Redcraft/Redcraft.Utility/Source/Public/Templates/Variant.h

423 lines
19 KiB
C++

#pragma once
#include "CoreTypes.h"
#include "Templates/Invoke.h"
#include "Templates/Utility.h"
#include "Templates/TypeHash.h"
#include "TypeTraits/TypeTraits.h"
#include "Templates/Meta.h"
#include "Memory/MemoryOperator.h"
#include "Miscellaneous/Compare.h"
#include "Miscellaneous/AssertionMacros.h"
NAMESPACE_REDCRAFT_BEGIN
NAMESPACE_MODULE_BEGIN(Redcraft)
NAMESPACE_MODULE_BEGIN(Utility)
template <typename... Ts> requires (sizeof...(Ts) > 0 && (true && ... && CDestructible<Ts>))
class TVariant;
NAMESPACE_PRIVATE_BEGIN
template <typename T > struct TIsTVariant : FFalse { };
template <typename... Ts> struct TIsTVariant<TVariant<Ts...>> : FTrue { };
template <typename VariantType>
struct TVariantNumImpl;
template <typename... Ts>
struct TVariantNumImpl<TVariant<Ts...>> : TConstant<size_t, Meta::TSize<TTypeSequence<Ts...>>> { };
template <typename T, typename VariantType>
struct TVariantIndexImpl;
template <typename T, typename... Ts>
struct TVariantIndexImpl<T, TVariant<Ts...>> : TConstant<size_t, Meta::TIndex<T, TTypeSequence<Ts...>>> { };
template <size_t I, typename VariantType>
struct TVariantAlternativeImpl;
template <size_t I, typename... Ts>
struct TVariantAlternativeImpl<I, TVariant<Ts...>>
{
using Type = Meta::TType<I, TTypeSequence<Ts...>>;
};
template <typename T, typename TSequence>
struct TVariantOverloadType
{
using FrontType = Meta::TFront<TSequence>;
using NextSequence = Meta::TPop<TSequence>;
using NextUniqueSequence = typename TVariantOverloadType<T, NextSequence>::Type;
// T_i x[] = { Forward<T>(t) };
static constexpr bool bConditional = requires { DeclVal<void(FrontType(&&)[1])>()({ DeclVal<T>() }); };
using Type = TConditional<bConditional, Meta::TPush<FrontType, NextUniqueSequence>, NextUniqueSequence>;
};
template <typename T>
struct TVariantOverloadType<T, TTypeSequence<>>
{
using Type = TTypeSequence<>;
};
template <typename T, typename... Ts>
using TVariantSelectedType = Meta::TOverloadResolution<T, typename NAMESPACE_PRIVATE::TVariantOverloadType<T, TTypeSequence<Ts...>>::Type>;
NAMESPACE_PRIVATE_END
template <typename T>
concept CTVariant = NAMESPACE_PRIVATE::TIsTVariant<TRemoveCV<T>>::Value;
template <CTVariant T>
inline constexpr size_t TVariantNum = NAMESPACE_PRIVATE::TVariantNumImpl<TRemoveCV<T>>::Value;
template <typename T, CTVariant U>
inline constexpr size_t TVariantIndex = NAMESPACE_PRIVATE::TVariantIndexImpl<T, TRemoveCV<U>>::Value;
template <size_t I, CTVariant U>
using TVariantAlternative = TCopyCV<U, typename NAMESPACE_PRIVATE::TVariantAlternativeImpl<I, TRemoveCV<U>>::Type>;
template <typename... Ts> requires (sizeof...(Ts) > 0 && (true && ... && CDestructible<Ts>))
class TVariant
{
public:
constexpr TVariant() : TypeIndex(0xFF) { };
constexpr TVariant(FInvalid) : TVariant() { };
constexpr TVariant(const TVariant& InValue) requires (true && ... && CTriviallyCopyConstructible<Ts>) = default;
constexpr TVariant(const TVariant& InValue) requires ((true && ... && CCopyConstructible<Ts>) && !(true && ... && CTriviallyCopyConstructible<Ts>))
: TypeIndex(static_cast<uint8>(InValue.GetIndex()))
{
if (IsValid()) CopyConstructImpl[InValue.GetIndex()](&Value, &InValue.Value);
}
constexpr TVariant(TVariant&& InValue) requires (true && ... && CTriviallyMoveConstructible<Ts>) = default;
constexpr TVariant(TVariant&& InValue) requires ((true && ... && CMoveConstructible<Ts>) && !(true && ... && CTriviallyMoveConstructible<Ts>))
: TypeIndex(static_cast<uint8>(InValue.GetIndex()))
{
if (IsValid()) MoveConstructImpl[InValue.GetIndex()](&Value, &InValue.Value);
}
template <size_t I, typename... ArgTypes> requires (I < sizeof...(Ts)
&& CConstructibleFrom<TVariantAlternative<I, TVariant<Ts...>>, ArgTypes...>)
constexpr explicit TVariant(TInPlaceIndex<I>, ArgTypes&&... Args)
: TypeIndex(I)
{
using SelectedType = TVariantAlternative<I, TVariant<Ts...>>;
new(&Value) SelectedType(Forward<ArgTypes>(Args)...);
}
template <typename T, typename... ArgTypes> requires (CConstructibleFrom<T, ArgTypes...>)
constexpr explicit TVariant(TInPlaceType<T>, ArgTypes&&... Args)
: TVariant(InPlaceIndex<TVariantIndex<T, TVariant<Ts...>>>, Forward<ArgTypes>(Args)...)
{ }
template <typename T> requires (requires { typename NAMESPACE_PRIVATE::TVariantSelectedType<T, Ts...>; }
&& !CTInPlaceType<TRemoveCVRef<T>> && !CTInPlaceIndex<TRemoveCVRef<T>>
&& !CBaseOf<TVariant, TRemoveCVRef<T>>)
constexpr TVariant(T&& InValue) : TVariant(InPlaceType<NAMESPACE_PRIVATE::TVariantSelectedType<T, Ts...>>, Forward<T>(InValue))
{ }
constexpr ~TVariant() requires (true && ... && CTriviallyDestructible<Ts>) = default;
constexpr ~TVariant() requires (!(true && ... && CTriviallyDestructible<Ts>))
{
Reset();
}
constexpr TVariant& operator=(const TVariant& InValue) requires (true && ... && (CTriviallyCopyConstructible<Ts> && CTriviallyCopyAssignable<Ts>)) = default;
constexpr TVariant& operator=(const TVariant& InValue) requires ((true && ... && (CCopyConstructible<Ts> && CCopyAssignable<Ts>))
&& !(true && ... && (CTriviallyCopyConstructible<Ts> && CTriviallyCopyAssignable<Ts>)))
{
if (&InValue == this) return *this;
if (!InValue.IsValid())
{
Reset();
return *this;
}
if (GetIndex() == InValue.GetIndex()) CopyAssignImpl[InValue.GetIndex()](&Value, &InValue.Value);
else
{
Reset();
CopyConstructImpl[InValue.GetIndex()](&Value, &InValue.Value);
TypeIndex = static_cast<uint8>(InValue.GetIndex());
}
return *this;
}
constexpr TVariant& operator=(TVariant&& InValue) requires (true && ... && (CTriviallyMoveConstructible<Ts> && CTriviallyMoveAssignable<Ts>)) = default;
constexpr TVariant& operator=(TVariant&& InValue) requires ((true && ... && (CMoveConstructible<Ts> && CMoveAssignable<Ts>))
&& !(true && ... && (CTriviallyMoveConstructible<Ts> && CTriviallyMoveAssignable<Ts>)))
{
if (&InValue == this) return *this;
if (!InValue.IsValid())
{
Reset();
return *this;
}
if (GetIndex() == InValue.GetIndex()) MoveAssignImpl[InValue.GetIndex()](&Value, &InValue.Value);
else
{
Reset();
MoveConstructImpl[InValue.GetIndex()](&Value, &InValue.Value);
TypeIndex = static_cast<uint8>(InValue.GetIndex());
}
return *this;
}
template <typename T> requires (requires { typename NAMESPACE_PRIVATE::TVariantSelectedType<T, Ts...>; })
constexpr TVariant& operator=(T&& InValue)
{
using SelectedType = NAMESPACE_PRIVATE::TVariantSelectedType<T, Ts...>;
if (GetIndex() == TVariantIndex<SelectedType, TVariant<Ts...>>) GetValue<SelectedType>() = Forward<T>(InValue);
else
{
Reset();
new(&Value) SelectedType(Forward<T>(InValue));
TypeIndex = TVariantIndex<SelectedType, TVariant<Ts...>>;
}
return *this;
}
template <size_t I, typename... ArgTypes> requires (I < sizeof...(Ts)
&& CConstructibleFrom<TVariantAlternative<I, TVariant<Ts...>>, ArgTypes...>)
constexpr TVariantAlternative<I, TVariant<Ts...>>& Emplace(ArgTypes&&... Args)
{
Reset();
using SelectedType = TVariantAlternative<I, TVariant<Ts...>>;
SelectedType* Result = new(&Value) SelectedType(Forward<ArgTypes>(Args)...);
TypeIndex = I;
return *Result;
}
template <typename T, typename... ArgTypes> requires (CConstructibleFrom<T, ArgTypes...>)
constexpr T& Emplace(ArgTypes&&... Args)
{
return Emplace<TVariantIndex<T, TVariant<Ts...>>>(Forward<ArgTypes>(Args)...);
}
constexpr const type_info& GetTypeInfo() const { return IsValid() ? *TypeInfos[GetIndex()] : typeid(void); }
constexpr size_t GetIndex() const { return TypeIndex != 0xFF ? TypeIndex : INDEX_NONE; }
constexpr bool IsValid() const { return TypeIndex != 0xFF; }
constexpr explicit operator bool() const { return TypeIndex != 0xFF; }
template <size_t I> constexpr bool HoldsAlternative() const { return IsValid() ? GetIndex() == I : false; }
template <typename T> constexpr bool HoldsAlternative() const { return IsValid() ? GetIndex() == TVariantIndex<T, TVariant<Ts...>> : false; }
template <size_t I> requires (I < sizeof...(Ts)) 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<Ts...>>*>(&Value); }
template <size_t I> requires (I < sizeof...(Ts)) 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<Ts...>>*>(&Value)); }
template <size_t I> requires (I < sizeof...(Ts)) 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<Ts...>>*>(&Value); }
template <size_t I> requires (I < sizeof...(Ts)) 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<Ts...>>*>(&Value)); }
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); }
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)); }
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); }
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)); }
template <size_t I> requires (I < sizeof...(Ts)) constexpr decltype(auto) Get( TVariantAlternative<I, TVariant<Ts...>>& DefaultValue) & { return HoldsAlternative<I>() ? GetValue<I>() : DefaultValue; }
template <size_t I> requires (I < sizeof...(Ts)) constexpr decltype(auto) Get(const TVariantAlternative<I, TVariant<Ts...>>& DefaultValue) const& { return HoldsAlternative<I>() ? GetValue<I>() : DefaultValue; }
template <typename T> constexpr decltype(auto) Get( T& DefaultValue) & { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
template <typename T> constexpr decltype(auto) Get(const T& DefaultValue) const& { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
template <typename F> requires (true && ... && CInvocable<F, Ts>)
FORCEINLINE decltype(auto) Visit(F&& Func) &
{
checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
using FInvokeImpl = ReturnType(*)(F&&, void*);
static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), *reinterpret_cast<Ts*>(This)); }... };
return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
}
template <typename F> requires (true && ... && CInvocable<F, Ts>)
FORCEINLINE decltype(auto) Visit(F&& Func) &&
{
checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
using FInvokeImpl = ReturnType(*)(F&&, void*);
static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), MoveTemp(*reinterpret_cast<Ts*>(This))); }... };
return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
}
template <typename F> requires (true && ... && CInvocable<F, Ts>)
FORCEINLINE decltype(auto) Visit(F&& Func) const&
{
checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
using FInvokeImpl = ReturnType(*)(F&&, const void*);
static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, const void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), *reinterpret_cast<const Ts*>(This)); }... };
return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
}
template <typename F> requires (true && ... && CInvocable<F, Ts>)
FORCEINLINE decltype(auto) Visit(F&& Func) const&&
{
checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
using FInvokeImpl = ReturnType(*)(F&&, const void*);
static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, const void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), MoveTemp(*reinterpret_cast<const Ts*>(This))); }... };
return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
}
template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
FORCEINLINE R Visit(F&& Func) & { return Visit(Forward<F>(Func)); }
template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
FORCEINLINE R Visit(F&& Func) && { return MoveTemp(*this).Visit(Forward<F>(Func)); }
template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
FORCEINLINE R Visit(F&& Func) const& { return Visit(Forward<F>(Func)); }
template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
FORCEINLINE R Visit(F&& Func) const&& { return MoveTemp(*this).Visit(Forward<F>(Func)); }
constexpr void Reset()
{
if (GetIndex() == INDEX_NONE) return;
if constexpr (!(true && ... && CTriviallyDestructible<Ts>))
{
DestroyImpl[GetIndex()](&Value);
}
TypeIndex = static_cast<uint8>(INDEX_NONE);
}
constexpr size_t GetTypeHash() const requires (true && ... && CHashable<Ts>)
{
if (!IsValid()) return 114514;
using NAMESPACE_REDCRAFT::GetTypeHash;
using FHashImpl = size_t(*)(const void*);
constexpr FHashImpl HashImpl[] = { [](const void* This) -> size_t { return GetTypeHash(*reinterpret_cast<const Ts*>(This)); }... };
return HashCombine(GetTypeHash(GetIndex()), HashImpl[GetIndex()](&Value));
}
constexpr void Swap(TVariant& InValue) requires (true && ... && (CMoveConstructible<Ts> && CSwappable<Ts>))
{
if (!IsValid() && !InValue.IsValid()) return;
if (IsValid() && !InValue.IsValid())
{
InValue = MoveTemp(*this);
Reset();
return;
}
if (InValue.IsValid() && !IsValid())
{
*this = MoveTemp(InValue);
InValue.Reset();
return;
}
if (GetIndex() == InValue.GetIndex())
{
using NAMESPACE_REDCRAFT::Swap;
using FSwapImpl = void(*)(void*, void*);
constexpr FSwapImpl SwapImpl[] = { [](void* A, void* B) { Swap(*reinterpret_cast<Ts*>(A), *reinterpret_cast<Ts*>(B)); }... };
SwapImpl[GetIndex()](&Value, &InValue.Value);
return;
}
TVariant Temp = MoveTemp(*this);
*this = MoveTemp(InValue);
InValue = MoveTemp(Temp);
}
private:
static constexpr const type_info* TypeInfos[] = { &typeid(Ts)... };
using FCopyConstructImpl = void(*)(void*, const void*);
using FMoveConstructImpl = void(*)(void*, void*);
using FCopyAssignImpl = void(*)(void*, const void*);
using FMoveAssignImpl = void(*)(void*, void*);
using FDestroyImpl = void(*)(void* );
static constexpr FCopyConstructImpl CopyConstructImpl[] = { [](void* A, const void* B) { if constexpr (requires(Ts* A, const Ts* B) { Memory::CopyConstruct (A, B); }) Memory::CopyConstruct (reinterpret_cast<Ts*>(A), reinterpret_cast<const Ts*>(B)); else checkf(false, TEXT("The type '%s' is not copy constructible."), typeid(Ts).name()); }... };
static constexpr FMoveConstructImpl MoveConstructImpl[] = { [](void* A, void* B) { if constexpr (requires(Ts* A, Ts* B) { Memory::MoveConstruct (A, B); }) Memory::MoveConstruct (reinterpret_cast<Ts*>(A), reinterpret_cast< Ts*>(B)); else checkf(false, TEXT("The type '%s' is not move constructible."), typeid(Ts).name()); }... };
static constexpr FCopyAssignImpl CopyAssignImpl[] = { [](void* A, const void* B) { if constexpr (requires(Ts* A, const Ts* B) { Memory::CopyAssign (A, B); }) Memory::CopyAssign (reinterpret_cast<Ts*>(A), reinterpret_cast<const Ts*>(B)); else checkf(false, TEXT("The type '%s' is not copy assignable."), typeid(Ts).name()); }... };
static constexpr FMoveAssignImpl MoveAssignImpl[] = { [](void* A, void* B) { if constexpr (requires(Ts* A, Ts* B) { Memory::MoveAssign (A, B); }) Memory::MoveAssign (reinterpret_cast<Ts*>(A), reinterpret_cast< Ts*>(B)); else checkf(false, TEXT("The type '%s' is not move assignable."), typeid(Ts).name()); }... };
static constexpr FDestroyImpl DestroyImpl[] = { [](void* A ) { if constexpr (requires(Ts* A ) { Memory::Destruct (A ); }) Memory::Destruct (reinterpret_cast<Ts*>(A) ); else checkf(false, TEXT("The type '%s' is not destructible."), typeid(Ts).name()); }... };
TAlignedUnion<1, Ts...> Value;
uint8 TypeIndex;
friend constexpr bool operator==(const TVariant& LHS, const TVariant& RHS) requires (true && ... && CEqualityComparable<Ts>)
{
if (LHS.GetIndex() != RHS.GetIndex()) return false;
if (LHS.IsValid() == false) return true;
using FCompareImpl = bool(*)(const void*, const void*);
constexpr FCompareImpl CompareImpl[] = { [](const void* LHS, const void* RHS) -> bool { return *reinterpret_cast<const Ts*>(LHS) == *reinterpret_cast<const Ts*>(RHS); }... };
return CompareImpl[LHS.GetIndex()](&LHS.Value, &RHS.Value);
}
friend constexpr partial_ordering operator<=>(const TVariant& LHS, const TVariant& RHS) requires (true && ... && CSynthThreeWayComparable<Ts>)
{
if (LHS.GetIndex() != RHS.GetIndex()) return partial_ordering::unordered;
if (LHS.IsValid() == false) return partial_ordering::equivalent;
using FCompareImpl = partial_ordering(*)(const void*, const void*);
constexpr FCompareImpl CompareImpl[] = { [](const void* LHS, const void* RHS) -> partial_ordering { return SynthThreeWayCompare(*reinterpret_cast<const Ts*>(LHS), *reinterpret_cast<const Ts*>(RHS)); }...};
return CompareImpl[LHS.GetIndex()](&LHS.Value, &RHS.Value);
}
};
template <typename T, typename... Ts> requires (!CBaseOf<TVariant<Ts...>, T> && CEqualityComparable<T>)
constexpr bool operator==(const TVariant<Ts...>& LHS, const T& RHS)
{
return LHS.template HoldsAlternative<T>() ? LHS.template GetValue<T>() == RHS : false;
}
template <typename... Ts>
constexpr bool operator==(const TVariant<Ts...>& LHS, FInvalid)
{
return !LHS.IsValid();
}
NAMESPACE_MODULE_END(Utility)
NAMESPACE_MODULE_END(Redcraft)
NAMESPACE_REDCRAFT_END