LargeMemoryWriter.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/UnrealString.h"
#include "CoreTypes.h"
#include "Memory/MemoryFwd.h"
#include "Memory/MemoryView.h"
#include "Serialization/LargeMemoryData.h"
#include "Serialization/MemoryArchive.h"
#include "UObject/NameTypes.h"
 
/**
* Archive for storing a large amount of arbitrary data to memory
*/
class FLargeMemoryWriter : public FMemoryArchive
{
public:
 
    FLargeMemoryWriter(const int64 PreAllocateBytes = 0, bool bIsPersistent = false, const TCHAR* InFilename = nullptr);
 
    virtual void Serialize(void* InData, int64 Num) override;
 
    /**
    * Returns the name of the Archive.  Useful for getting the name of the package a struct or object
    * is in when a loading error occurs.
    *
    * This is overridden for the specific Archive Types
    **/
    virtual FString GetArchiveName() const override;
 
    /**
     * Gets the total size of the data written
     */
    virtual int64 TotalSize() override
    {
        return Data.GetSize();
    }
 
    /**
     * Returns the written data. To release this archive's ownership of the data, call ReleaseOwnership()
     */
    uint8* GetData() const;
 
    /**
     * Returns a view on the written data
     * 
     * The view does not own the memory, so you must make sure you keep the memory writer
     * alive while you are using the returned view.
     * 
     */
    inline FMemoryView GetView() const { return MakeMemoryView(GetData(), Data.GetSize()); }
 
    /** 
     * Releases ownership of the written data
     *
     * Also returns the pointer, so that the caller only needs to call this function to take control
     * of the memory.
     */
    FORCEINLINE uint8* ReleaseOwnership()
    {
        return Data.ReleaseOwnership();
    }
 
    /**
     * Reserves memory such that the writer can contain at least Size number of bytes.
     */
    void Reserve(int64 Size)
    {
        Data.Reserve(Size);
    }
 
private:
 
    FLargeMemoryData Data;
 
    /** Non-copyable */
    FLargeMemoryWriter(const FLargeMemoryWriter&) = delete;
    FLargeMemoryWriter& operator=(const FLargeMemoryWriter&) = delete;
 
 
    /** Archive name, used for debugging, by default set to NAME_None. */
    const FString ArchiveName;
};