--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * 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 $guessers = array();
+
+ /**
+ * Returns the singleton instance.
+ *
+ * @return self
+ */
+ public static function getInstance()
+ {
+ if (null === self::$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;
+ }
+ }
+ }
+}