ApcClassLoader.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\ClassLoader;


/**
 * ApcClassLoader implements a wrapping autoloader cached in APC for PHP 5.3.
 *
 * It expects an object implementing a findFile method to find the file. This
 * allow using it as a wrapper around the other loaders of the component (the
 * ClassLoader and the UniversalClassLoader for instance) but also around any
 * other autoloader following this convention (the Composer one for instance)
 *
 *     $loader = new ClassLoader();
 *
 *     // register classes with namespaces
 *     $loader->add('Symfony\Component', __DIR__.'/component');
 *     $loader->add('Symfony',           __DIR__.'/framework');
 *
 *     $cachedLoader = new ApcClassLoader('my_prefix', $loader);
 *
 *     // activate the cached autoloader
 *     $cachedLoader->register();
 *
 *     // eventually deactivate the non-cached loader if it was registered previously
 *     // to be sure to use the cached one.
 *     $loader->unregister();
 *
 * @author Fabien Potencier <fabien@symfony.com>
 * @author Kris Wallsmith <kris@symfony.com>
 *
 * @api
 */
class ApcClassLoader {
  private $prefix;
  private $classFinder;

  /**
   * Constructor.
   *
   * @param string $prefix      A prefix to create a namespace in APC
   * @param object $classFinder An object that implements findFile() method.
   *
   * @api
   */
  public function __construct($prefix, $classFinder) {
    if (!extension_loaded('apc')) {
      throw new \RuntimeException('Unable to use ApcClassLoader as APC is not enabled.');
    }
    if (!method_exists($classFinder, 'findFile')) {
      throw new \InvalidArgumentException('The class finder must implement a "findFile" method.');
    }
    $this->prefix = $prefix;
    $this->classFinder = $classFinder;
  }

  /**
   * Registers this instance as an autoloader.
   *
   * @param Boolean $prepend Whether to prepend the autoloader or not
   */
  public function register($prepend = false) {
    spl_autoload_register(array(
      $this,
      'loadClass',
    ), true, $prepend);
  }

  /**
   * Unregisters this instance as an autoloader.
   */
  public function unregister() {
    spl_autoload_unregister(array(
      $this,
      'loadClass',
    ));
  }

  /**
   * Loads the given class or interface.
   *
   * @param string $class The name of the class
   *
   * @return Boolean|null True, if loaded
   */
  public function loadClass($class) {
    if ($file = $this
      ->findFile($class)) {
      require $file;
      return true;
    }
  }

  /**
   * Finds a file by class name while caching lookups to APC.
   *
   * @param string $class A class name to resolve to file
   *
   * @return string|null
   */
  public function findFile($class) {
    if (false === ($file = apc_fetch($this->prefix . $class))) {
      apc_store($this->prefix . $class, $file = $this->classFinder
        ->findFile($class));
    }
    return $file;
  }

}