IntrinsicClassBaseChain.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#if UE_WITH_CONSTINIT_UOBJECT
 
#include "UObject/Class.h"
 
namespace UE::Private
{
    template<typename IntrinsicClass>
    constexpr bool DeferFalse = false;
 
    template<typename IntrinsicClass>
    consteval UClass* GetConstInitClass()
    {
        static_assert(DeferFalse<IntrinsicClass>, "UE::Private::GetConstInitClass must be specialized for intrinsic classes");
        return nullptr;
    }
 
    template<typename... Classes>
    struct TIntrinsicClassBaseChainImpl
    {
        using BaseChainPtr = const FStructBaseChain*;
        static constexpr SIZE_T Num = sizeof...(Classes);
        static inline constinit BaseChainPtr Bases[] = { static_cast<BaseChainPtr>(GetConstInitClass<Classes>())... };
 
        static consteval TArrayView<const FStructBaseChain*> ToArrayView()
        {
            return MakeArrayView(Bases, Num);
        }
    };
 
    template<typename ClassType, typename... Ts>
    consteval auto DetermineIntrinsicClassBaseChain() 
    { 
        if constexpr (std::is_same_v<ClassType, typename ClassType::Super>) 
        {
            return TIntrinsicClassBaseChainImpl<ClassType, Ts...>{};
        } 
        else
        {
            return DetermineIntrinsicClassBaseChain<typename ClassType::Super, ClassType, Ts...>();
        }
    }
}
 
// Template to build a static array of base class pointers for an intrinsic class
template<typename T>
using TIntrinsicClassBaseChain = decltype(UE::Private::DetermineIntrinsicClassBaseChain<T>());
 
#endif // UE_WITH_CONSTINIT_UOBJECT