public function collectDir($dir, $ext = '.twig')
    {
        $iterator = new RegexIterator(
            new RecursiveIteratorIterator(
                new RecursiveDirectoryIterator($dir), RecursiveIteratorIterator::LEAVES_ONLY
            ), '{'.preg_quote($ext).'$}'
        );

        return $this->collect(new Twig_Util_TemplateDirIterator($iterator));
    }