/**
 * @name 状态模式
 * @brief: 允许对象在内部状态改变时改变行为
 * @note 场景：订单状态机、游戏角色状态、电梯控制
 */

class OrderState {
public:
    virtual void shipOrder(Order* order) = 0;
    virtual void cancelOrder(Order* order) = 0;
};

class NewState : public OrderState {
    void shipOrder(Order* order) override {};
    void cancelOrder(Order* order) override {};
};

class ShippedState : public OrderState {
    void shipOrder(Order* order) override { /* 已发货，不可重复操作 */ }
    void cancelOrder(Order* order) override { /* 已发货不可取消 */ }
};

class Order {
public:
    Order() : state(new NewState()) {}
    void ship() { state->shipOrder(this); }
    void cancel() { state->cancelOrder(this); }
    void changeState(OrderState* newState) {
        delete state;
        state = newState;
    }
private:
    OrderState* state;
};

// 状态转换实现
void NewState::shipOrder(Order* order) {
    // 发货逻辑...
    order->changeState(new ShippedState());
}