From 56e190068177855266f32a7efa329d145b279f94 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Wed, 26 Feb 2025 13:01:32 +0100
Subject: gh-128982: Substitute regular expression in
 `http.cookiejar.join_header_words` for an efficient alternative (GH-128983)

The function does not anymore rely on a regular expression
to find alphanumeric characters and underscores.
---
 Lib/http/cookiejar.py                                                   | 2 +-
 Misc/NEWS.d/next/Library/2025-01-18-11-40-11.gh-issue-128982.557lS5.rst | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2025-01-18-11-40-11.gh-issue-128982.557lS5.rst

diff --git a/Lib/http/cookiejar.py b/Lib/http/cookiejar.py
index fb0fd2e..4ebb160 100644
--- a/Lib/http/cookiejar.py
+++ b/Lib/http/cookiejar.py
@@ -448,7 +448,7 @@ def join_header_words(lists):
         attr = []
         for k, v in pairs:
             if v is not None:
-                if not re.search(r"^\w+$", v):
+                if not v.isalnum() and '_' not in v:
                     v = HEADER_JOIN_ESCAPE_RE.sub(r"\\\1", v)  # escape " and \
                     v = '"%s"' % v
                 k = "%s=%s" % (k, v)
diff --git a/Misc/NEWS.d/next/Library/2025-01-18-11-40-11.gh-issue-128982.557lS5.rst b/Misc/NEWS.d/next/Library/2025-01-18-11-40-11.gh-issue-128982.557lS5.rst
new file mode 100644
index 0000000..44b7a7b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-01-18-11-40-11.gh-issue-128982.557lS5.rst
@@ -0,0 +1,2 @@
+Improve the performance of :func:`!http.cookiejar.join_header_words` by up
+to 35%. Patch by Bénédikt Tran.
-- 
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