gistfile1.txt

/**
   * Merges max-age values (expressed in seconds), finds the lowest max-age.
   *
   * Ensures infinite max-age (Cache::PERMANENT) is taken into account.
   *
   * @param int $a
   *   Max age value to merge.
   * @param int $b
   *   Max age value to merge.
   *
   * @return int
   *   The minimum max-age value.
   */
  public static function mergeMaxAges($a = Cache::PERMANENT, $b = Cache::PERMANENT) {
    // If one of the values is Cache::PERMANENT, return the other value.
    if ($a === Cache::PERMANENT || $a == 0) {
      return $b;
    }
    if ($b === Cache::PERMANENT || $b == 0) {
      return $a;
    }

    // If none or the values are Cache::PERMANENT, return the minimum value.
    return min($a, $b);
  }