From: Simon Strandgaard <neoneye@...>
Date: 2006-12-27T17:29:16+09:00
Subject: Re: reg exp comparison hanging irb

On 12/27/06, gaurav bagga <gaurav.v.bagga@gmail.com> wrote:
> was just going trough reg exp
> the lines below just hangs irb and cpu usage goes 100% on windows xp
> can anyone explain me why?
>
>
> irb(main):001:0> r=/^(https?:\/\/)?[a-z0-9]+([\.\-\_=&\+\/\?]?[a-z0-9]+)+$/i
> => /^(https?:\/\/)?[a-z0-9]+([\.\-\_=&\+\/\?]?[a-z0-9]+)+$/i
> irb(main):002:0> "
> http://groups-beta.google.com/group/rubyonrails-talk/browse_th
> read/thread/8f085b191387d799/e78a71cbd7354c0c#e78a71cbd7354c0c"=~r


the GNU regexp engine has a few oddities..
here is another example that triggers an endless loop.

r='<META http-equiv="Content-Type content="text/html; charset=iso-8859-1">'
r.scan /<(?:[^">]+|"[^"]*")+>/

we have in common that our regexp has nested repeating patterns.


-- 
Simon Strandgaard
http://opcoders.com/