qd_resource_dispatcher.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program 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 program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef QDENGINE_QDCORE_QD_RESOURCE_DISPATCHER_H
#define QDENGINE_QDCORE_QD_RESOURCE_DISPATCHER_H

#include "qdengine/qdcore/qd_resource.h"


namespace QDEngine {

template<class T>
class qdResourceDispatcher {
public:
    qdResourceDispatcher() {}
    virtual ~qdResourceDispatcher() {}

    bool register_resource(qdResource *res, const T *res_owner) {
        qdResourceHandle<T> hres(res, res_owner);
        typename handle_container_t::iterator it = Common::find(_handles.begin(), _handles.end(), hres);

        if (it != _handles.end()) return false;
        _handles.push_back(hres);

        return true;
    }

    bool unregister_resource(qdResource *res, const T *res_owner) {
        qdResourceHandle<T> hres(res, res_owner);
        typename handle_container_t::iterator it = Common::find(_handles.begin(), _handles.end(), hres);

        if (it != _handles.end()) {
            _handles.erase(it);
            return true;
        }

        return false;
    }

    bool is_registered(const qdResource *res, const T *res_owner = NULL) const {
        if (res_owner) {
            qdResourceHandle<T> hres(const_cast<qdResource *>(res), res_owner);
            typename handle_container_t::const_iterator it = Common::find(_handles.begin(), _handles.end(), hres);
            return (it != _handles.end());
        } else {
            typename handle_container_t::const_iterator it = Common::find(_handles.begin(), _handles.end(), *res);
            return (it != _handles.end());
        }
    }

    const T *find_owner(const qdResource *res) const {
        typename handle_container_t::const_iterator it = Common::find(_handles.begin(), _handles.end(), *res);
        if (_handles.end() == it) return NULL;
        return (*it).resource_owner();
    }

    void load_resources(const T *owner = NULL) const {
        if (owner) {
            for (typename handle_container_t::const_iterator it = _handles.begin(); it != _handles.end(); ++it) {
                if (it->resource_owner() == owner)
                    it->load_resource();
            }
        } else {
            for (typename handle_container_t::const_iterator it = _handles.begin(); it != _handles.end(); ++it)
                it->load_resource();
        }
    }

    void release_resources(const T *owner = NULL, const T *hold_owner = NULL) const {
        if (owner) {
            for (typename handle_container_t::const_iterator it = _handles.begin(); it != _handles.end(); ++it) {
                if (it->resource_owner() == owner && (!hold_owner || !is_registered(it->resource(), hold_owner)))
                    it->release_resource();
            }
        } else {
            if (hold_owner) {
                for (typename handle_container_t::const_iterator it = _handles.begin(); it != _handles.end(); ++it) {
                    if (it->resource_owner() != hold_owner)
                        it->release_resource();
                }
            } else {
                for (typename handle_container_t::const_iterator it = _handles.begin(); it != _handles.end(); ++it)
                    it->release_resource();
            }
        }
    }

    bool load_resource(qdResource *res, const T *res_owner) {
        qdResourceHandle<T> hres(res, res_owner);
        register_resource(res, res_owner);
        return hres.load_resource();
    }

    bool release_resource(qdResource *res, const T *res_owner) {
        unregister_resource(res, res_owner);
        if (!is_registered(res)) {
            qdResourceHandle<T> hres(res, res_owner);
            return hres.release_resource();
        }

        return false;
    }

protected:

    template<class U>
    class qdResourceHandle {
    public:
        qdResourceHandle(qdResource *res, const U *res_owner) : _resource(res), _resource_owner(res_owner) {}
        qdResourceHandle(const qdResourceHandle<U> &h) : _resource(h._resource), _resource_owner(h._resource_owner) {}
        ~qdResourceHandle() {}

        qdResourceHandle<U> &operator = (const qdResourceHandle<U> &h) {
            if (this == &h) return *this;
            _resource = h._resource;
            _resource_owner = h._resource_owner;
            return *this;
        }

        bool operator == (const qdResource &res) const {
            return (_resource == &res);
        }
        bool operator == (const qdResourceHandle<U> &h) const {
            return (_resource == h._resource && _resource_owner == h._resource_owner);
        }

        qdResource *resource() const {
            return _resource;
        }
        const U *resource_owner() const {
            return _resource_owner;
        }

        bool load_resource() const {
            if (!_resource->is_resource_loaded())
                return _resource->load_resource();
            return true;
        }
        bool release_resource() const {
            if (_resource->is_resource_loaded())
                return _resource->free_resource();
            return true;
        }

    private:

        mutable qdResource *_resource;
        const T *_resource_owner;
    };

    typedef Std::list< qdResourceHandle<T> > handle_container_t;

    handle_container_t _handles;
};

} // namespace QDEngine

#endif // QDENGINE_QDCORE_QD_RESOURCE_DISPATCHER_H