messagehandler.h

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/*****************************************************************************
 * Copyright 2015 Haye Hinrichsen, Christoph Wick
 *
 * This file is part of Entropy Piano Tuner.
 *
 * Entropy Piano Tuner is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * Entropy Piano Tuner is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * Entropy Piano Tuner. If not, see http://www.gnu.org/licenses/.
 *****************************************************************************/

//======================================================================
//                          Message handler
//======================================================================

#ifndef MESSAGEHANDLER_H
#define MESSAGEHANDLER_H

#include <list>
#include <queue>
#include <memory>
#include <mutex>
#include "messagelistener.h"

class MessageHandler
{
public:
    template <class msgclass, class... Args>
    static void send(Args&&... args) {
        // this function has to be implemented in the header, since it is static template (linker errors elswise!)
        getSingleton().addMessage(std::make_shared<msgclass>(args...), false);
    }
    static void send(Message::MessageTypes type) {send<Message>(type);}

    template <class msgclass, class... Args>
    static void sendUnique(Args&&... args) {
        // this function has to be implemented in the header, since it is static template (linker errors elswise!)
        getSingleton().addMessage(std::make_shared<msgclass>(args...), true);
    }
    static void sendUnique(Message::MessageTypes type) {sendUnique<Message>(type);}
private:
    MessageHandler();

public:
    ~MessageHandler();                                      

    static MessageHandler &getSingleton();                  
    static MessageHandler *getSingletonPtr();               

    void process();                                         

    void addListener(MessageListener *listener);            
    void removeListener(MessageListener *listener);         
    void addMessage(MessagePtr message, bool dropOlder = false);  

private:

    static MessageHandler mSingleton;                       
    std::list<MessageListener*> mListeners;                 
    std::list<MessageListener*> mListenersToAdd;            
    std::list<MessageListener*> mListenersToRemove;         
    mutable std::mutex mListenersChangesMutex;              
    std::list<MessagePtr> mMessages;                        
    mutable std::mutex mMessageMutex;                       
};

#endif // MESSAGEHANDLER_H