CircularBuffer.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 "Containers/Array.h"
#include "Math/UnrealMathUtility.h"
 
template<typename InElementType> class TCircularBuffer
{
public:
    using ElementType = InElementType;
 
    [[nodiscard]] explicit TCircularBuffer(uint32 Capacity)
    {
        checkSlow(Capacity > 0);
        checkSlow(Capacity <= 0xffffffffU);
 
        Elements.AddZeroed(FMath::RoundUpToPowerOfTwo(Capacity));
        IndexMask = Elements.Num() - 1;
    }
 
    [[nodiscard]] TCircularBuffer(uint32 Capacity, const ElementType& InitialValue)
    {
        checkSlow(Capacity <= 0xffffffffU);
 
        Elements.Init(InitialValue, FMath::RoundUpToPowerOfTwo(Capacity));
        IndexMask = Elements.Num() - 1;
    }
 
public:
 
    [[nodiscard]] UE_FORCEINLINE_HINT ElementType& operator[](uint32 Index)
    {
        return Elements[Index & IndexMask];
    }
 
    [[nodiscard]] UE_FORCEINLINE_HINT const ElementType& operator[](uint32 Index) const
    {
        return Elements[Index & IndexMask];
    }
    
public:
 
    [[nodiscard]] UE_FORCEINLINE_HINT uint32 Capacity() const
    {
        return Elements.Num();
    }
 
    [[nodiscard]] UE_FORCEINLINE_HINT uint32 GetNextIndex(uint32 CurrentIndex) const
    {
        return ((CurrentIndex + 1) & IndexMask);
    }
 
    [[nodiscard]] UE_FORCEINLINE_HINT uint32 GetPreviousIndex(uint32 CurrentIndex) const
    {
        return ((CurrentIndex - 1) & IndexMask);
    }
 
private:
 
    uint32 IndexMask;
 
    TArray<ElementType> Elements;
};