From: Simon Strandgaard <neoneye@...>
Date: 2004-05-15T01:09:37+09:00
Subject: Re: Regexp Error?

On Sat, 15 May 2004 01:02:48 +0900
Guillaume Marcais <guslist@free.fr> wrote:

> On Fri, 2004-05-14 at 11:47, Simon Strandgaard wrote:
> > <advertisement>
> > my engine uses loop-detection, it thus outputs more desired results.
> > http://raa.ruby-lang.org/list.rhtml?name=regexp
> > 
> > For instance my engine outputs
> > 	/a(a|)*/ ~= 'aaab'     -> ['aaa', 'a']
> > 	/a(|ab)*b/ ~= 'aaabbb' -> ['aabb', 'ab']
> > 	/x(y?)*z/ ~= 'xyz'     -> ['xyz', 'y']
> > 	/x(y{0,2})*z/ ~= 'xyz' -> ['xyz', 'y'] 
> > If you try the same examples with Gnu or Oniguruma, you will see the last elements
> > are empty, I guess this is because they use the empty-token concept.
> > </advertisement>
> 
> Huh? False advertisement?
> 
> [gus@comp tmp]$ cat regexp.rb
> p /a(a|)*/.match('aaab').to_a
> p /a(|ab)*b/.match('aaabbb').to_a
> p /x(y?)*z/.match('xyz').to_a
> p /x(y{0,2})*z/.match('xyz').to_a
> [gus@comp tmp]$ ruby regexp.rb
> ["aaa", "a"]
> ["aabb", "ab"]
> ["xyz", "y"]
> ["xyz", "y"]
> [gus@comp tmp]$ ruby -v
> ruby 1.8.1 (2004-03-31) [i586-linux-gnu]
> 


I am sorry about the false statement.. however on Oniguruma (the future) it true


server> cat a.rb 
p /a(a|)*/.match('aaab').to_a
p /a(|ab)*b/.match('aaabbb').to_a
p /x(y?)*z/.match('xyz').to_a
p /x(y{0,2})*z/.match('xyz').to_a
server> ruby -v a.rb
ruby 1.9.0 (2004-04-16) [i386-freebsd5.1]
a.rb:1: warning: ambiguous first argument; put parentheses or even spaces
a.rb:2: warning: ambiguous first argument; put parentheses or even spaces
a.rb:3: warning: ambiguous first argument; put parentheses or even spaces
a.rb:4: warning: ambiguous first argument; put parentheses or even spaces
["aaa", ""]
["aabb", ""]
["xyz", ""]
["xyz", ""]
server>


--
Simon Strandgaard