树结构生成类

<?php
namespace util;

/**
 * 树结构生成类
 */
class Tree
{
    /**
     * @var object 对象实例
     */
    protected static $instance;

    /**
     * 配置参数
     * @var array
     */
    protected static $config = [
        'id'    => 'id',    // id名称
        'pid'   => 'pid',   // pid名称
        'title' => 'title', // 标题名称
        'child' => 'child', // 子元素键名
        'html'  => '┝ ',   // 层级标记
        'step'  => 4,       // 层级步进数量
    ];

    /**
     * 架构函数
     * @param array $config
     */
    public function __construct($config = [])
    {
        self::$config = array_merge(self::$config, $config);
    }

    /**
     * 配置参数
     * @param  array $config
     * @return object
     */
    public static function config($config = [])
    {
        if (!empty($config)) {
            $config = array_merge(self::$config, $config);
        }
        if (is_null(self::$instance)) {
            self::$instance = new static($config);
        }
        return self::$instance;
    }

    /**
     * 将数据集格式化成层次结构
     * @param array/object $lists 要格式化的数据集，可以是数组，也可以是对象
     * @param int $pid 父级id
     * @param int $max_level 最多返回多少层，0为不限制
     * @param int $curr_level 当前层数
     * @return array
     */
    public static function toLayer($lists = [], $pid = 0, $max_level = 0, $curr_level = 0)
    {
        $trees = [];
        $lists = array_values($lists);
        foreach ($lists as $key => $value) {
            if ($value[self::$config['pid']] == $pid) {
                if ($max_level > 0 && $curr_level == $max_level) {
                    return $trees;
                }
                unset($lists[$key]);
                $child = self::toLayer($lists, $value[self::$config['id']], $max_level, $curr_level + 1);
                if (!empty($child)) {
                    $value[self::$config['child']] = $child;
                }
                $trees[] = $value;
            }
        }
        return $trees;
    }

    /**
     * 将数据集格式化成列表结构
     * @param  array|object   $lists 要格式化的数据集，可以是数组，也可以是对象
     * @param  integer $pid        父级id
     * @param  integer $level      级别
     * @return array 列表结构(一维数组)
     */
    public static function toList($lists = [], $pid = 0, $level = 0)
    {
        if (is_array($lists)) {
            $trees = [];
            foreach ($lists as $key => $value) {
                if ($value[self::$config['pid']] == $pid) {
                    $title_prefix   = str_repeat(" ", $level * self::$config['step']).self::$config['html'];
                    $value['level'] = $level + 1;
                    $value['title_prefix']  = $level == 0 ? '' : $title_prefix;
                    $value['title_display'] = $level == 0 ? $value[self::$config['title']] : $title_prefix.$value[self::$config['title']];
                    $trees[] = $value;
                    unset($lists[$key]);
                    $trees   = array_merge($trees, self::toList($lists, $value[self::$config['id']], $level + 1));
                }
            }
            return $trees;
        } else {
            foreach ($lists as $key => $value) {
                if ($value[self::$config['pid']] == $pid && is_object($value)) {
                    $title_prefix   = str_repeat(" ", $level * self::$config['step']).self::$config['html'];
                    $value['level'] = $level + 1;
                    $value['title_prefix']  = $level == 0 ? '' : $title_prefix;
                    $value['title_display'] = $level == 0 ? $value[self::$config['title']] : $title_prefix.$value[self::$config['title']];
                    $lists->offsetUnset($key);
                    $lists[] = $value;
                    self::toList($lists, $value[self::$config['id']], $level + 1);
                }
            }
            return $lists;
        }
    }

    /**
     * 根据子节点返回所有父节点
     * @param  array  $lists 数据集
     * @param  string $id    子节点id
     * @return array
     */
    public static function getParents($lists = [], $id = '')
    {
        $trees = [];
        foreach ($lists as $value) {
            if ($value[self::$config['id']] == $id) {
                $trees[] = $value;
                $trees   = array_merge(self::getParents($lists, $value[self::$config['pid']]), $trees);
            }
        }
        return $trees;
    }

    /**
     * 获取所有子节点id
     * @param  array  $lists 数据集
     * @param  string $pid   父级id
     * @return array
     */
    public static function getChildsId($lists = [], $pid = '')
    {
        $result = [];
        foreach ($lists as $value) {
            if ($value[self::$config['pid']] == $pid) {
                $result[] = $value[self::$config['id']];
                $result = array_merge($result, self::getChildsId($lists, $value[self::$config['id']]));
            }
        }
        return $result;
    }

    /**
     * 获取所有子节点
     * @param  array  $lists 数据集
     * @param  string $pid   父级id
     * @return array
     */
    public static function getChilds($lists = [], $pid = '')
    {
        $result = [];
        foreach ($lists as $value) {
            if ($value[self::$config['pid']] == $pid) {
                $result[] = $value;
                $result = array_merge($result, self::getChilds($lists, $value[self::$config['id']]));
            }
        }
        return $result;
    }
}