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Applied patch #725106, by Greg Chapman, fixing capturing groups 

within repeats of alternatives. The only change to the original
patch was to convert the tests to the new test_re.py file.

This patch fixes cases like:

>>> re.match('((a)|b)*', 'abc').groups()
('b', '')

Which is wrong (it's impossible to match the empty string),
and incompatible with other regex systems, like the following
examples show:

% perl -e '"abc" =~ /^((a)|b)*/; print "$1 $2\n";'
b a

% echo "abc" | sed -r -e "s/^((a)|b)*/\1 \2|/"
b a|c
This commit is contained in:
Gustavo Niemeyer 2003-04-27 12:34:14 +00:00
parent 9dcbbea878
commit c34f2555bd
2 changed files with 29 additions and 0 deletions
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19
Lib/test/test_re.py
View File

@ -276,6 +276,25 @@ class ReTests(unittest.TestCase):
self.assertEqual(re.match(r'((.%s):)?z'%op, 'a:z').groups(),
('a:', 'a'))
def test_bug_725106(self):
# capturing groups in alternatives in repeats
self.assertEqual(re.match('^((a)|b)*', 'abc').groups(),
('b', 'a'))
self.assertEqual(re.match('^(([ab])|c)*', 'abc').groups(),
('c', 'b'))
self.assertEqual(re.match('^((d)|[ab])*', 'abc').groups(),
('b', None))
self.assertEqual(re.match('^((a)c|[ab])*', 'abc').groups(),
('b', None))
self.assertEqual(re.match('^((a)|b)*?c', 'abc').groups(),
('b', 'a'))
self.assertEqual(re.match('^(([ab])|c)*?d', 'abcd').groups(),
('c', 'b'))
self.assertEqual(re.match('^((d)|[ab])*?c', 'abc').groups(),
('b', None))
self.assertEqual(re.match('^((a)c|[ab])*?c', 'abc').groups(),
('b', None))
def test_finditer(self):
iter = re.finditer(r":+", "a:b::c:::d")
self.assertEqual([item.group(0) for item in iter],

10
Modules/_sre.c
View File

@ -947,10 +947,20 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
if (pattern[1] == SRE_OP_IN &&
(ptr >= end || !SRE_CHARSET(pattern + 3, (SRE_CODE) *ptr)))
continue;
if (state->repeat) {
i = mark_save(state, 0, lastmark);
if (i < 0)
return i;
}
state->ptr = ptr;
i = SRE_MATCH(state, pattern + 1, level + 1);
if (i)
return i;
if (state->repeat) {
i = mark_restore(state, 0, lastmark);
if (i < 0)
return i;
}
LASTMARK_RESTORE();
}
return 0;