<?php

namespace Symfony\Foundation;

/*
 * This file is part of the symfony package.
 *
 * (c) Fabien Potencier <fabien.potencier@symfony-project.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * UniversalClassLoader implements a "universal" autoloder for PHP 5.3.
 *
 * It is able to load classes that use either:
 *
 *  * The technical interoperability standards for PHP 5.3 namespaces and
 *    class names (http://groups.google.com/group/php-standards/web/final-proposal);
 *
 *  * The PEAR naming convention for classes (http://pear.php.net/).
 *
 * Classes from a sub-namespace or a sub-hierarchy of PEAR classes can be
 * looked for in a list of locations to ease the vendoring of a sub-set of
 * classes for large projects.
 *
 * Example usage:
 *
 *     $loader = new ClassLoader();
 *
 *     // register classes with namespaces
 *     $loader->registerNamespaces(array(
 *       'Symfony\Components' => __DIR__.'/components',
 *       'Symfony' => __DIR__.'/framework',
 *     ));
 *
 *     // register a library using the PEAR naming convention
 *     $loader->registerPrefixes(array(
 *       'Swift_' => __DIR__.'/Swift',
 *     ));
 *
 *     // activate the autoloader
 *     $loader->register();
 *
 * In this example, if you try to use a class in the Symfony\Components
 * namespace or one of its children (Symfony\Components\Console for instance),
 * the autoloader will first look for the class under the components/
 * directory, and it will then fallback to the framework/ directory if not
 * found before giving up.
 *
 * @package    symfony
 * @subpackage foundation
 * @author     Fabien Potencier <fabien.potencier@symfony-project.org>
 */
class UniversalClassLoader
{
  protected $namespaces = array();
  protected $prefixes = array();

  /**
   * Registers an array of namespaces
   *
   * @param array $namespaces An array of namespaces (namespaces as keys and locations as values)
   */
  public function registerNamespaces(array $namespaces)
  {
    $this->namespaces = array_merge($this->namespaces, $namespaces);
  }

  /**
   * Registers a namespace.
   *
   * @param string $namespace The namespace
   * @param string $path      The location of the namespace
   */
  public function registerNamespace($namespace, $path)
  {
    $this->namespaces[$namespace] = $path;
  }

  /**
   * Registers an array of classes using the PEAR naming convention.
   *
   * @param array $classes An array of classes (prefixes as keys and locations as values)
   */
  public function registerPrefixes(array $classes)
  {
    $this->prefixes = array_merge($this->prefixes, $classes);
  }

  /**
   * Registers a set of classes using the PEAR naming convention.
   *
   * @param string $prefix The classes prefix
   * @param string $path   The location of the classes
   */
  public function registerPrefix($prefix, $path)
  {
    $this->prefixes[$prefix] = $path;
  }

  /**
   * Registers this instance as an autoloader.
   */
  public function register()
  {
    spl_autoload_register(array($this, 'loadClass'));
  }

  /**
   * Loads the given class or interface.
   *
   * @param string $class The name of the class
   */
  public function loadClass($class)
  {
    if (false !== ($pos = strripos($class, '\\')))
    {
      // namespaced class name
      $namespace = substr($class, 0, $pos);
      foreach ($this->namespaces as $ns => $dir)
      {
        if (0 === strpos($namespace, $ns))
        {
          $class = substr($class, $pos + 1);
          require $dir.DIRECTORY_SEPARATOR.str_replace('\\', DIRECTORY_SEPARATOR, $namespace).DIRECTORY_SEPARATOR.str_replace('_', DIRECTORY_SEPARATOR, $class).'.php';

          return;
        }
      }
    }
    else
    {
      // PEAR-like class name
      foreach ($this->prefixes as $prefix => $dir)
      {
        if (0 === strpos($class, $prefix))
        {
          require $dir.DIRECTORY_SEPARATOR.str_replace('_', DIRECTORY_SEPARATOR, $class).'.php';

          return;
        }
      }
    }
  }
}