Design Patterns 19 - 组合模式

abstract class Component {
    protected string name;

    public Component(string name) {
        this.name = name;
    }
    public abstract void Add(Component component);
    public abstract void Remove(Component component);
    public abstract void Display(int depth);
}

class Leaf : Component {
    public Leaf(string name) : base(name) {}

    public override void Add(Component component) {
        // cannot add to a leaf
    }

    public override void Remove(Component component) {
        // cannot remove from a leaf
    }

    public override void Display(int depth) {
        // todo
    }
}

class Composite : Component {
    private List<Component> children = new List<Component>();

    public Composite(string name) : base (name) {}

    public override void Add(Component component) {
        children.Add(component);
    }

    public override void Remove(Component component) {
        children.Remove(component);
    }

    public override void Display(int depth) {
        // todo
    }
}

public static void Main(string agrs[]) {
    Composite root = new Composite("root");
    root.Add(new Leaf("Leaf A"));
    root.Add(new Leaf("Leaf B"));

    Composite composite = new Composite("Composite X");
    composite.Add(new Leaf("Leaf XA"));
    composite.Add(new Leaf("Leaf XB"));

    root.Add(composite);
    root.Add(new Leaf("Leaf C"));

    root.Display();
}