DllObjectFactory.h

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// DllObjectFactory.h
//
// Copyright (c) 1995-1998 - Richard Langlois and Grokksoft Inc.
//
// Licensed under GrokkSoft HoverRace SourceCode License v1.0(the "License");
// you may not use this file except in compliance with the License.
//
// A copy of the license should have been attached to the package from which
// you have taken this file. If you can not find the license you can not use
// this file.
//
//
// The author makes no representations about the suitability of
// this software for any purpose.  It is provided "as is" "AS IS",
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied.
//
// See the License for the specific language governing permissions
// and limitations under the License.
//

// This file constais fonctions for creating objects from
// two integer numbers. One of this number identify the
// dll containing the object to create and the other contain
// factory class

#pragma once

#include "../Parcel/ObjStream.h"

#include "MR_Types.h"

#if defined(_WIN32) && defined(HR_ENGINE_SHARED)
#   ifdef MR_ENGINE
#       define MR_DllDeclare   __declspec( dllexport )
#   else
#       define MR_DllDeclare   __declspec( dllimport )
#   endif
#else
#   define MR_DllDeclare
#endif

namespace HoverRace {
    namespace ObjFacTools {
        class ResourceLib;
    }
}

namespace HoverRace {
namespace Util {

struct ObjectFromFactoryId
{
    MR_UInt16 mDllId;
    MR_UInt16 mClassId;

    void Serialize(Parcel::ObjStream &pArchive);

    constexpr bool operator==(const ObjectFromFactoryId &pId) const noexcept
    {
        return
            mDllId == pId.mDllId &&
            mClassId == pId.mClassId;
    }
};

class ObjectFromFactory;

namespace DllObjectFactory {

MR_DllDeclare void Init() noexcept;

MR_DllDeclare void Clean() noexcept;

MR_DllDeclare std::shared_ptr<ObjectFromFactory> CreateObject(
    const ObjectFromFactoryId &pId);

}  // namespace DllObjectFactory

class MR_DllDeclare ObjectFromFactory
{
private:
    ObjectFromFactoryId mId;

public:
    ObjectFromFactory(const ObjectFromFactoryId &pId) noexcept : mId(pId) { }
    virtual ~ObjectFromFactory() { }

    const ObjectFromFactoryId &GetTypeId() const noexcept { return mId; }

private:
    static void ThrowUnexpected(const ObjectFromFactoryId &oid);

public:
    // Serialisation functions
    //
    // Warning this module do not support multiple references to objects
    // or looped structures

    template<class T>
    static void SerializeShared(Parcel::ObjStream &archive,
        typename std::enable_if<
            std::is_base_of<ObjectFromFactory, T>::value,
            std::shared_ptr<T>>::type &obj)
    {
        ObjectFromFactoryId oid = { 0, 0 };

        if (archive.IsWriting()) {
            if (obj) {
                oid = obj->mId;
            }
            oid.Serialize(archive);
            if (obj) {
                obj->Serialize(archive);
            }
        }
        else {
            oid.Serialize(archive);

            if (oid.mDllId == 0) {
                obj.reset();
            }
            else {
                auto dynObj = std::dynamic_pointer_cast<T>(
                    DllObjectFactory::CreateObject(oid));
                if (!dynObj) {
                    obj.reset();
                    // The ID is probably corrupt or unsupported, so we can't
                    // rely on the rest of the stream (we don't know where the
                    // next object starts!).
                    ThrowUnexpected(oid);
                }
                obj = std::move(dynObj);
                obj->Serialize(archive);
            }
        }
    }

    virtual void Serialize(Parcel::ObjStream &archive) = 0;
};

}  // namespace Util
}  // namespace HoverRace

#undef MR_DllDeclare