组合模式

以单个对象的方式来对待一组对象。  有点类似递归处理
组合模式（Composite Pattern）有时候又叫做部分-整体模式，用于将对象组合成树形结构以表示“部分-整体”的层次关系。组合模式使得用户对单个对象和组合对象的使用具有一致性。
常见使用场景：如树形菜单、文件夹菜单、部门组织架构图等。

 

<?php

interface Renderable
{
    public function render();
}


class Form implements Renderable
{
    private $elements;

    /**
     * runs through all elements and calls render() on them, then returns the complete representation
     * of the form.
     *
     * from the outside, one will not see this and the form will act like a single object instance
     *
     * @return string
     */
    public function render()
    {
        $formCode = '';

        foreach ($this->elements as $e) {
            $formCode .= $e->render();
        }

        return $formCode;
    }

    public function addElement(Renderable $element)
    {
        $this->elements[spl_object_hash($element)] = $element;
    }

    public function removeElement(Renderable $element)
    {
        unset($this->elements[spl_object_hash($element)]);
    }
}

class InputElement implements Renderable
{
    private $_name;

    public function __construct($name)
    {
        $this->_name = $name;
    }

    public function render()
    {
        return "<input name='".$this->_name."' placeholder='Please input your name' />";
    }
}

class TextElement implements Renderable
{
    private $_name;

    public function __construct($name)
    {
        $this->_name = $name;
    }

    public function render()
    {
        return "<textarea cols='5' rows='3' name='".$this->_name."'></textarea>";
    }
}



$form = new Form();
$input = new InputElement('name');
$text = new TextElement('text');

$form->addElement($input);
$form->addElement($text);

$embed  = new Form();
$embed->addElement($input);
$embed->addElement($text);

$form->addElement($embed);


print htmlspecialchars($form->render());