Todd Benson wrote:
>  On Thu, May 8, 2008 at 6:07 PM, ara.t.howard <ara.t.howard@[...].com> wrote:
> > On May 8, 2008, at 3:40 PM, Todd Benson wrote:
> >> This question arises out of a couple of recent threads and may or may
> >> not be a Ruby-specific question.
> >>
> >> I can check with a character class if one of the characters in the
> >> class exists or does not exist, but can I use a regexp to check if a
> >> string absolutely contains all of the characters in the class?
> >>
> >> Using a set perspective, I can do it like this in irb...
> >>
> >> s1 = "hello there"
> >> s2 = "ohi"
> >> (s2.unpack('c*') & s1.unpack('c*')).size == s2.size
> >>
> >> => false
> >>
> >> I use unpack to avoid creating a bunch of String objects, one for each
> >> element in the array, which would happen if I used #split.  What I'm
> >> wondering is if there is a way to do this with a simple regexp.
> >>
> >> Thanks,
> >> Todd
> > cfp:~ > cat a.rb
> > class String
> >  def all_chars? chars
> >    tr(chars, '').empty?
> >  end
> > end
> >
> > p 'foobar'.all_chars?('rabof')
> > p 'foobar'.all_chars?('abc')
> > p 'foobar'.all_chars?('')
> >
> >
> >
> > cfp:~ > ruby a.rb
> > true
> > false
> > false
>  
>  Cool :)  #tr is one of those useful methods I somehow consistently forget about.

But it can be done with regex, right? It's just more elegant with tr.

class String
   def all_chars? chars
     if chars.empty?
       empty?
     else
       /\A[#{chars}]*\z/ === self
     end
   end
end

p 'foobar'.all_chars?('rabof')  # =>  true
p 'foobar'.all_chars?('abc')    # =>  false
p 'foobar'.all_chars?('')       # =>  false

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407