VoidCast.h

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/*
 * Copyright (C) 2012 by
 *   MetraLabs GmbH (MLAB), GERMANY
 * and
 *   Neuroinformatics and Cognitive Robotics Labs (NICR) at TU Ilmenau, GERMANY
 * All rights reserved.
 *
 * Contact: info@mira-project.org
 *
 * Commercial Usage:
 *   Licensees holding valid commercial licenses may use this file in
 *   accordance with the commercial license agreement provided with the
 *   software or, alternatively, in accordance with the terms contained in
 *   a written agreement between you and MLAB or NICR.
 *
 * GNU General Public License Usage:
 *   Alternatively, this file may be used under the terms of the GNU
 *   General Public License version 3.0 as published by the Free Software
 *   Foundation and appearing in the file LICENSE.GPL3 included in the
 *   packaging of this file. Please review the following information to
 *   ensure the GNU General Public License version 3.0 requirements will be
 *   met: http://www.gnu.org/copyleft/gpl.html.
 *   Alternatively you may (at your option) use any later version of the GNU
 *   General Public License if such license has been publicly approved by
 *   MLAB and NICR (or its successors, if any).
 *
 * IN NO EVENT SHALL "MLAB" OR "NICR" BE LIABLE TO ANY PARTY FOR DIRECT,
 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
 * THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF "MLAB" OR
 * "NICR" HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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 */

#ifndef _MIRA_VOIDCAST_H_
#define _MIRA_VOIDCAST_H_

#include <type_traits>

#include <factory/Object.h>

namespace mira::serialization {

//@cond INTERNAL
// for internal use by void casts.

template<typename T>
void* voidUpcastNormal(T* pointer)
{
    typedef typename std::remove_const<T>::type Tc;
    Tc* p = const_cast<Tc*>(pointer);
    return static_cast<void*>(p);
}

template<typename T>
T* voidDowncastNormal(void* pointer)
{
    return static_cast<T*>(pointer);
}

// For polymorphic types we cast via the base mira::Object type. This ensures
// safety even for multiple inheritance, since the address of the mira::Object
// part is "fixed" for all classes along the type hierarchy.

template<typename T>
void* voidUpcastPolymorphic(T* pointer)
{
    typedef typename std::remove_const<T>::type Tc;
    Tc* p = const_cast<Tc*>(pointer);
    mira::Object* obj = p;
    return static_cast<void*>(obj);
}

template<typename T>
T* voidDowncastPolymorphic(void* pointer)
{
    auto* obj = static_cast<mira::Object*>(pointer);
    T* p = dynamic_cast<T*>(obj);
    assert(p != NULL); // this should never happen, since all polymorphic types
                       // MUST be derived from mira::Object
    return p;
}



template<typename T>
void* void_upcast(T* pointer)
{
    if constexpr (std::is_base_of_v<mira::Object, T>) {
        return voidUpcastPolymorphic(pointer);
    }
    else {
        return voidUpcastNormal(pointer);
    }
}

template<typename T>
T* void_downcast(void* pointer)
{
    if constexpr (std::is_base_of_v<mira::Object, T>) {
        return voidDowncastPolymorphic<T>(pointer);
    }
    else {
        return voidDowncastNormal<T>(pointer);
    }
}


} // namespace mira::serialization

#endif