php实现无限极分类

function getTree($data) {
    $items = [];
    foreach ($data as $v){
        $items[$v['id']] = $v;
    }
    $tree = array();//格式化好的树
    foreach ($items as $item)
       if (isset($items[$item['auth_pid']]))
             $items[$item['auth_pid']]['son'][] = &$items[$item['id']];
       else   $tree[] = &$items[$item['id']];
    return $tree;
};