PHP 循环获取顶级分类

public function getRootline($id){
        static $linest;
        empty($linest) && $linest = $this->getCnnameLists();
        $one = isset($linest[$id])?$linest[$id]:0;

        if(!empty($one)){
            $parent = $one;
            if ($parent['linelist_parent_id'] != 0){
                $parent = $linest[$one['linelist_parent_id']];
                while($parent['linelist_parent_id']>0){
                    $parent =  $linest[$parent['linelist_parent_id']];
                }
            }

            return !empty($parent)?$parent['linelist_cn_name']:'';
        }
        return '';
    }