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