MassEntityConcepts.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "MassEntityElementTypes.h"
#include "MassExternalSubsystemTraits.h"
#include "Subsystems/Subsystem.h"
 
 
namespace UE::Mass
{
    template<typename T>
    using Clean = typename TRemoveReference<T>::Type;
    
    template<typename T>
    concept CFragment = TIsDerivedFrom<Clean<T>, FMassFragment>::Value &&
        (
            std::is_trivially_copyable_v<Clean<T>> ||
            static_cast<bool>(TMassFragmentTraits<Clean<T>>::AuthorAcceptsItsNotTriviallyCopyable)
        );
    
    template<typename T>
    concept CTag = TIsDerivedFrom<Clean<T>, FMassTag>::Value;
 
    template<typename T>
    concept CChunkFragment = TIsDerivedFrom<Clean<T>, FMassChunkFragment>::Value;
 
    template<typename T>
    concept CSharedFragment = TIsDerivedFrom<Clean<T>, FMassSharedFragment>::Value;
 
    template<typename T>
    concept CConstSharedFragment = TIsDerivedFrom<Clean<T>, FMassConstSharedFragment>::Value;
 
    template<typename T>
    concept CNonTag = CFragment<T> || CChunkFragment<T> || CSharedFragment<T> || CConstSharedFragment<T>;
 
    template<typename T>
    concept CElement = CNonTag<T> || CTag<T>;
 
    template<typename T>
    concept CSubsystem = TIsDerivedFrom<Clean<T>, USubsystem>::Value;
 
    namespace Private
    {
        template<CElement T>
        struct TElementTypeHelper
        {
            using Type = std::conditional_t<CFragment<T>, FMassFragment
                , std::conditional_t<CTag<T>, FMassTag
                , std::conditional_t<CChunkFragment<T>, FMassChunkFragment
                , std::conditional_t<CSharedFragment<T>, FMassSharedFragment
                , std::conditional_t<CConstSharedFragment<T>, FMassConstSharedFragment
                , void>>>>>;
        };
    }
 
    template<typename T>
    using TElementType = typename Private::TElementTypeHelper<T>::Type;
}