util/Subject.h

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/*
 * Copyright 2011-2016 Universiteit Antwerpen
 *
 * Licensed under the EUPL, Version 1.1 or  as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at: http://ec.europa.eu/idabc/eupl5
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing
 * permissions and limitations under the Licence.
 */
#pragma once

#include <functional>
#include <map>
#include <memory>

namespace stride {
namespace util {

template <typename E>
class Subject
{
public:
        using EventType    = E;
        using CallbackType = std::function<void(const EventType&)>;

public:
        Subject() : m_observers() {}

        virtual ~Subject() { UnregisterAll(); }

        template <typename U>
        void Register(const std::shared_ptr<U>& u, CallbackType f)
        {
                m_observers.insert(make_pair(std::static_pointer_cast<const void>(u), f));
        }

        template <typename U>
        void Unregister(const std::shared_ptr<U>& u)
        {
                m_observers.erase(std::static_pointer_cast<const void>(u));
        }

        void UnregisterAll() { m_observers.clear(); }

        void Notify(const EventType& e)
        {
                for (const auto& o : m_observers) {
                        const auto spt = o.first.lock();
                        if (spt) {
                                (o.second)(e);
                        } else {
                                m_observers.erase(o.first);
                        }
                }
        }

private:
        std::map<std::weak_ptr<const void>, CallbackType, std::owner_less<std::weak_ptr<const void>>> m_observers;
};

} // namespace util
} // namespace stride