backout 9fcf4008b626 (#9179) for further consideration

1 files changed, 9 insertions, 24 deletions

diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
index fad8014..b56d437 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -66,25 +66,24 @@ class Pattern:
     # 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.subpatterns.append(None)
+        self.groups = gid + 1
         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, p):
-        self.subpatterns[gid] = p
+    def closegroup(self, gid):
+        self.open.remove(gid)
     def checkgroup(self, gid):
-        return gid < self.groups and self.subpatterns[gid] is not None
+        return gid < self.groups and gid not in self.open
 
 class SubPattern:
     # a subpattern, in intermediate form
@@ -182,21 +181,7 @@ class SubPattern:
             elif op in UNITCODES:
                 lo = lo + 1
                 hi = hi + 1
-            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:
+            elif op == SUCCESS:
                 break
         self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)
         return self.width
@@ -724,7 +709,7 @@ def _parse(source, state):
                 if not sourcematch(")"):
                     raise error("unbalanced parenthesis")
                 if group is not None:
-                    state.closegroup(group, p)
+                    state.closegroup(group)
                 subpatternappend((SUBPATTERN, (group, p)))
             else:
                 while 1: