C++状态模式如何管理状态 使用有限状态机的实现方法

// 状态接口
class TrafficLightState {
public:
    virtual ~TrafficLightState() = default;
    virtual TrafficLightState* handleInput(const std::string& input) = 0;
    virtual std::string getColor() const = 0;
};

// 具体状态：红灯
class RedLightState : public TrafficLightState {
public:
    TrafficLightState* handleInput(const std::string& input) override {
        if (input == "timer") {
            return new GreenLightState();
        }
        return this;
    }
    std::string getColor() const override { return "Red"; }
};

// 具体状态：绿灯
class GreenLightState : public TrafficLightState {
public:
    TrafficLightState* handleInput(const std::string& input) override {
        if (input == "timer") {
            return new YellowLightState();
        }
        return this;
    }
    std::string getColor() const override { return "Green"; }
};

// 具体状态：黄灯
class YellowLightState : public TrafficLightState {
public:
    TrafficLightState* handleInput(const std::string& input) override {
        if (input == "timer") {
            return new RedLightState();
        }
        return this;
    }
    std::string getColor() const override { return "Yellow"; }
};

// 上下文类
class TrafficLight {
private:
    TrafficLightState* currentState;
public:
    TrafficLight() : currentState(new RedLightState()) {}
    ~TrafficLight() { delete currentState; }

    void changeState(TrafficLightState* newState) {
        delete currentState;
        currentState = newState;
    }

    void handleInput(const std::string& input) {
        TrafficLightState* newState = currentState->handleInput(input);
        if (newState != currentState) {
            changeState(newState);
        }
    }

    std::string getColor() const { return currentState->getColor(); }
};

int main() {
    TrafficLight light;
    std::cout << "Current color: " << light.getColor() << std::endl; // 输出：Red

    light.handleInput("timer");
    std::cout << "Current color: " << light.getColor() << std::endl; // 输出：Green

    light.handleInput("timer");
    std::cout << "Current color: " << light.getColor() << std::endl; // 输出：Yellow

    light.handleInput("timer");
    std::cout << "Current color: " << light.getColor() << std::endl; // 输出：Red

    return 0;
}

//角色状态基类
class CharacterState {
public:
    virtual ~CharacterState() = default;
    virtual void handleInput(Character& character, const std::string& input) = 0;
    virtual void update(Character& character, float deltaTime) = 0;
    virtual void enter(Character& character) = 0;
    virtual void exit(Character& character) = 0;
};

//角色类
class Character {
private:
    CharacterState* currentState;
public:
    Character();
    ~Character();

    void setState(CharacterState* newState);
    void handleInput(const std::string& input);
    void update(float deltaTime);

    //角色属性和方法
};

//具体状态类，例如 IdleState, WalkingState, AttackingState 等