From: Kornelius Kalnbach <murphy@...>
Date: 2010-01-05T14:26:13+09:00
Subject: Re: Is ruby's regex slower?

Roger Pack wrote:
>> So perl is 7 or 8 times faster here.
> You could try ruby 1.9 and see if it helps the speed.
not very.

I get best results in Ruby with:

 regexp = %r{href="http://([^"/]*)/[^"]*"\s+target="_blank"}
 1000.times do
   puts File.read('index.html').scan(regexp)
 end

~/ruby/bench time ruby19 regex.rb > /dev/null
real  0m1.428s
user  0m1.359s
sys  0m0.056s

~/ruby/bench time perl5.10.0 regex.pl > /dev/null
real  0m1.189s
user  0m1.095s
sys  0m0.084s

It's still slower. Perl has regular expression magic beyond my 
imagination, though. I heard they take the most "rare" character in the 
literal part of the regex (let's say, the colon) and search for it using 
machine code, and then work their way backwards to the beginning of the 
regexp...

Say what you want, but Perl rocks when it comes to text processing 
speed.

Python is even faster:

 import re
 regexp = re.compile(r'href="http://([^"/]*)/[^"]*"\s+target="_blank"')
 for i in xrange(1000):
     with open("index.html") as f:
         for m in regexp.finditer(f.read()):
             print m.group(1)

time python2.6 regex.py > /dev/null
real  0m0.943s
user  0m0.880s
sys  0m0.053s
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