Issues #814253, #9179: Warnings now are raised when group references and
conditional group references are used in lookbehind assertions in regular
expressions.
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
index 5e2914d..588042a 100644
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -1,7 +1,9 @@
# -*- coding: utf-8 -*-
-from test.test_support import verbose, run_unittest, import_module
-from test.test_support import precisionbigmemtest, _2G, cpython_only
-from test.test_support import captured_stdout, have_unicode, requires_unicode, u
+from test.test_support import (
+ verbose, run_unittest, import_module,
+ precisionbigmemtest, _2G, cpython_only,
+ captured_stdout, have_unicode, requires_unicode, u,
+ check_warnings)
import locale
import re
from re import Scanner
@@ -449,7 +451,7 @@
self.assertEqual(re.match("a.*b", "a\n\nb", re.DOTALL).group(0),
"a\n\nb")
- def test_non_consuming(self):
+ def test_lookahead(self):
self.assertEqual(re.match("(a(?=\s[^a]))", "a b").group(1), "a")
self.assertEqual(re.match("(a(?=\s[^a]*))", "a b").group(1), "a")
self.assertEqual(re.match("(a(?=\s[abc]))", "a b").group(1), "a")
@@ -463,6 +465,41 @@
self.assertEqual(re.match(r"(a)(?!\s\1)", "a b").group(1), "a")
self.assertEqual(re.match(r"(a)(?!\s(abc|a))", "a b").group(1), "a")
+ # Group reference.
+ self.assertTrue(re.match(r'(a)b(?=\1)a', 'aba'))
+ self.assertIsNone(re.match(r'(a)b(?=\1)c', 'abac'))
+ # Named group reference.
+ self.assertTrue(re.match(r'(?P<g>a)b(?=(?P=g))a', 'aba'))
+ self.assertIsNone(re.match(r'(?P<g>a)b(?=(?P=g))c', 'abac'))
+ # Conditional group reference.
+ self.assertTrue(re.match(r'(?:(a)|(x))b(?=(?(2)x|c))c', 'abc'))
+ self.assertIsNone(re.match(r'(?:(a)|(x))b(?=(?(2)c|x))c', 'abc'))
+ self.assertTrue(re.match(r'(?:(a)|(x))b(?=(?(2)x|c))c', 'abc'))
+ self.assertIsNone(re.match(r'(?:(a)|(x))b(?=(?(1)b|x))c', 'abc'))
+ self.assertTrue(re.match(r'(?:(a)|(x))b(?=(?(1)c|x))c', 'abc'))
+ # Group used before defined.
+ self.assertTrue(re.match(r'(a)b(?=(?(2)x|c))(c)', 'abc'))
+ self.assertIsNone(re.match(r'(a)b(?=(?(2)b|x))(c)', 'abc'))
+ self.assertTrue(re.match(r'(a)b(?=(?(1)c|x))(c)', 'abc'))
+
+ def test_lookbehind(self):
+ self.assertTrue(re.match(r'ab(?<=b)c', 'abc'))
+ self.assertIsNone(re.match(r'ab(?<=c)c', 'abc'))
+ self.assertIsNone(re.match(r'ab(?<!b)c', 'abc'))
+ self.assertTrue(re.match(r'ab(?<!c)c', 'abc'))
+ # Group reference.
+ with check_warnings(('', RuntimeWarning)):
+ re.compile(r'(a)a(?<=\1)c')
+ # Named group reference.
+ with check_warnings(('', RuntimeWarning)):
+ re.compile(r'(?P<g>a)a(?<=(?P=g))c')
+ # Conditional group reference.
+ with check_warnings(('', RuntimeWarning)):
+ re.compile(r'(a)b(?<=(?(1)b|x))c')
+ # Group used before defined.
+ with check_warnings(('', RuntimeWarning)):
+ re.compile(r'(a)b(?<=(?(2)b|x))(c)')
+
def test_ignore_case(self):
self.assertEqual(re.match("abc", "ABC", re.I).group(0), "ABC")
self.assertEqual(re.match("abc", u"ABC", re.I).group(0), "ABC")