看着静态属性，静态方法有些别扭，我替换掉了；

<?php

/**
 * 无限极分类-二维无限分类数组处理类
 *
 **/
class MultiCat
{
    //无限分类数组，其中必须要有id和pid
    public $list = [];
    //id => pid 数组
    private $_sp_list = [];
    //子分类key
    private $_sk;
    //父分类key
    private $_pk;

    /**
     *对数组进行初始化处理
     * $cat_list 无限分类数组
     * $skey 数组中子分类的key值
     * $pkey 数组中父分类的key值
     * @return mixed array
     **/
    public function __construct($cat_list, $skey = 'id', $pkey = 'pid')
    {
        //parent::init();
        $this->_sk = $skey;
        $this->_pk = $pkey;
        $this->init($cat_list);
    }

    /**
     *对数组进行初始化处理
     * @return mixed array
     **/
    public function init($cat_list)
    {
        if (empty($cat_list)) {
            return false;
        }
        //对数组进行预处理
        foreach ($cat_list as $key => $val) {
            //生成sid => pid 数组
            $this->_sp_list[$val[$this->_sk]] = $val[$this->_pk];
            //以数组的子分类值作为索引
            $this->list[$val[$this->_sk]] = $val;
        }
        unset($cat_list);
    }

    /**
     * 获取格式化的树形数据
     * @param $pid int $list中顶级分类id
     * @param $level int $list中顶级分类的层级
     * @param $html string 上下层级之间的标示符号
     * @return mixed
     **/
    public function sort($pid = 0, $level = 0, $html = '-')
    {
        if (empty($this->list)) {
            return false;
        }
        static $tree = array();
        foreach ($this->list as $v) {
            if ($v[$this->_pk] == $pid) {
                $v['sort'] = $level + 1;
                $v['html'] = str_repeat($html, $level);
                $tree[$v[$this->_sk]] = $v;
                $this->sort($v[$this->_sk], $level + 1);
            }
        }
        return $tree;
    }

    /**
     * 获取分类的无限极子分类，以树型结构显示
     * @param $son string 子节点节点名
     * @return mixed
     **/
    public function tree($son = 'son')
    {
        if (empty($this->list)) {
            return [];
        }
        $list = $this->list;
        foreach ($list as $item) {
            $list[$item[$this->_pk]][$son][$item[$this->_sk]] = &$list[$item[$this->_sk]];
        }
        return isset($list[0][$son]) ? $list[0][$son] : array();
    }

    /**
     * 获取分类的祖先分类
     * @param $id int 分类id
     * @param $type bool true-返回祖先分类数组 false-返回祖先分类id
     * @return mixed
     **/
    public function ancestor($id, $type = true)
    {
        if (empty($this->list) || empty($this->_sp_list)) {
            return false;
        }
        while ($this->_sp_list[$id]) {
            $id = $this->_sp_list[$id];
        }
        return $type && isset($this->list[$id]) ? $this->list[$id] : $id;
    }

    /**
     * 获取所有父级分类对应层级关系
     * @param $id int 分类id
     * @param $type bool true-返回分类数组 false-返回分类id
     * @return mixed
     **/
    public function parents($id, $type = true)
    {
        if (empty($this->list)) {
            return false;
        }
        $info = [];
        while (isset($this->_sp_list[$id])) {
            $info[] = $type ? $this->list[$id] : $id;
            $id = $this->_sp_list[$id];
        }
        return $info;
    }

    /**
     * 获取所有子级分类对应层级关系
     * @param $id int 子分类id
     * @param $type bool true-返回分类数组 false-返回分类id
     * @return mixed
     **/
    public function sons($id, $type = true)
    {
        if (empty($this->list)) {
            return false;
        }
        static $info = [];
        foreach ($this->list as $val) {
            if ($val[$this->_pk] == $id) {
                $info[$val[$this->_sk]] = $type ? $val : $val[$this->_sk];
                if (self::has_son($val[$this->_sk])) {
                    self::sons($val[$this->_sk], $type);
                }
            }
        }
        return $info;
    }

    /**
     * 获取所有儿子分类
     * @param $p_id int 父id
     * @param $type bool true-返回分类数组 false-返回分类id
     * @return mixed
     **/
    public function son($p_id = 0, $type = true)
    {
        if (empty($this->list)) {
            return false;
        }
        $_arr = [];
        foreach ($this->list as $val) {
            if ($val[$this->_pk] == $p_id) {
                $_arr[$val[$this->_sk]] = $type ? $val : $val[$this->_sk];
            }
        }
        return $_arr;
    }

    /**
     * 是否含有子分类，是否是叶子节点
     * @param $pid int 父分类id
     * @return mixed
     **/
    public function has_son($pid)
    {
        if (empty($this->list) || empty($this->_sp_list)) {
            return false;
        }
        return in_array($pid, array_values($this->_sp_list));
    }

}

调用DEMO还是用你的：

 $cat_list = [
            ['id' => 1, 'pid' => 0, 'name' => "北京市",],
            ['id' => 2, 'pid' => 0, 'name' => "上海市",],
            //...
            ['id' => 5, 'pid' => 0, 'name' => "河北省",],
            ['id' => 43, 'pid' => 5, 'name' => "衡水市",],
            ['id' => 44, 'pid' => 5, 'name' => "廊坊市",],
            //...
            ['id' => 100, 'pid' => 44, 'name' => "三河市",],
            ['id' => 101, 'pid' => 44, 'name' => "香河市",],
            ['id' => 133, 'pid' => 100, 'name' => "燕郊镇",],
        ];
        $cat = new MultiCat($cat_list);
        $_city_tree = $cat->tree();
        $_city_html = $cat->sort(0, 0, '-');
        
        VarDumper::dump($_city_tree);
        VarDumper::dump($_city_html);

不错的总结。

@简单一点 跟node的版本有关系

私钥加密，公钥解密。公钥加密，私钥解密吧。楼主？