470 lines
21 KiB
C++
470 lines
21 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 "Memory/MemoryOperator.h"
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#include "Miscellaneous/Compare.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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template <typename... Types> requires (true && ... && CDestructible<Types>)
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class TVariant;
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NAMESPACE_PRIVATE_BEGIN
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template <typename T > struct TIsTVariant : FFalse { };
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template <typename... Types> struct TIsTVariant<TVariant<Types...>> : FTrue { };
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template <typename TupleType>
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struct TVariantNumImpl;
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template <typename... Types>
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struct TVariantNumImpl<TVariant<Types...>> : TConstant<size_t, sizeof...(Types)> { };
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template <typename... Types>
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struct TVariantNumImpl<const TVariant<Types...>> : TConstant<size_t, sizeof...(Types)> { };
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template <typename... Types>
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struct TVariantNumImpl<volatile TVariant<Types...>> : TConstant<size_t, sizeof...(Types)> { };
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template <typename... Types>
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struct TVariantNumImpl<const volatile TVariant<Types...>> : TConstant<size_t, sizeof...(Types)> { };
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template <typename T, typename TupleType>
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struct TVariantIndexImpl;
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template <typename T, typename U, typename... Types>
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struct TVariantIndexImpl<T, TVariant<U, Types...>> : TConstant<size_t, TVariantIndexImpl<T, TVariant<Types...>>::Value + 1>
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{
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static_assert(sizeof...(Types) != 0, "Non-existent types in variant");
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};
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template <typename T, typename... Types>
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struct TVariantIndexImpl<T, TVariant<T, Types...>> : TConstant<size_t, 0>
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{
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static_assert((true && ... && !CSameAs<T, Types>), "Duplicate type in variant");
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};
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template <typename T>
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struct TVariantIndexImpl<T, TVariant<>> : TConstant<size_t, INDEX_NONE> { };
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template <typename T, typename... Types>
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struct TVariantIndexImpl<T, const TVariant<Types...>> : TVariantIndexImpl<T, TVariant<Types...>> { };
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template <typename T, typename... Types>
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struct TVariantIndexImpl<T, volatile TVariant<Types...>> : TVariantIndexImpl<T, TVariant<Types...>> { };
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template <typename T, typename... Types>
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struct TVariantIndexImpl<T, const volatile TVariant<Types...>> : TVariantIndexImpl<T, TVariant<Types...>> { };
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template <size_t I, typename TupleType>
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struct TVariantAlternativeImpl;
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template <size_t I, typename T, typename... Types>
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struct TVariantAlternativeImpl<I, TVariant<T, Types...>>
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{
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static_assert(I < sizeof...(Types) + 1, "Invalid index in variant");
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using Type = TVariantAlternativeImpl<I - 1, TVariant<Types...>>::Type;
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};
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template <typename T, typename... Types>
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struct TVariantAlternativeImpl<0, TVariant<T, Types...>> { using Type = T; };
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template <size_t I, typename... Types>
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struct TVariantAlternativeImpl<I, TVariant<Types...>> { };
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template <>
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struct TVariantAlternativeImpl<0, TVariant<>> { };
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template <size_t I, typename... Types>
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struct TVariantAlternativeImpl<I, const TVariant<Types...>> { using Type = TAddConst<typename TVariantAlternativeImpl<I, TVariant<Types...>>::Type>; };
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template <size_t I, typename... Types>
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struct TVariantAlternativeImpl<I, volatile TVariant<Types...>> { using Type = TAddVolatile<typename TVariantAlternativeImpl<I, TVariant<Types...>>::Type>; };
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template <size_t I, typename... Types>
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struct TVariantAlternativeImpl<I, const volatile TVariant<Types...>> { using Type = TAddCV<typename TVariantAlternativeImpl<I, TVariant<Types...>>::Type>; };
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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 = TConditional<CConstructibleFrom<U, T&&>, U, void>;
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using TypeAlternativeB = typename TVariantSelectedType<T, Types...>::Type;
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using Type = TConditional<CSameAs<TRemoveCVRef<TypeAlternativeA>, void>, TypeAlternativeB,
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TConditional<CSameAs<TRemoveCVRef<TypeAlternativeB>, void>, TypeAlternativeA,
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TConditional<CSameAs<TRemoveCVRef<TypeAlternativeB>, TRemoveCVRef<T>>, TypeAlternativeB, TypeAlternativeA>>>;
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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 = CSameAs<TRemoveCVRef<Type>, void> ? 0 :
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CSameAs<TRemoveCVRef<TypeAlternativeA>, TRemoveCVRef<TypeAlternativeB>> ? 2 :
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CSameAs<TRemoveCVRef< Type>, TRemoveCVRef< T>> ? 1 :
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!CSameAs<TRemoveCVRef<TypeAlternativeA>, void> && !CSameAs<TypeAlternativeB, void> ? 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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NAMESPACE_PRIVATE_END
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template <typename T>
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concept CTVariant = NAMESPACE_PRIVATE::TIsTVariant<T>::Value;
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template <typename VariantType>
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inline constexpr size_t TVariantNum = NAMESPACE_PRIVATE::TVariantNumImpl<VariantType>::Value;
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template <typename T, typename VariantType>
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inline constexpr size_t TVariantIndex = NAMESPACE_PRIVATE::TVariantIndexImpl<T, VariantType>::Value;
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template <size_t I, typename VariantType>
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using TVariantAlternative = typename NAMESPACE_PRIVATE::TVariantAlternativeImpl<I, VariantType>::Type;
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template <typename... Types> requires (true && ... && CDestructible<Types>)
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class TVariant
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{
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public:
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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 && ... && CCopyConstructible<Types>)
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: TypeIndex(static_cast<uint8>(InValue.GetIndex()))
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{
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if (IsValid()) CopyConstructImpl[InValue.GetIndex()](&Value, &InValue.Value);
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}
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constexpr TVariant(TVariant&& InValue) requires (true && ... && CMoveConstructible<Types>)
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: TypeIndex(static_cast<uint8>(InValue.GetIndex()))
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{
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if (IsValid()) MoveConstructImpl[InValue.GetIndex()](&Value, &InValue.Value);
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}
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template <size_t I, typename... ArgTypes> requires (I < sizeof...(Types))
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&& CConstructibleFrom<TVariantAlternative<I, TVariant<Types...>>, ArgTypes...>
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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 = TVariantAlternative<I, TVariant<Types...>>;
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new(&Value) SelectedType(Forward<ArgTypes>(Args)...);
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}
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template <typename T, typename... ArgTypes> requires CConstructibleFrom<T, ArgTypes...>
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constexpr explicit TVariant(TInPlaceType<T>, ArgTypes&&... Args)
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: TVariant(InPlaceIndex<TVariantIndex<T, TVariant<Types...>>>, Forward<ArgTypes>(Args)...)
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{ }
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template <typename T> requires NAMESPACE_PRIVATE::TVariantSelectedType<TRemoveReference<T>, Types...>::Value
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&& (!CTInPlaceType<TRemoveCVRef<T>>) && (!CTInPlaceIndex<TRemoveCVRef<T>>)
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&& (!CSameAs<TRemoveCVRef<T>, TVariant>)
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constexpr TVariant(T&& InValue) : TVariant(InPlaceType<typename NAMESPACE_PRIVATE::TVariantSelectedType<TRemoveReference<T>, 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 && ... && CTriviallyDestructible<Types>)) Reset();
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}
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constexpr TVariant& operator=(const TVariant& InValue) requires (true && ... && (CCopyConstructible<Types> && CCopyAssignable<Types>))
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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()) CopyAssignImpl[InValue.GetIndex()](&Value, &InValue.Value);
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else
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{
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Reset();
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CopyConstructImpl[InValue.GetIndex()](&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 && ... && (CMoveConstructible<Types> && CMoveAssignable<Types>))
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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()) MoveAssignImpl[InValue.GetIndex()](&Value, &InValue.Value);
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else
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{
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Reset();
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MoveConstructImpl[InValue.GetIndex()](&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<TRemoveReference<T>, 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<TRemoveReference<T>, Types...>::Type;
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if (GetIndex() == TVariantIndex<SelectedType, TVariant<Types...>>) 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 = TVariantIndex<SelectedType, TVariant<Types...>>;
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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 < sizeof...(Types))
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&& CConstructibleFrom<TVariantAlternative<I, TVariant<Types...>>, ArgTypes...>
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constexpr TVariantAlternative<I, TVariant<Types...>>& Emplace(ArgTypes&&... Args)
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{
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Reset();
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using SelectedType = TVariantAlternative<I, TVariant<Types...>>;
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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 CConstructibleFrom<T, ArgTypes...>
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constexpr T& Emplace(ArgTypes&&... Args)
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{
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return Emplace<TVariantIndex<T, TVariant<Types...>>>(Forward<ArgTypes>(Args)...);
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}
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constexpr const type_info& 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() == TVariantIndex<T, TVariant<Types...>> : false; }
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template <size_t I> requires (I < sizeof...(Types)) constexpr decltype(auto) 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< TVariantAlternative<I, TVariant<Types...>>*>(&Value); }
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template <size_t I> requires (I < sizeof...(Types)) constexpr decltype(auto) 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< TVariantAlternative<I, TVariant<Types...>>*>(&Value)); }
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template <size_t I> requires (I < sizeof...(Types)) constexpr decltype(auto) 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 TVariantAlternative<I, TVariant<Types...>>*>(&Value); }
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template <size_t I> requires (I < sizeof...(Types)) constexpr decltype(auto) 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 TVariantAlternative<I, TVariant<Types...>>*>(&Value)); }
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template <typename T> constexpr decltype(auto) 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> constexpr decltype(auto) 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> constexpr decltype(auto) 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> constexpr decltype(auto) 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 < sizeof...(Types)) constexpr decltype(auto) Get( TVariantAlternative<I, TVariant<Types...>>& DefaultValue) & { return HoldsAlternative<I>() ? GetValue<I>() : DefaultValue; }
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template <size_t I> requires (I < sizeof...(Types)) constexpr decltype(auto) Get(const TVariantAlternative<I, TVariant<Types...>>& DefaultValue) const& { return HoldsAlternative<I>() ? GetValue<I>() : DefaultValue; }
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template <typename T> constexpr decltype(auto) Get( T& DefaultValue) & { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename T> constexpr decltype(auto) Get(const T& DefaultValue) const& { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename F> requires (true && ... && CInvocable<F, Types>)
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FORCEINLINE decltype(auto) 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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using ReturnType = TCommonType<TInvokeResult<F, Types>...>;
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using FInvokeImpl = ReturnType(*)(F&&, void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), *reinterpret_cast<Types*>(This)); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename F> requires (true && ... && CInvocable<F, Types>)
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FORCEINLINE decltype(auto) 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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using ReturnType = TCommonType<TInvokeResult<F, Types>...>;
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using FInvokeImpl = ReturnType(*)(F&&, void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), MoveTemp(*reinterpret_cast<Types*>(This))); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename F> requires (true && ... && CInvocable<F, Types>)
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FORCEINLINE decltype(auto) 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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using ReturnType = TCommonType<TInvokeResult<F, Types>...>;
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using FInvokeImpl = ReturnType(*)(F&&, const void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, const void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), *reinterpret_cast<const Types*>(This)); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename F> requires (true && ... && CInvocable<F, Types>)
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FORCEINLINE decltype(auto) 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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using ReturnType = TCommonType<TInvokeResult<F, Types>...>;
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using FInvokeImpl = ReturnType(*)(F&&, const void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, const void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), MoveTemp(*reinterpret_cast<const Types*>(This))); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Types>)
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FORCEINLINE R Visit(F&& Func) & { return Visit(Forward<F>(Func)); }
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Types>)
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FORCEINLINE R Visit(F&& Func) && { return MoveTemp(*this).Visit(Forward<F>(Func)); }
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Types>)
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FORCEINLINE R Visit(F&& Func) const& { return Visit(Forward<F>(Func)); }
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Types>)
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FORCEINLINE R Visit(F&& Func) const&& { return MoveTemp(*this).Visit(Forward<F>(Func)); }
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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 && ... && CTriviallyDestructible<Types>))
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{
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DestroyImpl[GetIndex()](&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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using NAMESPACE_REDCRAFT::GetTypeHash;
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using FHashImpl = size_t(*)(const void*);
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constexpr FHashImpl HashImpl[] = { [](const void* This) -> size_t { return GetTypeHash(*reinterpret_cast<const Types*>(This)); }... };
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return HashCombine(GetTypeHash(GetIndex()), HashImpl[GetIndex()](&Value));
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}
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constexpr void Swap(TVariant& InValue) requires (true && ... && (CMoveConstructible<Types> && CSwappable<Types>))
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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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using NAMESPACE_REDCRAFT::Swap;
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using FSwapImpl = void(*)(void*, void*);
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constexpr FSwapImpl SwapImpl[] = { [](void* A, void* B) { Swap(*reinterpret_cast<Types*>(A), *reinterpret_cast<Types*>(B)); }... };
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SwapImpl[GetIndex()](&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:
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static constexpr const type_info* TypeInfos[] = { &typeid(Types)... };
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using FCopyConstructImpl = void(*)(void*, const void*);
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using FMoveConstructImpl = void(*)(void*, void*);
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using FCopyAssignImpl = void(*)(void*, const void*);
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using FMoveAssignImpl = void(*)(void*, void*);
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using FDestroyImpl = void(*)(void* );
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static constexpr FCopyConstructImpl CopyConstructImpl[] = { [](void* A, const void* B) { if constexpr (requires(Types* A, const Types* B) { Memory::CopyConstruct (A, B); }) Memory::CopyConstruct (reinterpret_cast<Types*>(A), reinterpret_cast<const Types*>(B)); else checkf(false, TEXT("The type '%s' is not copy constructible."), typeid(Types).name()); }... };
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static constexpr FMoveConstructImpl MoveConstructImpl[] = { [](void* A, void* B) { if constexpr (requires(Types* A, Types* B) { Memory::MoveConstruct (A, B); }) Memory::MoveConstruct (reinterpret_cast<Types*>(A), reinterpret_cast< Types*>(B)); else checkf(false, TEXT("The type '%s' is not move constructible."), typeid(Types).name()); }... };
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static constexpr FCopyAssignImpl CopyAssignImpl[] = { [](void* A, const void* B) { if constexpr (requires(Types* A, const Types* B) { Memory::CopyAssign (A, B); }) Memory::CopyAssign (reinterpret_cast<Types*>(A), reinterpret_cast<const Types*>(B)); else checkf(false, TEXT("The type '%s' is not copy assignable."), typeid(Types).name()); }... };
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static constexpr FMoveAssignImpl MoveAssignImpl[] = { [](void* A, void* B) { if constexpr (requires(Types* A, Types* B) { Memory::MoveAssign (A, B); }) Memory::MoveAssign (reinterpret_cast<Types*>(A), reinterpret_cast< Types*>(B)); else checkf(false, TEXT("The type '%s' is not move assignable."), typeid(Types).name()); }... };
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static constexpr FDestroyImpl DestroyImpl[] = { [](void* A ) { if constexpr (requires(Types* A ) { Memory::Destruct (A ); }) Memory::Destruct (reinterpret_cast<Types*>(A) ); else checkf(false, TEXT("The type '%s' is not destructible."), typeid(Types).name()); }... };
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TAlignedUnion<1, Types...> Value;
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uint8 TypeIndex;
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friend constexpr bool operator==(const TVariant& LHS, const TVariant& RHS) requires (true && ... && CEqualityComparable<Types>)
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{
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if (LHS.GetIndex() != RHS.GetIndex()) return false;
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if (LHS.IsValid() == false) return true;
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using FCompareImpl = bool(*)(const void*, const void*);
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constexpr FCompareImpl CompareImpl[] = { [](const void* LHS, const void* RHS) -> bool { return *reinterpret_cast<const Types*>(LHS) == *reinterpret_cast<const Types*>(RHS); }... };
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return CompareImpl[LHS.GetIndex()](&LHS.Value, &RHS.Value);
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}
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friend constexpr partial_ordering operator<=>(const TVariant& LHS, const TVariant& RHS) requires (true && ... && CSynthThreeWayComparable<Types>)
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{
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if (LHS.GetIndex() != RHS.GetIndex()) return partial_ordering::unordered;
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if (LHS.IsValid() == false) return partial_ordering::equivalent;
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using FCompareImpl = partial_ordering(*)(const void*, const void*);
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constexpr FCompareImpl CompareImpl[] = { [](const void* LHS, const void* RHS) -> partial_ordering { return SynthThreeWayCompare(*reinterpret_cast<const Types*>(LHS), *reinterpret_cast<const Types*>(RHS)); }...};
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return CompareImpl[LHS.GetIndex()](&LHS.Value, &RHS.Value);
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}
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};
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template <typename T, typename... Types> requires (!CSameAs<T, TVariant<Types...>>) && CEqualityComparable<T>
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constexpr bool operator==(const TVariant<Types...>& LHS, const T& RHS)
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{
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return LHS.template HoldsAlternative<T>() ? LHS.template GetValue<T>() == RHS : false;
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}
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template <typename... Types>
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constexpr bool operator==(const TVariant<Types...>& LHS, FInvalid)
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{
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return !LHS.IsValid();
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}
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NAMESPACE_MODULE_END(Utility)
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NAMESPACE_MODULE_END(Redcraft)
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NAMESPACE_REDCRAFT_END
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