Issues #814253, #9179: Group references and conditional group references now
work in lookbehind assertions in regular expressions.
diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
index 1a7d316..98afd7c 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -68,12 +68,15 @@
# 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
+ self.lookbehindgroups = None
+ @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 self.groups > MAXGROUPS:
raise error("groups number is too large")
if name is not None:
@@ -82,12 +85,19 @@
raise error("redefinition of group name %r as group %d; "
"was group %d" % (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
+
+ def checklookbehindgroup(self, gid, source):
+ if self.lookbehindgroups is not None:
+ if not self.checkgroup(gid):
+ raise source.error('cannot refer to an open group')
+ if gid >= self.lookbehindgroups:
+ raise source.error('cannot refer to group defined in the same '
+ 'lookbehind subpattern')
class SubPattern:
# a subpattern, in intermediate form
@@ -183,7 +193,21 @@
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
@@ -379,6 +403,7 @@
if not state.checkgroup(group):
raise source.error("cannot refer to open group",
len(escape))
+ state.checklookbehindgroup(group, source)
return GROUPREF, group
raise ValueError
if len(escape) == 2:
@@ -641,6 +666,7 @@
if gid is None:
msg = "unknown group name: {0!r}".format(name)
raise source.error(msg, len(name) + 1)
+ state.checklookbehindgroup(gid, source)
subpatternappend((GROUPREF, gid))
continue
else:
@@ -668,7 +694,13 @@
if char is None or char not in "=!":
raise source.error("syntax error")
dir = -1 # lookbehind
+ lookbehindgroups = state.lookbehindgroups
+ if lookbehindgroups is None:
+ state.lookbehindgroups = state.groups
p = _parse_sub(source, state)
+ if dir < 0:
+ if lookbehindgroups is None:
+ state.lookbehindgroups = None
if not sourcematch(")"):
raise source.error("unbalanced parenthesis")
if char == "=":
@@ -701,6 +733,7 @@
if condgroup >= MAXGROUPS:
raise source.error("the group number is too large",
len(condname) + 1)
+ state.checklookbehindgroup(condgroup, source)
elif char in FLAGS:
# flags
state.flags |= FLAGS[char]
@@ -726,7 +759,7 @@
if not sourcematch(")"):
raise source.error("unbalanced parenthesis")
if group is not None:
- state.closegroup(group)
+ state.closegroup(group, p)
subpatternappend((SUBPATTERN, (group, p)))
else:
while True: