bash like brace expansion

brace_expansion.rb

# bash like brace expansion
#
# {1,2}.3.4.{5,6}.7.8.{9,10} becomes
# [1.3.4.5.7.8.9, 
#  2.3.4.5.7.8.9,
#  1.3.4.6.7.8.9,
#  2.3.4.6.7.8.9,
#  1.3.4.5.7.8.10,
#  2.3.4.5.7.8.10,
#  1.3.4.6.7.8.10,
#  2.3.4.6.7.8.10]
#
# to use with things that don't like cmd line params like Rake.
# For info this is how to pass params to a rake task (and you don't want to use ENV)
# rake task_name[param1,param2]
#
# @param [String] the string to expand
# @return [Array] an array of String
def expand(string, delim=',')
  #check for brace expansions
  res = ['']
  string.split(/\{(.*?)\}/).each do |part|
    if part.include?(delim)
      #expansion
      new_res = []
      part.split(delim).each do |sub|
        res.each do |r|
          new_res << r+sub
        end
      end
      res     = new_res
    else
      #constant
      res.each do |r|
        r << part
      end
    end
  end
  res
end