2个无限级分类

tree.php

<?php
	public static function data($items)
	{
		$items=array_column($items,null,'id');
		$tree = [];
		foreach($items as $item)
		{
			if(isset($items[$item['pid']]))
			{
				$items[$item['pid']]['child'][] = &$items[$item['id']];
			}
			else
			{
				$tree[] = &$items[$item['id']];
			}
		}
		return ['num'=>count($tree),'data'=>$tree];
	}

	public static function data2($items)
	{
		$tree=[]; //最终生成的结果
		$path=[]; //记录如何找到我
		foreach ($items as $item)
		{
			$id=$item['id'];
			$pid=$item['pid'];
			if(isset($path[$pid])) //可以追踪到他的上一级
			{
				$ppath=$path[$pid];///这是他父类所在的路径结构
				eval($ppath.";");
				$p['child'][$id]=$item;
				$path[$id]=$ppath."['child'][{$id}]";
			}
			else
			{
				$path[$id]='$p=&$tree'."[$id]";
				$tree[$id]=$item;
			}

		}
		return ['num'=>count($tree),'data'=>$tree];
	}