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New asynchat.py from Sam Rushing: this foregoes using the regex module

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to find the prefix of strings, thus removing a warning, and simply
   uses straightforward string slicing.
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Andrew M. Kuchling 2001-01-24 21:10:55 +00:00
parent 9368a12011
commit d305f515f9
1 changed files with 12 additions and 36 deletions
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48
Lib/asynchat.py
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@ -1,5 +1,5 @@
# -*- Mode: Python; tab-width: 4 -*-
# Id: asynchat.py,v 2.25 1999/11/18 11:01:08 rushing Exp
# Id: asynchat.py,v 2.26 2000/09/07 22:29:26 rushing Exp
# Author: Sam Rushing <rushing@nightmare.com>
# ======================================================================
@ -279,40 +279,16 @@ class fifo:
# f_p_a_e ("qwertydkjf", "\r\n") => 0
# this could maybe be made faster with a computed regex?
##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
# yes, this is about twice as fast, but still seems
# to be negligible CPU. The previous version could do about 290
# searches/sec. the new one about 555/sec.
import regex
prefix_cache = {}
def prefix_regex (needle):
if prefix_cache.has_key (needle):
return prefix_cache[needle]
else:
reg = needle[-1]
for i in range(1,len(needle)):
reg = '%c\(%s\)?' % (needle[-(i+1)], reg)
reg = regex.compile (reg+'$')
prefix_cache[needle] = reg, len(needle)
return reg, len(needle)
# [answer: no; circa Python-2.0, Jan 2001]
# python: 18307/s
# re: 12820/s
# regex: 14035/s
def find_prefix_at_end (haystack, needle):
reg, length = prefix_regex (needle)
lh = len(haystack)
result = reg.search (haystack, max(0,lh-length))
if result >= 0:
return (lh - result)
else:
return 0
nl = len(needle)
result = 0
for i in range (1,nl):
if haystack[-(nl-i):] == needle[:(nl-i)]:
result = nl-i
break
return result