From: David Garamond <davegaramond@...>
Date: 2002-10-07T12:45:55+09:00
Subject: regex speed

i am noticing ruby is much slower than perl when matching patterns with 
two or more quantifier (+ or *). consider this string:

  $ ruby -0 -ne 'print "A"*3,"\n"*10000,"B"*10,"\n"*10000' > str

and matching this string:

  $ perl -0 -ne'print 1 if /A.+\n+B/s' str   # 0m1.682s
  $ ruby -0 -ne'print 1 if /A.+\n+B/m' str   # 0m12.468s
  $ perl -0 -ne'print 1 if /A.+\n.+\nB/s' str   # 0m1.368s
  $ ruby -0 -ne'print 1 if /A.+\n.+\nB/m' str   # 0m11.427s

php (pcre) speed is somewhere in between.

of course, with patterns like /A.+\n+.+B/ or those with more quantifiers 
both become very slow, but i suspect perl is still faster then ruby 
especially when there are fewer ".+" and more "SINGLECHAR+" subpatterns. 
  i even have one case where perl takes less than a second and ruby 
takes more than five minutes (i don't know for sure, i interrupted the 
process so ruby never finished).

note that i'm not implying anything though, because i understand perl's 
regex engine has undergone a long period of tweaking and optimization.

-- 
dave

ps: using ruby 1.6.7 vs perl 5.8.0 on linux