FindLast.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Templates/IdentityFunctor.h"
#include "Templates/Invoke.h"
#include "Templates/UnrealTemplate.h" // For MoveTemp
 
namespace AlgoImpl
{
    template <typename T, typename ValueType, typename ProjectionType>
    T* FindLastBy(T* First, SIZE_T Num, const ValueType& Value, ProjectionType Proj)
    {
        for (T* Last = First + Num; First != Last;)
        {
            if (Invoke(Proj, *--Last) == Value)
            {
                return Last;
            }
        }
 
        return nullptr;
    }
 
    template <typename T, typename PredicateType>
    T* FindLastByPredicate(T* First, SIZE_T Num, PredicateType Pred)
    {
        for (T* Last = First + Num; First != Last;)
        {
            if (Invoke(Pred, *--Last))
            {
                return Last;
            }
        }
 
        return nullptr;
    }
}
 
namespace Algo
{
    /**
     * Returns a pointer to the last element in the range which is equal to the given value.
     *
     * @param  Range  The range to search.
     * @param  Value  The value to search for.
     *
     * @return A pointer to the last element found, or nullptr if none was found.
     */
    template <typename RangeType, typename ValueType>
    FORCEINLINE auto FindLast(RangeType&& Range, const ValueType& Value)
        -> decltype(AlgoImpl::FindLastBy(GetData(Range), GetNum(Range), Value, FIdentityFunctor()))
    {
        return AlgoImpl::FindLastBy(GetData(Range), GetNum(Range), Value, FIdentityFunctor());
    }
 
    /**
     * Returns a pointer to the last element in the range whose projection is equal to the given value.
     *
     * @param  Range  The range to search.
     * @param  Value  The value to search for.
     * @param  Proj   The projection to apply to the element.
     *
     * @return A pointer to the last element found, or nullptr if none was found.
     */
    template <typename RangeType, typename ValueType, typename ProjectionType>
    FORCEINLINE auto FindLastBy(RangeType&& Range, const ValueType& Value, ProjectionType Proj)
        -> decltype(AlgoImpl::FindLastBy(GetData(Range), GetNum(Range), Value, MoveTemp(Proj)))
    {
        return AlgoImpl::FindLastBy(GetData(Range), GetNum(Range), Value, MoveTemp(Proj));
    }
 
    /**
     * Returns a pointer to the last element in the range which matches the predicate.
     *
     * @param  Range  The range to search.
     * @param  Pred   The predicate to search for.
     *
     * @return A pointer to the last element found, or nullptr if none was found.
     */
    template <typename RangeType, typename PredicateType>
    FORCEINLINE auto FindLastByPredicate(RangeType&& Range, PredicateType Pred)
        -> decltype(AlgoImpl::FindLastByPredicate(GetData(Range), GetNum(Range), MoveTemp(Pred)))
    {
        return AlgoImpl::FindLastByPredicate(GetData(Range), GetNum(Range), MoveTemp(Pred));
    }
}