设计模式10-装饰器模式

装饰器的核心是“加料”，我往你身上“套”功能，但你还是你，外界并不知道你被套了

就像浏览器发送请求一样，我只需要拿到一个StreamProcesser，把我想发出去的内容交给它即可，至于它被依次套上了Html标签，经过TLS加密，还是IP层的封装，我不关心

#include <cstddef>
#include <iostream>
#include <string>
#include <memory>

class StreamProcesser {
public:
    virtual void process(std::string input) = 0;
    virtual ~StreamProcesser() {}
    StreamProcesser(std::shared_ptr<StreamProcesser> next = nullptr) {
        m_next = next;
    }
protected:
    std::shared_ptr<StreamProcesser> m_next;
};

class HtmlGenerator : public StreamProcesser {
public:
    using StreamProcesser::StreamProcesser;
    void process(std::string input) override {
        std::string result = "<" + input + "/>";
        m_next->process(result);
    }
};

class TLSProcesser : public StreamProcesser {
public:
    using StreamProcesser::StreamProcesser;
    void process(std::string input) override {
        int key = 3;
        for(auto& e : input) {
            e += key;
        }
        m_next->process(input);
    }
};

class NetProcesser : public StreamProcesser {
public:
    using StreamProcesser::StreamProcesser;
    void process(std::string input) override {
        std::string result = "src:192.168.31.100|dst:192.168.31.1|" + input;
        std::cout << result << std::endl;
    }
};

int main() {
    std::shared_ptr<StreamProcesser> p = std::make_shared<HtmlGenerator>(std::make_shared<TLSProcesser>(std::make_shared<NetProcesser>()));

    p->process("hello");

    return 0;
}