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feat(templates): add initializer_list overloads to the in place constructor and emplace

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_Redstone_c_
2022-12-31 19:19:30 +08:00
parent 5338cd286a
commit 0709f209c8
5 changed files with 219 additions and 28 deletions
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46
Redcraft.Utility/Source/Public/Templates/Variant.h
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@ -142,6 +142,22 @@ public:
using SelectedType = TVariantAlternative<I, TVariant<Ts...>>;
new (&Value) SelectedType(Forward<Us>(Args)...);
}
/** Constructs a variant with the specified alternative T and initializes the contained value with the arguments IL, Forward<Us>(Args).... */
template <typename T, typename U, typename... Us> requires (CConstructibleFrom<T, initializer_list<U>, Us...>)
FORCEINLINE constexpr explicit TVariant(TInPlaceType<T>, initializer_list<U> IL, Us&&... Args)
: TVariant(InPlaceIndex<TVariantIndex<T, TVariant<Ts...>>>, IL, Forward<Us>(Args)...)
{ }
/** Constructs a variant with the alternative T specified by the index I and initializes the contained value with the arguments IL, Forward<Us>(Args).... */
template <size_t I, typename T, typename... Us> requires (I < sizeof...(Ts)
&& CConstructibleFrom<TVariantAlternative<I, TVariant<Ts...>>, initializer_list<T>, Us...>)
FORCEINLINE constexpr explicit TVariant(TInPlaceIndex<I>, initializer_list<T> IL, Us&&... Args)
: TypeIndex(I)
{
using SelectedType = TVariantAlternative<I, TVariant<Ts...>>;
new (&Value) SelectedType(IL, Forward<Us>(Args)...);
}
/** Destroys the contained object, if any, as if by a call to Reset(). */
FORCEINLINE constexpr ~TVariant() requires (true && ... && CTriviallyDestructible<Ts>) = default;
@ -273,7 +289,7 @@ public:
* First, destroys the currently contained value if any.
* Then direct-initializes the contained value as if constructing a value of type T with the arguments Forward<Us>(Args)....
*
* @param Args - The arguments to be passed to the constructor of the contained object.
* @param Args - The arguments to be passed to the constructor of the contained object.
*
* @return A reference to the new contained object.
*/
@ -289,6 +305,34 @@ public:
return *Result;
}
/** Equivalent to Emplace<I>(IL, Forward<Us>(Args)...), where I is the zero-based index of T in Types.... */
template <typename T, typename U, typename... Us> requires (CConstructibleFrom<T, initializer_list<U>, Us...>)
FORCEINLINE constexpr T& Emplace(initializer_list<U> IL, Us&&... Args)
{
return Emplace<TVariantIndex<T, TVariant<Ts...>>>(IL, Forward<Us>(Args)...);
}
/**
* First, destroys the currently contained value if any.
* Then direct-initializes the contained value as if constructing a value of type T with the arguments IL, Forward<Us>(Args)....
*
* @param IL, Args - The arguments to be passed to the constructor of the contained object.
*
* @return A reference to the new contained object.
*/
template <size_t I, typename T, typename... Us> requires (I < sizeof...(Ts)
&& CConstructibleFrom<TVariantAlternative<I, TVariant<Ts...>>, initializer_list<T>, Us...>)
FORCEINLINE constexpr TVariantAlternative<I, TVariant<Ts...>>& Emplace(initializer_list<T> IL, Us&&... Args)
{
Reset();
using SelectedType = TVariantAlternative<I, TVariant<Ts...>>;
SelectedType* Result = new (&Value) SelectedType(IL, Forward<Us>(Args)...);
TypeIndex = I;
return *Result;
}
/** @return The typeid of the contained value if instance is non-empty, otherwise typeid(void). */
NODISCARD FORCEINLINE constexpr const type_info& GetTypeInfo() const { return IsValid() ? *TypeInfos[GetIndex()] : typeid(void); }