440 lines
20 KiB
C++
440 lines
20 KiB
C++
#pragma once
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#include "CoreTypes.h"
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#include "Templates/Invoke.h"
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#include "Templates/Utility.h"
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#include "Templates/TypeHash.h"
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#include "TypeTraits/TypeTraits.h"
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#include "Miscellaneous/Compare.h"
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#include "Miscellaneous/TypeInfo.h"
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#include "Miscellaneous/AssertionMacros.h"
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NAMESPACE_REDCRAFT_BEGIN
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NAMESPACE_MODULE_BEGIN(Redcraft)
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NAMESPACE_MODULE_BEGIN(Utility)
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NAMESPACE_PRIVATE_BEGIN
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template <typename T, typename... Types>
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struct TVariantAlternativeIndex;
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template <typename T, typename U, typename... Types>
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struct TVariantAlternativeIndex<T, U, Types...>
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: TConstant<size_t, TIsSame<T, U>::Value ? 0 : (TVariantAlternativeIndex<T, Types...>::Value == INDEX_NONE
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? INDEX_NONE : TVariantAlternativeIndex<T, Types...>::Value + 1)>
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{ };
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template <typename T>
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struct TVariantAlternativeIndex<T> : TConstant<size_t, INDEX_NONE> { };
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template <size_t I, typename... Types>
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struct TVariantAlternativeType;
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template <size_t I, typename T, typename... Types>
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struct TVariantAlternativeType<I, T, Types...>
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{
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static_assert(I < sizeof...(Types) + 1, "Variant type index is invalid");
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using Type = TVariantAlternativeType<I - 1, Types...>::Type;
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};
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template <typename T, typename... Types>
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struct TVariantAlternativeType<0, T, Types...> { using Type = T; };
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template <>
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struct TVariantAlternativeType<0> { };
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template <typename T, typename... Types>
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struct TVariantSelectedType;
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template <typename T, typename U, typename... Types>
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struct TVariantSelectedType<T, U, Types...>
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{
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using TypeAlternativeA = typename TConditional<TIsConstructible<U, T&&>::Value, U, void>::Type;
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using TypeAlternativeB = typename TVariantSelectedType<T, Types...>::Type;
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using Type = typename TConditional<TIsSame<typename TRemoveCVRef<TypeAlternativeA>::Type, void>::Value, TypeAlternativeB,
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typename TConditional<TIsSame<typename TRemoveCVRef<TypeAlternativeB>::Type, void>::Value, TypeAlternativeA,
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typename TConditional<TIsSame<typename TRemoveCVRef<TypeAlternativeB>::Type, typename TRemoveCVRef<T>::Type>::Value, TypeAlternativeB, TypeAlternativeA>::Type>::Type>::Type;
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// 0 - Type not found
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// 1 - Same type found
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// 2 - Multiple types found
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// 3 - The type found
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static constexpr uint8 Flag = TIsSame<typename TRemoveCVRef<Type>::Type, void>::Value ? 0 :
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TIsSame<typename TRemoveCVRef<TypeAlternativeA>::Type, typename TRemoveCVRef<TypeAlternativeB>::Type>::Value ? 2 :
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TIsSame<typename TRemoveCVRef< Type>::Type, typename TRemoveCVRef< T>::Type>::Value ? 1 :
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!TIsSame<typename TRemoveCVRef<TypeAlternativeA>::Type, void>::Value && !TIsSame<TypeAlternativeB, void>::Value ? 2 : 3;
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static constexpr bool Value = Flag & 1;
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};
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template <typename T>
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struct TVariantSelectedType<T>
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{
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static constexpr uint8 Flag = 0;
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using Type = void;
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};
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template <typename R, typename F, typename T>
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constexpr R VariantVisitLValue(F&& Func, void* Arg)
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{
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if constexpr(TIsVoid<R>::Value) Invoke(Forward<F>(Func), *reinterpret_cast<T*>(Arg));
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else return InvokeResult<R>(Forward<F>(Func), *reinterpret_cast<T*>(Arg));
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}
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template <typename R, typename F>
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using FVariantVisitLValueFunc = R(*)(F&&, void*);
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template <typename R, typename F, typename T>
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constexpr R VariantVisitRValue(F&& Func, void* Arg)
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{
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if constexpr (TIsVoid<R>::Value) Invoke(Forward<F>(Func), MoveTemp(*reinterpret_cast<T*>(Arg)));
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else return InvokeResult<R>(Forward<F>(Func), MoveTemp(*reinterpret_cast<T*>(Arg)));
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}
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template <typename R, typename F>
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using FVariantVisitRValueFunc = R(*)(F&&, void*);
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template <typename R, typename F, typename T>
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constexpr R VariantVisitConstLValue(F&& Func, const void* Arg)
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{
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if constexpr (TIsVoid<R>::Value) Invoke(Forward<F>(Func), *reinterpret_cast<const T*>(Arg));
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else return InvokeResult<R>(Forward<F>(Func), *reinterpret_cast<const T*>(Arg));
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}
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template <typename R, typename F>
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using FVariantVisitConstLValueFunc = R(*)(F&&, const void*);
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template <typename R, typename F, typename T>
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constexpr R VariantVisitConstRValue(F&& Func, const void* Arg)
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{
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if constexpr (TIsVoid<R>::Value) Invoke(Forward<F>(Func), MoveTemp(*reinterpret_cast<const T*>(Arg)));
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else return InvokeResult<R>(Forward<F>(Func), MoveTemp(*reinterpret_cast<const T*>(Arg)));
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}
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template <typename R, typename F>
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using FVariantVisitConstRValueFunc = R(*)(F&&, const void*);
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template <typename R, typename F, typename... Types>
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struct TVariantVisitHelper
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{
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static constexpr FVariantVisitLValueFunc<R, F> VisitLValueFuncs[] = { VariantVisitLValue<R, F, Types>... };
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static constexpr FVariantVisitRValueFunc<R, F> VisitRValueFuncs[] = { VariantVisitRValue<R, F, Types>... };
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static constexpr FVariantVisitConstLValueFunc<R, F> VisitConstLValueFuncs[] = { VariantVisitConstLValue<R, F, Types>... };
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static constexpr FVariantVisitConstRValueFunc<R, F> VisitConstRValueFuncs[] = { VariantVisitConstRValue<R, F, Types>... };
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};
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NAMESPACE_PRIVATE_END
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template <typename... Types> requires (true && ... && (TIsObject<Types>::Value && !TIsArray<Types>::Value && TIsDestructible<Types>::Value)) && (sizeof...(Types) < 0xFF)
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struct TVariant
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{
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static constexpr size_t AlternativeSize = sizeof...(Types);
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template <size_t I> struct TAlternativeType : NAMESPACE_PRIVATE::TVariantAlternativeType<I, Types...> { };
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template <typename T> struct TAlternativeIndex : NAMESPACE_PRIVATE::TVariantAlternativeIndex<T, Types...> { };
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constexpr TVariant() : TypeIndex(0xFF) { };
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constexpr TVariant(FInvalid) : TVariant() { };
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constexpr TVariant(const TVariant& InValue) requires (true && ... && TIsCopyConstructible<Types>::Value)
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: TypeIndex(static_cast<uint8>(InValue.GetIndex()))
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{
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if (IsValid()) TypeInfos[InValue.GetIndex()]->CopyConstruct(&Value, &InValue.Value);
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}
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constexpr TVariant(TVariant&& InValue) requires (true && ... && TIsMoveConstructible<Types>::Value)
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: TypeIndex(static_cast<uint8>(InValue.GetIndex()))
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{
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if (IsValid()) TypeInfos[InValue.GetIndex()]->MoveConstruct(&Value, &InValue.Value);
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}
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template <size_t I, typename... ArgTypes> requires (I < AlternativeSize)
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&& TIsConstructible<typename TAlternativeType<I>::Type, ArgTypes...>::Value
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constexpr explicit TVariant(TInPlaceIndex<I>, ArgTypes&&... Args)
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: TypeIndex(I)
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{
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using SelectedType = typename TAlternativeType<I>::Type;
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new(&Value) SelectedType(Forward<ArgTypes>(Args)...);
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}
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template <typename T, typename... ArgTypes> requires (TAlternativeIndex<T>::Value != INDEX_NONE)
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&& TIsConstructible<typename TAlternativeType<TAlternativeIndex<T>::Value>::Type, ArgTypes...>::Value
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constexpr explicit TVariant(TInPlaceType<T>, ArgTypes&&... Args)
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: TVariant(InPlaceIndex<TAlternativeIndex<T>::Value>, Forward<ArgTypes>(Args)...)
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{ }
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template <typename T> requires NAMESPACE_PRIVATE::TVariantSelectedType<typename TRemoveReference<T>::Type, Types...>::Value
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&& (!TIsTInPlaceType<typename TRemoveCVRef<T>::Type>::Value) && (!TIsTInPlaceIndex<typename TRemoveCVRef<T>::Type>::Value)
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&& (!TIsSame<typename TRemoveCVRef<T>::Type, TVariant>::Value)
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constexpr TVariant(T&& InValue) : TVariant(InPlaceType<typename NAMESPACE_PRIVATE::TVariantSelectedType<typename TRemoveReference<T>::Type, Types...>::Type>, Forward<T>(InValue))
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{ }
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constexpr ~TVariant()
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{
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if constexpr (!(true && ... && TIsTriviallyDestructible<Types>::Value)) Reset();
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}
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constexpr TVariant& operator=(const TVariant& InValue) requires (true && ... && (TIsCopyConstructible<Types>::Value && TIsCopyAssignable<Types>::Value))
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{
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if (&InValue == this) return *this;
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if (!InValue.IsValid())
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{
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Reset();
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return *this;
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}
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if (GetIndex() == InValue.GetIndex()) TypeInfos[InValue.GetIndex()]->CopyAssign(&Value, &InValue.Value);
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else
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{
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Reset();
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TypeInfos[InValue.GetIndex()]->CopyConstruct(&Value, &InValue.Value);
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TypeIndex = static_cast<uint8>(InValue.GetIndex());
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}
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return *this;
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}
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constexpr TVariant& operator=(TVariant&& InValue) requires (true && ... && (TIsMoveConstructible<Types>::Value && TIsMoveAssignable<Types>::Value))
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{
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if (&InValue == this) return *this;
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if (!InValue.IsValid())
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{
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Reset();
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return *this;
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}
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if (GetIndex() == InValue.GetIndex()) TypeInfos[InValue.GetIndex()]->MoveAssign(&Value, &InValue.Value);
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else
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{
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Reset();
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TypeInfos[InValue.GetIndex()]->MoveConstruct(&Value, &InValue.Value);
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TypeIndex = static_cast<uint8>(InValue.GetIndex());
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}
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return *this;
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}
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template <typename T> requires NAMESPACE_PRIVATE::TVariantSelectedType<typename TRemoveReference<T>::Type, Types...>::Value
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constexpr TVariant& operator=(T&& InValue)
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{
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using SelectedType = typename NAMESPACE_PRIVATE::TVariantSelectedType<typename TRemoveReference<T>::Type, Types...>::Type;
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if (GetIndex() == TAlternativeIndex<SelectedType>::Value) GetValue<SelectedType>() = Forward<T>(InValue);
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else
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{
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Reset();
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new(&Value) SelectedType(Forward<T>(InValue));
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TypeIndex = TAlternativeIndex<SelectedType>::Value;
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}
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return *this;
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}
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template <size_t I, typename... ArgTypes> requires (I < AlternativeSize)
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&& TIsConstructible<typename TAlternativeType<I>::Type, ArgTypes...>::Value
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constexpr typename TAlternativeType<I>::Type& Emplace(ArgTypes&&... Args)
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{
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Reset();
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using SelectedType = typename TAlternativeType<I>::Type;
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SelectedType* Result = new(&Value) SelectedType(Forward<ArgTypes>(Args)...);
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TypeIndex = I;
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return *Result;
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}
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template <typename T, typename... ArgTypes> requires (TAlternativeIndex<T>::Value != INDEX_NONE)
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&& TIsConstructible<typename TAlternativeType<TAlternativeIndex<T>::Value>::Type, ArgTypes...>::Value
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constexpr T& Emplace(ArgTypes&&... Args)
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{
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return Emplace<TAlternativeIndex<T>::Value>(Forward<ArgTypes>(Args)...);
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}
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constexpr const FTypeInfo& GetTypeInfo() const { return IsValid() ? *TypeInfos[GetIndex()] : Typeid(void); }
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constexpr size_t GetIndex() const { return TypeIndex != 0xFF ? TypeIndex : INDEX_NONE; }
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constexpr bool IsValid() const { return TypeIndex != 0xFF; }
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constexpr explicit operator bool() const { return TypeIndex != 0xFF; }
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template <size_t I> constexpr bool HoldsAlternative() const { return IsValid() ? GetIndex() == I : false; }
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template <typename T> constexpr bool HoldsAlternative() const { return IsValid() ? GetIndex() == TAlternativeIndex<T>::Value : false; }
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template <size_t I> requires (I < AlternativeSize) constexpr typename TAlternativeType<I>::Type& GetValue() & { checkf(HoldsAlternative<I>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return *reinterpret_cast< TAlternativeType<I>::Type*>(&Value); }
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template <size_t I> requires (I < AlternativeSize) constexpr typename TAlternativeType<I>::Type&& GetValue() && { checkf(HoldsAlternative<I>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast< TAlternativeType<I>::Type*>(&Value)); }
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template <size_t I> requires (I < AlternativeSize) constexpr const typename TAlternativeType<I>::Type& GetValue() const& { checkf(HoldsAlternative<I>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return *reinterpret_cast<const TAlternativeType<I>::Type*>(&Value); }
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template <size_t I> requires (I < AlternativeSize) constexpr const typename TAlternativeType<I>::Type&& GetValue() const&& { checkf(HoldsAlternative<I>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast<const TAlternativeType<I>::Type*>(&Value)); }
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template <typename T> requires (TAlternativeIndex<T>::Value != INDEX_NONE) constexpr T& GetValue() & { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return *reinterpret_cast< T*>(&Value); }
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template <typename T> requires (TAlternativeIndex<T>::Value != INDEX_NONE) constexpr T&& GetValue() && { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast< T*>(&Value)); }
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template <typename T> requires (TAlternativeIndex<T>::Value != INDEX_NONE) constexpr const T& GetValue() const& { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return *reinterpret_cast<const T*>(&Value); }
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template <typename T> requires (TAlternativeIndex<T>::Value != INDEX_NONE) constexpr const T&& GetValue() const&& { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TVariant. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast<const T*>(&Value)); }
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template <size_t I> requires (I < AlternativeSize) constexpr typename TAlternativeType<I>::Type& Get( typename TAlternativeType<I>::Type& DefaultValue) & { return HoldsAlternative<I>() ? GetValue<I>() : DefaultValue; }
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template <size_t I> requires (I < AlternativeSize) constexpr const typename TAlternativeType<I>::Type& Get(const typename TAlternativeType<I>::Type& DefaultValue) const& { return HoldsAlternative<I>() ? GetValue<I>() : DefaultValue; }
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template <typename T> requires (TAlternativeIndex<T>::Value != INDEX_NONE) constexpr T& Get(T& DefaultValue)& { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename T> requires (TAlternativeIndex<T>::Value != INDEX_NONE) constexpr const T& Get(const T& DefaultValue) const& { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename F> requires (true && ... && TIsInvocable<F, Types>::Value)
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constexpr auto Visit(F&& Func) &
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{
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using ReturnType = typename TCommonType<typename TInvokeResult<F, Types>::Type...>::Type;
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return ReturnType(NAMESPACE_PRIVATE::TVariantVisitHelper<ReturnType, F, Types...>::VisitLValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename F> requires (true && ... && TIsInvocable<F, Types>::Value)
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constexpr auto Visit(F&& Func) &&
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{
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using ReturnType = typename TCommonType<typename TInvokeResult<F, Types>::Type...>::Type;
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return ReturnType(NAMESPACE_PRIVATE::TVariantVisitHelper<ReturnType, F, Types...>::VisitRValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename F> requires (true && ... && TIsInvocable<F, Types>::Value)
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constexpr auto Visit(F&& Func) const&
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{
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using ReturnType = typename TCommonType<typename TInvokeResult<F, Types>::Type...>::Type;
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return ReturnType(NAMESPACE_PRIVATE::TVariantVisitHelper<ReturnType, F, Types...>::VisitConstLValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename F> requires (true && ... && TIsInvocable<F, Types>::Value)
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constexpr auto Visit(F&& Func) const&&
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{
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using ReturnType = typename TCommonType<typename TInvokeResult<F, Types>::Type...>::Type;
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return ReturnType(NAMESPACE_PRIVATE::TVariantVisitHelper<ReturnType, F, Types...>::VisitConstRValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename R, typename F> requires (true && ... && TIsInvocableResult<R, F, Types>::Value)
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constexpr R Visit(F&& Func) &
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return R(NAMESPACE_PRIVATE::TVariantVisitHelper<R, F, Types...>::VisitLValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename R, typename F> requires (true && ... && TIsInvocableResult<R, F, Types>::Value)
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constexpr R Visit(F&& Func) &&
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return R(NAMESPACE_PRIVATE::TVariantVisitHelper<R, F, Types...>::VisitRValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename R, typename F> requires (true && ... && TIsInvocableResult<R, F, Types>::Value)
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constexpr R Visit(F&& Func) const&
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return R(NAMESPACE_PRIVATE::TVariantVisitHelper<R, F, Types...>::VisitConstLValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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template <typename R, typename F> requires (true && ... && TIsInvocableResult<R, F, Types>::Value)
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constexpr R Visit(F&& Func) const&&
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return R(NAMESPACE_PRIVATE::TVariantVisitHelper<R, F, Types...>::VisitConstRValueFuncs[GetIndex()](Forward<F>(Func), &Value));
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}
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constexpr void Reset()
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{
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if (GetIndex() == INDEX_NONE) return;
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if constexpr (!(true && ... && TIsTriviallyDestructible<Types>::Value))
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{
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TypeInfos[GetIndex()]->Destroy(&Value);
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}
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TypeIndex = static_cast<uint8>(INDEX_NONE);
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}
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constexpr size_t GetTypeHash() const requires (true && ... && CHashable<Types>)
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{
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if (!IsValid()) return 114514;
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return HashCombine(NAMESPACE_REDCRAFT::GetTypeHash(GetIndex()), TypeInfos[GetIndex()]->HashItem(&Value));
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}
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constexpr void Swap(TVariant& InValue) requires (true && ... && (TIsMoveConstructible<Types>::Value && TIsSwappable<Types>::Value))
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{
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if (!IsValid() && !InValue.IsValid()) return;
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if (IsValid() && !InValue.IsValid())
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{
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InValue = MoveTemp(*this);
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Reset();
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return;
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}
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if (InValue.IsValid() && !IsValid())
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{
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*this = MoveTemp(InValue);
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InValue.Reset();
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return;
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}
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if (GetIndex() == InValue.GetIndex())
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{
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TypeInfos[GetIndex()]->SwapItem(&Value, &InValue.Value);
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return;
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}
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TVariant Temp = MoveTemp(*this);
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*this = MoveTemp(InValue);
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InValue = MoveTemp(Temp);
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}
|
|
|
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private:
|
|
|
|
static constexpr const FTypeInfo* TypeInfos[] = { &Typeid(Types)... };
|
|
|
|
TAlignedUnion<1, Types...>::Type Value;
|
|
uint8 TypeIndex;
|
|
|
|
friend constexpr bool operator==(const TVariant& LHS, const TVariant& RHS) requires (true && ... && CEqualityComparable<Types>)
|
|
{
|
|
if (LHS.GetIndex() != RHS.GetIndex()) return false;
|
|
if (LHS.IsValid() == false) return true;
|
|
return TypeInfos[LHS.GetIndex()]->EqualityCompare(&LHS.Value, &RHS.Value);
|
|
}
|
|
|
|
friend constexpr partial_ordering operator<=>(const TVariant& LHS, const TVariant& RHS) requires (true && ... && CSynthThreeWayComparable<Types>)
|
|
{
|
|
if (LHS.GetIndex() != RHS.GetIndex()) return partial_ordering::unordered;
|
|
if (LHS.IsValid() == false) return partial_ordering::equivalent;
|
|
return TypeInfos[LHS.GetIndex()]->SynthThreeWayCompare(&LHS.Value, &RHS.Value);
|
|
}
|
|
|
|
};
|
|
|
|
template <typename T, typename... Types> requires (!TIsSame<T, TVariant<Types...>>::Value) && CEqualityComparable<T>
|
|
constexpr bool operator==(const TVariant<Types...>& LHS, const T& RHS)
|
|
{
|
|
return LHS.template HoldsAlternative<T>() ? LHS.template GetValue<T>() == RHS : false;
|
|
}
|
|
|
|
template <typename... Types>
|
|
constexpr bool operator==(const TVariant<Types...>& LHS, FInvalid)
|
|
{
|
|
return !LHS.IsValid();
|
|
}
|
|
|
|
template <typename T > struct TIsTVariant : FFalse { };
|
|
template <typename... Types> struct TIsTVariant<TVariant<Types...>> : FTrue { };
|
|
|
|
template <typename VariantType> requires TIsTVariant<typename TRemoveCVRef<VariantType>::Type>::Value
|
|
struct TVariantAlternativeSize : TConstant<size_t, VariantType::AlternativeSize> { };
|
|
|
|
template <size_t I, typename VariantType> requires TIsTVariant<typename TRemoveCVRef<VariantType>::Type>::Value
|
|
struct TVariantAlternativeType { using Type = typename TCopyCV<typename TRemoveReference<VariantType>::Type, typename TRemoveCVRef<VariantType>::Type::template TAlternativeType<I>::Type>::Type; };
|
|
|
|
template <typename T, typename VariantType> requires TIsTVariant<typename TRemoveCVRef<VariantType>::Type>::Value
|
|
struct TVariantAlternativeIndex : VariantType::template TAlternativeIndex<T> { };
|
|
|
|
NAMESPACE_MODULE_END(Utility)
|
|
NAMESPACE_MODULE_END(Redcraft)
|
|
NAMESPACE_REDCRAFT_END
|