撤消/重做备忘录到模式c#

// 备忘录类
class Memento
{
    public string State { get; private set; }

    public Memento(string state)
    {
        State = state;
    }
}

// 原发器类
class Originator
{
    private string state;

    public string State
    {
        get { return state; }
        set { state = value; }
    }

    public Memento CreateMemento()
    {
        return new Memento(state);
    }

    public void SetMemento(Memento memento)
    {
        state = memento.State;
    }
}

// 管理者类
class CareTaker
{
    private List<Memento> mementos = new List<Memento>();

    public void AddMemento(Memento memento)
    {
        mementos.Add(memento);
    }

    public Memento GetMemento(int index)
    {
        return mementos[index];
    }
}

// 使用示例
class Program
{
    static void Main(string[] args)
    {
        Originator originator = new Originator();
        CareTaker careTaker = new CareTaker();

        originator.State = "State 1";
        careTaker.AddMemento(originator.CreateMemento());

        originator.State = "State 2";
        careTaker.AddMemento(originator.CreateMemento());

        originator.State = "State 3";
        careTaker.AddMemento(originator.CreateMemento());

        // 撤消操作
        originator.SetMemento(careTaker.GetMemento(1));
        Console.WriteLine(originator.State);  // 输出 "State 2"

        // 重做操作
        originator.SetMemento(careTaker.GetMemento(2));
        Console.WriteLine(originator.State);  // 输出 "State 3"
    }
}