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

now is non-modifiable mapping.

3 files changed, 14 insertions, 4 deletions

diff --git a/Lib/csv.py b/Lib/csv.py
index a56eed8..c3c31f0 100644
--- a/Lib/csv.py
+++ b/Lib/csv.py
@@ -231,20 +231,21 @@ class Sniffer:
         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
index 0bce71e..c0f539d 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -855,6 +855,7 @@ def parse_template(source, pattern):
             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 parse_template(source, pattern):
                 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
index 020656a..5b71612 100644
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -577,6 +577,14 @@ class ReTests(unittest.TestCase):
         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")