MemoryImageWriter.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Serialization/MemoryLayout.h"
 
struct FScriptName;
class FMemoryImage;
class FMemoryImageSection;
class FPointerTableBase;
 
class FMemoryImageWriter
{
public:
    CORE_API explicit FMemoryImageWriter(FMemoryImage& InImage);
    CORE_API explicit FMemoryImageWriter(FMemoryImageSection* InSection);
    CORE_API ~FMemoryImageWriter();
 
    CORE_API FMemoryImage& GetImage() const;
    CORE_API const FPlatformTypeLayoutParameters& GetHostLayoutParams() const;
    CORE_API const FPlatformTypeLayoutParameters& GetTargetLayoutParams() const;
    CORE_API FPointerTableBase& GetPointerTable() const;
    CORE_API const FPointerTableBase* TryGetPrevPointerTable() const;
 
    inline bool Is32BitTarget() const { return GetTargetLayoutParams().Is32Bit(); }
    inline bool Is64BitTarget() const { return !Is32BitTarget(); }
 
    CORE_API int32 AddTypeDependency(const FTypeLayoutDesc& TypeDesc);
 
    CORE_API void WriteObject(const void* Object, const FTypeLayoutDesc& TypeDesc);
    CORE_API void WriteObjectArray(const void* Object, const FTypeLayoutDesc& TypeDesc, uint32_t NumArray);
    CORE_API void WriteRootObject(const void* Object, const FTypeLayoutDesc& TypeDesc);
 
    CORE_API uint32 GetOffset() const;
    CORE_API uint32 WriteAlignment(uint32 Alignment);
    CORE_API void WritePaddingToSize(uint32 Offset);
    CORE_API uint32 WriteBytes(const void* Data, uint32 Size);
    CORE_API FMemoryImageWriter WritePointer(const FTypeLayoutDesc& StaticTypeDesc, const FTypeLayoutDesc& DerivedTypeDesc, uint32* OutOffsetToBase = nullptr);
    CORE_API FMemoryImageWriter WritePointer(const FTypeLayoutDesc& TypeDesc);
    CORE_API uint32 WriteNullPointer();
    CORE_API uint32 WriteRawPointerSizedBytes(uint64 PointerValue);
    CORE_API uint32 WriteVTable(const FTypeLayoutDesc& TypeDesc, const FTypeLayoutDesc& DerivedTypeDesc);
    CORE_API uint32 WriteFMemoryImageName(int32 NumBytes, const FName& Name);
    CORE_API uint32 WriteFScriptName(const FScriptName& Name);
 
    template<typename T>
    void WriteObject(const T& Object)
    {
        const FTypeLayoutDesc& TypeDesc = GetTypeLayoutDesc(TryGetPrevPointerTable(), Object);
        WriteObject(&Object, TypeDesc);
    }
 
    template<typename T>
    void WriteRootObject(const T& Object)
    {
        const FTypeLayoutDesc& TypeDesc = GetTypeLayoutDesc(TryGetPrevPointerTable(), Object);
        WriteRootObject(&Object, TypeDesc);
    }
 
    template<typename T>
    uint32 WriteAlignment()
    {
        return WriteAlignment(alignof(T));
    }
 
    template<typename T>
    uint32 WriteBytes(const T& Data)
    {
        return WriteBytes(&Data, sizeof(T));
    }
 
//private:
    FMemoryImageSection* Section;
};
 
class FMemoryUnfreezeContent
{
public:
    explicit FMemoryUnfreezeContent(const FPointerTableBase* InPointerTable)
        : PrevPointerTable(InPointerTable)
        , bIsFrozenForCurrentPlatform(true)
    {
        FrozenLayoutParameters.InitializeForCurrent();
    }
 
    FMemoryUnfreezeContent(const FPointerTableBase* InPointerTable, const FPlatformTypeLayoutParameters& InLayoutParams)
        : PrevPointerTable(InPointerTable)
        , FrozenLayoutParameters(InLayoutParams)
        , bIsFrozenForCurrentPlatform(InLayoutParams.IsCurrentPlatform())
    {
    }
 
    inline const FPointerTableBase* TryGetPrevPointerTable() const { return PrevPointerTable; }
 
    CORE_API const FTypeLayoutDesc* GetDerivedTypeDesc(const FTypeLayoutDesc& StaticTypeDesc, int32 TypeIndex) const;
 
    inline uint32 UnfreezeObject(const void* Object, const FTypeLayoutDesc& TypeDesc, void* OutDst) const
    {
        return TypeDesc.UnfrozenCopyFunc(*this, Object, TypeDesc, OutDst);
    }
 
    template<typename T>
    inline uint32 UnfreezeObject(const T& Object, void* OutDst) const
    {
        const FTypeLayoutDesc& TypeDesc = GetTypeLayoutDesc(TryGetPrevPointerTable(), Object);
        return UnfreezeObject(&Object, TypeDesc, OutDst);
    }
 
    const FPointerTableBase* PrevPointerTable = nullptr;
 
    // Layout of the frozen data
    FPlatformTypeLayoutParameters FrozenLayoutParameters;
    bool bIsFrozenForCurrentPlatform; // FrozenLayoutParameters.IsCurrentPlatform
};