Find.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Algo/Impl/RangePointerType.h"
#include "Templates/IdentityFunctor.h"
#include "Templates/Invoke.h"
#include "Templates/UnrealTemplate.h" // For MoveTemp
 
namespace AlgoImpl
{
    template <typename RangeType, typename ValueType, typename ProjectionType>
    constexpr typename TRangePointerType<typename TRemoveReference<RangeType>::Type>::Type FindBy(RangeType&& Range, const ValueType& Value, ProjectionType Proj)
    {
        for (auto&& Elem : Forward<RangeType>(Range))
        {
            if (Invoke(Proj, Elem) == Value)
            {
                return &Elem;
            }
        }
 
        return nullptr;
    }
 
    template <typename RangeType, typename PredicateType>
    constexpr typename TRangePointerType<typename TRemoveReference<RangeType>::Type>::Type FindByPredicate(RangeType&& Range, PredicateType Pred)
    {
        for (auto&& Elem : Forward<RangeType>(Range))
        {
            if (Invoke(Pred, Elem))
            {
                return &Elem;
            }
        }
 
        return nullptr;
    }
}
 
namespace Algo
{
    template <typename RangeType, typename ValueType>
    [[nodiscard]] UE_REWRITE constexpr auto Find(RangeType&& Range, const ValueType& Value)
        -> decltype(AlgoImpl::FindBy(Forward<RangeType>(Range), Value, FIdentityFunctor()))
    {
        return AlgoImpl::FindBy(Forward<RangeType>(Range), Value, FIdentityFunctor());
    }
 
    template <typename RangeType, typename ValueType, typename ProjectionType>
    [[nodiscard]] UE_REWRITE constexpr auto FindBy(RangeType&& Range, const ValueType& Value, ProjectionType Proj)
        -> decltype(AlgoImpl::FindBy(Forward<RangeType>(Range), Value, MoveTemp(Proj)))
    {
        return AlgoImpl::FindBy(Forward<RangeType>(Range), Value, MoveTemp(Proj));
    }
 
    template <typename RangeType, typename PredicateType>
    [[nodiscard]] UE_REWRITE constexpr auto FindByPredicate(RangeType&& Range, PredicateType Pred)
        -> decltype(AlgoImpl::FindByPredicate(Forward<RangeType>(Range), MoveTemp(Pred)))
    {
        return AlgoImpl::FindByPredicate(Forward<RangeType>(Range), MoveTemp(Pred));
    }
}