gistfile1.txt

 # Scan it for all instances of (unescaped) <rules>
      # Each match will be an array containing the portion of string before
      # the <rule>; and the <rule> itself (which may be empty on the last match)
      
      choice.scan(Regexp.new("/(.*?(?<!\\)(?:\\\\)*)(<.*?>|$)/",nil,"u")) do |match|
        local_res << match[0]
        unless match[1].empty?
          local_res << invoke(match[1].match(/<(.*?)>/)[1].to_sym)
        end
      end