C++装饰器模式动态添加行为方法

#include <iostream>
#include <memory>

// 抽象组件
class Component {
public:
    virtual ~Component() = default;
    virtual void operation() const = 0;
};

// 具体组件
class ConcreteComponent : public Component {
public:
    void operation() const override {
        std::cout << "基础功能执行\n";
    }
};

// 装饰器基类
class Decorator : public Component {
protected:
    std::shared_ptr<Component> component_;
public:
    explicit Decorator(std::shared_ptr<Component> comp) : component_(comp) {}

    void operation() const override {
        component_->operation();
    }
};

// 具体装饰器A：添加日志
class LoggingDecorator : public Decorator {
public:
    using Decorator::Decorator;

    void operation() const override {
        std::cout << "[日志] 开始执行操作\n";
        Decorator::operation();
        std::cout << "[日志] 操作完成\n";
    }
};

// 具体装饰器B：添加权限检查
class SecurityDecorator : public Decorator {
public:
    using Decorator::Decorator;

    void operation() const override {
        std::cout << "[安全] 正在校验权限...\n";
        // 模拟权限通过
        Decorator::operation();
    }
};

int main() {
    auto comp = std::make_shared<ConcreteComponent>();

    // 只有基础功能
    comp->operation();

    // 添加日志
    auto logged = std::make_shared<LoggingDecorator>(comp);
    logged->operation();

    // 再添加安全检查
    auto secured = std::make_shared<SecurityDecorator>(logged);
    secured->operation();

    return 0;
}