From: Andrew M. Kuchling <amk@amk.ca>
Date: Wed, 20 Mar 2002 02:22:58 +0000 (+0000)
Subject: A faster version of the find_prefix_at_end() function (that I found in the
X-Git-Tag: v2.3c1~6432
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c63a396c5fc55beeaf3c973f137e160fc844d5a6;p=python

A faster version of the find_prefix_at_end() function (that I found in the
    last Medusa release)

Should be safe as a bugfix candidate, though it's not fixing a bug.
---

diff --git a/Lib/asynchat.py b/Lib/asynchat.py
index 3b2b37d978..762070f6b9 100644
--- a/Lib/asynchat.py
+++ b/Lib/asynchat.py
@@ -280,20 +280,18 @@ class fifo:
 # characters matched.
 # for example:
 # f_p_a_e ("qwerty\r", "\r\n") => 1
-# f_p_a_e ("qwerty\r\n", "\r\n") => 2
 # f_p_a_e ("qwertydkjf", "\r\n") => 0
+# f_p_a_e ("qwerty\r\n", "\r\n") => <undefined>
 
 # this could maybe be made faster with a computed regex?
 # [answer: no; circa Python-2.0, Jan 2001]
-# python:    18307/s
+# new python:   28961/s
+# old python:   18307/s
 # re:        12820/s
 # regex:     14035/s
 
 def find_prefix_at_end (haystack, needle):
-    nl = len(needle)
-    result = 0
-    for i in range (1,nl):
-        if haystack[-(nl-i):] == needle[:(nl-i)]:
-            result = nl-i
-            break
-    return result
+	l = len(needle) - 1
+	while l and not haystack.endswith(needle[:l]):
+		l -= 1
+	return l