ArrayAlgorithm.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
#include "Chaos/Core.h"
#include "Containers/Array.h"
 
namespace Chaos
{
    template<typename TItemArray>
    void MoveArrayItemsDown(TItemArray& Items, const int32 BeginIndex, const int32 EndIndex, const int32 DownShift)
    {
        check(DownShift >= 0);
        check(BeginIndex - DownShift >= 0);
        check(EndIndex >= BeginIndex);
        check(EndIndex <= Items.Num());
 
        if (DownShift > 0)
        {
            for (int32 SrcIndex = BeginIndex; SrcIndex < EndIndex; ++SrcIndex)
            {
                Items[SrcIndex - DownShift] = MoveTemp(Items[SrcIndex]);
            }
        }
    }
 
    template<typename TItemArray>
    void RemoveArrayItemsAtSortedIndices(TItemArray& Items, const TArrayView<const int32>& SortedIndicesToRemove)
    {
        if (SortedIndicesToRemove.IsEmpty())
        {
            return;
        }
 
        int32 DestShift = 1;
        int32 IndexToRemove0 = SortedIndicesToRemove[0];
        for (int32 IndicesIndex = 1; IndicesIndex < SortedIndicesToRemove.Num(); ++IndicesIndex)
        {
            const int32 IndexToRemove1 = SortedIndicesToRemove[IndicesIndex];
 
            if (IndexToRemove1 != IndexToRemove0)
            {
                MoveArrayItemsDown(Items, IndexToRemove0 + 1, IndexToRemove1, DestShift);
 
                IndexToRemove0 = IndexToRemove1;
                DestShift++;
            }
        }
 
        MoveArrayItemsDown(Items, IndexToRemove0 + 1, Items.Num(), DestShift);
 
        Items.SetNum(Items.Num() - DestShift, EAllowShrinking::No);
    }
 
}