MemoryHasher.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Misc/AssertionMacros.h"
#include "HAL/UnrealMemory.h"
#include "Math/NumericLimits.h"
#include "Containers/UnrealString.h"
#include "UObject/NameTypes.h"
#include "Logging/LogMacros.h"
#include "CoreGlobals.h"
#include "Serialization/MemoryArchive.h"
#include "Misc/SecureHash.h"
#include "Hash/Blake3.h"
 
/**
 * Archive for hashing arbitrary data
 */
template <typename HashBuilder, typename HashDigest>
class TMemoryHasher : public FMemoryArchive
{
public:
    TMemoryHasher()
    : FMemoryArchive()
    {
        this->SetIsSaving(true);
        this->SetIsPersistent(false);
    }
 
    virtual void Serialize(void* Data, int64 Num) override
    {
        BuilderState.Update(reinterpret_cast<uint8*>(Data), Num);
    }
 
    HashDigest Finalize()
    {
        return BuilderState.Finalize();
    }
 
    /**
     * 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 { return TEXT("TMemoryHasherTemplate"); }
 
    int64 TotalSize() override
    {
        return 0;
    }
 
protected:
 
    /** Context data needed to build the hash */
    HashBuilder     BuilderState;
};
 
using FMemoryHasherSHA1 = TMemoryHasher<FSHA1, FSHAHash>;
using FMemoryHasherBlake3 = TMemoryHasher<FBlake3, FBlake3Hash>;