#pragma once #include "CoreTypes.h" #include "Templates/Utility.h" #include "Templates/TypeHash.h" #include "TypeTraits/TypeTraits.h" #include "Miscellaneous/Compare.h" #include "Miscellaneous/AssertionMacros.h" NAMESPACE_REDCRAFT_BEGIN NAMESPACE_MODULE_BEGIN(Redcraft) NAMESPACE_MODULE_BEGIN(Utility) /** The class template manages an optional contained value or reference, i.e. a value or reference that may or may not be present. */ template <typename OptionalType, bool = CReference<OptionalType>> requires (CDestructible<TRemoveReference<OptionalType>>) class TOptional; NAMESPACE_PRIVATE_BEGIN template <typename T> struct TIsTOptional : FFalse { }; template <typename T> struct TIsTOptional<TOptional<T>> : FTrue { }; template <typename T, typename U> concept CTOptionalAllowUnwrappable = !(CConstructibleFrom<U, TOptional<T>& > || CConstructibleFrom<U, const TOptional<T>& > || CConstructibleFrom<U, TOptional<T>&&> || CConstructibleFrom<U, const TOptional<T>&&> || CConvertibleTo< TOptional<T>&, U> || CConvertibleTo<const TOptional<T>&, U> || CConvertibleTo< TOptional<T>&&, U> || CConvertibleTo<const TOptional<T>&&, U> || CAssignableFrom<U&, TOptional<T>& > || CAssignableFrom<U&, const TOptional<T>& > || CAssignableFrom<U&, TOptional<T>&&> || CAssignableFrom<U&, const TOptional<T>&&>); NAMESPACE_PRIVATE_END template <typename T> concept CTOptional = NAMESPACE_PRIVATE::TIsTOptional<TRemoveCV<T>>::Value; /** The class template manages an optional contained value, i.e. a value that may or may not be present. */ template <typename T> requires (!CReference<T>) class TOptional<T, false> final { public: using FValueType = T; static_assert(!CReference<FValueType>); /** Constructs an object that does not contain a value. */ FORCEINLINE constexpr TOptional() : bIsValid(false) { } /** Constructs an object that does not contain a value. */ FORCEINLINE constexpr TOptional(FInvalid) : TOptional() { } /** Constructs an object with initial content an object, direct-initialized from Forward<U>(InValue). */ template <typename U = T> requires (CConstructibleFrom<T, U&&>) && (!CSameAs<TRemoveCVRef<U>, FInPlace>) && (!CSameAs<TOptional, TRemoveCVRef<U>>) FORCEINLINE constexpr explicit (!CConvertibleTo<U&&, T>) TOptional(U&& InValue) : TOptional(InPlace, Forward<U>(InValue)) { } /** Constructs an object with initial content an object, direct-non-list-initialized from Forward<Ts>(Args).... */ template <typename... Ts> requires (CConstructibleFrom<T, Ts...>) FORCEINLINE constexpr explicit TOptional(FInPlace, Ts&&... Args) : bIsValid(true) { new (&Value) FValueType(Forward<Ts>(Args)...); } /** Constructs an object with initial content an object, direct-non-list-initialized from IL, Forward<Ts>(Args).... */ template <typename W, typename... Ts> requires (CConstructibleFrom<T, initializer_list<W>, Ts...>) FORCEINLINE constexpr explicit TOptional(FInPlace, initializer_list<W> IL, Ts&&... Args) : bIsValid(true) { new (&Value) FValueType(IL, Forward<Ts>(Args)...); } /** Copies content of other into a new instance. */ FORCEINLINE constexpr TOptional(const TOptional& InValue) requires (CTriviallyCopyConstructible<T>) = default; /** Copies content of other into a new instance. */ FORCEINLINE constexpr TOptional(const TOptional& InValue) requires (CCopyConstructible<T> && !CTriviallyCopyConstructible<T>) : bIsValid(InValue.IsValid()) { if (InValue.IsValid()) new (&Value) FValueType(InValue.GetValue()); } /** Moves content of other into a new instance. */ FORCEINLINE constexpr TOptional(TOptional&& InValue) requires (CTriviallyMoveConstructible<T>) = default; /** Moves content of other into a new instance. */ FORCEINLINE constexpr TOptional(TOptional&& InValue) requires (CMoveConstructible<T> && !CTriviallyMoveConstructible<T>) : bIsValid(InValue.IsValid()) { if (InValue.IsValid()) new (&Value) FValueType(MoveTemp(InValue.GetValue())); } /** Converting copy constructor. */ template <typename U> requires (CConstructibleFrom<T, const U&> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) FORCEINLINE constexpr explicit (!CConvertibleTo<const U&, T>) TOptional(const TOptional<U>& InValue) : bIsValid(InValue.IsValid()) { if (InValue.IsValid()) new (&Value) FValueType(InValue.GetValue()); } /** Converting move constructor. */ template <typename U> requires (CConstructibleFrom<T, U&&> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) FORCEINLINE constexpr explicit (!CConvertibleTo<U&&, T>) TOptional(TOptional<U>&& InValue) : bIsValid(InValue.IsValid()) { if (InValue.IsValid()) new (&Value) FValueType(MoveTemp(InValue.GetValue())); } /** Destroys the contained object, if any, as if by a call to Reset(). */ FORCEINLINE constexpr ~TOptional() requires (CTriviallyDestructible<T>) = default; /** Destroys the contained object, if any, as if by a call to Reset(). */ FORCEINLINE constexpr ~TOptional() requires (!CTriviallyDestructible<T>) { Reset(); } /** Assigns by copying the state of 'InValue'. */ FORCEINLINE constexpr TOptional& operator=(const TOptional& InValue) requires (CTriviallyCopyConstructible<T> && CTriviallyCopyAssignable<T>) = default; /** Assigns by copying the state of 'InValue'. */ constexpr TOptional& operator=(const TOptional& InValue) requires (CCopyConstructible<T> && CCopyAssignable<T> && !CTriviallyCopyConstructible<T> && !CTriviallyCopyAssignable<T>) { if (&InValue == this) return *this; if (!InValue.IsValid()) { Reset(); return *this; } if (IsValid()) GetValue() = InValue.GetValue(); else { new (&Value) FValueType(InValue.GetValue()); bIsValid = true; } return *this; } /** Assigns by moving the state of 'InValue'. */ FORCEINLINE constexpr TOptional& operator=(TOptional&& InValue) requires (CTriviallyMoveConstructible<T> && CTriviallyMoveAssignable<T>) = default; /** Assigns by moving the state of 'InValue'. */ constexpr TOptional& operator=(TOptional&& InValue) requires (CMoveConstructible<T> && CMoveAssignable<T> && !CTriviallyMoveConstructible<T> && !CTriviallyMoveAssignable<T>) { if (&InValue == this) return *this; if (!InValue.IsValid()) { Reset(); return *this; } if (IsValid()) GetValue() = MoveTemp(InValue.GetValue()); else { new (&Value) FValueType(MoveTemp(InValue.GetValue())); bIsValid = true; } return *this; } /** Assigns by copying the state of 'InValue'. */ template <typename U> requires (CConstructibleFrom<T, const U&> && CAssignableFrom<T&, const U&> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) constexpr TOptional& operator=(const TOptional<U>& InValue) { if (!InValue.IsValid()) { Reset(); return *this; } if (IsValid()) GetValue() = InValue.GetValue(); else { new (&Value) FValueType(InValue.GetValue()); bIsValid = true; } return *this; } /** Assigns by moving the state of 'InValue'. */ template <typename U> requires (CConstructibleFrom<T, U&&> && CAssignableFrom<T&, U&&> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) constexpr TOptional& operator=(TOptional<U>&& InValue) { if (!InValue.IsValid()) { Reset(); return *this; } if (IsValid()) GetValue() = MoveTemp(InValue.GetValue()); else { new (&Value) FValueType(MoveTemp(InValue.GetValue())); bIsValid = true; } return *this; } /** Assigns the value of 'InValue'. */ template <typename U = T> requires (CConstructibleFrom<T, U&&> && CAssignableFrom<T&, U&&>) FORCEINLINE constexpr TOptional& operator=(U&& InValue) { if (IsValid()) GetValue() = Forward<U>(InValue); else { new (&Value) FValueType(Forward<U>(InValue)); bIsValid = true; } return *this; } /** Check if the two optional are equivalent. */ template <typename U> requires (CWeaklyEqualityComparable<T, U>) NODISCARD friend FORCEINLINE constexpr bool operator==(const TOptional& LHS, const TOptional<U>& RHS) { if (LHS.IsValid() != RHS.IsValid()) return false; if (LHS.IsValid() == false) return true; return *LHS == *RHS; } /** Check the order relationship between two optional. */ template <typename U> requires (CSynthThreeWayComparable<T, U>) NODISCARD friend FORCEINLINE constexpr partial_ordering operator<=>(const TOptional& LHS, const TOptional<U>& RHS) { if (LHS.IsValid() != RHS.IsValid()) return partial_ordering::unordered; if (LHS.IsValid() == false) return partial_ordering::equivalent; return SynthThreeWayCompare(*LHS, *RHS); } /** Check if the optional value is equivalent to 'InValue'. */ template <typename U> requires (!CTOptional<U> && CWeaklyEqualityComparable<T, U>) NODISCARD FORCEINLINE constexpr bool operator==(const U& InValue) const& { return IsValid() ? GetValue() == InValue : false; } /** Check that the optional value is in ordered relationship with 'InValue'. */ template <typename U> requires (!CTOptional<U> && CSynthThreeWayComparable<T, U>) NODISCARD FORCEINLINE constexpr partial_ordering operator<=>(const U& InValue) const& { return IsValid() ? SynthThreeWayCompare(GetValue(), InValue) : partial_ordering::unordered; } /** @return true if instance does not contain a value, otherwise false. */ NODISCARD FORCEINLINE constexpr bool operator==(FInvalid) const& { return !IsValid(); } /** * Changes the contained object to one constructed from the arguments. * First destroys the current contained object (if any) by Reset(), * then constructs an object, direct-non-list-initialized from Forward<Ts>(Args)..., as the contained object. * * @param Args - The arguments to be passed to the constructor of the object. * * @return A reference to the new object. */ template <typename... Ts> requires (CConstructibleFrom<T, Ts...>) FORCEINLINE constexpr T& Emplace(Ts&&... Args) { Reset(); T* Result = new (&Value) FValueType(Forward<Ts>(Args)...); bIsValid = true; return *Result; } /** * Changes the contained object to one constructed from the arguments. * First destroys the current contained object (if any) by Reset(), * then constructs an object, direct-non-list-initialized from IL, Forward<Ts>(Args)..., as the contained object. * * @param IL, Args - The arguments to be passed to the constructor of the object. * * @return A reference to the new object. */ template <typename W, typename... Ts> requires (CConstructibleFrom<T, initializer_list<W>, Ts...>) FORCEINLINE constexpr T& Emplace(initializer_list<W> IL, Ts&&... Args) { Reset(); T* Result = new (&Value) FValueType(IL, Forward<Ts>(Args)...); bIsValid = true; return *Result; } /** @return true if instance contains a value, otherwise false. */ NODISCARD FORCEINLINE constexpr bool IsValid() const { return bIsValid; } NODISCARD FORCEINLINE constexpr explicit operator bool() const { return bIsValid; } /** @return The contained object. */ NODISCARD FORCEINLINE constexpr T& GetValue() & { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return *reinterpret_cast< T*>(&Value); } NODISCARD FORCEINLINE constexpr T&& GetValue() && { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast< T*>(&Value)); } NODISCARD FORCEINLINE constexpr const T& GetValue() const& { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return *reinterpret_cast<const T*>(&Value); } NODISCARD FORCEINLINE constexpr const T&& GetValue() const&& { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast<const T*>(&Value)); } /** @return The contained object. */ NODISCARD FORCEINLINE constexpr T& operator*() & { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return *reinterpret_cast< T*>(&Value); } NODISCARD FORCEINLINE constexpr T&& operator*() && { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast< T*>(&Value)); } NODISCARD FORCEINLINE constexpr const T& operator*() const& { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return *reinterpret_cast<const T*>(&Value); } NODISCARD FORCEINLINE constexpr const T&& operator*() const&& { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return MoveTemp(*reinterpret_cast<const T*>(&Value)); } /** @return The pointer to the contained object. */ NODISCARD FORCEINLINE constexpr const T* operator->() const { return &GetValue(); } NODISCARD FORCEINLINE constexpr T* operator->() { return &GetValue(); } /** @return The contained object when IsValid() returns true, 'DefaultValue' otherwise. */ NODISCARD FORCEINLINE constexpr T& Get( T& DefaultValue) & { return IsValid() ? GetValue() : DefaultValue; } NODISCARD FORCEINLINE constexpr const T& Get(const T& DefaultValue) const& { return IsValid() ? GetValue() : DefaultValue; } /** If not empty, destroys the contained object. */ FORCEINLINE constexpr void Reset() { if (bIsValid) { bIsValid = false; reinterpret_cast<T*>(&Value)->~FValueType(); } } /** Overloads the GetTypeHash algorithm for TOptional. */ NODISCARD friend FORCEINLINE constexpr size_t GetTypeHash(const TOptional& A) requires (CHashable<T>) { if (!A.IsValid()) return 2824517378; return GetTypeHash(A.GetValue()); } /** Overloads the Swap algorithm for TOptional. */ friend constexpr void Swap(TOptional& A, TOptional& B) requires (CMoveConstructible<T> && CSwappable<T>) { if (!A.IsValid() && !B.IsValid()) return; if (A.IsValid() && !B.IsValid()) { B = MoveTemp(A); A.Reset(); } else if (!A.IsValid() && B.IsValid()) { A = MoveTemp(B); B.Reset(); } else { Swap(A.GetValue(), B.GetValue()); } } private: TAlignedStorage<sizeof(T), alignof(T)> Value; bool bIsValid; }; /** The class template manages an optional contained reference, i.e. a reference that may or may not be present. */ template <typename T> requires (CLValueReference<T>) class TOptional<T, true> final { public: using FValueType = TRemoveReference<T>; static_assert(!CReference<FValueType>); /** Constructs an object that does not contain a reference. */ FORCEINLINE constexpr TOptional() : Ptr(nullptr) { } /** Constructs an object that does not contain a reference. */ FORCEINLINE constexpr TOptional(FInvalid) : TOptional() { } /** Constructs an object with initial content an object, direct-initialized from Forward<U>(InValue). */ template <typename U = T> requires (CConstructibleFrom<T, U>) && (!CSameAs<TRemoveCVRef<U>, FInPlace>) && (!CSameAs<TOptional, TRemoveCVRef<U>>) FORCEINLINE constexpr explicit (!CConvertibleTo<U&&, T>) TOptional(U&& InValue) : Ptr(AddressOf(static_cast<T>(Forward<U>(InValue)))) { } /** Copies content of other into a new instance. */ FORCEINLINE constexpr TOptional(const TOptional&) = default; FORCEINLINE constexpr TOptional(TOptional&&) = default; /** Converting constructor. */ template <typename U> requires (CConstructibleFrom<T, U> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) FORCEINLINE constexpr explicit (!CConvertibleTo<U, T>) TOptional(TOptional<U, true> InValue) : Ptr(InValue.IsValid() ? AddressOf(static_cast<T>(InValue.GetValue())) : nullptr) { } /** Converting constructor. */ template <typename U> requires (!CConst<FValueType> && CConstructibleFrom<T, U&> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) FORCEINLINE constexpr explicit (!CConvertibleTo<U&, T>) TOptional(TOptional<U, false>& InValue) : Ptr(InValue.IsValid() ? AddressOf(static_cast<T>(InValue.GetValue())) : nullptr) { } /** Converting constructor. */ template <typename U> requires (CConst<FValueType> && CConstructibleFrom<T, const U&> && NAMESPACE_PRIVATE::CTOptionalAllowUnwrappable<U, T>) FORCEINLINE constexpr explicit (!CConvertibleTo<const U&, T>) TOptional(const TOptional<U, false>& InValue) : Ptr(InValue.IsValid() ? AddressOf(static_cast<T>(InValue.GetValue())) : nullptr) { } /** Assigns by copying the state of 'InValue'. */ FORCEINLINE constexpr TOptional& operator=(const TOptional&) = default; FORCEINLINE constexpr TOptional& operator=(TOptional&&) = default; /** Destructor. */ FORCEINLINE constexpr ~TOptional() = default; /** Check if the two optional are equivalent. */ template <typename U> requires (CWeaklyEqualityComparable<T, U>) NODISCARD friend FORCEINLINE constexpr bool operator==(TOptional LHS, TOptional<U, true> RHS) { if (LHS.IsValid() != RHS.IsValid()) return false; if (LHS.IsValid() == false) return true; return *LHS == *RHS; } /** Check the order relationship between two optional. */ template <typename U> requires (CSynthThreeWayComparable<T, U>) NODISCARD friend FORCEINLINE constexpr partial_ordering operator<=>(TOptional LHS, TOptional<U, true> RHS) { if (LHS.IsValid() != RHS.IsValid()) return partial_ordering::unordered; if (LHS.IsValid() == false) return partial_ordering::equivalent; return SynthThreeWayCompare(*LHS, *RHS); } /** Check if the optional reference is equivalent to 'InValue'. */ template <typename U> requires (!CTOptional<U> && CWeaklyEqualityComparable<T, U>) NODISCARD FORCEINLINE constexpr bool operator==(const U& InValue) const& { return IsValid() ? GetValue() == InValue : false; } /** Check that the optional reference is in ordered relationship with 'InValue'. */ template <typename U> requires (!CTOptional<U> && CSynthThreeWayComparable<T, U>) NODISCARD FORCEINLINE constexpr partial_ordering operator<=>(const U& InValue) const& { return IsValid() ? SynthThreeWayCompare(GetValue(), InValue) : partial_ordering::unordered; } /** @return true if instance does not contain a reference, otherwise false. */ NODISCARD FORCEINLINE constexpr bool operator==(FInvalid) const& { return !IsValid(); } /** @return true if instance contains a reference, otherwise false. */ NODISCARD FORCEINLINE constexpr bool IsValid() const { return Ptr != nullptr; } NODISCARD FORCEINLINE constexpr explicit operator bool() const { return Ptr != nullptr; } /** @return The contained object. */ NODISCARD FORCEINLINE constexpr T GetValue() const { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead.")); return *Ptr; } /** @return The pointer to the contained object. */ NODISCARD FORCEINLINE constexpr auto operator->() const { return Ptr; } /** @return The contained object. */ NODISCARD FORCEINLINE constexpr T operator*() const { return GetValue(); } /** @return The contained object when IsValid() returns true, 'DefaultValue' otherwise. */ NODISCARD FORCEINLINE constexpr T Get(T DefaultValue) const { return IsValid() ? GetValue() : DefaultValue; } /** If not empty, destroys the contained object. */ FORCEINLINE constexpr void Reset() { Ptr = nullptr; } /** Overloads the GetTypeHash algorithm for TOptional. */ NODISCARD friend FORCEINLINE constexpr size_t GetTypeHash(const TOptional& A) requires (CHashable<T>) { if (!A.IsValid()) return 2824517378; return GetTypeHash(A.GetValue()); } private: FValueType* Ptr; }; template <typename T> TOptional(T) -> TOptional<T>; /** Creates an optional object from value. */ template <typename T> requires (CDestructible<TDecay<T>> && CConstructibleFrom<TDecay<T>, T>) NODISCARD FORCEINLINE constexpr TOptional<TDecay<T>> MakeOptional(T&& InValue) { return TOptional<TDecay<T>>(Forward<T>(InValue)); } /** Creates an optional object constructed in-place from Args.... */ template <typename T, typename... Ts> requires (CDestructible<T> && CConstructibleFrom<T, Ts...>) NODISCARD FORCEINLINE constexpr TOptional<T> MakeOptional(Ts&&... Args) { return TOptional<T>(InPlace, Forward<T>(Args)...); } /** Creates an optional object constructed in-place from IL, Args.... */ template <typename T, typename U, typename... Ts> requires (CDestructible<T> && CConstructibleFrom<T, initializer_list<U>, Ts...>) NODISCARD FORCEINLINE constexpr TOptional<T> MakeOptional(initializer_list<U> IL, Ts&&... Args) { return TOptional<T>(InPlace, IL, Forward<T>(Args)...); } NAMESPACE_MODULE_END(Utility) NAMESPACE_MODULE_END(Redcraft) NAMESPACE_REDCRAFT_END