class Twig_Loader_Filesystem

class Twig_Loader_Filesystem implements Twig_LoaderInterface, Twig_ExistsLoaderInterface {
  protected $paths;
  protected $cache;

  /**
   * Constructor.
   *
   * @param string|array $paths A path or an array of paths where to look for templates
   */
  public function __construct($paths) {
    $this
      ->setPaths($paths);
  }

  /**
   * Returns the paths to the templates.
   *
   * @param string $namespace A path namespace
   *
   * @return array The array of paths where to look for templates
   */
  public function getPaths($namespace = '__main__') {
    return isset($this->paths[$namespace]) ? $this->paths[$namespace] : array();
  }

  /**
   * Returns the path namespaces.
   *
   * The "__main__" namespace is always defined.
   *
   * @return array The array of defined namespaces
   */
  public function getNamespaces() {
    return array_keys($this->paths);
  }

  /**
   * Sets the paths where templates are stored.
   *
   * @param string|array $paths     A path or an array of paths where to look for templates
   * @param string       $namespace A path namespace
   */
  public function setPaths($paths, $namespace = '__main__') {
    if (!is_array($paths)) {
      $paths = array(
        $paths,
      );
    }
    $this->paths[$namespace] = array();
    foreach ($paths as $path) {
      $this
        ->addPath($path, $namespace);
    }
  }

  /**
   * Adds a path where templates are stored.
   *
   * @param string $path      A path where to look for templates
   * @param string $namespace A path name
   *
   * @throws Twig_Error_Loader
   */
  public function addPath($path, $namespace = '__main__') {

    // invalidate the cache
    $this->cache = array();
    if (!is_dir($path)) {
      throw new Twig_Error_Loader(sprintf('The "%s" directory does not exist.', $path));
    }
    $this->paths[$namespace][] = rtrim($path, '/\\');
  }

  /**
   * Prepends a path where templates are stored.
   *
   * @param string $path      A path where to look for templates
   * @param string $namespace A path name
   *
   * @throws Twig_Error_Loader
   */
  public function prependPath($path, $namespace = '__main__') {

    // invalidate the cache
    $this->cache = array();
    if (!is_dir($path)) {
      throw new Twig_Error_Loader(sprintf('The "%s" directory does not exist.', $path));
    }
    $path = rtrim($path, '/\\');
    if (!isset($this->paths[$namespace])) {
      $this->paths[$namespace][] = $path;
    }
    else {
      array_unshift($this->paths[$namespace], $path);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getSource($name) {
    return file_get_contents($this
      ->findTemplate($name));
  }

  /**
   * {@inheritdoc}
   */
  public function getCacheKey($name) {
    return $this
      ->findTemplate($name);
  }

  /**
   * {@inheritdoc}
   */
  public function exists($name) {
    $name = (string) $name;
    if (isset($this->cache[$name])) {
      return true;
    }
    try {
      $this
        ->findTemplate($name);
      return true;
    } catch (Twig_Error_Loader $exception) {
      return false;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function isFresh($name, $time) {
    return filemtime($this
      ->findTemplate($name)) <= $time;
  }
  protected function findTemplate($name) {
    $name = (string) $name;

    // normalize name
    $name = preg_replace('#/{2,}#', '/', strtr($name, '\\', '/'));
    if (isset($this->cache[$name])) {
      return $this->cache[$name];
    }
    $this
      ->validateName($name);
    $namespace = '__main__';
    if (isset($name[0]) && '@' == $name[0]) {
      if (false === ($pos = strpos($name, '/'))) {
        throw new Twig_Error_Loader(sprintf('Malformed namespaced template name "%s" (expecting "@namespace/template_name").', $name));
      }
      $namespace = substr($name, 1, $pos - 1);
      $name = substr($name, $pos + 1);
    }
    if (!isset($this->paths[$namespace])) {
      throw new Twig_Error_Loader(sprintf('There are no registered paths for namespace "%s".', $namespace));
    }
    foreach ($this->paths[$namespace] as $path) {
      if (is_file($path . '/' . $name)) {
        return $this->cache[$name] = $path . '/' . $name;
      }
    }
    throw new Twig_Error_Loader(sprintf('Unable to find template "%s" (looked into: %s).', $name, implode(', ', $this->paths[$namespace])));
  }
  protected function validateName($name) {
    if (false !== strpos($name, "\0")) {
      throw new Twig_Error_Loader('A template name cannot contain NUL bytes.');
    }
    $name = ltrim($name, '/');
    $parts = explode('/', $name);
    $level = 0;
    foreach ($parts as $part) {
      if ('..' === $part) {
        --$level;
      }
      elseif ('.' !== $part) {
        ++$level;
      }
      if ($level < 0) {
        throw new Twig_Error_Loader(sprintf('Looks like you try to load a template outside configured directories (%s).', $name));
      }
    }
  }

}