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work in lookbehind assertions in regular expressions.
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@ -352,10 +352,11 @@ def __init__(self, lexicon, flags=0):
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s = sre_parse.Pattern()
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s.flags = flags
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for phrase, action in lexicon:
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gid = s.opengroup()
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p.append(sre_parse.SubPattern(s, [
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(SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
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(SUBPATTERN, (gid, sre_parse.parse(phrase, flags))),
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]))
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s.groups = len(p)+1
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s.closegroup(gid, p[-1])
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p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
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self.scanner = sre_compile.compile(p)
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def scan(self, string):
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@ -66,24 +66,25 @@ class Pattern:
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# master pattern object. keeps track of global attributes
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def __init__(self):
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self.flags = 0
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self.open = []
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self.groups = 1
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self.groupdict = {}
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self.subpatterns = [None] # group 0
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@property
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def groups(self):
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return len(self.subpatterns)
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def opengroup(self, name=None):
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gid = self.groups
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self.groups = gid + 1
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self.subpatterns.append(None)
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if name is not None:
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ogid = self.groupdict.get(name, None)
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if ogid is not None:
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raise error("redefinition of group name %s as group %d; "
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"was group %d" % (repr(name), gid, ogid))
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self.groupdict[name] = gid
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self.open.append(gid)
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return gid
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def closegroup(self, gid):
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self.open.remove(gid)
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def closegroup(self, gid, p):
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self.subpatterns[gid] = p
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def checkgroup(self, gid):
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return gid < self.groups and gid not in self.open
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return gid < self.groups and self.subpatterns[gid] is not None
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class SubPattern:
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# a subpattern, in intermediate form
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@ -181,7 +182,21 @@ def getwidth(self):
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elif op in UNITCODES:
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lo = lo + 1
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hi = hi + 1
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elif op == SUCCESS:
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elif op is GROUPREF:
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i, j = self.pattern.subpatterns[av].getwidth()
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lo = lo + i
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hi = hi + j
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elif op is GROUPREF_EXISTS:
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i, j = av[1].getwidth()
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if av[2] is not None:
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l, h = av[2].getwidth()
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i = min(i, l)
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j = max(j, h)
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else:
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i = 0
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lo = lo + i
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hi = hi + j
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elif op is SUCCESS:
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break
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self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)
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return self.width
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@ -709,7 +724,7 @@ def _parse(source, state):
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if not sourcematch(")"):
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raise error("unbalanced parenthesis")
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if group is not None:
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state.closegroup(group)
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state.closegroup(group, p)
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subpatternappend((SUBPATTERN, (group, p)))
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else:
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while 1:
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@ -557,7 +557,7 @@ def test_anyall(self):
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self.assertEqual(re.match("a.*b", "a\n\nb", re.DOTALL).group(0),
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"a\n\nb")
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def test_non_consuming(self):
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def test_lookahead(self):
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self.assertEqual(re.match("(a(?=\s[^a]))", "a b").group(1), "a")
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self.assertEqual(re.match("(a(?=\s[^a]*))", "a b").group(1), "a")
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self.assertEqual(re.match("(a(?=\s[abc]))", "a b").group(1), "a")
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@ -571,6 +571,42 @@ def test_non_consuming(self):
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self.assertEqual(re.match(r"(a)(?!\s\1)", "a b").group(1), "a")
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self.assertEqual(re.match(r"(a)(?!\s(abc|a))", "a b").group(1), "a")
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# Group reference.
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self.assertTrue(re.match(r'(a)b(?=\1)a', 'aba'))
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self.assertIsNone(re.match(r'(a)b(?=\1)c', 'abac'))
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# Conditional group reference.
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self.assertTrue(re.match('(?:(a)|(x))b(?=(?(2)x|c))c', 'abc'))
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self.assertIsNone(re.match('(?:(a)|(x))b(?=(?(2)c|x))c', 'abc'))
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self.assertTrue(re.match('(?:(a)|(x))b(?=(?(2)x|c))c', 'abc'))
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self.assertIsNone(re.match('(?:(a)|(x))b(?=(?(1)b|x))c', 'abc'))
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self.assertTrue(re.match('(?:(a)|(x))b(?=(?(1)c|x))c', 'abc'))
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# Group used before defined.
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self.assertTrue(re.match('(a)b(?=(?(2)x|c))(c)', 'abc'))
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self.assertIsNone(re.match('(a)b(?=(?(2)b|x))(c)', 'abc'))
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self.assertTrue(re.match('(a)b(?=(?(1)c|x))(c)', 'abc'))
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def test_lookbehind(self):
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self.assertTrue(re.match('ab(?<=b)c', 'abc'))
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self.assertIsNone(re.match('ab(?<=c)c', 'abc'))
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self.assertIsNone(re.match('ab(?<!b)c', 'abc'))
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self.assertTrue(re.match('ab(?<!c)c', 'abc'))
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# Group reference.
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self.assertTrue(re.match(r'(a)a(?<=\1)c', 'aac'))
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self.assertIsNone(re.match(r'(a)b(?<=\1)a', 'abaa'))
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self.assertIsNone(re.match(r'(a)a(?<!\1)c', 'aac'))
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self.assertTrue(re.match(r'(a)b(?<!\1)a', 'abaa'))
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# Conditional group reference.
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self.assertIsNone(re.match('(?:(a)|(x))b(?<=(?(2)x|c))c', 'abc'))
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self.assertIsNone(re.match('(?:(a)|(x))b(?<=(?(2)b|x))c', 'abc'))
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self.assertTrue(re.match('(?:(a)|(x))b(?<=(?(2)x|b))c', 'abc'))
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self.assertIsNone(re.match('(?:(a)|(x))b(?<=(?(1)c|x))c', 'abc'))
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self.assertTrue(re.match('(?:(a)|(x))b(?<=(?(1)b|x))c', 'abc'))
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# Group used before defined.
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self.assertIsNone(re.match('(a)b(?<=(?(2)x|c))(c)', 'abc'))
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self.assertIsNone(re.match('(a)b(?<=(?(2)b|x))(c)', 'abc'))
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self.assertIsNone(re.match('(a)b(?<=(?(1)c|x))(c)', 'abc'))
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self.assertTrue(re.match('(a)b(?<=(?(1)b|x))(c)', 'abc'))
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def test_ignore_case(self):
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self.assertEqual(re.match("abc", "ABC", re.I).group(0), "ABC")
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self.assertEqual(re.match(b"abc", b"ABC", re.I).group(0), b"ABC")
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@ -36,6 +36,9 @@ Core and Builtins
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Library
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-------
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- Issues #814253, #9179: Group references and conditional group references now
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work in lookbehind assertions in regular expressions.
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- Issue #22406: Fixed the uu_codec codec incorrectly ported to 3.x.
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Based on patch by Martin Panter.
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