FieldArrayView.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Containers/Array.h"
 
template<typename InElementType>
class TFieldArrayView
{
public:
    using ElementType = InElementType;
    using SizeType = int32;
 
    TFieldArrayView(TArray<ElementType>& InElementArray, const SizeType InArrayOffset, const SizeType InArrayNum)
        : ElementArray(InElementArray)
        , ArrayOffset(InArrayOffset)
        , ArrayNum(InArrayNum)
    {
        checkf(InArrayOffset + InArrayNum <= ElementArray.Num(), TEXT("Field array size out of bounds: %i from an array of size %i"), InArrayOffset + InArrayNum, ElementArray.Num());
    }
 
    FORCEINLINE ElementType* GetData() const
    {
        return ElementArray.GetData() + ArrayOffset;
    }
 
    FORCEINLINE static constexpr size_t GetTypeSize()
    {
        return sizeof(ElementType);
    }
 
    FORCEINLINE static constexpr size_t GetTypeAlignment()
    {
        return alignof(ElementType);
    }
 
    FORCEINLINE void CheckInvariants() const
    {
        checkSlow(ArrayNum >= 0);
    }
 
    FORCEINLINE void RangeCheck(SizeType Index) const
    {
        CheckInvariants();
 
        checkf((Index >= 0) & (Index < ArrayNum), TEXT("Array index out of bounds: %i from an array of size %i"), Index, ArrayNum); // & for one branch
    }
 
    FORCEINLINE bool IsValidIndex(SizeType Index) const
    {
        return (Index >= 0) && (Index < ArrayNum);
    }
 
    bool IsEmpty() const
    {
        return ArrayNum == 0;
    }
 
    FORCEINLINE SizeType Num() const
    {
        return ArrayNum;
    }
 
    FORCEINLINE ElementType& operator[](SizeType Index) const
    {
        RangeCheck(Index);
        return ElementArray[ArrayOffset + Index];
    }
 
    FORCEINLINE ElementType* begin() const { return GetData(); }
    FORCEINLINE ElementType* end() const { return GetData() + Num(); }
 
private:
 
    TArray<InElementType>& ElementArray;
    SizeType ArrayOffset;
    SizeType ArrayNum;
};