class CardSchemeValidator

CardSchemeValidatorTest.php in drupal/core/vendor/symfony/validator/Symfony/Component/Validator/Tests/Constraints/CardSchemeValidatorTest.php

class CardSchemeValidator extends ConstraintValidator {
  protected $schemes = array(
    /**
     * American Express card numbers start with 34 or 37 and have 15 digits.
     */
    'AMEX' => array(
      '/^3[47][0-9]{13}$/',
    ),
    /**
     * China UnionPay cards start with 62 and have between 16 and 19 digits.
     * Please note that these cards do not follow Luhn Algorithm as a checksum.
     */
    'CHINA_UNIONPAY' => array(
      '/^62[0-9]{14,17}$/',
    ),
    /**
     * Diners Club card numbers begin with 300 through 305, 36 or 38. All have 14 digits.
     * There are Diners Club cards that begin with 5 and have 16 digits.
     * These are a joint venture between Diners Club and MasterCard, and should be processed like a MasterCard.
     */
    'DINERS' => array(
      '/^3(?:0[0-5]|[68][0-9])[0-9]{11}$/',
    ),
    /**
     * Discover card numbers begin with 6011, 622126 through 622925, 644 through 649 or 65.
     * All have 16 digits
     */
    'DISCOVER' => array(
      '/^6011[0-9]{12}$/',
      '/^64[4-9][0-9]{13}$/',
      '/^65[0-9]{14}$/',
      '/^622(12[6-9]|1[3-9][0-9]|[2-8][0-9][0-9]|91[0-9]|92[0-5])[0-9]{10}$/',
    ),
    /**
     * InstaPayment cards begin with 637 through 639 and have 16 digits
     */
    'INSTAPAYMENT' => array(
      '/^63[7-9][0-9]{13}$/',
    ),
    /**
     * JCB cards beginning with 2131 or 1800 have 15 digits.
     * JCB cards beginning with 35 have 16 digits.
     */
    'JCB' => array(
      '/^(?:2131|1800|35[0-9]{3})[0-9]{11}$/',
    ),
    /**
     * Laser cards begin with either 6304, 6706, 6709 or 6771 and have between 16 and 19 digits
     */
    'LASER' => array(
      '/^(6304|670[69]|6771)[0-9]{12,15}$/',
    ),
    /**
     * Maestro cards begin with either 5018, 5020, 5038, 5893, 6304, 6759, 6761, 6762, 6763 or 0604
     * They have between 12 and 19 digits
     */
    'MAESTRO' => array(
      '/^(5018|5020|5038|6304|6759|6761|676[23]|0604)[0-9]{8,15}$/',
    ),
    /**
     * All MasterCard numbers start with the numbers 51 through 55. All have 16 digits.
     */
    'MASTERCARD' => array(
      '/^5[1-5][0-9]{14}$/',
    ),
    /**
     * All Visa card numbers start with a 4. New cards have 16 digits. Old cards have 13.
     */
    'VISA' => array(
      '/^4([0-9]{12}|[0-9]{15})$/',
    ),
  );

  /**
   * Validates a creditcard belongs to a specified scheme.
   *
   * @param mixed $value
   * @param Constraint $constraint
   */
  public function validate($value, Constraint $constraint) {
    if (null === $value || '' === $value) {
      return;
    }
    if (!is_numeric($value)) {
      $this->context
        ->addViolation($constraint->message);
      return;
    }
    $schemes = array_flip((array) $constraint->schemes);
    $schemeRegexes = array_intersect_key($this->schemes, $schemes);
    foreach ($schemeRegexes as $regexes) {
      foreach ($regexes as $regex) {
        if (preg_match($regex, $value)) {
          return;
        }
      }
    }
    $this->context
      ->addViolation($constraint->message);
  }

}