* * For the full copyright and license information, please view the LICENSE * file that was distributed with this source code. */ namespace Symfony\Component\HttpFoundation\File\MimeType; /** * A singleton mime type to file extension guesser. * * A default guesser is provided. * You can register custom guessers by calling the register() * method on the singleton instance: * * $guesser = ExtensionGuesser::getInstance(); * $guesser->register(new MyCustomExtensionGuesser()); * * The last registered guesser is preferred over previously registered ones. */ class ExtensionGuesser implements ExtensionGuesserInterface { /** * The singleton instance * * @var ExtensionGuesser */ private static $instance = null; /** * All registered ExtensionGuesserInterface instances * * @var array */ protected $guessers = array(); /** * Returns the singleton instance * * @return ExtensionGuesser */ public static function getInstance() { if (null === self::$instance) { self::$instance = new self(); } return self::$instance; } /** * Registers all natively provided extension guessers */ private function __construct() { $this->register(new MimeTypeExtensionGuesser()); } /** * Registers a new extension guesser * * When guessing, this guesser is preferred over previously registered ones. * * @param ExtensionGuesserInterface $guesser */ public function register(ExtensionGuesserInterface $guesser) { array_unshift($this->guessers, $guesser); } /** * Tries to guess the extension * * The mime type is passed to each registered mime type guesser in reverse order * of their registration (last registered is queried first). Once a guesser * returns a value that is not NULL, this method terminates and returns the * value. * * @param string $mimeType The mime type * * @return string The guessed extension or NULL, if none could be guessed */ public function guess($mimeType) { foreach ($this->guessers as $guesser) { if (null !== $extension = $guesser->guess($mimeType)) { return $extension; } } } }