MapHelper.h

/*     Copyright 2015-2018 Egor Yusov
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF ANY PROPRIETARY RIGHTS.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#pragma once


#include "DebugUtilities.h"

namespace Diligent
{


template<typename DataType, bool KeepStrongReferences = false>
class MapHelper
{
public:

    MapHelper() : 
        m_pMappedData(nullptr),
        m_pBuffer(nullptr),
        m_pContext(nullptr),
        m_MapType(static_cast<MAP_TYPE>(-1)),
        m_MapFlags(static_cast<Uint32>(-1))
    {
    }

    MapHelper( IDeviceContext *pContext, IBuffer *pBuffer, MAP_TYPE MapType, Uint32 MapFlags ) :
        MapHelper()
    {
        Map(pContext, pBuffer, MapType, MapFlags);
    }

    MapHelper(MapHelper&& Helper) :
        m_pBuffer( std::move(Helper.m_pBuffer) ),
        m_pMappedData( std::move(Helper.m_pMappedData) ),
        m_pContext( std::move(Helper.m_pContext) ),
        m_MapType( std::move(Helper.m_MapType) ),
        m_MapFlags( std::move(Helper.m_MapFlags) )
    {
        Helper.m_pBuffer = nullptr;
        Helper.m_pContext = nullptr;
        Helper.m_pMappedData = nullptr;
        Helper.m_MapType = static_cast<MAP_TYPE>(-1);
        Helper.m_MapFlags = static_cast<Uint32>(-1);
    }

    MapHelper& operator = (MapHelper&& Helper)
    {
        m_pBuffer = std::move(Helper.m_pBuffer);
        m_pMappedData = std::move(Helper.m_pMappedData);
        m_pContext = std::move( Helper.m_pContext );
        m_MapType = std::move(Helper.m_MapType);
        m_MapFlags = std::move(Helper.m_MapFlags);
        Helper.m_pBuffer = nullptr;
        Helper.m_pContext = nullptr;
        Helper.m_pMappedData = nullptr;
        Helper.m_MapType = static_cast<MAP_TYPE>(-1);
        Helper.m_MapFlags = static_cast<Uint32>(-1);
        return *this;
    }


    void Map( IDeviceContext *pContext, IBuffer *pBuffer, MAP_TYPE MapType, Uint32 MapFlags )
    {
        VERIFY(!m_pBuffer && !m_pMappedData && !m_pContext, "Object already mapped");
        Unmap();
#ifdef _DEBUG
        auto &BuffDesc = pBuffer->GetDesc();
        VERIFY(sizeof(DataType) <= BuffDesc.uiSizeInBytes, "Data type size exceeds buffer size");
#endif
        m_pContext = pContext;
        m_pBuffer = pBuffer;
        m_MapType = MapType;
        m_MapFlags = MapFlags;
        m_pBuffer->Map(m_pContext, MapType, MapFlags, (PVoid&)m_pMappedData);
        VERIFY( m_pMappedData, "Map failed" );
    }

    void Unmap()
    {
        if( m_pBuffer )
        {
            m_pBuffer->Unmap(m_pContext, m_MapType, m_MapFlags);
            m_pBuffer = nullptr;
            m_MapType = static_cast<MAP_TYPE>(-1);
            m_MapFlags = static_cast<Uint32>(-1);
        }
        m_pContext = nullptr;
        m_pMappedData = nullptr;
    }
    
    operator DataType* (){return m_pMappedData;}

    operator const DataType* ()const{return m_pMappedData;}

    DataType* operator->() {return m_pMappedData;}

    const DataType* operator->() const{return m_pMappedData;}

    ~MapHelper()
    {
        Unmap();
    }

private:
    MapHelper(const MapHelper&);
    MapHelper& operator=(const MapHelper&);

    template<typename PtrType, bool UseStrongReference>
    struct PtrTypeSelector{};

    template<typename PtrType>
    struct PtrTypeSelector<PtrType, true>
    {
        typedef RefCntAutoPtr<PtrType> Type;
    };

    template<typename PtrType>
    struct PtrTypeSelector<PtrType, false>
    {
        typedef PtrType* Type;
    };

    typename PtrTypeSelector<IBuffer, KeepStrongReferences>::Type m_pBuffer;

    typename PtrTypeSelector<IDeviceContext, KeepStrongReferences>::Type m_pContext;

    DataType *m_pMappedData;

    MAP_TYPE m_MapType;

    Uint32 m_MapFlags;
};

}