PHP code PHP singly linked list implementation code

<&#63;php
/**
* 单链表
*/ 
class Demo
{
private $id;
public $name;
public $next;
public function __construct ($id = '', $name = '')
{
$this->id = $id;
$this->name = $name;
}
static public function show ($head)
{
$cur = $head;
while ($cur->next) {
echo $cur->next->id,'###',$cur->next->name,'<br />';
$cur = $cur->next;
}
echo '<hr />';
}
//尾插法
static public function push ($head, $node)
{
$cur = $head;
while (NULL != $cur->next) {
$cur = $cur->next;
}
$cur->next = $node;
return $head;
}
static public function insert($head, $node)
{
$cur = $head;
while (NULL != $cur->next) {
if ($cur->next->id > $node->id) {
break;
}
$cur = $cur->next;
}
$node->next = $cur->next;
$cur->next = $node;
return $head;
}
static public function edit($head, $node)
{
$cur = $head;
while (NULL != $cur->next) {
if ($cur->next->id == $node->id) {
break;
}
$cur = $cur->next;
}
$cur->next->name = $node->name;
return $head; 
}
static public function pop ($head, $node)
{
$cur = $head;
while (NULL != $cur->next) {
if ($cur->next == $node) {
break;
}
$cur = $cur->next;
}
$cur->next = $node->next;
return $head; 
}
}
$team = new Demo();
$node1 = new Demo(1, '唐三藏');
Demo::push($team, $node1);
$node1->name = '唐僧';
Demo::show($team);
// Demo::show($team);
$node2 = new Demo(2, '孙悟空');
Demo::insert($team, $node2);
// Demo::show($team);
$node3 = new Demo(5, '白龙马');
Demo::push($team, $node3);
// Demo::show($team);
$node4 = new Demo(3, '猪八戒');
Demo::insert($team, $node4);
// Demo::show($team);
$node5 = new Demo(4, '沙和尚');
Demo::insert($team, $node5);
// Demo::show($team);
$node4->name = '猪悟能';//php对象传引用，所以Demo::edit没有必要
// unset($node4);
// $node4 = new Demo(3, '猪悟能');
// Demo::edit($team, $node4);
Demo::pop($team, $node1);
Demo::show($team);