bpo-34294: re module, fix wrong capturing groups in rare cases. (GH-11546)
Need to reset capturing groups between two SRE(match) callings in loops, this fixes wrong capturing groups in rare cases.
Also add a missing index in re.rst.
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
index ab1d985..797d85d 100644
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -2067,6 +2067,40 @@
self.assertEqual(m.group(), b'xyz')
self.assertEqual(m2.group(), b'')
+ def test_bug_34294(self):
+ # Issue 34294: wrong capturing groups
+
+ # exists since Python 2
+ s = "a\tx"
+ p = r"\b(?=(\t)|(x))x"
+ self.assertEqual(re.search(p, s).groups(), (None, 'x'))
+
+ # introduced in Python 3.7.0
+ s = "ab"
+ p = r"(?=(.)(.)?)"
+ self.assertEqual(re.findall(p, s),
+ [('a', 'b'), ('b', '')])
+ self.assertEqual([m.groups() for m in re.finditer(p, s)],
+ [('a', 'b'), ('b', None)])
+
+ # test-cases provided by issue34294, introduced in Python 3.7.0
+ p = r"(?=<(?P<tag>\w+)/?>(?:(?P<text>.+?)</(?P=tag)>)?)"
+ s = "<test><foo2/></test>"
+ self.assertEqual(re.findall(p, s),
+ [('test', '<foo2/>'), ('foo2', '')])
+ self.assertEqual([m.groupdict() for m in re.finditer(p, s)],
+ [{'tag': 'test', 'text': '<foo2/>'},
+ {'tag': 'foo2', 'text': None}])
+ s = "<test>Hello</test><foo/>"
+ self.assertEqual([m.groupdict() for m in re.finditer(p, s)],
+ [{'tag': 'test', 'text': 'Hello'},
+ {'tag': 'foo', 'text': None}])
+ s = "<test>Hello</test><foo/><foo/>"
+ self.assertEqual([m.groupdict() for m in re.finditer(p, s)],
+ [{'tag': 'test', 'text': 'Hello'},
+ {'tag': 'foo', 'text': None},
+ {'tag': 'foo', 'text': None}])
+
class PatternReprTests(unittest.TestCase):
def check(self, pattern, expected):