std::_Optional_base< _Tp, bool, bool > Struct Template Reference

Inheritance diagram for std::_Optional_base< _Tp, bool, bool >:

Public Member Functions
constexpr	_Optional_base (_Optional_base &&__other) noexcept(is_nothrow_move_constructible_v< _Tp >)
constexpr	_Optional_base (const _Optional_base &__other)
template<typename... _Args, enable_if_t< is_constructible_v< _Tp, _Args... >, bool > = false>
constexpr	_Optional_base (in_place_t, _Args &&... __args)
template<typename _Up , typename... _Args, enable_if_t< is_constructible_v< _Tp, initializer_list< _Up > &, _Args... >, bool > = false>
constexpr	_Optional_base (in_place_t, initializer_list< _Up > __il, _Args &&... __args)
_Optional_base &	operator= (_Optional_base &&)=default
_Optional_base &	operator= (const _Optional_base &)=default

Public Attributes
_Optional_payload< _Tp >	_M_payload

Protected Types
using	_Stored_type = remove_const_t< _Tp >

Protected Member Functions
template<typename... _Args>
constexpr void	_M_construct (_Args &&... __args) noexcept(is_nothrow_constructible_v< _Stored_type, _Args... >)
constexpr void	_M_destruct () noexcept
constexpr const _Tp &	_M_get () const noexcept
constexpr _Tp &	_M_get () noexcept
constexpr bool	_M_is_engaged () const noexcept
constexpr void	_M_reset () noexcept

Detailed Description

template<typename _Tp, bool = is_trivially_copy_constructible_v<_Tp>, bool = is_trivially_move_constructible_v<_Tp>>
struct std::_Optional_base< _Tp, bool, bool >

Class template that provides copy/move constructors of optional.

Such a separate base class template is necessary in order to conditionally make copy/move constructors trivial.

When the contained value is trivially copy/move constructible, the copy/move constructors of _Optional_base will invoke the trivial copy/move constructor of _Optional_payload. Otherwise, they will invoke _Optional_payload(bool, const _Optional_payload&) or _Optional_payload(bool, _Optional_payload&&) to initialize the contained value, if copying/moving an engaged optional.

Whether the other special members are trivial is determined by the _Optional_payload<_Tp> specialization used for the _M_payload member.

See also

optional, _Enable_special_members

Definition at line 510 of file optional.

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The documentation for this struct was generated from the following file:

• optional