From: William James <w_a_x_man@...>
Date: 2009-02-12T10:18:48+09:00
Subject: Re: Method to get string combinations

Christoph Blank wrote:

> Hi,
> 
> I have a text like this:
> 
> "This {is|was} a {good|nice} day" and want to generate possible
> combinations like:
> 
> This is a good day
> This was a good day
> This is a nice day
> 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?
> 
> Thank you.

def comb ary
  ary.inject([[]]){|old,lst|
    lst.inject([]){|new,e| new + old.map{|c| c + [ e ] }}}
end

s = "This {is|was|will be} a {good|nice} day to {surf|swim}."

f = nil
a,b = s.split( /\{(.*?)\}/ ).partition{f=!f}

a = a.join( "%s" ) + "\n"
b.map!{|s| s.split "|"}

comb(b).each{|x| printf a % x }

--- output ---
This is a good day to surf.
This was a good day to surf.
This will be a good day to surf.
This is a nice day to surf.
This was a nice day to surf.
This will be a nice day to surf.
This is a good day to swim.
This was a good day to swim.
This will be a good day to swim.
This is a nice day to swim.
This was a nice day to swim.
This will be a nice day to swim.