How to use recursion to achieve infinite grading under the TP5 framework (code example)

<?php
namespace catetree;
class Catetree {
    
    public function catetree($cateRes){
        return $this->sort($cateRes);
    }
    public function sort($cateRes,$pid=0,$level=0){
        static $arr=array();
        foreach ($cateRes as $k => $v) {
            if($v[&#39;pid&#39;]==$pid){
                $v[&#39;level&#39;]=$level;
                $arr[]=$v;
                $this->sort($cateRes,$v[&#39;id&#39;],$level+1);
            }
        }
        return $arr;
    }
    //获取子栏目id
   public function childrenids($cateid,$obj){
        $data=$obj->field(&#39;id,pid&#39;)->select();
        return $this->_childrenids($data,$cateid,TRUE);
   }
   private function _childrenids($data,$cateid,$clear=FALSE){
        static $arr=array();
        if($clear){
          $arr=array();
        }
        foreach ($data as $k => $v) {
            if($v[&#39;pid&#39;]==$cateid){
                $arr[]=$v[&#39;id&#39;];
                $this->_childrenids($data,$v[&#39;id&#39;]);
            }
        }
        return $arr;
   }
   //处理栏目排序
   public function cateSort($data,$obj){
    foreach ($data as $k => $v) {
        $obj->update([&#39;id&#39;=>$k,&#39;sort&#39;=>$v]);
    }
   }
   //处理批量删除
   public function pdel($cateids){
            foreach ($cateids as $k => $v) {
                $childrenidsarr[]=$this->childrenids($v);
                $childrenidsarr[]=(int)$v;
            }  
            $_childrenidsarr=array();
            foreach ($childrenidsarr as $k => $v) {
                if(is_array($v)){
                    foreach ($v as $k1 => $v1) {
                       $_childrenidsarr[]=$v1;
                    }
                }else{
                    $_childrenidsarr[]=$v;
                }
            }
            $_childrenidsarr=array_unique($_childrenidsarr);
            $this::destroy($_childrenidsarr);
    
   }
}