gistfile1.rb

  # http://en.wikipedia.org/wiki/Bank_card_number  
  CARDTYPES = {
    :visa => /^4(?!571|917|913|508|844|17500)[0-9]{12,15}$/,
    :mastercard => /^5(?!4130380)[1-5][0-9]{14}$/,
    :dinersclub => /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/,
    :amex => /^3[47][0-9]{13}$/,
    :discover => /^6(?:011|5[0-9]{2})[0-9]{12}$/,
    :visadankort => /^4571[0-9]{12}$/,
    :dankort => /^5019[0-9]{12}$/,
    :eurocardbyinvitation => /^54130380\d{8}/,
    :visaelectron => /(^(4917|4913|4508|4844|)\d{12}$)|^(417500)[0-9]{10}$/,
    :maestro => /^(5018|5020|5038|6304|6759|6761|6763)\d{8,15}$/,
    :jcb => /^(?:2131|1800|35\d{3})\d{11}$/
  }