php实现无限极分类

private function GetTree($arr,$pid,$step){
    global $tree;
    foreach($arr as $key=>$val) {
        if($val[‘pid‘] == $pid) {
            $flg = str_repeat(‘└―‘,$step);
            $val[‘name‘] = $flg.$val[‘name‘];
            $tree[] = $val;
            $this->GetTree($arr , $val[‘cid‘] ,$step+1);
        }
    }
    return $tree;
}
调用：
$newarr = $this->GetTree($arr, 0, 0);

 //$arr 所有分类列表
 //$id 父级分类id
public static function get_parent_list($arr,$id)
{
        static $list=array();
        foreach($arr as $u)
       {
            if($u[‘id‘]== $id)
            {   //父级分类id等于所查找的id
                $list[]=$u;
                if($u[‘parent_id‘]>0)
                {
                    self::get_parent_list($arr,$u[‘parent_id‘]);
                }
            }
        }
       return $list;
 }                

// $id  要查询的 子栏目id 
public static function get_parents($id)
{
        static $list = [];
        // Yii2 框架 
        $cat_data = Category::findOne($id)->toarray();
        if($cat_data)
       {
            $list[] = $cat_data;
            $id = $cat_data[‘parent_id‘];
             if($cat_data[‘parent_id‘] > 0)
            {
                self::get_parents($id);
             }
        }
        return $list;
}     

//$id = 父级id  $array = 所有分类
public function getSon($id,$array)
{
        static $list;
        foreach ($array as $k => $v)
        {
            if($v[‘parent_id‘] == $id)
            {
                $list[] = $array[$k];
                self::getSon($v[‘id‘],$array);
            }
        }
        return $list;
}