Question

我目前正在使用HttpServer并遇到以下问题：

我想注册我的控制器，当我收到请求时，我想检查其中一个控制器是否有所请求URL的处理程序，然后调用处理程序。

到目前为止一直很好，但我不知道如何用c ++解决它，在PHP中它很容易。

在Easteregg控制器函数getControllerCallbacks中我想返回我可用的回调但它不会编译因为我不能将派生类的成员函数指针强制转换为成员函数指针（EastereggController）的基类（Controller）。我已经考虑过让ControllerCallback成为一个＆＃34;模板类＆＃34;但是我必须知道ControllerHandler中Controller的类，我不知道因为我有一个std :: vector

我对C ++很新，也许我忽视了一些事情。

这是我现在的代码：

或者Controller.h

#ifndef CONTROLLER_H
#define CONTROLLER_H

#include "Config.h"
#include "Request.h"
#include "ControllerCallback.h"

namespace HttpServer {

class ControllerCallback;

class Controller {
    public:
        Controller();
        virtual std::vector<ControllerCallback> getControllerCallbacks() = 0;

    private:
        Config *config;
        const Request *request;
};
}
#endif // CONTROLLER_H

EastereggController.h

#ifndef EASTEREGGCONTROLLER_H
#define EASTEREGGCONTROLLER_H

#include "../HttpServer/Controller.h"

namespace Controller {

    class EastereggController: public HttpServer::Controller  {
        public:
            EastereggController() {};
            std::vector<HttpServer::ControllerCallback> getControllerCallbacks();
            HttpServer::Reply easteregg();
    };
}

#endif // EASTEREGGCONTROLLER_H

EastereggController.cpp

#include "EastereggController.h"

namespace Controller {
    std::vector<HttpServer::ControllerCallback> EastereggController::getControllerCallbacks() {
        std::vector<HttpServer::ControllerCallback> controllerCallbacks;
        HttpServer::ControllerCallback callback;

        callback.pathTemplate = "/easteregg";
        callback.handlerFunctionPtr = &EastereggController::easteregg;
        return controllerCallbacks;
    }

    HttpServer::Reply EastereggController::easteregg() {
        HttpServer::Reply rep;
        rep.content.append("you have found an easteregg\n");
        rep.status = HttpServer::Reply::ok;
        rep.headers.resize(2);
        rep.headers[0].name = "Content-Length";
        rep.headers[0].value = std::to_string(rep.content.size());
        rep.headers[1].name = "Content-Type";
        rep.headers[1].value = "text/plain";
        return rep;
    }
}

ControllerCallback.h

#ifndef CONTROLLERCALLBACK_H
#define CONTROLLERCALLBACK_H


#include "Reply.h"
#include <string>

namespace HttpServer {

    class Controller;

    class ControllerCallback {

        public:
            ControllerCallback()
                : pathTemplate("") {};
            //,handlerFunctionPtr(nullptr){}

            std::string pathTemplate;
            Reply(Controller::*handlerFunctionPtr)();
    };
}

#endif

ControllerHandler.h

#ifndef CONTROLLERHANDLER_H
#define CONTROLLERHANDLER_H

#include <vector>
#include <string>
#include "Controller.h"
#include "Config.h"
#include "Request.h"
#include "Reply.h"

namespace HttpServer {

    class ControllerHandler {
        public:
            ControllerHandler(Config &conf);
            void registerController(Controller &controller);
            bool invokeController(std::string requestPath, Request &req, Reply &rep);

        private:
            Config &config;
            std::vector<Controller *> controllers;

    };

}

#endif // CONTROLLERHANDLER_H

ControllerHandler.cpp

#include "ControllerHandler.h"
#include "Controller.h"
#include "PathHandler.h"

namespace HttpServer {
    ControllerHandler::ControllerHandler(Config &conf)
        : config(conf) {
    }

    void ControllerHandler::registerController(Controller &controller) {
        controllers.push_back(&controller);
    }

    bool ControllerHandler::invokeController(std::string requestPath, Request &req, Reply &rep) {
        PathHandler pathHandler(requestPath, ':');

        for(Controller *controller : controllers) {
            std::vector<ControllerCallback> callbacks = controller->getControllerCallbacks();
            for(ControllerCallback controllerCallback : callbacks) {
                if(pathHandler.compare(controllerCallback.pathTemplate)) {
                    rep = ((*controller).*(controllerCallback.handlerFunctionPtr))();
                    return true;
                }
            }
        }

        return false;
    }
}

Answer 1

我终于找到了答案（这是我不得不承认的语法错误）

在尝试不同的解决方案时（在此处发布之前），我有以下代码段：

<强> EastereggController.cpp

callback.handlerFunctionPtr = reinterpret_cast<HttpServer::Reply HttpServer::Controller::*>(&EastereggController::easteregg);

这是完全错误的，但我没有注意到它，因为我有以下编译错误：

error: invalid cast from type 'HttpServer::Reply (Controller::EastereggController::*)()' to type 'HttpServer::Reply HttpServer::Controller::*()'
     callback.handlerFunctionPtr = reinterpret_cast<HttpServer::Reply HttpServer::Controller::*()>(&EastereggController::easteregg);

现在版本正确：

callback.handlerFunctionPtr = reinterpret_cast<HttpServer::Reply(HttpServer::Controller::*)()>(&EastereggController::easteregg);

刚刚添加了括号，现在它可以正常工作。

c ++将派生类的指针转换为基类指针

1 个答案: