ObservableStatus.hpp

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/***************************************************
 *       _   _            _                        *
 *      | | | |          (_)                       *
 *      | |_| | ___  _ __ _ _______  _ __          *
 *      |  _  |/ _ \| '__| |_  / _ \| '_  \        *
 *      | | | | (_) | |  | |/ / (_) | | | |        *
 *      \_| |_/\___/|_|  |_/___\___/|_| |_|        *
 ***************************************************
 * This file is part of Horizon (c).
 *
 * Copyright (c) 2019 Sagun K. (sagunxp@gmail.com).
 * Copyright (c) 2019 Horizon Dev Team.
 *
 * Base Author - Sagun K. (sagunxp@gmail.com)
 *
 * This library 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.
 * 
 * This library 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 this library.  If not, see <http://www.gnu.org/licenses/>.
 **************************************************/
 
#ifndef HORIZON_ZONE_GAME_TRAITS_OBSERVABLESTATUS_HPP
#define HORIZON_ZONE_GAME_TRAITS_OBSERVABLESTATUS_HPP
 
#include <type_traits>
#include <tuple>
template <typename OBSERVABLE, typename ... HAS_OBSERVERS>
class ObservableStatus
{
public:
    explicit ObservableStatus(HAS_OBSERVERS ... args)
    : _observers(args...)
    {
    }
    ~ObservableStatus() { }
 
    template<std::size_t I = 0, typename... Tp>
    inline typename std::enable_if<I == sizeof...(Tp), void>::type
    notify(std::tuple<Tp...>& /*t*/)
    { }
 
    template<std::size_t I = 0, typename... Tp>
    inline typename std::enable_if<I < sizeof...(Tp), void>::type
    notify(std::tuple<Tp...>& t)
    {   
        if (std::get<I>(_observers) != nullptr)
            std::get<I>(_observers)->on_observable_changed(_observable);
        notify<I + 1, Tp...>(t);
    }
 
    inline void notify_observers() { notify<0, HAS_OBSERVERS...>(_observers); }
 
    void register_observable(OBSERVABLE obs) { _observable = obs; }
    void register_observers(HAS_OBSERVERS... obs) { _observers = std::make_tuple(obs...); }
 
    OBSERVABLE _observable;
    std::tuple<HAS_OBSERVERS...> _observers;
};
 
#endif /* HORIZON_ZONE_GAME_STATUS_OBSERVABLESTATUS_HPP */