diff --git a/Lib/re/__init__.py b/Lib/re/__init__.py index e0d6c844b4fa7c..af2808a77da691 100644 --- a/Lib/re/__init__.py +++ b/Lib/re/__init__.py @@ -399,12 +399,9 @@ def __init__(self, lexicon, flags=0): s = _parser.State() s.flags = flags for phrase, action in lexicon: - sub_pattern = _parser.parse(phrase, flags) - if sub_pattern.state.groups != 1: - raise ValueError("Cannot use capturing groups in re.Scanner") gid = s.opengroup() p.append(_parser.SubPattern(s, [ - (SUBPATTERN, (gid, 0, 0, sub_pattern)), + (SUBPATTERN, (gid, 0, 0, _parser.parse(phrase, flags))), ])) s.closegroup(gid, p[-1]) p = _parser.SubPattern(s, [(BRANCH, (None, p))]) diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py index b7ed86849cb193..f6e797b3785dbe 100644 --- a/Lib/test/test_re.py +++ b/Lib/test/test_re.py @@ -1639,24 +1639,6 @@ def s_int(scanner, token): return int(token) (['sum', 'op=', 3, 'op*', 'foo', 'op+', 312.5, 'op+', 'bar'], '')) - def test_bug_gh140797(self): - # gh140797: Capturing groups are not allowed in re.Scanner - - msg = r"Cannot use capturing groups in re\.Scanner" - # Capturing group throws an error - with self.assertRaisesRegex(ValueError, msg): - Scanner([("(a)b", None)]) - - # Named Group - with self.assertRaisesRegex(ValueError, msg): - Scanner([("(?Pa)", None)]) - - # Non-capturing groups should pass normally - s = Scanner([("(?:a)b", lambda scanner, token: token)]) - result, rem = s.scan("ab") - self.assertEqual(result,['ab']) - self.assertEqual(rem,'') - def test_bug_448951(self): # bug 448951 (similar to 429357, but with single char match) # (Also test greedy matches.) diff --git a/Misc/NEWS.d/next/Library/2025-12-05-17-58-29.gh-issue-140797.YxB27u.rst b/Misc/NEWS.d/next/Library/2025-12-05-17-58-29.gh-issue-140797.YxB27u.rst new file mode 100644 index 00000000000000..ebbe06fddfb372 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2025-12-05-17-58-29.gh-issue-140797.YxB27u.rst @@ -0,0 +1,3 @@ +Revert changes to the undocumented :class:`!re.Scanner` class. Capturing +groups are still allowed for backward compatibility, although using them can +lead to incorrect result. They will be forbidden in future Python versions.