From 55593c3ef530ea01b1cfb1f7c81ee34fd994d0ef Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sun, 26 Sep 2004 18:56:44 +0000
Subject: [PATCH] Make the regex pattern easier to read, understand, and modify
 by factoring out the common prefix (the delimiter).

---
 Lib/string.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/Lib/string.py b/Lib/string.py
index 623eb0edab..7371c915a1 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -101,10 +101,12 @@ class _multimap:
 
 class _TemplateMetaclass(type):
     pattern = r"""
-    (?P<escaped>%(delim)s{2})       |   # Escape sequence of two delimiters
-    %(delim)s(?P<named>%(id)s)      |   # delimiter and a Python identifier
-    %(delim)s{(?P<braced>%(id)s)}   |   # delimiter and a braced identifier
-    (?P<invalid>%(delim)s)              # Other ill-formed delimiter exprs
+    %(delim)s(?:
+      (?P<escaped>%(delim)s) |   # Escape sequence of two delimiters
+      (?P<named>%(id)s)      |   # delimiter and a Python identifier
+      {(?P<braced>%(id)s)}   |   # delimiter and a braced identifier
+      (?P<invalid>)              # Other ill-formed delimiter exprs
+    )
     """
 
     def __init__(cls, name, bases, dct):
-- 
2.40.0