MimeTypeGuesser.php

<?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;

use Symfony\Component\HttpFoundation\File\Exception\FileException;
use Symfony\Component\HttpFoundation\File\Exception\FileNotFoundException;
use Symfony\Component\HttpFoundation\File\Exception\AccessDeniedException;

/**
 * A singleton mime type guesser.
 *
 * By default, all mime type guessers provided by the framework are installed
 * (if available on the current OS/PHP setup). You can register custom
 * guessers by calling the register() method on the singleton instance.
 *
 * <code>
 * $guesser = MimeTypeGuesser::getInstance();
 * $guesser->register(new MyCustomMimeTypeGuesser());
 * </code>
 *
 * The last registered guesser is preferred over previously registered ones.
 *
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
class MimeTypeGuesser implements MimeTypeGuesserInterface {

  /**
   * The singleton instance
   *
   * @var MimeTypeGuesser
   */
  private static $instance = null;

  /**
   * All registered MimeTypeGuesserInterface instances
   *
   * @var array
   */
  protected $guessers = array();

  /**
   * Returns the singleton instance
   *
   * @return MimeTypeGuesser
   */
  public static function getInstance() {
    if (null === self::$instance) {
      self::$instance = new self();
    }
    return self::$instance;
  }

  /**
   * Registers all natively provided mime type guessers
   */
  private function __construct() {
    if (FileBinaryMimeTypeGuesser::isSupported()) {
      $this
        ->register(new FileBinaryMimeTypeGuesser());
    }
    if (FileinfoMimeTypeGuesser::isSupported()) {
      $this
        ->register(new FileinfoMimeTypeGuesser());
    }
  }

  /**
   * Registers a new mime type guesser
   *
   * When guessing, this guesser is preferred over previously registered ones.
   *
   * @param MimeTypeGuesserInterface $guesser
   */
  public function register(MimeTypeGuesserInterface $guesser) {
    array_unshift($this->guessers, $guesser);
  }

  /**
   * Tries to guess the mime type of the given file
   *
   * The file 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 $path The path to the file
   *
   * @return string         The mime type or NULL, if none could be guessed
   *
   * @throws FileException  If the file does not exist
   */
  public function guess($path) {
    if (!is_file($path)) {
      throw new FileNotFoundException($path);
    }
    if (!is_readable($path)) {
      throw new AccessDeniedException($path);
    }
    if (!$this->guessers) {
      throw new \LogicException('Unable to guess the mime type as no guessers are available (Did you enable the php_fileinfo extension?)');
    }
    foreach ($this->guessers as $guesser) {
      if (null !== ($mimeType = $guesser
        ->guess($path))) {
        return $mimeType;
      }
    }
  }

}