flat nested set to bootstrap 2.3 nested menu

gistfile1.phtml

<?php
    $current_depth = 1;
    $html = '';
    foreach($menu as $key => $value)
    {
        if(isset($menu[$key+1]) && $menu[$key+1]->DEPTH > $current_depth)
        {

            if($current_depth > 1)
            {
                $html .= "<li class='dropdown-submenu'>" . "\n";
                $html .= '<a tabindex="-1" href="#">'.$value->title.' </a>' . "\n";
            }
            else
            {
                $html .= "<li class='dropdown'>" . "\n";
                $html .= '<a class="dropdown-toggle" data-toggle="dropdown" href="#">'.$value->title.' <b class="caret"></b></a>' . "\n";
            }

            $html .= '<ul class="dropdown-menu">' . "\n";

            ++$current_depth;
            continue;
        }
        elseif($value->DEPTH < $current_depth)
        {
            $html .= '</ul>' . "\n";
            $html .= "</li>" . "\n";

            --$current_depth;
        }

        if($value->type_title == 'link')
        {
            $html .= '<li><a href="'.$value->url.'">'.$value->title.'</a></li>' . "\n";
        }
        elseif($value->type_title == 'separator')
        {
            $html .= '<li class="divider"></li>' . "\n";
        }
    }

    echo $html;
?>