Find.h

Go to the documentation of this file.

// 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>
    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>
    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
{
    /**
     * Returns a pointer to the first 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 first element found, or nullptr if none was found.
     */
    template <typename RangeType, typename ValueType>
    FORCEINLINE auto Find(RangeType&& Range, const ValueType& Value)
        -> decltype(AlgoImpl::FindBy(Forward<RangeType>(Range), Value, FIdentityFunctor()))
    {
        return AlgoImpl::FindBy(Forward<RangeType>(Range), Value, FIdentityFunctor());
    }
 
    /**
     * Returns a pointer to the first 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 first element found, or nullptr if none was found.
     */
    template <typename RangeType, typename ValueType, typename ProjectionType>
    FORCEINLINE 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));
    }
 
    /**
     * Returns a pointer to the first 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 first element found, or nullptr if none was found.
     */
    template <typename RangeType, typename PredicateType>
    FORCEINLINE auto FindByPredicate(RangeType&& Range, PredicateType Pred)
        -> decltype(AlgoImpl::FindByPredicate(Forward<RangeType>(Range), MoveTemp(Pred)))
    {
        return AlgoImpl::FindByPredicate(Forward<RangeType>(Range), MoveTemp(Pred));
    }
}