phone number formatter

phone.rb

class Phone
  attr_accessor :num, :code
  def initialize(num, code)
    self.code = code
    self.num = num
  end
  
  def to_num
     rec = num.gsub(/[^\d]/, '')
    if rec[0..2] == code
      rec
    elsif rec[0] == "0"
      "#{code}#{rec[1..-1]}"
    else
      "#{code}#{rec}"
    end
  end
  
  def to_hyphen(delimiter = '-')
    <<<-DOC
      R = /
        \d{2,3}   # match 2 or 3 digits (greedily)
        (?=       # begin positive lookahead
          \d{2,3} # match 2 or 3 digits 
          |       # or
          \z      # match the end of the string
        )         # end positive lookahead
        /x        # free-spacing regex definition mode
    DOC
    R = /\d{2,3}(?=\d{2,3}|\z)/
    s = num.gsub(/\D/,'')
    return s if s.size < 4
    s.scan(R).join(delimeter)
  end
end