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optional
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// -*- C++ -*-
//===-------------------------- optional ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP_OPTIONAL
#define _LIBCPP_OPTIONAL
/*
optional synopsis
// C++1z
namespace std {
// 23.6.3, optional for object types
template <class T> class optional;
// 23.6.4, no-value state indicator
struct nullopt_t{see below };
inline constexpr nullopt_t nullopt(unspecified );
// 23.6.5, class bad_optional_access
class bad_optional_access;
// 23.6.6, relational operators
template <class T, class U>
constexpr bool operator==(const optional<T>&, const optional<U>&);
template <class T, class U>
constexpr bool operator!=(const optional<T>&, const optional<U>&);
template <class T, class U>
constexpr bool operator<(const optional<T>&, const optional<U>&);
template <class T, class U>
constexpr bool operator>(const optional<T>&, const optional<U>&);
template <class T, class U>
constexpr bool operator<=(const optional<T>&, const optional<U>&);
template <class T, class U>
constexpr bool operator>=(const optional<T>&, const optional<U>&);
// 23.6.7 comparison with nullopt
template <class T> constexpr bool operator==(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator==(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator!=(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator!=(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator<(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator<=(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator>(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator>=(nullopt_t, const optional<T>&) noexcept;
// 23.6.8, comparison with T
template <class T, class U> constexpr bool operator==(const optional<T>&, const U&);
template <class T, class U> constexpr bool operator==(const T&, const optional<U>&);
template <class T, class U> constexpr bool operator!=(const optional<T>&, const U&);
template <class T, class U> constexpr bool operator!=(const T&, const optional<U>&);
template <class T, class U> constexpr bool operator<(const optional<T>&, const U&);
template <class T, class U> constexpr bool operator<(const T&, const optional<U>&);
template <class T, class U> constexpr bool operator<=(const optional<T>&, const U&);
template <class T, class U> constexpr bool operator<=(const T&, const optional<U>&);
template <class T, class U> constexpr bool operator>(const optional<T>&, const U&);
template <class T, class U> constexpr bool operator>(const T&, const optional<U>&);
template <class T, class U> constexpr bool operator>=(const optional<T>&, const U&);
template <class T, class U> constexpr bool operator>=(const T&, const optional<U>&);
// 23.6.9, specialized algorithms
template <class T> void swap(optional<T>&, optional<T>&) noexcept(see below );
template <class T> constexpr optional<see below > make_optional(T&&);
template <class T, class... Args>
constexpr optional<T> make_optional(Args&&... args);
template <class T, class U, class... Args>
constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args);
// 23.6.10, hash support
template <class T> struct hash;
template <class T> struct hash<optional<T>>;
template <class T> class optional {
public:
using value_type = T;
// 23.6.3.1, constructors
constexpr optional() noexcept;
constexpr optional(nullopt_t) noexcept;
optional(const optional &);
optional(optional &&) noexcept(see below);
template <class... Args> constexpr explicit optional(in_place_t, Args &&...);
template <class U, class... Args>
constexpr explicit optional(in_place_t, initializer_list<U>, Args &&...);
template <class U = T>
constexpr EXPLICIT optional(U &&);
template <class U>
constexpr EXPLICIT optional(const optional<U> &);
template <class U>
constexpr EXPLICIT optional(optional<U> &&);
// 23.6.3.2, destructor
~optional();
// 23.6.3.3, assignment
optional &operator=(nullopt_t) noexcept;
optional &operator=(const optional &); // constexpr in C++20
optional &operator=(optional &&) noexcept(see below); // constexpr in C++20
template <class U = T> optional &operator=(U &&);
template <class U> optional &operator=(const optional<U> &);
template <class U> optional &operator=(optional<U> &&);
template <class... Args> T& emplace(Args &&...);
template <class U, class... Args>
T& emplace(initializer_list<U>, Args &&...);
// 23.6.3.4, swap
void swap(optional &) noexcept(see below );
// 23.6.3.5, observers
constexpr T const *operator->() const;
constexpr T *operator->();
constexpr T const &operator*() const &;
constexpr T &operator*() &;
constexpr T &&operator*() &&;
constexpr const T &&operator*() const &&;
constexpr explicit operator bool() const noexcept;
constexpr bool has_value() const noexcept;
constexpr T const &value() const &;
constexpr T &value() &;
constexpr T &&value() &&;
constexpr const T &&value() const &&;
template <class U> constexpr T value_or(U &&) const &;
template <class U> constexpr T value_or(U &&) &&;
// 23.6.3.6, modifiers
void reset() noexcept;
private:
T *val; // exposition only
};
template<class T>
optional(T) -> optional<T>;
} // namespace std
*/
#include <__config>
#include <__debug>
#include <__functional_base>
#include <functional>
#include <initializer_list>
#include <new>
#include <stdexcept>
#include <type_traits>
#include <utility>
#include <version>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
namespace std // purposefully not using versioning namespace
{
class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS bad_optional_access
: public exception
{
public:
// Get the key function ~bad_optional_access() into the dylib
virtual ~bad_optional_access() _NOEXCEPT;
virtual const char* what() const _NOEXCEPT;
};
} // std
#if _LIBCPP_STD_VER > 14
_LIBCPP_BEGIN_NAMESPACE_STD
_LIBCPP_NORETURN
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
void __throw_bad_optional_access() {
#ifndef _LIBCPP_NO_EXCEPTIONS
throw bad_optional_access();
#else
_VSTD::abort();
#endif
}
struct nullopt_t
{
struct __secret_tag { _LIBCPP_INLINE_VISIBILITY explicit __secret_tag() = default; };
_LIBCPP_INLINE_VISIBILITY constexpr explicit nullopt_t(__secret_tag, __secret_tag) noexcept {}
};
_LIBCPP_INLINE_VAR constexpr nullopt_t nullopt{nullopt_t::__secret_tag{}, nullopt_t::__secret_tag{}};
template <class _Tp, bool = is_trivially_destructible<_Tp>::value>
struct __optional_destruct_base;
template <class _Tp>
struct __optional_destruct_base<_Tp, false>
{
typedef _Tp value_type;
static_assert(is_object_v<value_type>,
"instantiation of optional with a non-object type is undefined behavior");
union
{
char __null_state_;
value_type __val_;
};
bool __engaged_;
_LIBCPP_INLINE_VISIBILITY
~__optional_destruct_base()
{
if (__engaged_)
__val_.~value_type();
}
_LIBCPP_INLINE_VISIBILITY
constexpr __optional_destruct_base() noexcept
: __null_state_(),
__engaged_(false) {}
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
constexpr explicit __optional_destruct_base(in_place_t, _Args&&... __args)
: __val_(_VSTD::forward<_Args>(__args)...),
__engaged_(true) {}
_LIBCPP_INLINE_VISIBILITY
void reset() noexcept
{
if (__engaged_)
{
__val_.~value_type();
__engaged_ = false;
}
}
};
template <class _Tp>
struct __optional_destruct_base<_Tp, true>
{
typedef _Tp value_type;
static_assert(is_object_v<value_type>,
"instantiation of optional with a non-object type is undefined behavior");
union
{
char __null_state_;
value_type __val_;
};
bool __engaged_;
_LIBCPP_INLINE_VISIBILITY
constexpr __optional_destruct_base() noexcept
: __null_state_(),
__engaged_(false) {}
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
constexpr explicit __optional_destruct_base(in_place_t, _Args&&... __args)
: __val_(_VSTD::forward<_Args>(__args)...),
__engaged_(true) {}
_LIBCPP_INLINE_VISIBILITY
void reset() noexcept
{
if (__engaged_)
{
__engaged_ = false;
}
}
};
template <class _Tp, bool = is_reference<_Tp>::value>
struct __optional_storage_base : __optional_destruct_base<_Tp>
{
using __base = __optional_destruct_base<_Tp>;
using value_type = _Tp;
using __base::__base;
_LIBCPP_INLINE_VISIBILITY
constexpr bool has_value() const noexcept
{
return this->__engaged_;
}
_LIBCPP_INLINE_VISIBILITY
constexpr value_type& __get() & noexcept
{
return this->__val_;
}
_LIBCPP_INLINE_VISIBILITY
constexpr const value_type& __get() const& noexcept
{
return this->__val_;
}
_LIBCPP_INLINE_VISIBILITY
constexpr value_type&& __get() && noexcept
{
return _VSTD::move(this->__val_);
}
_LIBCPP_INLINE_VISIBILITY
constexpr const value_type&& __get() const&& noexcept
{
return _VSTD::move(this->__val_);
}
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
void __construct(_Args&&... __args)
{
_LIBCPP_ASSERT(!has_value(), "__construct called for engaged __optional_storage");
::new((void*)_VSTD::addressof(this->__val_)) value_type(_VSTD::forward<_Args>(__args)...);
this->__engaged_ = true;
}
template <class _That>
_LIBCPP_INLINE_VISIBILITY
void __construct_from(_That&& __opt)
{
if (__opt.has_value())
__construct(_VSTD::forward<_That>(__opt).__get());
}
template <class _That>
_LIBCPP_INLINE_VISIBILITY
void __assign_from(_That&& __opt)
{
if (this->__engaged_ == __opt.has_value())
{
if (this->__engaged_)
this->__val_ = _VSTD::forward<_That>(__opt).__get();
}
else
{
if (this->__engaged_)
this->reset();
else
__construct(_VSTD::forward<_That>(__opt).__get());
}
}
};
// optional<T&> is currently required ill-formed, however it may to be in the
// future. For this reason it has already been implemented to ensure we can
// make the change in an ABI compatible manner.
template <class _Tp>
struct __optional_storage_base<_Tp, true>
{
using value_type = _Tp;
using __raw_type = remove_reference_t<_Tp>;
__raw_type* __value_;
template <class _Up>
static constexpr bool __can_bind_reference() {
using _RawUp = typename remove_reference<_Up>::type;
using _UpPtr = _RawUp*;
using _RawTp = typename remove_reference<_Tp>::type;
using _TpPtr = _RawTp*;
using _CheckLValueArg = integral_constant<bool,
(is_lvalue_reference<_Up>::value && is_convertible<_UpPtr, _TpPtr>::value)
|| is_same<_RawUp, reference_wrapper<_RawTp>>::value
|| is_same<_RawUp, reference_wrapper<typename remove_const<_RawTp>::type>>::value
>;
return (is_lvalue_reference<_Tp>::value && _CheckLValueArg::value)
|| (is_rvalue_reference<_Tp>::value && !is_lvalue_reference<_Up>::value &&
is_convertible<_UpPtr, _TpPtr>::value);
}
_LIBCPP_INLINE_VISIBILITY
constexpr __optional_storage_base() noexcept
: __value_(nullptr) {}
template <class _UArg>
_LIBCPP_INLINE_VISIBILITY
constexpr explicit __optional_storage_base(in_place_t, _UArg&& __uarg)
: __value_(_VSTD::addressof(__uarg))
{
static_assert(__can_bind_reference<_UArg>(),
"Attempted to construct a reference element in tuple from a "
"possible temporary");
}
_LIBCPP_INLINE_VISIBILITY
void reset() noexcept { __value_ = nullptr; }
_LIBCPP_INLINE_VISIBILITY
constexpr bool has_value() const noexcept
{ return __value_ != nullptr; }
_LIBCPP_INLINE_VISIBILITY
constexpr value_type& __get() const& noexcept
{ return *__value_; }
_LIBCPP_INLINE_VISIBILITY
constexpr value_type&& __get() const&& noexcept
{ return _VSTD::forward<value_type>(*__value_); }
template <class _UArg>
_LIBCPP_INLINE_VISIBILITY
void __construct(_UArg&& __val)
{
_LIBCPP_ASSERT(!has_value(), "__construct called for engaged __optional_storage");
static_assert(__can_bind_reference<_UArg>(),
"Attempted to construct a reference element in tuple from a "
"possible temporary");
__value_ = _VSTD::addressof(__val);
}
template <class _That>
_LIBCPP_INLINE_VISIBILITY
void __construct_from(_That&& __opt)
{
if (__opt.has_value())
__construct(_VSTD::forward<_That>(__opt).__get());
}
template <class _That>
_LIBCPP_INLINE_VISIBILITY
void __assign_from(_That&& __opt)
{
if (has_value() == __opt.has_value())
{
if (has_value())
*__value_ = _VSTD::forward<_That>(__opt).__get();
}
else
{
if (has_value())
reset();
else
__construct(_VSTD::forward<_That>(__opt).__get());
}
}
};
template <class _Tp, bool = is_trivially_copy_constructible<_Tp>::value>
struct __optional_copy_base : __optional_storage_base<_Tp>
{
using __optional_storage_base<_Tp>::__optional_storage_base;
};
template <class _Tp>
struct __optional_copy_base<_Tp, false> : __optional_storage_base<_Tp>
{
using __optional_storage_base<_Tp>::__optional_storage_base;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_base() = default;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_base(const __optional_copy_base& __opt)
{
this->__construct_from(__opt);
}
_LIBCPP_INLINE_VISIBILITY
__optional_copy_base(__optional_copy_base&&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_base& operator=(const __optional_copy_base&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_base& operator=(__optional_copy_base&&) = default;
};
template <class _Tp, bool = is_trivially_move_constructible<_Tp>::value>
struct __optional_move_base : __optional_copy_base<_Tp>
{
using __optional_copy_base<_Tp>::__optional_copy_base;
};
template <class _Tp>
struct __optional_move_base<_Tp, false> : __optional_copy_base<_Tp>
{
using value_type = _Tp;
using __optional_copy_base<_Tp>::__optional_copy_base;
_LIBCPP_INLINE_VISIBILITY
__optional_move_base() = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_base(const __optional_move_base&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_base(__optional_move_base&& __opt)
noexcept(is_nothrow_move_constructible_v<value_type>)
{
this->__construct_from(_VSTD::move(__opt));
}
_LIBCPP_INLINE_VISIBILITY
__optional_move_base& operator=(const __optional_move_base&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_base& operator=(__optional_move_base&&) = default;
};
template <class _Tp, bool =
is_trivially_destructible<_Tp>::value &&
is_trivially_copy_constructible<_Tp>::value &&
is_trivially_copy_assignable<_Tp>::value>
struct __optional_copy_assign_base : __optional_move_base<_Tp>
{
using __optional_move_base<_Tp>::__optional_move_base;
};
template <class _Tp>
struct __optional_copy_assign_base<_Tp, false> : __optional_move_base<_Tp>
{
using __optional_move_base<_Tp>::__optional_move_base;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_assign_base() = default;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_assign_base(const __optional_copy_assign_base&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_assign_base(__optional_copy_assign_base&&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_copy_assign_base& operator=(const __optional_copy_assign_base& __opt)
{
this->__assign_from(__opt);
return *this;
}
_LIBCPP_INLINE_VISIBILITY
__optional_copy_assign_base& operator=(__optional_copy_assign_base&&) = default;
};
template <class _Tp, bool =
is_trivially_destructible<_Tp>::value &&
is_trivially_move_constructible<_Tp>::value &&
is_trivially_move_assignable<_Tp>::value>
struct __optional_move_assign_base : __optional_copy_assign_base<_Tp>
{
using __optional_copy_assign_base<_Tp>::__optional_copy_assign_base;
};
template <class _Tp>
struct __optional_move_assign_base<_Tp, false> : __optional_copy_assign_base<_Tp>
{
using value_type = _Tp;
using __optional_copy_assign_base<_Tp>::__optional_copy_assign_base;
_LIBCPP_INLINE_VISIBILITY
__optional_move_assign_base() = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_assign_base(const __optional_move_assign_base& __opt) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_assign_base(__optional_move_assign_base&&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_assign_base& operator=(const __optional_move_assign_base&) = default;
_LIBCPP_INLINE_VISIBILITY
__optional_move_assign_base& operator=(__optional_move_assign_base&& __opt)
noexcept(is_nothrow_move_assignable_v<value_type> &&
is_nothrow_move_constructible_v<value_type>)
{
this->__assign_from(_VSTD::move(__opt));
return *this;
}
};
template <class _Tp>
using __optional_sfinae_ctor_base_t = __sfinae_ctor_base<
is_copy_constructible<_Tp>::value,
is_move_constructible<_Tp>::value
>;
template <class _Tp>
using __optional_sfinae_assign_base_t = __sfinae_assign_base<
(is_copy_constructible<_Tp>::value && is_copy_assignable<_Tp>::value),
(is_move_constructible<_Tp>::value && is_move_assignable<_Tp>::value)
>;
template <class _Tp>
class optional
: private __optional_move_assign_base<_Tp>
, private __optional_sfinae_ctor_base_t<_Tp>
, private __optional_sfinae_assign_base_t<_Tp>
{
using __base = __optional_move_assign_base<_Tp>;
public:
using value_type = _Tp;
private:
// Disable the reference extension using this static assert.
static_assert(!is_same_v<__uncvref_t<value_type>, in_place_t>,
"instantiation of optional with in_place_t is ill-formed");
static_assert(!is_same_v<__uncvref_t<value_type>, nullopt_t>,
"instantiation of optional with nullopt_t is ill-formed");
static_assert(!is_reference_v<value_type>,
"instantiation of optional with a reference type is ill-formed");
static_assert(is_destructible_v<value_type>,
"instantiation of optional with a non-destructible type is ill-formed");
static_assert(!is_array_v<value_type>,
"instantiation of optional with an array type is ill-formed");
// LWG2756: conditionally explicit conversion from _Up
struct _CheckOptionalArgsConstructor {
template <class _Up>
static constexpr bool __enable_implicit() {
return is_constructible_v<_Tp, _Up&&> &&
is_convertible_v<_Up&&, _Tp>;
}
template <class _Up>
static constexpr bool __enable_explicit() {
return is_constructible_v<_Tp, _Up&&> &&
!is_convertible_v<_Up&&, _Tp>;
}
};
template <class _Up>
using _CheckOptionalArgsCtor = _If<
_IsNotSame<__uncvref_t<_Up>, in_place_t>::value &&
_IsNotSame<__uncvref_t<_Up>, optional>::value,
_CheckOptionalArgsConstructor,
__check_tuple_constructor_fail
>;
template <class _QualUp>
struct _CheckOptionalLikeConstructor {
template <class _Up, class _Opt = optional<_Up>>
using __check_constructible_from_opt = _Or<
is_constructible<_Tp, _Opt&>,
is_constructible<_Tp, _Opt const&>,
is_constructible<_Tp, _Opt&&>,
is_constructible<_Tp, _Opt const&&>,
is_convertible<_Opt&, _Tp>,
is_convertible<_Opt const&, _Tp>,
is_convertible<_Opt&&, _Tp>,
is_convertible<_Opt const&&, _Tp>
>;
template <class _Up, class _Opt = optional<_Up>>
using __check_assignable_from_opt = _Or<
is_assignable<_Tp&, _Opt&>,
is_assignable<_Tp&, _Opt const&>,
is_assignable<_Tp&, _Opt&&>,
is_assignable<_Tp&, _Opt const&&>
>;
template <class _Up, class _QUp = _QualUp>
static constexpr bool __enable_implicit() {
return is_convertible<_QUp, _Tp>::value &&
!__check_constructible_from_opt<_Up>::value;
}
template <class _Up, class _QUp = _QualUp>
static constexpr bool __enable_explicit() {
return !is_convertible<_QUp, _Tp>::value &&
!__check_constructible_from_opt<_Up>::value;
}
template <class _Up, class _QUp = _QualUp>
static constexpr bool __enable_assign() {
// Construction and assignability of _Qup to _Tp has already been
// checked.
return !__check_constructible_from_opt<_Up>::value &&
!__check_assignable_from_opt<_Up>::value;
}
};
template <class _Up, class _QualUp>
using _CheckOptionalLikeCtor = _If<
_And<
_IsNotSame<_Up, _Tp>,
is_constructible<_Tp, _QualUp>
>::value,
_CheckOptionalLikeConstructor<_QualUp>,
__check_tuple_constructor_fail
>;
template <class _Up, class _QualUp>
using _CheckOptionalLikeAssign = _If<
_And<
_IsNotSame<_Up, _Tp>,
is_constructible<_Tp, _QualUp>,
is_assignable<_Tp&, _QualUp>
>::value,
_CheckOptionalLikeConstructor<_QualUp>,
__check_tuple_constructor_fail
>;
public:
_LIBCPP_INLINE_VISIBILITY constexpr optional() noexcept {}
_LIBCPP_INLINE_VISIBILITY constexpr optional(const optional&) = default;
_LIBCPP_INLINE_VISIBILITY constexpr optional(optional&&) = default;
_LIBCPP_INLINE_VISIBILITY constexpr optional(nullopt_t) noexcept {}
template <class _InPlaceT, class... _Args, class = _EnableIf<
_And<
_IsSame<_InPlaceT, in_place_t>,
is_constructible<value_type, _Args...>
>::value
>
>
_LIBCPP_INLINE_VISIBILITY
constexpr explicit optional(_InPlaceT, _Args&&... __args)
: __base(in_place, _VSTD::forward<_Args>(__args)...) {}
template <class _Up, class... _Args, class = _EnableIf<
is_constructible_v<value_type, initializer_list<_Up>&, _Args...>>
>
_LIBCPP_INLINE_VISIBILITY
constexpr explicit optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args)
: __base(in_place, __il, _VSTD::forward<_Args>(__args)...) {}
template <class _Up = value_type, _EnableIf<
_CheckOptionalArgsCtor<_Up>::template __enable_implicit<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
constexpr optional(_Up&& __v)
: __base(in_place, _VSTD::forward<_Up>(__v)) {}
template <class _Up, _EnableIf<
_CheckOptionalArgsCtor<_Up>::template __enable_explicit<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
constexpr explicit optional(_Up&& __v)
: __base(in_place, _VSTD::forward<_Up>(__v)) {}
// LWG2756: conditionally explicit conversion from const optional<_Up>&
template <class _Up, _EnableIf<
_CheckOptionalLikeCtor<_Up, _Up const&>::template __enable_implicit<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
optional(const optional<_Up>& __v)
{
this->__construct_from(__v);
}
template <class _Up, _EnableIf<
_CheckOptionalLikeCtor<_Up, _Up const&>::template __enable_explicit<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
explicit optional(const optional<_Up>& __v)
{
this->__construct_from(__v);
}
// LWG2756: conditionally explicit conversion from optional<_Up>&&
template <class _Up, _EnableIf<
_CheckOptionalLikeCtor<_Up, _Up &&>::template __enable_implicit<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
optional(optional<_Up>&& __v)
{
this->__construct_from(_VSTD::move(__v));
}
template <class _Up, _EnableIf<
_CheckOptionalLikeCtor<_Up, _Up &&>::template __enable_explicit<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
explicit optional(optional<_Up>&& __v)
{
this->__construct_from(_VSTD::move(__v));
}
_LIBCPP_INLINE_VISIBILITY
optional& operator=(nullopt_t) noexcept
{
reset();
return *this;
}
_LIBCPP_INLINE_VISIBILITY optional& operator=(const optional&) = default;
_LIBCPP_INLINE_VISIBILITY optional& operator=(optional&&) = default;
// LWG2756
template <class _Up = value_type,
class = _EnableIf<
_And<
_IsNotSame<__uncvref_t<_Up>, optional>,
_Or<
_IsNotSame<__uncvref_t<_Up>, value_type>,
_Not<is_scalar<value_type>>
>,
is_constructible<value_type, _Up>,
is_assignable<value_type&, _Up>
>::value>
>
_LIBCPP_INLINE_VISIBILITY
optional&
operator=(_Up&& __v)
{
if (this->has_value())
this->__get() = _VSTD::forward<_Up>(__v);
else
this->__construct(_VSTD::forward<_Up>(__v));
return *this;
}
// LWG2756
template <class _Up, _EnableIf<
_CheckOptionalLikeAssign<_Up, _Up const&>::template __enable_assign<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
optional&
operator=(const optional<_Up>& __v)
{
this->__assign_from(__v);
return *this;
}
// LWG2756
template <class _Up, _EnableIf<
_CheckOptionalLikeCtor<_Up, _Up &&>::template __enable_assign<_Up>()
, int> = 0>
_LIBCPP_INLINE_VISIBILITY
optional&
operator=(optional<_Up>&& __v)
{
this->__assign_from(_VSTD::move(__v));
return *this;
}
template <class... _Args,
class = _EnableIf
<
is_constructible_v<value_type, _Args...>
>
>
_LIBCPP_INLINE_VISIBILITY
_Tp &
emplace(_Args&&... __args)
{
reset();
this->__construct(_VSTD::forward<_Args>(__args)...);
return this->__get();
}
template <class _Up, class... _Args,
class = _EnableIf
<
is_constructible_v<value_type, initializer_list<_Up>&, _Args...>
>
>
_LIBCPP_INLINE_VISIBILITY
_Tp &
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
reset();
this->__construct(__il, _VSTD::forward<_Args>(__args)...);
return this->__get();
}
_LIBCPP_INLINE_VISIBILITY
void swap(optional& __opt)
noexcept(is_nothrow_move_constructible_v<value_type> &&
is_nothrow_swappable_v<value_type>)
{
if (this->has_value() == __opt.has_value())
{
using _VSTD::swap;
if (this->has_value())
swap(this->__get(), __opt.__get());
}
else
{
if (this->has_value())
{
__opt.__construct(_VSTD::move(this->__get()));
reset();
}
else
{
this->__construct(_VSTD::move(__opt.__get()));
__opt.reset();
}
}
}
_LIBCPP_INLINE_VISIBILITY
constexpr
add_pointer_t<value_type const>
operator->() const
{
_LIBCPP_ASSERT(this->has_value(), "optional operator-> called for disengaged value");
#ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
return _VSTD::addressof(this->__get());
#else
return __operator_arrow(__has_operator_addressof<value_type>{}, this->__get());
#endif
}
_LIBCPP_INLINE_VISIBILITY
constexpr
add_pointer_t<value_type>
operator->()
{
_LIBCPP_ASSERT(this->has_value(), "optional operator-> called for disengaged value");
#ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
return _VSTD::addressof(this->__get());
#else
return __operator_arrow(__has_operator_addressof<value_type>{}, this->__get());
#endif
}
_LIBCPP_INLINE_VISIBILITY
constexpr
const value_type&
operator*() const&
{
_LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
return this->__get();
}
_LIBCPP_INLINE_VISIBILITY
constexpr
value_type&
operator*() &
{
_LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
return this->__get();
}
_LIBCPP_INLINE_VISIBILITY
constexpr
value_type&&
operator*() &&
{
_LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
return _VSTD::move(this->__get());
}
_LIBCPP_INLINE_VISIBILITY
constexpr
const value_type&&
operator*() const&&
{
_LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
return _VSTD::move(this->__get());
}
_LIBCPP_INLINE_VISIBILITY
constexpr explicit operator bool() const noexcept { return has_value(); }
using __base::has_value;
using __base::__get;
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
constexpr value_type const& value() const&
{
if (!this->has_value())
__throw_bad_optional_access();
return this->__get();
}
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
constexpr value_type& value() &
{
if (!this->has_value())
__throw_bad_optional_access();
return this->__get();
}
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
constexpr value_type&& value() &&
{
if (!this->has_value())
__throw_bad_optional_access();
return _VSTD::move(this->__get());
}
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
constexpr value_type const&& value() const&&
{
if (!this->has_value())
__throw_bad_optional_access();
return _VSTD::move(this->__get());
}
template <class _Up>
_LIBCPP_INLINE_VISIBILITY
constexpr value_type value_or(_Up&& __v) const&
{
static_assert(is_copy_constructible_v<value_type>,
"optional<T>::value_or: T must be copy constructible");
static_assert(is_convertible_v<_Up, value_type>,
"optional<T>::value_or: U must be convertible to T");
return this->has_value() ? this->__get() :
static_cast<value_type>(_VSTD::forward<_Up>(__v));
}
template <class _Up>
_LIBCPP_INLINE_VISIBILITY
constexpr value_type value_or(_Up&& __v) &&
{
static_assert(is_move_constructible_v<value_type>,
"optional<T>::value_or: T must be move constructible");
static_assert(is_convertible_v<_Up, value_type>,
"optional<T>::value_or: U must be convertible to T");
return this->has_value() ? _VSTD::move(this->__get()) :
static_cast<value_type>(_VSTD::forward<_Up>(__v));
}