bpo-40480: restore ability to join fnmatch.translate() results (GH-20049)
In translate(), generate unique group names across calls.
The restores the undocumented ability to get a valid regexp
by joining multiple translate() results via `|`.
diff --git a/Lib/test/test_fnmatch.py b/Lib/test/test_fnmatch.py
index 4c17306..10668e4 100644
--- a/Lib/test/test_fnmatch.py
+++ b/Lib/test/test_fnmatch.py
@@ -106,6 +106,7 @@
class TranslateTestCase(unittest.TestCase):
def test_translate(self):
+ import re
self.assertEqual(translate('*'), r'(?s:.*)\Z')
self.assertEqual(translate('?'), r'(?s:.)\Z')
self.assertEqual(translate('a?b*'), r'(?s:a.b.*)\Z')
@@ -122,9 +123,26 @@
self.assertEqual(translate('*********A'), r'(?s:.*A)\Z')
self.assertEqual(translate('A*********?[?]?'), r'(?s:A.*.[?].)\Z')
# fancy translation to prevent exponential-time match failure
- self.assertEqual(translate('**a*a****a'),
- r'(?s:(?=(?P<g1>.*?a))(?P=g1)(?=(?P<g2>.*?a))(?P=g2).*a)\Z')
-
+ t = translate('**a*a****a')
+ digits = re.findall(r'\d+', t)
+ self.assertEqual(len(digits), 4)
+ self.assertEqual(digits[0], digits[1])
+ self.assertEqual(digits[2], digits[3])
+ g1 = f"g{digits[0]}" # e.g., group name "g4"
+ g2 = f"g{digits[2]}" # e.g., group name "g5"
+ self.assertEqual(t,
+ fr'(?s:(?=(?P<{g1}>.*?a))(?P={g1})(?=(?P<{g2}>.*?a))(?P={g2}).*a)\Z')
+ # and try pasting multiple translate results - it's an undocumented
+ # feature that this works; all the pain of generating unique group
+ # names across calls exists to support this
+ r1 = translate('**a**a**a*')
+ r2 = translate('**b**b**b*')
+ r3 = translate('*c*c*c*')
+ fatre = "|".join([r1, r2, r3])
+ self.assertTrue(re.match(fatre, 'abaccad'))
+ self.assertTrue(re.match(fatre, 'abxbcab'))
+ self.assertTrue(re.match(fatre, 'cbabcaxc'))
+ self.assertFalse(re.match(fatre, 'dabccbad'))
class FilterTestCase(unittest.TestCase):