PHP无限梯归

<?php
class Tree
{
      //  public $data=array();//所有节点值
       // public $cateArray=array();//所有父节点
        function Tree()
        {
        }
        //setNode(目录ID,上级ID，目录名字);
        function setNode ($id, $parent, $value){
        $parent = $parent?$parent:0;
        $this->data[$id] = $value;//获取当前ID对应的当前目录名
        $this->cateArray[$id] = $parent;//获取当前ID对应的父分类ID
       //echo $id."->".$this->cateArray[$id]."--".$this->data[$id]."<br>";
        }
     function getChilds($id=0)
     {
            $childArray=array();
            $childs=$this->getChild($id);
            foreach ($childs as $child)
            {
                     $childArray[]=$child;
                     $childArray=array_merge($childArray,$this->getChilds($child));//id 递归 累加
            }
            return $childArray;
     }
     function getChild($id)
     {
 &nbs