Add page/post slug class to menu item classes

//http://www.wpreso.com/blog/tutorials/2011/01/04/add-pagepost-slug-class-to-menu-item-classes/
function add_slug_class_to_menu_item($output){
    $ps = get_option('permalink_structure');
    if(!empty($ps)){
        $idstr = preg_match_all('/<li id="menu-item-(\d+)/', $output, $matches);
        foreach($matches[1] as $mid){
            $id = get_post_meta($mid, '_menu_item_object_id', true);
            $slug = basename(get_permalink($id));
            $output = preg_replace('/menu-item-'.$mid.'">/', 'menu-item-'.$mid.' menu-item-'.$slug.'">', $output, 1);
        }
    }
    return $output;
}
add_filter('wp_nav_menu', 'add_slug_class_to_menu_item');