NAME

       std::experimental::optional< _Tp > - Class template for optional values.

SYNOPSIS

       Inherits std::experimental::_Optional_base< _Tp >, and std::_Enable_copy_move<
       is_copy_constructible< _Tp >::value, __and_< is_copy_constructible< _Tp >,
       is_copy_assignable< _Tp > >::value, is_move_constructible< _Tp >::value, __and_<
       is_move_constructible< _Tp >, is_move_assignable< _Tp > >::value, optional< _Tp > >.

   Public Types
       using value_type = _Tp

   Public Member Functions
       template<typename _Up  = _Tp, enable_if_t< __and_< __not_< is_same< optional< _Tp >,
           decay_t< _Up >>>, is_constructible< _Tp, _Up &&>, is_convertible< _Up &&, _Tp >
           >::value, bool >  = true> constexpr optional (_Up &&__t)
       template<typename _Up  = _Tp, enable_if_t< __and_< __not_< is_same< optional< _Tp >,
           decay_t< _Up >>>, is_constructible< _Tp, _Up &&>, __not_< is_convertible< _Up &&, _Tp
           >> >::value, bool >  = false> constexpr optional (_Up &&__t)
       template<typename _Up , enable_if_t< __and_< __not_< is_same< _Tp, _Up >>,
           is_constructible< _Tp, const _Up &>, is_convertible< const _Up &, _Tp >, __not_<
           __converts_from_optional< _Tp, _Up >> >::value, bool >  = true> constexpr optional
           (const optional< _Up > &__t)
       template<typename _Up , enable_if_t< __and_< __not_< is_same< _Tp, _Up >>,
           is_constructible< _Tp, const _Up &>, __not_< is_convertible< const _Up &, _Tp >>,
           __not_< __converts_from_optional< _Tp, _Up >> >::value, bool >  = false> constexpr
           optional (const optional< _Up > &__t)
       template<typename _Up , enable_if_t< __and_< __not_< is_same< _Tp, _Up >>,
           is_constructible< _Tp, _Up &&>, is_convertible< _Up &&, _Tp >, __not_<
           __converts_from_optional< _Tp, _Up >> >::value, bool >  = true> constexpr optional
           (optional< _Up > &&__t)
       template<typename _Up , enable_if_t< __and_< __not_< is_same< _Tp, _Up >>,
           is_constructible< _Tp, _Up &&>, __not_< is_convertible< _Up &&, _Tp >>, __not_<
           __converts_from_optional< _Tp, _Up >> >::value, bool >  = false> constexpr optional
           (optional< _Up > &&__t)
       template<typename... _Args> enable_if_t< is_constructible< _Tp, _Args &&... >::value >
           emplace (_Args &&... __args)
       template<typename _Up , typename... _Args> enable_if_t< is_constructible< _Tp,
           initializer_list< _Up > &, _Args &&... >::value > emplace (initializer_list< _Up >
           __il, _Args &&... __args)
       constexpr operator bool () const noexcept
       constexpr const _Tp & operator* () const &
       constexpr _Tp & operator* () &
       constexpr _Tp && operator* () &&
       constexpr const _Tp && operator* () const &&
       constexpr const _Tp * operator-> () const
       _Tp * operator-> ()
       optional & operator= (nullopt_t) noexcept
       template<typename _Up  = _Tp> enable_if_t< __and_< __not_< is_same< optional< _Tp >,
           decay_t< _Up > > >, is_constructible< _Tp, _Up >, __not_< __and_< is_scalar< _Tp >,
           is_same< _Tp, decay_t< _Up > > > >, is_assignable< _Tp &, _Up > >::value, optional & >
           operator= (_Up &&__u)
       template<typename _Up > enable_if_t< __and_< __not_< is_same< _Tp, _Up > >,
           is_constructible< _Tp, const _Up & >, is_assignable< _Tp &, _Up >, __not_<
           __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > >
           >::value, optional & > operator= (const optional< _Up > &__u)
       template<typename _Up > enable_if_t< __and_< __not_< is_same< _Tp, _Up > >,
           is_constructible< _Tp, _Up >, is_assignable< _Tp &, _Up >, __not_<
           __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > >
           >::value, optional & > operator= (optional< _Up > &&__u)
       void swap (optional &__other) noexcept(is_nothrow_move_constructible< _Tp >()
           &&__is_nothrow_swappable< _Tp >::value)
       constexpr const _Tp & value () const &
       constexpr _Tp & value () &
       constexpr _Tp && value () &&
       constexpr const _Tp && value () const &&
       template<typename _Up > constexpr _Tp value_or (_Up &&__u) const &
       template<typename _Up > _Tp value_or (_Up &&__u) &&

   Private Member Functions
       void _M_construct (_Args &&... __args) noexcept(is_nothrow_constructible< _Stored_type,
           _Args... >())
       void _M_destruct ()
       constexpr _Tp & _M_get () noexcept
       constexpr const _Tp & _M_get () const noexcept
       constexpr bool _M_is_engaged () const noexcept
       void _M_reset ()

   Private Attributes
       _Empty_byte _M_empty
       _Stored_type _M_payload

Detailed Description

   template<typename _Tp>
       class std::experimental::optional< _Tp >" Class template for optional values.

       Definition at line 81 of file optional.

Author

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