Issue python#14260: The groupindex attribute of regular expression pattern object

serhiy-storchaka · serhiy-storchaka · commit 07360df481ad · 2015-03-30T01:01:48.000+03:00
now is non-modifiable mapping.
diff --git a/Lib/csv.py b/Lib/csv.py
@@ -231,20 +231,21 @@ def _guess_quote_and_delimiter(self, data, delimiters):
         quotes = {}
         delims = {}
         spaces = 0
+        groupindex = regexp.groupindex
         for m in matches:
-            n = regexp.groupindex['quote'] - 1
+            n = groupindex['quote'] - 1
             key = m[n]
             if key:
                 quotes[key] = quotes.get(key, 0) + 1
             try:
-                n = regexp.groupindex['delim'] - 1
+                n = groupindex['delim'] - 1
                 key = m[n]
             except KeyError:
                 continue
             if key and (delimiters is None or key in delimiters):
                 delims[key] = delims.get(key, 0) + 1
             try:
-                n = regexp.groupindex['space'] - 1
+                n = groupindex['space'] - 1
             except KeyError:
                 continue
             if m[n]:
diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
@@ -855,6 +855,7 @@ def addgroup(index):
             del literal[:]
         groups.append((len(literals), index))
         literals.append(None)
+    groupindex = pattern.groupindex
     while True:
         this = sget()
         if this is None:
@@ -869,7 +870,7 @@ def addgroup(index):
                 name = s.getuntil(">")
                 if name.isidentifier():
                     try:
-                        index = pattern.groupindex[name]
+                        index = groupindex[name]
                     except KeyError:
                         raise IndexError("unknown group name %r" % name)
                 else:
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
@@ -577,6 +577,14 @@ def test_getattr(self):
         self.assertEqual(re.match("(a)", "a").regs, ((0, 1), (0, 1)))
         self.assertTrue(re.match("(a)", "a").re)
 
+        # Issue 14260. groupindex should be non-modifiable mapping.
+        p = re.compile(r'(?i)(?P<first>a)(?P<other>b)')
+        self.assertEqual(sorted(p.groupindex), ['first', 'other'])
+        self.assertEqual(p.groupindex['other'], 2)
+        with self.assertRaises(TypeError):
+            p.groupindex['other'] = 0
+        self.assertEqual(p.groupindex['other'], 2)
+
     def test_special_escapes(self):
         self.assertEqual(re.search(r"\b(b.)\b",
                                    "abcd abc bcd bx").group(1), "bx")
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -30,6 +30,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #14260: The groupindex attribute of regular expression pattern object
+  now is non-modifiable mapping.
+
 - Issue #23792: Ignore KeyboardInterrupt when the pydoc pager is active.
   This mimics the behavior of the standard unix pagers, and prevents
   pipepager from shutting down while the pager itself is still running.
diff --git a/Modules/_sre.c b/Modules/_sre.c
@@ -1384,12 +1384,24 @@ static PyMethodDef pattern_methods[] = {
     {NULL, NULL}
 };
 
+/* PatternObject's 'groupindex' method. */
+static PyObject *
+pattern_groupindex(PatternObject *self)
+{
+    return PyDictProxy_New(self->groupindex);
+}
+
+static PyGetSetDef pattern_getset[] = {
+    {"groupindex", (getter)pattern_groupindex, (setter)NULL,
+      "A dictionary mapping group names to group numbers."},
+    {NULL}  /* Sentinel */
+};
+
 #define PAT_OFF(x) offsetof(PatternObject, x)
 static PyMemberDef pattern_members[] = {
     {"pattern",    T_OBJECT,    PAT_OFF(pattern),       READONLY},
     {"flags",      T_INT,       PAT_OFF(flags),         READONLY},
     {"groups",     T_PYSSIZET,  PAT_OFF(groups),        READONLY},
-    {"groupindex", T_OBJECT,    PAT_OFF(groupindex),    READONLY},
     {NULL}  /* Sentinel */
 };
 
@@ -1422,6 +1434,7 @@ static PyTypeObject Pattern_Type = {
     0,                                  /* tp_iternext */
     pattern_methods,                    /* tp_methods */
     pattern_members,                    /* tp_members */
+    pattern_getset,                     /* tp_getset */
 };
 
 static int _validate(PatternObject *self); /* Forward */
