欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  php教程

php设计模式 Visitor 访问者模式

程序员文章站 2024-02-10 22:32:59
...
复制代码 代码如下:


/**
* 访问者模式
*
* 表示一个作用于某对象结构中的各元素的操作,可以在不改变各元素的类的前提下定义作用于这些元素的新操作
*
*/
abstract class Visitor
{
abstract public function visitCroncreteElementA($element);
abstract public function visitCroncreteElementB($element);
}
class ConcreteVisitor1 extends Visitor
{
public function visitCroncreteElementA($element)
{
echo get_class($element)." visit 1A
";
}
public function visitCroncreteElementB($element)
{
echo get_class($element)." visit 1B
";
}
}
class ConcreteVisitor2 extends Visitor
{
public function visitCroncreteElementA($element)
{
echo get_class($element)." visit 2A
";
}
public function visitCroncreteElementB($element)
{
echo get_class($element)." visit 2B
";
}
}
abstract class Element
{
abstract public function accept($visitor);
}
class ConcreteElementA extends Element
{
public function accept($visitor)
{
$visitor->visitCroncreteElementA($this);
}
}
class ConcreteElementB extends Element
{
public function accept($visitor)
{
$visitor->visitCroncreteElementB($this);
}
}
class ObjectStructure
{
private $_elements = array();
public function attach($element)
{
$this->_elements[] = $element;
}
public function detach($element)
{
if($key = array_search($element,$this->_elements) !== false) unset($this->_elements[$key]);
}
public function accept($visitor)
{
foreach($this->_elements as $element)
{
$element->accept($visitor);
}
}
}
//
$objOS = new ObjectStructure();
$objOS->attach(new ConcreteElementA());
$objOS->attach(new ConcreteElementB());
$objCV1 = new ConcreteVisitor1();
$objCV2 = new ConcreteVisitor2();
$objOS->accept($objCV1);
$objOS->accept($objCV2);