JWT::jsonDecode PHP Method

    public static function jsonDecode($input)
    {
        if (version_compare(PHP_VERSION, '5.4.0', '>=') && !(defined('JSON_C_VERSION') && PHP_INT_SIZE > 4)) {
            /** In PHP >=5.4.0, json_decode() accepts an options parameter, that allows you
             * to specify that large ints (like Steam Transaction IDs) should be treated as
             * strings, rather than the PHP default behaviour of converting them to floats.
             */
            $obj = json_decode($input, false, 512, JSON_BIGINT_AS_STRING);
        } else {
            /** Not all servers will support that, however, so for older versions we must
             * manually detect large ints in the JSON string and quote them (thus converting
             *them to strings) before decoding, hence the preg_replace() call.
             */
            $max_int_length = strlen((string) PHP_INT_MAX) - 1;
            $json_without_bigints = preg_replace('/:\\s*(-?\\d{' . $max_int_length . ',})/', ': "$1"', $input);
            $obj = json_decode($json_without_bigints);
        }
        if (function_exists('json_last_error') && ($errno = json_last_error())) {
            JWT::handleJsonError($errno);
        } elseif ($obj === null && $input !== 'null') {
            throw new DomainException('Null result with non-null input');
        }
        return $obj;
    }

 /**
  * Decodes a JWT string into a PHP object.
  *
  * @param string      $jwt       The JWT
  * @param string|Array|null $key The secret key, or map of keys
  * @param bool        $verify    Don't skip verification process
  *
  * @return object      The JWT's payload as a PHP object
  * @throws UnexpectedValueException Provided JWT was invalid
  * @throws DomainException          Algorithm was not provided
  * 
  * @uses jsonDecode
  * @uses urlsafeB64Decode
  */
 public static function decode($jwt, $key = null, $verify = true)
 {
     $tks = explode('.', $jwt);
     if (count($tks) != 3) {
         throw new UnexpectedValueException('Wrong number of segments');
     }
     list($headb64, $bodyb64, $cryptob64) = $tks;
     if (null === ($header = JWT::jsonDecode(JWT::urlsafeB64Decode($headb64)))) {
         throw new UnexpectedValueException('Invalid segment encoding');
     }
     if (null === ($payload = JWT::jsonDecode(JWT::urlsafeB64Decode($bodyb64)))) {
         throw new UnexpectedValueException('Invalid segment encoding');
     }
     $sig = JWT::urlsafeB64Decode($cryptob64);
     if ($verify) {
         if (empty($header->alg)) {
             throw new DomainException('Empty algorithm');
         }
         if (is_array($key)) {
             if (isset($header->kid)) {
                 $key = $key[$header->kid];
             } else {
                 throw new DomainException('"kid" empty, unable to lookup correct key');
             }
         }
         if (!JWT::verify("{$headb64}.{$bodyb64}", $sig, $key, $header->alg)) {
             throw new UnexpectedValueException('Signature verification failed');
         }
         // Check token expiry time if defined.
         if (isset($payload->exp) && time() >= $payload->exp) {
             throw new UnexpectedValueException('Expired Token');
         }
     }
     return $payload;
 }