设计模式——组合模式

说明

又叫部分-整体模式,在处理类似树形结构的问题时比较方便。

示例

下面看下组合模式的代码实现

class TreeNode{
    private string $name;
    private TreeNode $parent;
    private ?TreeNode $children=null;

    public function __construct(string $name){
        $this->name = $name;
    }
    public function getName(): string{
        return $this->name;
    }
    public function setName(string $name){
        $this->name = $name;
    }

    public function getParent(): TreeNode{
        return $this->parent;
    }

    public function setParent(TreeNode $parent){
        $this->parent = $parent;
    }

    //添加子节点
    public function add(TreeNode $node){
        $this->children = $node;
    }
    //删除子节点
    public function remove(TreeNode $node){
        //unset($this->children->{$node});
        $this->children->remove($node);
    }
    //取得子节点
    public function getChildren(): ?TreeNode{
        return $this->children;
    }
}

// test
$root = new TreeNode('A');
$nodeB = new TreeNode('B');
$nodeC = new TreeNode('C');


$nodeB->add($nodeC);
$root->add($nodeB);
print_r($root);
echo "build the tree finished!";

/**
 * output:
 *
TreeNode Object
(
[name:TreeNode:private] => A
[children:TreeNode:private] => TreeNode Object
(
[name:TreeNode:private] => B
[children:TreeNode:private] => TreeNode Object
(
[name:TreeNode:private] => C
[children:TreeNode:private] =>
)

)

)
build the tree finished!
 */

总结

使用场景：将多个对象组合在一起进行操作，常用于表示树形结构中，例如二叉树，数等。