Issues #814253, #9179: Group references and conditional group references now
work in lookbehind assertions in regular expressions.
diff --git a/Lib/re.py b/Lib/re.py
index 671a904..3edbafd 100644
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -312,10 +312,11 @@
s = sre_parse.Pattern()
s.flags = flags
for phrase, action in lexicon:
+ gid = s.opengroup()
p.append(sre_parse.SubPattern(s, [
- (SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
+ (SUBPATTERN, (gid, sre_parse.parse(phrase, flags))),
]))
- s.groups = len(p)+1
+ s.closegroup(gid, p[-1])
p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
self.scanner = sre_compile.compile(p)
def scan(self, string):
diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
index b85ce88..39341c6 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -66,24 +66,25 @@
# master pattern object. keeps track of global attributes
def __init__(self):
self.flags = 0
- self.open = []
- self.groups = 1
self.groupdict = {}
+ self.subpatterns = [None] # group 0
+ @property
+ def groups(self):
+ return len(self.subpatterns)
def opengroup(self, name=None):
gid = self.groups
- self.groups = gid + 1
+ self.subpatterns.append(None)
if name is not None:
ogid = self.groupdict.get(name, None)
if ogid is not None:
raise error, ("redefinition of group name %s as group %d; "
"was group %d" % (repr(name), gid, ogid))
self.groupdict[name] = gid
- self.open.append(gid)
return gid
- def closegroup(self, gid):
- self.open.remove(gid)
+ def closegroup(self, gid, p):
+ self.subpatterns[gid] = p
def checkgroup(self, gid):
- return gid < self.groups and gid not in self.open
+ return gid < self.groups and self.subpatterns[gid] is not None
class SubPattern:
# a subpattern, in intermediate form
@@ -178,7 +179,21 @@
elif op in UNITCODES:
lo = lo + 1
hi = hi + 1
- elif op == SUCCESS:
+ elif op is GROUPREF:
+ i, j = self.pattern.subpatterns[av].getwidth()
+ lo = lo + i
+ hi = hi + j
+ elif op is GROUPREF_EXISTS:
+ i, j = av[1].getwidth()
+ if av[2] is not None:
+ l, h = av[2].getwidth()
+ i = min(i, l)
+ j = max(j, h)
+ else:
+ i = 0
+ lo = lo + i
+ hi = hi + j
+ elif op is SUCCESS:
break
self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)
return self.width
@@ -657,7 +672,7 @@
if not sourcematch(")"):
raise error, "unbalanced parenthesis"
if group is not None:
- state.closegroup(group)
+ state.closegroup(group, p)
subpatternappend((SUBPATTERN, (group, p)))
else:
while 1:
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
index 7a25dbe..d2cc0c3 100644
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -448,7 +448,7 @@
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")
@@ -462,6 +462,42 @@
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'))
+ # Conditional group reference.
+ self.assertTrue(re.match('(?:(a)|(x))b(?=(?(2)x|c))c', 'abc'))
+ self.assertIsNone(re.match('(?:(a)|(x))b(?=(?(2)c|x))c', 'abc'))
+ self.assertTrue(re.match('(?:(a)|(x))b(?=(?(2)x|c))c', 'abc'))
+ self.assertIsNone(re.match('(?:(a)|(x))b(?=(?(1)b|x))c', 'abc'))
+ self.assertTrue(re.match('(?:(a)|(x))b(?=(?(1)c|x))c', 'abc'))
+ # Group used before defined.
+ self.assertTrue(re.match('(a)b(?=(?(2)x|c))(c)', 'abc'))
+ self.assertIsNone(re.match('(a)b(?=(?(2)b|x))(c)', 'abc'))
+ self.assertTrue(re.match('(a)b(?=(?(1)c|x))(c)', 'abc'))
+
+ def test_lookbehind(self):
+ self.assertTrue(re.match('ab(?<=b)c', 'abc'))
+ self.assertIsNone(re.match('ab(?<=c)c', 'abc'))
+ self.assertIsNone(re.match('ab(?<!b)c', 'abc'))
+ self.assertTrue(re.match('ab(?<!c)c', 'abc'))
+ # Group reference.
+ self.assertTrue(re.match(r'(a)a(?<=\1)c', 'aac'))
+ self.assertIsNone(re.match(r'(a)b(?<=\1)a', 'abaa'))
+ self.assertIsNone(re.match(r'(a)a(?<!\1)c', 'aac'))
+ self.assertTrue(re.match(r'(a)b(?<!\1)a', 'abaa'))
+ # Conditional group reference.
+ self.assertIsNone(re.match('(?:(a)|(x))b(?<=(?(2)x|c))c', 'abc'))
+ self.assertIsNone(re.match('(?:(a)|(x))b(?<=(?(2)b|x))c', 'abc'))
+ self.assertTrue(re.match('(?:(a)|(x))b(?<=(?(2)x|b))c', 'abc'))
+ self.assertIsNone(re.match('(?:(a)|(x))b(?<=(?(1)c|x))c', 'abc'))
+ self.assertTrue(re.match('(?:(a)|(x))b(?<=(?(1)b|x))c', 'abc'))
+ # Group used before defined.
+ self.assertIsNone(re.match('(a)b(?<=(?(2)x|c))(c)', 'abc'))
+ self.assertIsNone(re.match('(a)b(?<=(?(2)b|x))(c)', 'abc'))
+ self.assertIsNone(re.match('(a)b(?<=(?(1)c|x))(c)', 'abc'))
+ self.assertTrue(re.match('(a)b(?<=(?(1)b|x))(c)', 'abc'))
+
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")