<select>
  <option value="1">Category1</option>
  <option value="4">::SubCategory2</option>
  <option value="2">::SubCategory1</option>
  <option value="3">::::SubSubCategory</option>
  <option></option>
</select>

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => Category1
            [parent] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 4
                            [name] => SubCategory2
                            [parent] => 1
                            [children] => Array
                                (
                                )

                        )

                    [1] => Array
                        (
                            [id] => 2
                            [name] => SubCategory1
                            [parent] => 1
                            [children] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 3
                                            [name] => SubSubCategory
                                            [parent] => 2
                                            [children] => Array
                                                (
                                                )

                                        )

                                )

                        )

                )

        )
)

function GenerateSet($nav, $tabs = "") {
        $html = !strlen($tabs) ?
                "n".$tabs.'<ul class="categories">'."n" :
                "n".$tabs.'<ul>'."n";

        foreach($nav as $page) {

            $html .= $tabs."    ".'<li id="cat-'.$page['id'].'">';
            $html .= ' <a href="#">
                                <span class="linker">
                                    <span class="title">'.$page['name'].'</span>
                                </span>
                            </a>';

            if(isset($page['children'][0])) {
                $html .= $this->GenerateSet($page['children'], $tabs."        ");
            }
            $html .= '</li>'."n";
        }
        $html .= $tabs.'</ul>'."n";

        return $html;
}