQRTVXY':
with self.subTest(c):
with self.assertWarns(DeprecationWarning):
self.assertEqual(re.fullmatch('\\%c' % c, c).group(), c)
self.assertIsNone(re.match('\\%c' % c, 'a'))
for c in 'ceghijklmopqyzABCEFGHIJKLMNOPQRTVXYZ':
with self.subTest(c):
with self.assertWarns(DeprecationWarning):
self.assertEqual(re.fullmatch('[\\%c]' % c, c).group(), c)
self.assertIsNone(re.match('[\\%c]' % c, 'a'))
def test_string_boundaries(self):
# See http://bugs.python.org/issue10713
@ -907,8 +919,10 @@ class ReTests(unittest.TestCase):
self.assertTrue(re.match((r"\x%02x" % i).encode(), bytes([i])))
self.assertTrue(re.match((r"\x%02x0" % i).encode(), bytes([i])+b"0"))
self.assertTrue(re.match((r"\x%02xz" % i).encode(), bytes([i])+b"z"))
self.assertTrue(re.match(br"\u", b'u'))
self.assertTrue(re.match(br"\U", b'U'))
with self.assertWarns(DeprecationWarning):
self.assertTrue(re.match(br"\u1234", b'u1234'))
with self.assertWarns(DeprecationWarning):
self.assertTrue(re.match(br"\U00012345", b'U00012345'))
self.assertTrue(re.match(br"\0", b"\000"))
self.assertTrue(re.match(br"\08", b"\0008"))
self.assertTrue(re.match(br"\01", b"\001"))
@ -928,8 +942,10 @@ class ReTests(unittest.TestCase):
self.assertTrue(re.match((r"[\x%02x]" % i).encode(), bytes([i])))
self.assertTrue(re.match((r"[\x%02x0]" % i).encode(), bytes([i])))
self.assertTrue(re.match((r"[\x%02xz]" % i).encode(), bytes([i])))
self.assertTrue(re.match(br"[\u]", b'u'))
self.assertTrue(re.match(br"[\U]", b'U'))
with self.assertWarns(DeprecationWarning):
self.assertTrue(re.match(br"[\u1234]", b'u'))
with self.assertWarns(DeprecationWarning):
self.assertTrue(re.match(br"[\U00012345]", b'U'))
self.assertRaises(re.error, re.match, br"[\567]", b"")
self.assertRaises(re.error, re.match, br"[\911]", b"")
self.assertRaises(re.error, re.match, br"[\x1z]", b"")
@ -1304,6 +1320,7 @@ class ReTests(unittest.TestCase):
def test_bug_13899(self):
# Issue #13899: re pattern r"[\A]" should work like "A" but matches
# nothing. Ditto B and Z.
with self.assertWarns(DeprecationWarning):
self.assertEqual(re.findall(r'[\A\B\b\C\Z]', 'AB\bCZ'),
['A', 'B', '\b', 'C', 'Z'])

4
Misc/NEWS
View File

@ -30,6 +30,10 @@ Core and Builtins
Library
-------
- Issue #23622: Unknown escapes in regular expressions that consist of ``'\'``
and ASCII letter now raise a deprecation warning and will be forbidden in
Python 3.6.
- Issue #23671: string.Template now allows to specify the "self" parameter as
keyword argument. string.Formatter now allows to specify the "self" and
the "format_string" parameters as keyword arguments.