PHP中的组合模式及其应用场景分析

interface Component {
    public function operation();
}

class Leaf implements Component {
    private $name;

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

    public function operation() {
        echo "$this->name : Leaf
";
    }
}

class Composite implements Component {
    private $name;
    private $components = [];

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

    public function add(Component $component) {
        $this->components[] = $component;
    }

    public function remove(Component $component) {
        foreach ($this->components as $key => $value) {
            if ($value === $component) {
                unset($this->components[$key]);
                break;
            }
        }
        $this->components = array_values($this->components);
    }

    public function getChild($index) {
        if (isset($this->components[$index])) {
            return $this->components[$index];
        }
        return null;
    }

    public function operation() {
        echo "$this->name : Composite
";
        foreach ($this->components as $component) {
            $component->operation();
        }
    }
}

$root = new Composite("root");

$branch1 = new Composite("branch1");
$branch1->add(new Leaf("leaf1"));
$branch1->add(new Leaf("leaf2"));

$branch2 = new Composite("branch2");
$branch2->add(new Leaf("leaf3"));

$root->add($branch1);
$root->add($branch2);

$root->operation();

root : Composite
branch1 : Composite
leaf1 : Leaf
leaf2 : Leaf
branch2 : Composite
leaf3 : Leaf