1: <?php
  2: 
  3: /*
  4:  * This file is part of the Symfony package.
  5:  *
  6:  * (c) Fabien Potencier <fabien@symfony.com>
  7:  *
  8:  * For the full copyright and license information, please view the LICENSE
  9:  * file that was distributed with this source code.
 10:  */
 11: 
 12: namespace Symfony\Component\HttpFoundation\File\MimeType;
 13: 
 14: /**
 15:  * A singleton mime type to file extension guesser.
 16:  *
 17:  * A default guesser is provided.
 18:  * You can register custom guessers by calling the register()
 19:  * method on the singleton instance.
 20:  *
 21:  * <code>
 22:  * $guesser = ExtensionGuesser::getInstance();
 23:  * $guesser->register(new MyCustomExtensionGuesser());
 24:  * </code>
 25:  *
 26:  * The last registered guesser is preferred over previously registered ones.
 27:  *
 28:  */
 29: class ExtensionGuesser implements ExtensionGuesserInterface
 30: {
 31:     /**
 32:      * The singleton instance
 33:      *
 34:      * @var ExtensionGuesser
 35:      */
 36:     private static $instance = null;
 37: 
 38:     /**
 39:      * All registered ExtensionGuesserInterface instances
 40:      *
 41:      * @var array
 42:      */
 43:     protected $guessers = array();
 44: 
 45:     /**
 46:      * Returns the singleton instance
 47:      *
 48:      * @return ExtensionGuesser
 49:      */
 50:     public static function getInstance()
 51:     {
 52:         if (null === self::$instance) {
 53:             self::$instance = new self();
 54:         }
 55: 
 56:         return self::$instance;
 57:     }
 58: 
 59:     /**
 60:      * Registers all natively provided extension guessers
 61:      */
 62:     private function __construct()
 63:     {
 64:         $this->register(new MimeTypeExtensionGuesser());
 65:     }
 66: 
 67:     /**
 68:      * Registers a new extension guesser
 69:      *
 70:      * When guessing, this guesser is preferred over previously registered ones.
 71:      *
 72:      * @param ExtensionGuesserInterface $guesser
 73:      */
 74:     public function register(ExtensionGuesserInterface $guesser)
 75:     {
 76:         array_unshift($this->guessers, $guesser);
 77:     }
 78: 
 79:     /**
 80:      * Tries to guess the extension
 81:      *
 82:      * The mime type is passed to each registered mime type guesser in reverse order
 83:      * of their registration (last registered is queried first). Once a guesser
 84:      * returns a value that is not NULL, this method terminates and returns the
 85:      * value.
 86:      *
 87:      * @param string $mimeType The mime type
 88:      * @return string          The guessed extension or NULL, if none could be guessed
 89:      */
 90:     public function guess($mimeType)
 91:     {
 92:         foreach ($this->guessers as $guesser) {
 93:             $extension = $guesser->guess($mimeType);
 94: 
 95:             if (null !== $extension) {
 96:                 break;
 97:             }
 98:         }
 99: 
100:         return $extension;
101:     }
102: }
103: