classregistry.h

/*
    This file is part of Cute Chess.
    Copyright (C) 2008-2018 Cute Chess authors
 
    Cute Chess 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.
 
    Cute Chess 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 Cute Chess.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifndef CLASSREGISTRY_H
#define CLASSREGISTRY_H
 
#include <QString>
#include <QMap>

#define REGISTER_CLASS(BASE, TYPE, KEY, REGISTRY) \
    static ClassRegistration<BASE> _class_registration_ ## TYPE(REGISTRY, &ClassRegistry<BASE>::factory<TYPE>, KEY);

template<class T>
class ClassRegistry
{
    public:
        typedef T* (*Factory)(void);

        template<class Subclass>
        static T* factory()
        {
            return new Subclass;
        }

        const QMap<QString, Factory>& items() const
        {
            return m_items;
        }

        void add(Factory f, const QString& key)
        {
            m_items[key] = f;
        }

        T* create(const QString& key)
        {
            if (!m_items.contains(key))
                return nullptr;
 
            return m_items[key]();
        }
 
    private:
        QMap<QString, Factory> m_items;
};

template<class T>
class ClassRegistration
{
    public:
        ClassRegistration(ClassRegistry<T>* registry,
                  typename ClassRegistry<T>::Factory factory,
                  const QString& key)
        {
            registry->add(factory, key);
        }
};
 
#endif // CLASSREGISTRY_H