550 lines
16 KiB
C++
550 lines
16 KiB
C++
#pragma once
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#include "CoreTypes.h"
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#include "Memory/Memory.h"
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#include "Memory/Alignment.h"
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#include "Templates/Utility.h"
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#include "Templates/TypeHash.h"
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#include "Memory/MemoryOperator.h"
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#include "TypeTraits/TypeTraits.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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// NOTE: In the STL, the assignment operation of the std::any type uses the copy-and-swap idiom
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// instead of directly calling the assignment operation of the contained value.
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// The purpose of this is as follows:
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// 1) the copy assignment might not exist.
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// 2) the typical case is that the objects are different.
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// 3) it is less exception-safe
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// But we don't follow the the copy-and-swap idiom, because we assume that no function throws an exception.
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NAMESPACE_PRIVATE_BEGIN
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template <typename T>
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concept CFAnyPlaceable = CDestructible<TDecay<T>> && CCopyConstructible<TDecay<T>> && CMoveConstructible<TDecay<T>> && CSwappable<TDecay<T>>;
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NAMESPACE_PRIVATE_END
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class alignas(16) FAny
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{
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public:
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FORCEINLINE constexpr FAny() { Invalidate(); }
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FORCEINLINE constexpr FAny(FInvalid) : FAny() { }
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FORCEINLINE FAny(const FAny& InValue)
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: TypeInfo(InValue.TypeInfo)
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{
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if (!IsValid()) return;
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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Memory::Memcpy(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI = InValue.SmallStorage.RTTI;
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SmallStorage.RTTI->CopyConstruct(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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BigStorage.RTTI = InValue.BigStorage.RTTI;
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BigStorage.External = Memory::Malloc(BigStorage.RTTI->TypeSize, BigStorage.RTTI->TypeAlignment);
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BigStorage.RTTI->CopyConstruct(BigStorage.External, InValue.BigStorage.External);
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break;
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default: check_no_entry();
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}
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}
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FORCEINLINE FAny(FAny&& InValue)
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: TypeInfo(InValue.TypeInfo)
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{
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if (!IsValid()) return;
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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Memory::Memmove(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI = InValue.SmallStorage.RTTI;
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SmallStorage.RTTI->MoveConstruct(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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BigStorage.RTTI = InValue.BigStorage.RTTI;
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BigStorage.External = InValue.BigStorage.External;
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InValue.Invalidate();
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break;
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default: check_no_entry();
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}
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}
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template <typename T, typename... Ts> requires (NAMESPACE_PRIVATE::CFAnyPlaceable<T> && CConstructibleFrom<TDecay<T>, Ts&&...>)
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FORCEINLINE explicit FAny(TInPlaceType<T>, Ts&&... Args)
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{
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EmplaceImpl<T>(Forward<Ts>(Args)...);
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}
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template <typename T> requires (!CBaseOf<FAny, TDecay<T>> && !CTInPlaceType<TDecay<T>>
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&& NAMESPACE_PRIVATE::CFAnyPlaceable<T> && CConstructibleFrom<TDecay<T>, T&&>)
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FORCEINLINE FAny(T&& InValue) : FAny(InPlaceType<TDecay<T>>, Forward<T>(InValue))
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{ }
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FORCEINLINE ~FAny()
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{
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Destroy();
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}
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FORCEINLINE FAny& operator=(const FAny& InValue)
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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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}
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else if (GetTypeInfo() == InValue.GetTypeInfo())
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{
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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Memory::Memcpy(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI = InValue.SmallStorage.RTTI;
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SmallStorage.RTTI->CopyAssign(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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BigStorage.RTTI = InValue.BigStorage.RTTI;
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BigStorage.RTTI->CopyAssign(BigStorage.External, InValue.BigStorage.External);
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break;
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default: check_no_entry();
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}
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}
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else
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{
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Destroy();
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TypeInfo = InValue.TypeInfo;
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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Memory::Memcpy(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI = InValue.SmallStorage.RTTI;
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SmallStorage.RTTI->CopyConstruct(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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BigStorage.RTTI = InValue.BigStorage.RTTI;
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BigStorage.External = Memory::Malloc(BigStorage.RTTI->TypeSize, BigStorage.RTTI->TypeAlignment);
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BigStorage.RTTI->CopyConstruct(BigStorage.External, InValue.BigStorage.External);
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break;
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default: check_no_entry();
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}
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}
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return *this;
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}
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FORCEINLINE FAny& operator=(FAny&& InValue)
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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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}
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else if (GetTypeInfo() == InValue.GetTypeInfo())
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{
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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Memory::Memmove(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI = InValue.SmallStorage.RTTI;
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SmallStorage.RTTI->MoveAssign(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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Destroy();
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BigStorage.RTTI = InValue.BigStorage.RTTI;
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BigStorage.External = InValue.BigStorage.External;
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InValue.Invalidate();
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break;
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default: check_no_entry();
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}
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}
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else
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{
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Destroy();
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TypeInfo = InValue.TypeInfo;
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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Memory::Memmove(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI = InValue.SmallStorage.RTTI;
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SmallStorage.RTTI->MoveConstruct(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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BigStorage.RTTI = InValue.BigStorage.RTTI;
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BigStorage.External = InValue.BigStorage.External;
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InValue.Invalidate();
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break;
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default: check_no_entry();
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}
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}
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return *this;
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}
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template <typename T> requires (!CBaseOf<FAny, TDecay<T>> && !CTInPlaceType<TDecay<T>>
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&& NAMESPACE_PRIVATE::CFAnyPlaceable<T> && CConstructibleFrom<TDecay<T>, T&&>)
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FORCEINLINE FAny& operator=(T&& InValue)
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{
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using DecayedType = TDecay<T>;
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if (HoldsAlternative<DecayedType>())
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{
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GetValue<DecayedType>() = Forward<T>(InValue);
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}
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else
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{
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Destroy();
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EmplaceImpl<DecayedType>(Forward<T>(InValue));
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}
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return *this;
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}
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template <typename T, typename... Ts> requires (NAMESPACE_PRIVATE::CFAnyPlaceable<T> && CConstructibleFrom<TDecay<T>, Ts&&...>)
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FORCEINLINE TDecay<T>& Emplace(Ts&&... Args)
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{
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Destroy();
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EmplaceImpl<T>(Forward<Ts>(Args)...);
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return GetValue<TDecay<T>>();
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}
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FORCEINLINE constexpr const type_info& GetTypeInfo() const { return IsValid() ? GetTypeInfoImpl() : typeid(void); }
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FORCEINLINE constexpr bool IsValid() const { return TypeInfo != 0; }
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FORCEINLINE constexpr explicit operator bool() const { return TypeInfo != 0; }
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template <typename T> FORCEINLINE constexpr bool HoldsAlternative() const { return IsValid() ? GetTypeInfo() == typeid(T) : false; }
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template <typename T> requires (CSameAs<T, TDecay<T>> && NAMESPACE_PRIVATE::CFAnyPlaceable<T>)
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FORCEINLINE constexpr T& GetValue() & { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TAny. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return *reinterpret_cast< T*>(GetStorage()); }
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template <typename T> requires (CSameAs<T, TDecay<T>> && NAMESPACE_PRIVATE::CFAnyPlaceable<T>)
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FORCEINLINE constexpr T&& GetValue() && { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TAny. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast< T*>(GetStorage())); }
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template <typename T> requires (CSameAs<T, TDecay<T>> && NAMESPACE_PRIVATE::CFAnyPlaceable<T>)
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FORCEINLINE constexpr const T& GetValue() const& { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TAny. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return *reinterpret_cast<const T*>(GetStorage()); }
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template <typename T> requires (CSameAs<T, TDecay<T>> && NAMESPACE_PRIVATE::CFAnyPlaceable<T>)
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FORCEINLINE constexpr const T&& GetValue() const&& { checkf(HoldsAlternative<T>(), TEXT("It is an error to call GetValue() on an wrong TAny. Please either check HoldsAlternative() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast<const T*>(GetStorage())); }
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template <typename T> requires (CSameAs<T, TDecay<T>> && NAMESPACE_PRIVATE::CFAnyPlaceable<T>)
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FORCEINLINE constexpr T& Get( T& DefaultValue) & { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename T> requires (CSameAs<T, TDecay<T>> && NAMESPACE_PRIVATE::CFAnyPlaceable<T>)
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FORCEINLINE constexpr const T& Get(const T& DefaultValue) const& { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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FORCEINLINE void Reset()
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{
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Destroy();
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Invalidate();
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}
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FORCEINLINE void Swap(FAny& InValue)
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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 (GetTypeInfo() == InValue.GetTypeInfo())
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{
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switch (GetRepresentation())
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{
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case ERepresentation::Empty:
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break;
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case ERepresentation::Trivial:
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uint8 Buffer[sizeof(TrivialStorage.Internal)];
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Memory::Memmove(Buffer, TrivialStorage.Internal);
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Memory::Memmove(TrivialStorage.Internal, InValue.TrivialStorage.Internal);
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Memory::Memmove(InValue.TrivialStorage.Internal, Buffer);
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break;
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case ERepresentation::Small:
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SmallStorage.RTTI->SwapObject(&SmallStorage.Internal, &InValue.SmallStorage.Internal);
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break;
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case ERepresentation::Big:
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NAMESPACE_REDCRAFT::Swap(BigStorage.External, InValue.BigStorage.External);
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break;
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default: check_no_entry();
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}
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return;
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}
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FAny 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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struct FRTTI
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{
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const size_t TypeSize;
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const size_t TypeAlignment;
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using FCopyConstruct = void(*)(void*, const void*);
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using FMoveConstruct = void(*)(void*, void*);
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using FCopyAssign = void(*)(void*, const void*);
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using FMoveAssign = void(*)(void*, void*);
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using FDestruct = void(*)(void* );
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using FSwapObject = void(*)(void*, void*);
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const FCopyConstruct CopyConstruct;
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const FMoveConstruct MoveConstruct;
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const FCopyAssign CopyAssign;
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const FMoveAssign MoveAssign;
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const FDestruct Destruct;
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const FSwapObject SwapObject;
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template <typename T>
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FORCEINLINE constexpr FRTTI(TInPlaceType<T>)
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: TypeSize( sizeof(T)), TypeAlignment(alignof(T))
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, CopyConstruct(
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[](void* A, const void* B)
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{
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new (A) T(*reinterpret_cast<const T*>(B));
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}
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)
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, MoveConstruct(
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[](void* A, void* B)
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{
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new (A) T(MoveTemp(*reinterpret_cast<T*>(B)));
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}
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)
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, CopyAssign(
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[](void* A, const void* B)
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{
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if constexpr (CCopyAssignable<T>)
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{
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*reinterpret_cast<T*>(A) = *reinterpret_cast<const T*>(B);
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}
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else
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{
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reinterpret_cast<T*>(A)->~T();
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new (A) T(*reinterpret_cast<const T*>(B));
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}
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}
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)
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, MoveAssign(
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[](void* A, void* B)
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{
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if constexpr (CMoveAssignable<T>)
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{
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*reinterpret_cast<T*>(A) = MoveTemp(*reinterpret_cast<T*>(B));
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}
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else
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{
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reinterpret_cast<T*>(A)->~T();
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new (A) T(MoveTemp(*reinterpret_cast<T*>(B)));
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}
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}
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)
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, Destruct(
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[](void* A)
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{
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reinterpret_cast<T*>(A)->~T();
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}
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)
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, SwapObject{
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[](void* A, void* B)
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{
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NAMESPACE_REDCRAFT::Swap(*reinterpret_cast<T*>(A), *reinterpret_cast<T*>(B));
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}
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}
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{ }
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};
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struct FTrivialStorage
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{
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uint8 Internal[64 - sizeof(uintptr)];
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};
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struct FSmallStorage
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{
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uint8 Internal[sizeof(FTrivialStorage) - sizeof(const FRTTI*)];
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const FRTTI* RTTI;
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};
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struct FBigStorage
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{
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uint8 Padding[sizeof(FTrivialStorage) - sizeof(void*) - sizeof(const FRTTI*)];
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void* External;
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const FRTTI* RTTI;
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};
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static_assert(sizeof(FTrivialStorage) == sizeof(FSmallStorage));
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static_assert(sizeof(FTrivialStorage) == sizeof( FBigStorage));
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static_assert(alignof(type_info) >= 4);
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static constexpr uintptr_t RepresentationMask = 3;
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enum class ERepresentation : uintptr
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{
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Empty = 0, // EmptyType
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Trivial = 1, // TrivialStorage
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Small = 2, // SmallStorage
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Big = 3, // BigStorage
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};
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union
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{
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FTrivialStorage TrivialStorage;
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FSmallStorage SmallStorage;
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FBigStorage BigStorage;
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};
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uintptr TypeInfo;
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FORCEINLINE ERepresentation GetRepresentation() const { return static_cast<ERepresentation>(TypeInfo & RepresentationMask); }
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FORCEINLINE const type_info& GetTypeInfoImpl() const { return *reinterpret_cast<const type_info*>(TypeInfo & ~RepresentationMask); }
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FORCEINLINE void* GetStorage()
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{
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switch (GetRepresentation())
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{
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case ERepresentation::Empty: return nullptr;
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case ERepresentation::Trivial: return &TrivialStorage.Internal;
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case ERepresentation::Small: return &SmallStorage.Internal;
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case ERepresentation::Big: return BigStorage.External;
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default: check_no_entry(); return nullptr;
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}
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}
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FORCEINLINE const void* GetStorage() const
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{
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switch (GetRepresentation())
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{
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case ERepresentation::Empty: return nullptr;
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case ERepresentation::Trivial: return &TrivialStorage.Internal;
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case ERepresentation::Small: return &SmallStorage.Internal;
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case ERepresentation::Big: return BigStorage.External;
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default: check_no_entry(); return nullptr;
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}
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}
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template <typename T, typename... Ts>
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FORCEINLINE void EmplaceImpl(Ts&&... Args)
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{
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using DecayedType = TDecay<T>;
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TypeInfo = reinterpret_cast<uintptr>(&typeid(DecayedType));
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if constexpr (CEmpty<DecayedType> && CTrivial<DecayedType>) return; // ERepresentation::Empty
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constexpr bool bIsTriviallyStorable = sizeof(DecayedType) <= sizeof(TrivialStorage.Internal) && alignof(DecayedType) <= alignof(FAny) && CTriviallyCopyable<DecayedType>;
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constexpr bool bIsSmallStorable = sizeof(DecayedType) <= sizeof( SmallStorage.Internal) && alignof(DecayedType) <= alignof(FAny);
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static constexpr const FRTTI SelectedRTTI(InPlaceType<DecayedType>);
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if constexpr (bIsTriviallyStorable)
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{
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new (&TrivialStorage.Internal) DecayedType(Forward<Ts>(Args)...);
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TypeInfo |= static_cast<uintptr>(ERepresentation::Trivial);
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}
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else if constexpr (bIsSmallStorable)
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{
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new (&SmallStorage.Internal) DecayedType(Forward<Ts>(Args)...);
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SmallStorage.RTTI = &SelectedRTTI;
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TypeInfo |= static_cast<uintptr>(ERepresentation::Small);
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}
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else
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{
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BigStorage.External = Memory::Malloc(sizeof(DecayedType), alignof(DecayedType));
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new (BigStorage.External) DecayedType(Forward<Ts>(Args)...);
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BigStorage.RTTI = &SelectedRTTI;
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TypeInfo |= static_cast<uintptr>(ERepresentation::Big);
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}
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}
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FORCEINLINE void Destroy()
|
|
{
|
|
if (!IsValid()) return;
|
|
|
|
switch (GetRepresentation())
|
|
{
|
|
case ERepresentation::Empty:
|
|
case ERepresentation::Trivial:
|
|
break;
|
|
case ERepresentation::Small:
|
|
SmallStorage.RTTI->Destruct(&SmallStorage.Internal);
|
|
break;
|
|
case ERepresentation::Big:
|
|
BigStorage.RTTI->Destruct(BigStorage.External);
|
|
Memory::Free(BigStorage.External);
|
|
break;
|
|
default: check_no_entry();
|
|
}
|
|
}
|
|
|
|
FORCEINLINE constexpr void Invalidate() { TypeInfo = 0; }
|
|
|
|
template <typename T> requires (!CBaseOf<FAny, TRemoveCVRef<T>>)
|
|
friend FORCEINLINE constexpr bool operator==(const FAny& LHS, const T& RHS)
|
|
{
|
|
return LHS.template HoldsAlternative<T>() ? LHS.template GetValue<T>() == RHS : false;
|
|
}
|
|
|
|
friend FORCEINLINE constexpr bool operator==(const FAny& LHS, FInvalid)
|
|
{
|
|
return !LHS.IsValid();
|
|
}
|
|
|
|
};
|
|
|
|
static_assert(sizeof(FAny) == 64, "The byte size of FAny is unexpected");
|
|
|
|
static_assert(alignof(FAny) == 16, "The byte alignment of FAny is unexpected");
|
|
|
|
NAMESPACE_MODULE_END(Utility)
|
|
NAMESPACE_MODULE_END(Redcraft)
|
|
NAMESPACE_REDCRAFT_END
|