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std::optional< _Tp >(3cxx) std::optional< _Tp >(3cxx)

NAME

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

SYNOPSIS

Inherits std::_Optional_base< _Tp, bool, bool >, and std::_Enable_copy_move< is_copy_constructible_v< _Tp >, __and_v< is_copy_constructible< _Tp >, is_copy_assignable< _Tp > >, is_move_constructible_v< _Tp >, __and_v< is_move_constructible< _Tp >, is_move_assignable< _Tp > >, optional< _Tp > >.

Public Types


using value_type = _Tp

Public Member Functions


template<typename _Up = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, is_constructible< _Tp, _Up >, is_convertible< _Up, _Tp >> = true> constexpr optional (_Up &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)
template<typename _Up = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, is_constructible< _Tp, _Up >, __not_< is_convertible< _Up, _Tp >>> = false> constexpr optional (_Up &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)
template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, const _Up & >, is_convertible< const _Up &, _Tp >, __not_< __converts_from_optional< _Tp, _Up >>> = true> constexpr optional (const optional< _Up > &__t) noexcept(is_nothrow_constructible_v< _Tp, const _Up & >)
template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, const _Up & >, __not_< is_convertible< const _Up &, _Tp >>, __not_< __converts_from_optional< _Tp, _Up >>> = false> constexpr optional (const optional< _Up > &__t) noexcept(is_nothrow_constructible_v< _Tp, const _Up & >)
template<typename... _Args, _Requires< is_constructible< _Tp, _Args... >> = false> constexpr optional (in_place_t, _Args &&... __args) noexcept(is_nothrow_constructible_v< _Tp, _Args... >)
template<typename _Up , typename... _Args, _Requires< is_constructible< _Tp, initializer_list< _Up > &, _Args... >> = false> constexpr optional (in_place_t, initializer_list< _Up > __il, _Args &&... __args) noexcept(is_nothrow_constructible_v< _Tp, initializer_list< _Up > &, _Args... >)
constexpr optional (nullopt_t) noexcept
template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, _Up >, is_convertible< _Up, _Tp >, __not_< __converts_from_optional< _Tp, _Up >>> = true> constexpr optional (optional< _Up > &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)
template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, _Up >, __not_< is_convertible< _Up, _Tp >>, __not_< __converts_from_optional< _Tp, _Up >>> = false> constexpr optional (optional< _Up > &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)
template<typename... _Args> enable_if_t< is_constructible_v< _Tp, _Args... >, _Tp & > emplace (_Args &&... __args) noexcept(is_nothrow_constructible_v< _Tp, _Args... >)
template<typename _Up , typename... _Args> enable_if_t< is_constructible_v< _Tp, initializer_list< _Up > &, _Args... >, _Tp & > emplace (initializer_list< _Up > __il, _Args &&... __args) noexcept(is_nothrow_constructible_v< _Tp, initializer_list< _Up > &, _Args... >)
constexpr bool has_value () const noexcept
constexpr operator bool () const noexcept
constexpr _Tp && operator* () &&noexcept
constexpr _Tp & operator* () &noexcept
constexpr const _Tp && operator* () const &&noexcept
constexpr const _Tp & operator* () const &noexcept
constexpr const _Tp * operator-> () const noexcept
constexpr _Tp * operator-> () noexcept
template<typename _Up = _Tp> enable_if_t< __and_v< __not_self< _Up >, __not_< __and_< is_scalar< _Tp >, is_same< _Tp, decay_t< _Up > > > >, is_constructible< _Tp, _Up >, is_assignable< _Tp &, _Up > >, optional & > operator= (_Up &&__u) noexcept(__and_v< is_nothrow_constructible< _Tp, _Up >, is_nothrow_assignable< _Tp &, _Up >>)
template<typename _Up > enable_if_t< __and_v< __not_< is_same< _Tp, _Up > >, is_constructible< _Tp, const _Up & >, is_assignable< _Tp &, const _Up & >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >, optional & > operator= (const optional< _Up > &__u) noexcept(__and_v< is_nothrow_constructible< _Tp, const _Up & >, is_nothrow_assignable< _Tp &, const _Up & >>)
optional & operator= (nullopt_t) noexcept
template<typename _Up > enable_if_t< __and_v< __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 > > >, optional & > operator= (optional< _Up > &&__u) noexcept(__and_v< is_nothrow_constructible< _Tp, _Up >, is_nothrow_assignable< _Tp &, _Up >>)
void reset () noexcept
void swap (optional &__other) noexcept(is_nothrow_move_constructible_v< _Tp > &&is_nothrow_swappable_v< _Tp >)
constexpr _Tp & value () &
constexpr _Tp && value () &&
constexpr const _Tp & value () const &
constexpr const _Tp && value () const &&
template<typename _Up > constexpr _Tp value_or (_Up &&__u) &&
template<typename _Up > constexpr _Tp value_or (_Up &&__u) const &

Detailed Description

template<typename _Tp>

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

Definition at line 663 of file optional.

Author

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Thu Oct 21 2021 libstdc++