data_access.hpp

/*
    data_access.hpp - support file for writing LV2 plugins in C++

    Copyright (C) 2012 Michael Fisher <mfisher31@gmail.com>

    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, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 01222-1307  USA
 */
#ifndef LVTK_DATA_ACCESS_HPP
#define LVTK_DATA_ACCESS_HPP

#include <lv2/lv2plug.in/ns/ext/data-access/data-access.h>

#include <lvtk/private/types.hpp>

namespace lvtk
{

    template<bool Required = true>
    struct DataAccess
    {
        template<class Derived>
        struct I : Extension<Required>
        {
            I() : p_da(NULL) { }

            static void
            map_feature_handlers(FeatureHandlerMap& hmap)
            {
                hmap[LV2_DATA_ACCESS_URI] = &I<Derived>::handle_feature;
            }

            static void
            handle_feature(LV2UI_Handle instance, FeatureData data)
            {
                Derived* derived = reinterpret_cast<Derived*>(instance);
                I<Derived>* mixin = static_cast<I<Derived>*>(derived);

                mixin->p_da =
                        reinterpret_cast<LV2_Extension_Data_Feature*>(data);
                mixin->m_ok = (mixin->p_da != NULL);
            }

            bool
            check_ok()
            {
                if (!Required)
                    return true;

                if (LVTK_DEBUG)
                {
                    std::clog << "    [DataAccess] Validation "
                            << (this->m_ok ? "succeeded" : "failed")
                            << "." << std::endl;
                }
                return this->m_ok;
            }

            const void*
            data_access(const char *uri)
            {
                if (NULL != p_da)
                    return p_da->data_access(uri);
                return NULL;
            }

        protected:
            LV2_Extension_Data_Feature *p_da;
        };
    };

} /* namespace lvtk */

#endif /* LVTK_DATA_ACCESS_HPP */