Resolve relative URLs

function resolve_rurl($url)
{
    $url = explode("/", $url);

    foreach ($url as $key => $part)
    {
        if ($part == '..')
        {
            unset($url[$key]);
            unset($url[$key - 1]);
        }
        else if ($part == '.')
        {
            unset($url[$key]);
        }
    }

    return implode("/", $url);
}