From: Christoph Blank <cb@...>
Date: 2009-02-11T19:47:23+09:00
Subject: Re: Method to get string combinations

Wow, this is really useful! Especially in a general way like that.

Thanks a lot for the quick and helpful answer!

greetings,
Christoph

Jes炭s Gabriel y Gal叩n wrote:
> On Wed, Feb 11, 2009 at 11:22 AM, Christoph Blank <cb@unused.at> wrote:
>> This was a nice day
>>
>> I tried using zsh functionality to output this, but it doesn't seem that
>> easy.
>> Does anyone know an easy way how to do this in ruby?
> 
> There was a similar question on this list recently, I'll try to find
> it later for reference. For a ruby quiz
> (http://rubyquiz.com/quiz143.html) I built a regexp "generator". It
> adds a method to the Regexp to generate all possible strings that
> match the regexp. If you use my code:
> 
> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/274375
> 
> Then this works:
> 
> irb(main):001:0> require 'quiz143'
> => true
> irb(main):002:0> a = "This {is|was} a {good|nice} day"
> => "This {is|was} a {good|nice} day"
> irb(main):006:0> s = a.gsub(/\{(.*?)\}/, "(\\1)")
> => "This (is|was) a (good|nice) day"
> irb(main):008:0> Regexp.new(s).generate
> => ["This is a good day", "This is a nice day", "This was a good day",
> "This was a nice day"]
> 
> I'm changing your string to a valid regexp, changing all occurrences
> of {} with () (depending on your case you might want to change that).
> Then I create a regexp with that and call my method.
> 
> This supports many constructs from regexps, which might be overkill
> for your problem. For sure there will be easier solutions for your
> specific case. Anyway, I hope you find it interesting.
> 
> Jesus.

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