feat(templates): add three-way comparison operator support
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223
Redcraft.Utility/Source/Public/Templates/Optional.h
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223
Redcraft.Utility/Source/Public/Templates/Optional.h
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#pragma once
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#include "CoreTypes.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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template <typename T>
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struct TOptional
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{
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public:
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using Type = T;
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constexpr TOptional() : bIsValid(false) { }
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template <typename... Types> requires TIsConstructible<T, Types...>::Value
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constexpr explicit TOptional(EInPlace, Types&&... Args)
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: bIsValid(true)
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{
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new(&Value) T(Forward<Types>(Args)...);
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}
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template <typename U = T> requires TIsConstructible<T, U&&>::Value && !TIsSame<typename TRemoveCVRef<U>::Type, EInPlace>::Value && !TIsSame<typename TRemoveCVRef<U>::Type, TOptional>::Value
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constexpr explicit(!TIsConvertible<U&&, T>::Value) TOptional(U&& InValue)
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: TOptional(InPlace, Forward<U>(InValue))
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{ }
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template <typename U = T> requires TIsConstructible<T, const U&>::Value
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constexpr explicit(!TIsConvertible<const U&, T>::Value) TOptional(const TOptional<U>& InValue)
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: bIsValid(InValue.bIsValid)
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{
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if (InValue.bIsValid) new(&Value) T(InValue.GetValue());
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}
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template <typename U = T> requires TIsConstructible<T, U&&>::Value
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constexpr explicit(!TIsConvertible<U&&, T>::Value) TOptional(TOptional<U>&& InValue)
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: bIsValid(InValue.bIsValid)
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{
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if (InValue.bIsValid) new(&Value) T(MoveTempIfPossible(InValue).GetValue());
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}
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constexpr ~TOptional()
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{
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Reset();
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}
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template <typename U = T> requires TIsConstructible<T, const U&>::Value
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constexpr TOptional& operator=(const TOptional<U>& InValue)
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{
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if (InValue == this) return *this;
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Reset();
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if (InValue.bIsValid)
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{
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new(&Value) T(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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template <typename U = T> requires TIsConstructible<T, U&&>::Value
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constexpr TOptional& operator=(TOptional<U>&& InValue)
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{
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if (InValue == this) return *this;
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Reset();
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if (InValue.bIsValid)
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{
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new(&Value) T(MoveTempIfPossible(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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template <typename U = T> requires TIsConstructible<T, U&&>::Value
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constexpr TOptional& operator=(U&& InValue)
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{
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Reset();
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new(&Value) T(MoveTempIfPossible(InValue));
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bIsValid = true;
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return *this;
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}
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template <typename... ArgsType>
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constexpr T& Emplace(ArgsType&&... Args)
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{
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Reset();
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T* Result = new(&Value) T(Forward<ArgsType>(Args)...);
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bIsValid = true;
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return *Result;
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}
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constexpr bool IsValid() const { return bIsValid; }
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constexpr explicit operator bool() const { return bIsValid; }
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constexpr T& GetValue() & { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsSet() or use Get(DefaultValue) instead.")); return *(T*)&Value; }
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constexpr T&& GetValue() && { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsSet() or use Get(DefaultValue) instead.")); return *(T*)&Value; }
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constexpr const T& GetValue() const& { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsSet() or use Get(DefaultValue) instead.")); return *(T*)&Value; }
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constexpr const T&& GetValue() const&& { checkf(IsValid(), TEXT("It is an error to call GetValue() on an unset TOptional. Please either check IsSet() or use Get(DefaultValue) instead.")); return *(T*)&Value; }
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constexpr const T* operator->() const { return &GetValue(); }
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constexpr T* operator->() { return &GetValue(); }
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constexpr T& operator*() & { return GetValue(); }
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constexpr T&& operator*() && { return GetValue(); }
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constexpr const T& operator*() const& { return GetValue(); }
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constexpr const T&& operator*() const&& { return GetValue(); }
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template <typename U = T>
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constexpr T Get(U&& DefaultValue) && { return IsValid() ? GetValue() : DefaultValue; }
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template <typename U = T>
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constexpr T Get(U&& DefaultValue) const& { return IsValid() ? GetValue() : DefaultValue; }
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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 T DestructOptionalType;
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((T*)&Value)->DestructOptionalType::~DestructOptionalType();
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}
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}
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private:
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TAlignedStorage<sizeof(T), alignof(T)>::Type 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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template <typename T, typename U>
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constexpr bool operator==(const TOptional<T>& LHS, const TOptional<U>& RHS)
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{
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if (LHS.IsValid() != LHS.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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template <typename T, typename U>
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constexpr bool operator!=(const TOptional<T>& LHS, const TOptional<U>& RHS)
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{
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if (LHS.IsValid() != LHS.IsValid()) return true;
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if (LHS.IsValid() == false) return false;
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return *LHS != *RHS;
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}
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//template <typename T, typename U>
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//constexpr bool operator<(const TOptional<T>&, const TOptional<U>&);
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//template <typename T, typename U>
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//constexpr bool operator>(const TOptional<T>&, const TOptional<U>&);
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//template <typename T, typename U>
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//constexpr bool operator<=(const TOptional<T>&, const TOptional<U>&);
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//template <typename T, typename U>
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//constexpr bool operator>=(const TOptional<T>&, const TOptional<U>&);
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//template <typename T, typename U> constexpr bool operator==(const TOptional<T>&, const U&);
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//template <typename T, typename U> constexpr bool operator==(const T&, const TOptional<U>&);
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//template <typename T, typename U> constexpr bool operator!=(const TOptional<T>&, const U&);
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//template <typename T, typename U> constexpr bool operator!=(const T&, const TOptional<U>&);
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//template <typename T, typename U> constexpr bool operator<(const TOptional<T>&, const U&);
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//template <typename T, typename U> constexpr bool operator<(const T&, const TOptional<U>&);
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//template <typename T, typename U> constexpr bool operator>(const TOptional<T>&, const U&);
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//template <typename T, typename U> constexpr bool operator>(const T&, const TOptional<U>&);
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//template <typename T, typename U> constexpr bool operator<=(const TOptional<T>&, const U&);
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//template <typename T, typename U> constexpr bool operator<=(const T&, const TOptional<U>&);
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//template <typename T, typename U> constexpr bool operator>=(const TOptional<T>&, const U&);
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//template <typename T, typename U> constexpr bool operator>=(const T&, const TOptional<U>&);
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template <typename T>
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constexpr TOptional<typename TDecay<T>::Type> MakeOptional(T&& InValue)
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{
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return TOptional<typename TDecay<T>::Type>(Forward<T>(InValue));
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}
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template <typename T, typename... Types>
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constexpr TOptional<T> MakeOptional(Types&&... Args)
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{
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return TOptional<T>(InPlace, Forward<T>(Args)...);
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}
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template <typename T>
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constexpr void Swap(TOptional<T>& A, TOptional<T>& B)
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{
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if (!A && !B) return;
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if (A && !B)
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{
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B = A;
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A.Reset();
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return;
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}
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if (B && !A)
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{
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A = B;
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B.Reset();
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return;
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}
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Swap(*A, *B);
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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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