| // <optional> -*- C++ -*- |
| |
| // Copyright (C) 2013-2021 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| /** @file include/optional |
| * This is a Standard C++ Library header. |
| */ |
| |
| #ifndef _GLIBCXX_OPTIONAL |
| #define _GLIBCXX_OPTIONAL 1 |
| |
| #pragma GCC system_header |
| |
| #if __cplusplus >= 201703L |
| |
| #include <type_traits> |
| #include <exception> |
| #include <new> |
| #include <initializer_list> |
| #include <bits/enable_special_members.h> |
| #include <bits/exception_defines.h> |
| #include <bits/functional_hash.h> |
| #include <bits/utility.h> // in_place_t |
| #if __cplusplus > 201703L |
| # include <compare> |
| #endif |
| |
| namespace std _GLIBCXX_VISIBILITY(default) |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_VERSION |
| |
| /** |
| * @addtogroup utilities |
| * @{ |
| */ |
| |
| #define __cpp_lib_optional 201606L |
| |
| template<typename _Tp> |
| class optional; |
| |
| /// Tag type to disengage optional objects. |
| struct nullopt_t |
| { |
| // Do not user-declare default constructor at all for |
| // optional_value = {} syntax to work. |
| // nullopt_t() = delete; |
| |
| // Used for constructing nullopt. |
| enum class _Construct { _Token }; |
| |
| // Must be constexpr for nullopt_t to be literal. |
| explicit constexpr nullopt_t(_Construct) noexcept { } |
| }; |
| |
| /// Tag to disengage optional objects. |
| inline constexpr nullopt_t nullopt { nullopt_t::_Construct::_Token }; |
| |
| /** |
| * @brief Exception class thrown when a disengaged optional object is |
| * dereferenced. |
| * @ingroup exceptions |
| */ |
| class bad_optional_access : public exception |
| { |
| public: |
| bad_optional_access() = default; |
| virtual ~bad_optional_access() = default; |
| |
| const char* what() const noexcept override |
| { return "bad optional access"; } |
| }; |
| |
| // XXX Does not belong here. |
| [[__noreturn__]] inline void |
| __throw_bad_optional_access() |
| { _GLIBCXX_THROW_OR_ABORT(bad_optional_access()); } |
| |
| // This class template manages construction/destruction of |
| // the contained value for a std::optional. |
| template <typename _Tp> |
| struct _Optional_payload_base |
| { |
| using _Stored_type = remove_const_t<_Tp>; |
| |
| _Optional_payload_base() = default; |
| ~_Optional_payload_base() = default; |
| |
| template<typename... _Args> |
| constexpr |
| _Optional_payload_base(in_place_t __tag, _Args&&... __args) |
| : _M_payload(__tag, std::forward<_Args>(__args)...), |
| _M_engaged(true) |
| { } |
| |
| template<typename _Up, typename... _Args> |
| constexpr |
| _Optional_payload_base(std::initializer_list<_Up> __il, |
| _Args&&... __args) |
| : _M_payload(__il, std::forward<_Args>(__args)...), |
| _M_engaged(true) |
| { } |
| |
| // Constructor used by _Optional_base copy constructor when the |
| // contained value is not trivially copy constructible. |
| constexpr |
| _Optional_payload_base(bool __engaged, |
| const _Optional_payload_base& __other) |
| { |
| if (__other._M_engaged) |
| this->_M_construct(__other._M_get()); |
| } |
| |
| // Constructor used by _Optional_base move constructor when the |
| // contained value is not trivially move constructible. |
| constexpr |
| _Optional_payload_base(bool __engaged, |
| _Optional_payload_base&& __other) |
| { |
| if (__other._M_engaged) |
| this->_M_construct(std::move(__other._M_get())); |
| } |
| |
| // Copy constructor is only used to when the contained value is |
| // trivially copy constructible. |
| _Optional_payload_base(const _Optional_payload_base&) = default; |
| |
| // Move constructor is only used to when the contained value is |
| // trivially copy constructible. |
| _Optional_payload_base(_Optional_payload_base&&) = default; |
| |
| _Optional_payload_base& |
| operator=(const _Optional_payload_base&) = default; |
| |
| _Optional_payload_base& |
| operator=(_Optional_payload_base&&) = default; |
| |
| // used to perform non-trivial copy assignment. |
| constexpr void |
| _M_copy_assign(const _Optional_payload_base& __other) |
| { |
| if (this->_M_engaged && __other._M_engaged) |
| this->_M_get() = __other._M_get(); |
| else |
| { |
| if (__other._M_engaged) |
| this->_M_construct(__other._M_get()); |
| else |
| this->_M_reset(); |
| } |
| } |
| |
| // used to perform non-trivial move assignment. |
| constexpr void |
| _M_move_assign(_Optional_payload_base&& __other) |
| noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
| is_nothrow_move_assignable<_Tp>>) |
| { |
| if (this->_M_engaged && __other._M_engaged) |
| this->_M_get() = std::move(__other._M_get()); |
| else |
| { |
| if (__other._M_engaged) |
| this->_M_construct(std::move(__other._M_get())); |
| else |
| this->_M_reset(); |
| } |
| } |
| |
| struct _Empty_byte { }; |
| |
| template<typename _Up, bool = is_trivially_destructible_v<_Up>> |
| union _Storage |
| { |
| constexpr _Storage() noexcept : _M_empty() { } |
| |
| template<typename... _Args> |
| constexpr |
| _Storage(in_place_t, _Args&&... __args) |
| : _M_value(std::forward<_Args>(__args)...) |
| { } |
| |
| template<typename _Vp, typename... _Args> |
| constexpr |
| _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
| : _M_value(__il, std::forward<_Args>(__args)...) |
| { } |
| |
| _Empty_byte _M_empty; |
| _Up _M_value; |
| }; |
| |
| template<typename _Up> |
| union _Storage<_Up, false> |
| { |
| constexpr _Storage() noexcept : _M_empty() { } |
| |
| template<typename... _Args> |
| constexpr |
| _Storage(in_place_t, _Args&&... __args) |
| : _M_value(std::forward<_Args>(__args)...) |
| { } |
| |
| template<typename _Vp, typename... _Args> |
| constexpr |
| _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
| : _M_value(__il, std::forward<_Args>(__args)...) |
| { } |
| |
| // User-provided destructor is needed when _Up has non-trivial dtor. |
| ~_Storage() { } |
| |
| _Empty_byte _M_empty; |
| _Up _M_value; |
| }; |
| |
| _Storage<_Stored_type> _M_payload; |
| |
| bool _M_engaged = false; |
| |
| template<typename... _Args> |
| void |
| _M_construct(_Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
| { |
| ::new ((void *) std::__addressof(this->_M_payload)) |
| _Stored_type(std::forward<_Args>(__args)...); |
| this->_M_engaged = true; |
| } |
| |
| constexpr void |
| _M_destroy() noexcept |
| { |
| _M_engaged = false; |
| _M_payload._M_value.~_Stored_type(); |
| } |
| |
| // The _M_get() operations have _M_engaged as a precondition. |
| // They exist to access the contained value with the appropriate |
| // const-qualification, because _M_payload has had the const removed. |
| |
| constexpr _Tp& |
| _M_get() noexcept |
| { return this->_M_payload._M_value; } |
| |
| constexpr const _Tp& |
| _M_get() const noexcept |
| { return this->_M_payload._M_value; } |
| |
| // _M_reset is a 'safe' operation with no precondition. |
| constexpr void |
| _M_reset() noexcept |
| { |
| if (this->_M_engaged) |
| _M_destroy(); |
| } |
| }; |
| |
| // Class template that manages the payload for optionals. |
| template <typename _Tp, |
| bool /*_HasTrivialDestructor*/ = |
| is_trivially_destructible_v<_Tp>, |
| bool /*_HasTrivialCopy */ = |
| is_trivially_copy_assignable_v<_Tp> |
| && is_trivially_copy_constructible_v<_Tp>, |
| bool /*_HasTrivialMove */ = |
| is_trivially_move_assignable_v<_Tp> |
| && is_trivially_move_constructible_v<_Tp>> |
| struct _Optional_payload; |
| |
| // Payload for potentially-constexpr optionals (trivial copy/move/destroy). |
| template <typename _Tp> |
| struct _Optional_payload<_Tp, true, true, true> |
| : _Optional_payload_base<_Tp> |
| { |
| using _Optional_payload_base<_Tp>::_Optional_payload_base; |
| |
| _Optional_payload() = default; |
| }; |
| |
| // Payload for optionals with non-trivial copy construction/assignment. |
| template <typename _Tp> |
| struct _Optional_payload<_Tp, true, false, true> |
| : _Optional_payload_base<_Tp> |
| { |
| using _Optional_payload_base<_Tp>::_Optional_payload_base; |
| |
| _Optional_payload() = default; |
| ~_Optional_payload() = default; |
| _Optional_payload(const _Optional_payload&) = default; |
| _Optional_payload(_Optional_payload&&) = default; |
| _Optional_payload& operator=(_Optional_payload&&) = default; |
| |
| // Non-trivial copy assignment. |
| constexpr |
| _Optional_payload& |
| operator=(const _Optional_payload& __other) |
| { |
| this->_M_copy_assign(__other); |
| return *this; |
| } |
| }; |
| |
| // Payload for optionals with non-trivial move construction/assignment. |
| template <typename _Tp> |
| struct _Optional_payload<_Tp, true, true, false> |
| : _Optional_payload_base<_Tp> |
| { |
| using _Optional_payload_base<_Tp>::_Optional_payload_base; |
| |
| _Optional_payload() = default; |
| ~_Optional_payload() = default; |
| _Optional_payload(const _Optional_payload&) = default; |
| _Optional_payload(_Optional_payload&&) = default; |
| _Optional_payload& operator=(const _Optional_payload&) = default; |
| |
| // Non-trivial move assignment. |
| constexpr |
| _Optional_payload& |
| operator=(_Optional_payload&& __other) |
| noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
| is_nothrow_move_assignable<_Tp>>) |
| { |
| this->_M_move_assign(std::move(__other)); |
| return *this; |
| } |
| }; |
| |
| // Payload for optionals with non-trivial copy and move assignment. |
| template <typename _Tp> |
| struct _Optional_payload<_Tp, true, false, false> |
| : _Optional_payload_base<_Tp> |
| { |
| using _Optional_payload_base<_Tp>::_Optional_payload_base; |
| |
| _Optional_payload() = default; |
| ~_Optional_payload() = default; |
| _Optional_payload(const _Optional_payload&) = default; |
| _Optional_payload(_Optional_payload&&) = default; |
| |
| // Non-trivial copy assignment. |
| constexpr |
| _Optional_payload& |
| operator=(const _Optional_payload& __other) |
| { |
| this->_M_copy_assign(__other); |
| return *this; |
| } |
| |
| // Non-trivial move assignment. |
| constexpr |
| _Optional_payload& |
| operator=(_Optional_payload&& __other) |
| noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
| is_nothrow_move_assignable<_Tp>>) |
| { |
| this->_M_move_assign(std::move(__other)); |
| return *this; |
| } |
| }; |
| |
| // Payload for optionals with non-trivial destructors. |
| template <typename _Tp, bool _Copy, bool _Move> |
| struct _Optional_payload<_Tp, false, _Copy, _Move> |
| : _Optional_payload<_Tp, true, false, false> |
| { |
| // Base class implements all the constructors and assignment operators: |
| using _Optional_payload<_Tp, true, false, false>::_Optional_payload; |
| _Optional_payload() = default; |
| _Optional_payload(const _Optional_payload&) = default; |
| _Optional_payload(_Optional_payload&&) = default; |
| _Optional_payload& operator=(const _Optional_payload&) = default; |
| _Optional_payload& operator=(_Optional_payload&&) = default; |
| |
| // Destructor needs to destroy the contained value: |
| ~_Optional_payload() { this->_M_reset(); } |
| }; |
| |
| // Common base class for _Optional_base<T> to avoid repeating these |
| // member functions in each specialization. |
| template<typename _Tp, typename _Dp> |
| class _Optional_base_impl |
| { |
| protected: |
| using _Stored_type = remove_const_t<_Tp>; |
| |
| // The _M_construct operation has !_M_engaged as a precondition |
| // while _M_destruct has _M_engaged as a precondition. |
| template<typename... _Args> |
| void |
| _M_construct(_Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
| { |
| ::new |
| (std::__addressof(static_cast<_Dp*>(this)->_M_payload._M_payload)) |
| _Stored_type(std::forward<_Args>(__args)...); |
| static_cast<_Dp*>(this)->_M_payload._M_engaged = true; |
| } |
| |
| void |
| _M_destruct() noexcept |
| { static_cast<_Dp*>(this)->_M_payload._M_destroy(); } |
| |
| // _M_reset is a 'safe' operation with no precondition. |
| constexpr void |
| _M_reset() noexcept |
| { static_cast<_Dp*>(this)->_M_payload._M_reset(); } |
| |
| constexpr bool _M_is_engaged() const noexcept |
| { return static_cast<const _Dp*>(this)->_M_payload._M_engaged; } |
| |
| // The _M_get operations have _M_engaged as a precondition. |
| constexpr _Tp& |
| _M_get() noexcept |
| { |
| __glibcxx_assert(this->_M_is_engaged()); |
| return static_cast<_Dp*>(this)->_M_payload._M_get(); |
| } |
| |
| constexpr const _Tp& |
| _M_get() const noexcept |
| { |
| __glibcxx_assert(this->_M_is_engaged()); |
| return static_cast<const _Dp*>(this)->_M_payload._M_get(); |
| } |
| }; |
| |
| /** |
| * @brief 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 optional, _Enable_special_members |
| */ |
| template<typename _Tp, |
| bool = is_trivially_copy_constructible_v<_Tp>, |
| bool = is_trivially_move_constructible_v<_Tp>> |
| struct _Optional_base |
| : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
| { |
| // Constructors for disengaged optionals. |
| constexpr _Optional_base() = default; |
| |
| // Constructors for engaged optionals. |
| template<typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, _Args&&... __args) |
| : _M_payload(in_place, std::forward<_Args>(__args)...) |
| { } |
| |
| template<typename _Up, typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, |
| initializer_list<_Up>&, |
| _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, |
| initializer_list<_Up> __il, |
| _Args&&... __args) |
| : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
| { } |
| |
| // Copy and move constructors. |
| constexpr |
| _Optional_base(const _Optional_base& __other) |
| : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
| { } |
| |
| constexpr |
| _Optional_base(_Optional_base&& __other) |
| noexcept(is_nothrow_move_constructible_v<_Tp>) |
| : _M_payload(__other._M_payload._M_engaged, |
| std::move(__other._M_payload)) |
| { } |
| |
| // Assignment operators. |
| _Optional_base& operator=(const _Optional_base&) = default; |
| _Optional_base& operator=(_Optional_base&&) = default; |
| |
| _Optional_payload<_Tp> _M_payload; |
| }; |
| |
| template<typename _Tp> |
| struct _Optional_base<_Tp, false, true> |
| : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
| { |
| // Constructors for disengaged optionals. |
| constexpr _Optional_base() = default; |
| |
| // Constructors for engaged optionals. |
| template<typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, _Args&&... __args) |
| : _M_payload(in_place, std::forward<_Args>(__args)...) |
| { } |
| |
| template<typename _Up, typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, |
| initializer_list<_Up>&, |
| _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, |
| initializer_list<_Up> __il, |
| _Args... __args) |
| : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
| { } |
| |
| // Copy and move constructors. |
| constexpr _Optional_base(const _Optional_base& __other) |
| : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
| { } |
| |
| constexpr _Optional_base(_Optional_base&& __other) = default; |
| |
| // Assignment operators. |
| _Optional_base& operator=(const _Optional_base&) = default; |
| _Optional_base& operator=(_Optional_base&&) = default; |
| |
| _Optional_payload<_Tp> _M_payload; |
| }; |
| |
| template<typename _Tp> |
| struct _Optional_base<_Tp, true, false> |
| : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
| { |
| // Constructors for disengaged optionals. |
| constexpr _Optional_base() = default; |
| |
| // Constructors for engaged optionals. |
| template<typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, _Args&&... __args) |
| : _M_payload(in_place, std::forward<_Args>(__args)...) |
| { } |
| |
| template<typename _Up, typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, |
| initializer_list<_Up>&, |
| _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, |
| initializer_list<_Up> __il, |
| _Args&&... __args) |
| : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
| { } |
| |
| // Copy and move constructors. |
| constexpr _Optional_base(const _Optional_base& __other) = default; |
| |
| constexpr |
| _Optional_base(_Optional_base&& __other) |
| noexcept(is_nothrow_move_constructible_v<_Tp>) |
| : _M_payload(__other._M_payload._M_engaged, |
| std::move(__other._M_payload)) |
| { } |
| |
| // Assignment operators. |
| _Optional_base& operator=(const _Optional_base&) = default; |
| _Optional_base& operator=(_Optional_base&&) = default; |
| |
| _Optional_payload<_Tp> _M_payload; |
| }; |
| |
| template<typename _Tp> |
| struct _Optional_base<_Tp, true, true> |
| : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
| { |
| // Constructors for disengaged optionals. |
| constexpr _Optional_base() = default; |
| |
| // Constructors for engaged optionals. |
| template<typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, _Args&&... __args) |
| : _M_payload(in_place, std::forward<_Args>(__args)...) |
| { } |
| |
| template<typename _Up, typename... _Args, |
| enable_if_t<is_constructible_v<_Tp, |
| initializer_list<_Up>&, |
| _Args...>, bool> = false> |
| constexpr explicit |
| _Optional_base(in_place_t, |
| initializer_list<_Up> __il, |
| _Args&&... __args) |
| : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
| { } |
| |
| // Copy and move constructors. |
| constexpr _Optional_base(const _Optional_base& __other) = default; |
| constexpr _Optional_base(_Optional_base&& __other) = default; |
| |
| // Assignment operators. |
| _Optional_base& operator=(const _Optional_base&) = default; |
| _Optional_base& operator=(_Optional_base&&) = default; |
| |
| _Optional_payload<_Tp> _M_payload; |
| }; |
| |
| template<typename _Tp> |
| class optional; |
| |
| template<typename _Tp, typename _Up> |
| using __converts_from_optional = |
| __or_<is_constructible<_Tp, const optional<_Up>&>, |
| is_constructible<_Tp, optional<_Up>&>, |
| is_constructible<_Tp, const optional<_Up>&&>, |
| is_constructible<_Tp, optional<_Up>&&>, |
| is_convertible<const optional<_Up>&, _Tp>, |
| is_convertible<optional<_Up>&, _Tp>, |
| is_convertible<const optional<_Up>&&, _Tp>, |
| is_convertible<optional<_Up>&&, _Tp>>; |
| |
| template<typename _Tp, typename _Up> |
| using __assigns_from_optional = |
| __or_<is_assignable<_Tp&, const optional<_Up>&>, |
| is_assignable<_Tp&, optional<_Up>&>, |
| is_assignable<_Tp&, const optional<_Up>&&>, |
| is_assignable<_Tp&, optional<_Up>&&>>; |
| |
| /** |
| * @brief Class template for optional values. |
| */ |
| template<typename _Tp> |
| class optional |
| : private _Optional_base<_Tp>, |
| private _Enable_copy_move< |
| // Copy constructor. |
| is_copy_constructible_v<_Tp>, |
| // Copy assignment. |
| __and_v<is_copy_constructible<_Tp>, is_copy_assignable<_Tp>>, |
| // Move constructor. |
| is_move_constructible_v<_Tp>, |
| // Move assignment. |
| __and_v<is_move_constructible<_Tp>, is_move_assignable<_Tp>>, |
| // Unique tag type. |
| optional<_Tp>> |
| { |
| static_assert(!is_same_v<remove_cv_t<_Tp>, nullopt_t>); |
| static_assert(!is_same_v<remove_cv_t<_Tp>, in_place_t>); |
| static_assert(!is_reference_v<_Tp>); |
| |
| private: |
| using _Base = _Optional_base<_Tp>; |
| |
| // SFINAE helpers |
| template<typename _Up> |
| using __not_self = __not_<is_same<optional, __remove_cvref_t<_Up>>>; |
| template<typename _Up> |
| using __not_tag = __not_<is_same<in_place_t, __remove_cvref_t<_Up>>>; |
| template<typename... _Cond> |
| using _Requires = enable_if_t<__and_v<_Cond...>, bool>; |
| |
| public: |
| using value_type = _Tp; |
| |
| constexpr optional() noexcept { } |
| |
| constexpr optional(nullopt_t) noexcept { } |
| |
| // Converting constructors for engaged optionals. |
| 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>) |
| : _Base(std::in_place, std::forward<_Up>(__t)) { } |
| |
| template<typename _Up = _Tp, |
| _Requires<__not_self<_Up>, __not_tag<_Up>, |
| is_constructible<_Tp, _Up>, |
| __not_<is_convertible<_Up, _Tp>>> = false> |
| explicit constexpr |
| optional(_Up&& __t) |
| noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
| : _Base(std::in_place, std::forward<_Up>(__t)) { } |
| |
| 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&>) |
| { |
| if (__t) |
| emplace(*__t); |
| } |
| |
| 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> |
| explicit constexpr |
| optional(const optional<_Up>& __t) |
| noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
| { |
| if (__t) |
| emplace(*__t); |
| } |
| |
| 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>) |
| { |
| if (__t) |
| emplace(std::move(*__t)); |
| } |
| |
| 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> |
| explicit constexpr |
| optional(optional<_Up>&& __t) |
| noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
| { |
| if (__t) |
| emplace(std::move(*__t)); |
| } |
| |
| template<typename... _Args, |
| _Requires<is_constructible<_Tp, _Args...>> = false> |
| explicit constexpr |
| optional(in_place_t, _Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
| : _Base(std::in_place, std::forward<_Args>(__args)...) { } |
| |
| template<typename _Up, typename... _Args, |
| _Requires<is_constructible<_Tp, |
| initializer_list<_Up>&, |
| _Args...>> = false> |
| explicit constexpr |
| optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
| _Args...>) |
| : _Base(std::in_place, __il, std::forward<_Args>(__args)...) { } |
| |
| |
| // Assignment operators. |
| optional& |
| operator=(nullopt_t) noexcept |
| { |
| this->_M_reset(); |
| return *this; |
| } |
| |
| 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>>) |
| { |
| if (this->_M_is_engaged()) |
| this->_M_get() = std::forward<_Up>(__u); |
| else |
| this->_M_construct(std::forward<_Up>(__u)); |
| |
| return *this; |
| } |
| |
| 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&>>) |
| { |
| if (__u) |
| { |
| if (this->_M_is_engaged()) |
| this->_M_get() = *__u; |
| else |
| this->_M_construct(*__u); |
| } |
| else |
| { |
| this->_M_reset(); |
| } |
| return *this; |
| } |
| |
| 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>>) |
| { |
| if (__u) |
| { |
| if (this->_M_is_engaged()) |
| this->_M_get() = std::move(*__u); |
| else |
| this->_M_construct(std::move(*__u)); |
| } |
| else |
| { |
| this->_M_reset(); |
| } |
| |
| return *this; |
| } |
| |
| template<typename... _Args> |
| enable_if_t<is_constructible_v<_Tp, _Args...>, _Tp&> |
| emplace(_Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
| { |
| this->_M_reset(); |
| this->_M_construct(std::forward<_Args>(__args)...); |
| return this->_M_get(); |
| } |
| |
| 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...>) |
| { |
| this->_M_reset(); |
| this->_M_construct(__il, std::forward<_Args>(__args)...); |
| return this->_M_get(); |
| } |
| |
| // Destructor is implicit, implemented in _Optional_base. |
| |
| // Swap. |
| void |
| swap(optional& __other) |
| noexcept(is_nothrow_move_constructible_v<_Tp> |
| && is_nothrow_swappable_v<_Tp>) |
| { |
| using std::swap; |
| |
| if (this->_M_is_engaged() && __other._M_is_engaged()) |
| swap(this->_M_get(), __other._M_get()); |
| else if (this->_M_is_engaged()) |
| { |
| __other._M_construct(std::move(this->_M_get())); |
| this->_M_destruct(); |
| } |
| else if (__other._M_is_engaged()) |
| { |
| this->_M_construct(std::move(__other._M_get())); |
| __other._M_destruct(); |
| } |
| } |
| |
| // Observers. |
| constexpr const _Tp* |
| operator->() const noexcept |
| { return std::__addressof(this->_M_get()); } |
| |
| constexpr _Tp* |
| operator->() noexcept |
| { return std::__addressof(this->_M_get()); } |
| |
| constexpr const _Tp& |
| operator*() const& noexcept |
| { return this->_M_get(); } |
| |
| constexpr _Tp& |
| operator*()& noexcept |
| { return this->_M_get(); } |
| |
| constexpr _Tp&& |
| operator*()&& noexcept |
| { return std::move(this->_M_get()); } |
| |
| constexpr const _Tp&& |
| operator*() const&& noexcept |
| { return std::move(this->_M_get()); } |
| |
| constexpr explicit operator bool() const noexcept |
| { return this->_M_is_engaged(); } |
| |
| constexpr bool has_value() const noexcept |
| { return this->_M_is_engaged(); } |
| |
| constexpr const _Tp& |
| value() const& |
| { |
| if (this->_M_is_engaged()) |
| return this->_M_get(); |
| __throw_bad_optional_access(); |
| } |
| |
| constexpr _Tp& |
| value()& |
| { |
| if (this->_M_is_engaged()) |
| return this->_M_get(); |
| __throw_bad_optional_access(); |
| } |
| |
| constexpr _Tp&& |
| value()&& |
| { |
| if (this->_M_is_engaged()) |
| return std::move(this->_M_get()); |
| __throw_bad_optional_access(); |
| } |
| |
| constexpr const _Tp&& |
| value() const&& |
| { |
| if (this->_M_is_engaged()) |
| return std::move(this->_M_get()); |
| __throw_bad_optional_access(); |
| } |
| |
| template<typename _Up> |
| constexpr _Tp |
| value_or(_Up&& __u) const& |
| { |
| static_assert(is_copy_constructible_v<_Tp>); |
| static_assert(is_convertible_v<_Up&&, _Tp>); |
| |
| if (this->_M_is_engaged()) |
| return this->_M_get(); |
| else |
| return static_cast<_Tp>(std::forward<_Up>(__u)); |
| } |
| |
| template<typename _Up> |
| constexpr _Tp |
| value_or(_Up&& __u) && |
| { |
| static_assert(is_move_constructible_v<_Tp>); |
| static_assert(is_convertible_v<_Up&&, _Tp>); |
| |
| if (this->_M_is_engaged()) |
| return std::move(this->_M_get()); |
| else |
| return static_cast<_Tp>(std::forward<_Up>(__u)); |
| } |
| |
| void reset() noexcept { this->_M_reset(); } |
| }; |
| |
| template<typename _Tp> |
| using __optional_relop_t = |
| enable_if_t<is_convertible<_Tp, bool>::value, bool>; |
| |
| template<typename _Tp, typename _Up> |
| using __optional_eq_t = __optional_relop_t< |
| decltype(std::declval<const _Tp&>() == std::declval<const _Up&>()) |
| >; |
| |
| template<typename _Tp, typename _Up> |
| using __optional_ne_t = __optional_relop_t< |
| decltype(std::declval<const _Tp&>() != std::declval<const _Up&>()) |
| >; |
| |
| template<typename _Tp, typename _Up> |
| using __optional_lt_t = __optional_relop_t< |
| decltype(std::declval<const _Tp&>() < std::declval<const _Up&>()) |
| >; |
| |
| template<typename _Tp, typename _Up> |
| using __optional_gt_t = __optional_relop_t< |
| decltype(std::declval<const _Tp&>() > std::declval<const _Up&>()) |
| >; |
| |
| template<typename _Tp, typename _Up> |
| using __optional_le_t = __optional_relop_t< |
| decltype(std::declval<const _Tp&>() <= std::declval<const _Up&>()) |
| >; |
| |
| template<typename _Tp, typename _Up> |
| using __optional_ge_t = __optional_relop_t< |
| decltype(std::declval<const _Tp&>() >= std::declval<const _Up&>()) |
| >; |
| |
| // Comparisons between optional values. |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator==(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
| -> __optional_eq_t<_Tp, _Up> |
| { |
| return static_cast<bool>(__lhs) == static_cast<bool>(__rhs) |
| && (!__lhs || *__lhs == *__rhs); |
| } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
| -> __optional_ne_t<_Tp, _Up> |
| { |
| return static_cast<bool>(__lhs) != static_cast<bool>(__rhs) |
| || (static_cast<bool>(__lhs) && *__lhs != *__rhs); |
| } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator<(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
| -> __optional_lt_t<_Tp, _Up> |
| { |
| return static_cast<bool>(__rhs) && (!__lhs || *__lhs < *__rhs); |
| } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator>(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
| -> __optional_gt_t<_Tp, _Up> |
| { |
| return static_cast<bool>(__lhs) && (!__rhs || *__lhs > *__rhs); |
| } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator<=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
| -> __optional_le_t<_Tp, _Up> |
| { |
| return !__lhs || (static_cast<bool>(__rhs) && *__lhs <= *__rhs); |
| } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator>=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
| -> __optional_ge_t<_Tp, _Up> |
| { |
| return !__rhs || (static_cast<bool>(__lhs) && *__lhs >= *__rhs); |
| } |
| |
| #ifdef __cpp_lib_three_way_comparison |
| template<typename _Tp, three_way_comparable_with<_Tp> _Up> |
| constexpr compare_three_way_result_t<_Tp, _Up> |
| operator<=>(const optional<_Tp>& __x, const optional<_Up>& __y) |
| { |
| return __x && __y ? *__x <=> *__y : bool(__x) <=> bool(__y); |
| } |
| #endif |
| |
| // Comparisons with nullopt. |
| template<typename _Tp> |
| constexpr bool |
| operator==(const optional<_Tp>& __lhs, nullopt_t) noexcept |
| { return !__lhs; } |
| |
| #ifdef __cpp_lib_three_way_comparison |
| template<typename _Tp> |
| constexpr strong_ordering |
| operator<=>(const optional<_Tp>& __x, nullopt_t) noexcept |
| { return bool(__x) <=> false; } |
| #else |
| template<typename _Tp> |
| constexpr bool |
| operator==(nullopt_t, const optional<_Tp>& __rhs) noexcept |
| { return !__rhs; } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator!=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
| { return static_cast<bool>(__lhs); } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator!=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
| { return static_cast<bool>(__rhs); } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator<(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
| { return false; } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator<(nullopt_t, const optional<_Tp>& __rhs) noexcept |
| { return static_cast<bool>(__rhs); } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator>(const optional<_Tp>& __lhs, nullopt_t) noexcept |
| { return static_cast<bool>(__lhs); } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator>(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
| { return false; } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator<=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
| { return !__lhs; } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator<=(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
| { return true; } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator>=(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
| { return true; } |
| |
| template<typename _Tp> |
| constexpr bool |
| operator>=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
| { return !__rhs; } |
| #endif // three-way-comparison |
| |
| // Comparisons with value type. |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator==(const optional<_Tp>& __lhs, const _Up& __rhs) |
| -> __optional_eq_t<_Tp, _Up> |
| { return __lhs && *__lhs == __rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator==(const _Up& __lhs, const optional<_Tp>& __rhs) |
| -> __optional_eq_t<_Up, _Tp> |
| { return __rhs && __lhs == *__rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator!=(const optional<_Tp>& __lhs, const _Up& __rhs) |
| -> __optional_ne_t<_Tp, _Up> |
| { return !__lhs || *__lhs != __rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator!=(const _Up& __lhs, const optional<_Tp>& __rhs) |
| -> __optional_ne_t<_Up, _Tp> |
| { return !__rhs || __lhs != *__rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator<(const optional<_Tp>& __lhs, const _Up& __rhs) |
| -> __optional_lt_t<_Tp, _Up> |
| { return !__lhs || *__lhs < __rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator<(const _Up& __lhs, const optional<_Tp>& __rhs) |
| -> __optional_lt_t<_Up, _Tp> |
| { return __rhs && __lhs < *__rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator>(const optional<_Tp>& __lhs, const _Up& __rhs) |
| -> __optional_gt_t<_Tp, _Up> |
| { return __lhs && *__lhs > __rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator>(const _Up& __lhs, const optional<_Tp>& __rhs) |
| -> __optional_gt_t<_Up, _Tp> |
| { return !__rhs || __lhs > *__rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator<=(const optional<_Tp>& __lhs, const _Up& __rhs) |
| -> __optional_le_t<_Tp, _Up> |
| { return !__lhs || *__lhs <= __rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator<=(const _Up& __lhs, const optional<_Tp>& __rhs) |
| -> __optional_le_t<_Up, _Tp> |
| { return __rhs && __lhs <= *__rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator>=(const optional<_Tp>& __lhs, const _Up& __rhs) |
| -> __optional_ge_t<_Tp, _Up> |
| { return __lhs && *__lhs >= __rhs; } |
| |
| template<typename _Tp, typename _Up> |
| constexpr auto |
| operator>=(const _Up& __lhs, const optional<_Tp>& __rhs) |
| -> __optional_ge_t<_Up, _Tp> |
| { return !__rhs || __lhs >= *__rhs; } |
| |
| #ifdef __cpp_lib_three_way_comparison |
| template<typename _Tp> |
| inline constexpr bool __is_optional_v = false; |
| template<typename _Tp> |
| inline constexpr bool __is_optional_v<optional<_Tp>> = true; |
| |
| template<typename _Tp, typename _Up> |
| requires (!__is_optional_v<_Up>) |
| && three_way_comparable_with<_Tp, _Up> |
| constexpr compare_three_way_result_t<_Tp, _Up> |
| operator<=>(const optional<_Tp>& __x, const _Up& __v) |
| { return bool(__x) ? *__x <=> __v : strong_ordering::less; } |
| #endif |
| |
| // Swap and creation functions. |
| |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2748. swappable traits for optionals |
| template<typename _Tp> |
| inline enable_if_t<is_move_constructible_v<_Tp> && is_swappable_v<_Tp>> |
| swap(optional<_Tp>& __lhs, optional<_Tp>& __rhs) |
| noexcept(noexcept(__lhs.swap(__rhs))) |
| { __lhs.swap(__rhs); } |
| |
| template<typename _Tp> |
| enable_if_t<!(is_move_constructible_v<_Tp> && is_swappable_v<_Tp>)> |
| swap(optional<_Tp>&, optional<_Tp>&) = delete; |
| |
| template<typename _Tp> |
| constexpr |
| enable_if_t<is_constructible_v<decay_t<_Tp>, _Tp>, |
| optional<decay_t<_Tp>>> |
| make_optional(_Tp&& __t) |
| noexcept(is_nothrow_constructible_v<optional<decay_t<_Tp>>, _Tp>) |
| { return optional<decay_t<_Tp>>{ std::forward<_Tp>(__t) }; } |
| |
| template<typename _Tp, typename... _Args> |
| constexpr |
| enable_if_t<is_constructible_v<_Tp, _Args...>, |
| optional<_Tp>> |
| make_optional(_Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
| { return optional<_Tp>{ in_place, std::forward<_Args>(__args)... }; } |
| |
| template<typename _Tp, typename _Up, typename... _Args> |
| constexpr |
| enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
| optional<_Tp>> |
| make_optional(initializer_list<_Up> __il, _Args&&... __args) |
| noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) |
| { return optional<_Tp>{ in_place, __il, std::forward<_Args>(__args)... }; } |
| |
| // Hash. |
| |
| template<typename _Tp, typename _Up = remove_const_t<_Tp>, |
| bool = __poison_hash<_Up>::__enable_hash_call> |
| struct __optional_hash_call_base |
| { |
| size_t |
| operator()(const optional<_Tp>& __t) const |
| noexcept(noexcept(hash<_Up>{}(*__t))) |
| { |
| // We pick an arbitrary hash for disengaged optionals which hopefully |
| // usual values of _Tp won't typically hash to. |
| constexpr size_t __magic_disengaged_hash = static_cast<size_t>(-3333); |
| return __t ? hash<_Up>{}(*__t) : __magic_disengaged_hash; |
| } |
| }; |
| |
| template<typename _Tp, typename _Up> |
| struct __optional_hash_call_base<_Tp, _Up, false> {}; |
| |
| template<typename _Tp> |
| struct hash<optional<_Tp>> |
| : private __poison_hash<remove_const_t<_Tp>>, |
| public __optional_hash_call_base<_Tp> |
| { |
| using result_type [[__deprecated__]] = size_t; |
| using argument_type [[__deprecated__]] = optional<_Tp>; |
| }; |
| |
| template<typename _Tp> |
| struct __is_fast_hash<hash<optional<_Tp>>> : __is_fast_hash<hash<_Tp>> |
| { }; |
| |
| /// @} |
| |
| #if __cpp_deduction_guides >= 201606 |
| template <typename _Tp> optional(_Tp) -> optional<_Tp>; |
| #endif |
| |
| _GLIBCXX_END_NAMESPACE_VERSION |
| } // namespace std |
| |
| #endif // C++17 |
| |
| #endif // _GLIBCXX_OPTIONAL |
