PHP unlimited classification [enhanced version]

/**
 +------------------------------------------------
 * Universal tree class
 +----------------------------------------- -------
 * @author yangyunzhou@foxmail.com
 +-------------------------------- ----------------
 *@date November 23, 2010 10:09:31
 +----------------- ----------------------------------
*/
class Tree
{

    /**
 +------------------------------------------------
 * 2-dimensional array needed to generate tree structure
 +------------------------------------ ------------
 * @author yangyunzhou@foxmail.com
 +-------------------------- --------------------------
 * @var Array
*/
    var $arr = array();

    /**
 +------------------------------------------------
 * The modification symbols required to generate a tree structure can be replaced by pictures
 +--------------------------------- ---------------
 * @author yangyunzhou@foxmail.com
 +------------------------ --------------------------
 * @var Array
*/
    var $icon = array('│','├',' └');

    /**
    * @access private
*/
    var $ret = '';

    /**
 * Constructor, initialize class
 * @param array 2-dimensional array, for example:
 * array(
 * 1 => array('id'=>'1','parentid'=>0,'name '=>'First-level column one'),
 * 2 => array('id'=>'2','parentid'=>0,'name'=>'First-level column two' ),
 * 3 => array('id'=>'3','parentid'=>1,'name'=>'Second-level column one'),
 * 4 => array( 'id'=>'4','parentid'=>1,'name'=>'Second-level column two'),
 * 5 => array('id'=>'5', 'parentid'=>2,'name'=>'Second-level column three'),
 * 6 => array('id'=>'6','parentid'=>3,'name '=>'Third-level column one'),
 * 7 => array('id'=>'7','parentid'=>3,'name'=>'Third-level column two' )
 * )
*/
    function tree($arr=array())
    {
       $this->arr = $arr;
       $this->ret = '';
       return is_array($arr);
    }

    /**
 * Get the parent array
 * @param int
 * @return array
*/
    function get_parent($myid)
    {
        $newarr = array();
        if(!isset($this->arr[$myid])) return false;
        $pid = $this->arr[$myid]['parentid'];
        $pid = $this->arr[$pid]['parentid'];
        if(is_array($this->arr))
        {
            foreach($this->arr as $id => $a)
            {
                if($a['parentid'] == $pid) $newarr[$id] = $a;
            }
        }
        return $newarr;
    }

    /**
 * Get the child array
 * @param int
 * @return array
*/
    function get_child($myid)
    {
        $a = $newarr = array();
        if(is_array($this->arr))
        {
            foreach($this->arr as $id => $a)
            {
                if($a['parentid'] == $myid) $newarr[$id] = $a;
            }
        }
        return $newarr ? $newarr : false;
    }

    /**
 * Get the current position array
 * @param int
 * @return array
*/
    function get_pos($myid,&$newarr)
    {
        $a = array();
        if(!isset($this->arr[$myid])) return false;
        $newarr[] = $this->arr[$myid];
        $pid = $this->arr[$myid]['parentid'];
        if(isset($this->arr[$pid]))
        {
            $this->get_pos($pid,$newarr);
        }
        if(is_array($newarr))
        {
            krsort($newarr);
            foreach($newarr as $v)
            {
                $a[$v['id']] = $v;
            }
        }
        return $a;
    }

    /**
 * ----------------------------------------
 * Get tree structure
 * --- ----------------------------------
 * @author yangyunzhou@foxmail.com
 * @param $myid said Get all the children under this ID
 * @param $str Generate the basic code of the tree structure, for example: "$spacer$name"
 * @param $sid is The selected ID, for example, needed when making a tree drop-down box
 * @param $adds
 * @param $str_group
*/
    function get_tree($myid, $str, $sid = 0, $adds = '', $str_group = '')
    {
        $number=1;
        $child = $this->get_child($myid);
        if(is_array($child)) {
            $total = count($child);
            foreach($child as $id=>$a) {
                $j=$k='';
                if($number==$total) {
                    $j .= $this->icon[2];
                } else {
                    $j .= $this->icon[1];
                    $k = $adds ? $this->icon[0] : '';
                }
                $spacer = $adds ? $adds.$j : '';
                $selected = $id==$sid ? 'selected' : '';
                @extract($a);
                $parentid == 0 && $str_group ? eval("$nstr = "$str_group";") : eval("$nstr = "$str";");
                $this->ret .= $nstr;
                $this->get_tree($id, $str, $sid, $adds.$k.' ',$str_group);
                $number++;
            }
        }
        return $this->ret;
    }

    /**
 *Similar to the previous method, but allows multiple selections
*/
    function get_tree_multi($myid, $str, $sid = 0, $adds = '')
    {
        $number=1;
        $child = $this->get_child($myid);
        if(is_array($child))
        {
            $total = count($child);
            foreach($child as $id=>$a)
            {
                $j=$k='';
                if($number==$total)
                {
                    $j .= $this->icon[2];
                }
                else
                {
                    $j .= $this->icon[1];
                    $k = $adds ? $this->icon[0] : '';
                }
                $spacer = $adds ? $adds.$j : '';

                $selected = $this->have($sid,$id) ? 'selected' : '';
                @extract($a);
                eval("$nstr = "$str";");
                $this->ret .= $nstr;
                $this->get_tree_multi($id, $str, $sid, $adds.$k.' ');
                $number++;
            }
        }
        return $this->ret;
    }

    function have($list,$item){
        return(strpos(',,'.$list.',',','.$item.','));
    }

    /**
 +------------------------------------------------
 * Format array
 +---------------------------------------------- -----
 * @author yangyunzhou@foxmail.com
 +---------------------------------- ---------------
*/
    function getArray($myid=0, $sid=0, $adds='')
    {
        $number=1;
        $child = $this->get_child($myid);
        if(is_array($child)) {
            $total = count($child);
            foreach($child as $id=>$a) {
                $j=$k='';
                if($number==$total) {
                    $j .= $this->icon[2];
                } else {
                    $j .= $this->icon[1];
                    $k = $adds ? $this->icon[0] : '';
                }
                $spacer = $adds ? $adds.$j : '';
                @extract($a);
                $a['name'] = $spacer.' '.$a['name'];
                $this->ret[$a['id']] = $a;
                $fd = $adds.$k.' ';
                $this->getArray($id, $sid, $fd);
                $number++;
            }
        }

        return $this->ret;
    }
}
?>

用法:

$tree = new Tree;           // new 之前请记得包含tree文件!
$tree->tree($data);         // 数据格式请参考 tree方法上面的注释!

// 如果使用数组, 请使用 getArray方法
$tree->getArray();

// 下拉菜单选项使用 get_tree方法
$tree->get_tree();

增强版, PHP