// <optional> -*- C++ -*-
-// Copyright (C) 2013-2017 Free Software Foundation, Inc.
+// Copyright (C) 2013-2020 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
#include <utility>
#include <type_traits>
-#include <stdexcept>
+#include <exception>
#include <new>
#include <initializer_list>
-#include <bits/functexcept.h>
+#include <bits/exception_defines.h>
#include <bits/functional_hash.h>
#include <bits/enable_special_members.h>
* @{
*/
-#define __cpp_lib_optional 201603
+#define __cpp_lib_optional 201606L
template<typename _Tp>
class optional;
{
public:
bad_optional_access() { }
+
virtual const char* what() const noexcept override
- {return "bad optional access";}
+ { return "bad optional access"; }
virtual ~bad_optional_access() noexcept = default;
};
__throw_bad_optional_access()
{ _GLIBCXX_THROW_OR_ABORT(bad_optional_access()); }
-
- // Payload for constexpr optionals.
- template <typename _Tp,
- bool /*_TrivialCopyMove*/ =
- is_trivially_copy_constructible<_Tp>::value
- && is_trivially_move_constructible<_Tp>::value,
- bool /*_ShouldProvideDestructor*/ =
- is_trivially_destructible<_Tp>::value>
- struct _Optional_payload
+ // This class template manages construction/destruction of
+ // the contained value for a std::optional.
+ template <typename _Tp>
+ struct _Optional_payload_base
{
- constexpr _Optional_payload()
- : _M_empty() {}
+ using _Stored_type = remove_const_t<_Tp>;
+
+ _Optional_payload_base() = default;
+ ~_Optional_payload_base() = default;
template<typename... _Args>
- constexpr _Optional_payload(in_place_t, _Args&&... __args)
- : _M_payload(std::forward<_Args>(__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(std::initializer_list<_Up> __il,
- _Args&&... __args)
+ constexpr
+ _Optional_payload_base(std::initializer_list<_Up> __il,
+ _Args&&... __args)
: _M_payload(__il, std::forward<_Args>(__args)...),
- _M_engaged(true) {}
-
- template <class _Up> struct __ctor_tag {};
-
- constexpr _Optional_payload(__ctor_tag<bool>,
- const _Tp& __other)
- : _M_payload(__other),
_M_engaged(true)
- {}
-
- constexpr _Optional_payload(__ctor_tag<void>)
- : _M_empty()
- {}
+ { }
- constexpr _Optional_payload(__ctor_tag<bool>, _Tp&& __other)
- : _M_payload(std::move(__other)),
- _M_engaged(true)
- {}
-
- constexpr _Optional_payload(bool __engaged,
- const _Optional_payload& __other)
- : _Optional_payload(__engaged ?
- _Optional_payload(__ctor_tag<bool>{},
- __other._M_payload) :
- _Optional_payload(__ctor_tag<void>{}))
- {}
-
- constexpr _Optional_payload(bool __engaged,
- _Optional_payload&& __other)
- : _Optional_payload(__engaged
- ? _Optional_payload(__ctor_tag<bool>{},
- std::move(__other._M_payload))
- : _Optional_payload(__ctor_tag<void>{}))
- {}
+ // 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());
+ }
- using _Stored_type = remove_const_t<_Tp>;
- struct _Empty_byte { };
- union {
- _Empty_byte _M_empty;
- _Stored_type _M_payload;
- };
- bool _M_engaged = false;
- };
+ // 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()));
+ }
- // Payload for non-constexpr optionals with non-trivial destructor.
- template <typename _Tp>
- struct _Optional_payload<_Tp, false, false>
- {
- constexpr _Optional_payload()
- : _M_empty() {}
+ // Copy constructor is only used to when the contained value is
+ // trivially copy constructible.
+ _Optional_payload_base(const _Optional_payload_base&) = default;
- template <typename... _Args>
- constexpr _Optional_payload(in_place_t, _Args&&... __args)
- : _M_payload(std::forward<_Args>(__args)...),
- _M_engaged(true) {}
+ // Move constructor is only used to when the contained value is
+ // trivially copy constructible.
+ _Optional_payload_base(_Optional_payload_base&&) = default;
- template<typename _Up, typename... _Args>
- constexpr _Optional_payload(std::initializer_list<_Up> __il,
- _Args&&... __args)
- : _M_payload(__il, std::forward<_Args>(__args)...),
- _M_engaged(true) {}
- constexpr
- _Optional_payload(bool __engaged, const _Optional_payload& __other)
- : _Optional_payload(__other)
- {}
+ _Optional_payload_base&
+ operator=(const _Optional_payload_base&) = default;
- constexpr
- _Optional_payload(bool __engaged, _Optional_payload&& __other)
- : _Optional_payload(std::move(__other))
- {}
+ _Optional_payload_base&
+ operator=(_Optional_payload_base&&) = default;
- constexpr _Optional_payload(const _Optional_payload& __other)
+ // used to perform non-trivial copy assignment.
+ constexpr void
+ _M_copy_assign(const _Optional_payload_base& __other)
{
- if (__other._M_engaged)
- this->_M_construct(__other._M_payload);
+ 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();
+ }
}
- constexpr _Optional_payload(_Optional_payload&& __other)
+ // 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 (__other._M_engaged)
- this->_M_construct(std::move(__other._M_payload));
+ 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();
+ }
}
- using _Stored_type = remove_const_t<_Tp>;
struct _Empty_byte { };
- union {
- _Empty_byte _M_empty;
- _Stored_type _M_payload;
- };
- bool _M_engaged = false;
- ~_Optional_payload()
- {
- if (_M_engaged)
- _M_payload.~_Stored_type();
- }
+ 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<_Stored_type, _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();
+ }
};
- // Payload for non-constexpr optionals with trivial destructor.
+ // 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, false, true>
+ struct _Optional_payload<_Tp, true, true, true>
+ : _Optional_payload_base<_Tp>
{
- constexpr _Optional_payload()
- : _M_empty() {}
+ using _Optional_payload_base<_Tp>::_Optional_payload_base;
+
+ _Optional_payload() = default;
+ };
- template <typename... _Args>
- constexpr _Optional_payload(in_place_t, _Args&&... __args)
- : _M_payload(std::forward<_Args>(__args)...),
- _M_engaged(true) {}
+ // 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;
- template<typename _Up, typename... _Args>
- constexpr _Optional_payload(std::initializer_list<_Up> __il,
- _Args&&... __args)
- : _M_payload(__il, std::forward<_Args>(__args)...),
- _M_engaged(true) {}
+ _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(bool __engaged, const _Optional_payload& __other)
- : _Optional_payload(__other)
- {}
+ _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(bool __engaged, _Optional_payload&& __other)
- : _Optional_payload(std::move(__other))
- {}
+ _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;
- constexpr _Optional_payload(const _Optional_payload& __other)
+ _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)
{
- if (__other._M_engaged)
- this->_M_construct(__other._M_payload);
+ this->_M_copy_assign(__other);
+ return *this;
}
- constexpr _Optional_payload(_Optional_payload&& __other)
+ // Non-trivial move assignment.
+ constexpr
+ _Optional_payload&
+ operator=(_Optional_payload&& __other)
+ noexcept(__and_v<is_nothrow_move_constructible<_Tp>,
+ is_nothrow_move_assignable<_Tp>>)
{
- if (__other._M_engaged)
- this->_M_construct(std::move(__other._M_payload));
+ 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>;
- struct _Empty_byte { };
- union {
- _Empty_byte _M_empty;
- _Stored_type _M_payload;
- };
- bool _M_engaged = false;
+ // 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<_Stored_type, _Args...>())
- {
- ::new ((void *) std::__addressof(this->_M_payload))
- _Stored_type(std::forward<_Args>(__args)...);
- this->_M_engaged = true;
- }
+ 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 holds the necessary state for @ref optional
- * and that has the responsibility for construction and the special members.
+ * @brief Class template that provides copy/move constructors of optional.
*
* Such a separate base class template is necessary in order to
- * conditionally enable the special members (e.g. copy/move constructors).
- * Note that this means that @ref _Optional_base implements the
- * functionality for copy and move assignment, but not for converting
- * assignment.
+ * conditionally make copy/move constructors trivial.
+ *
+ * When the contained value is trivally 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>
- class _Optional_base
+ 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>>
{
- private:
- // Remove const to avoid prohibition of reusing object storage for
- // const-qualified types in [3.8/9]. This is strictly internal
- // and even optional itself is oblivious to it.
- using _Stored_type = remove_const_t<_Tp>;
+ // Constructors for disengaged optionals.
+ constexpr _Optional_base() = default;
- public:
+ // 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)...) { }
- // Constructors for disengaged optionals.
- constexpr _Optional_base() noexcept
+ 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(nullopt_t) noexcept
+ 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>
__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<_Tp>())
+ 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& __other)
- {
- if (this->_M_payload._M_engaged && __other._M_payload._M_engaged)
- this->_M_get() = __other._M_get();
- else
- {
- if (__other._M_payload._M_engaged)
- this->_M_construct(__other._M_get());
- else
- this->_M_reset();
- }
+ _Optional_base& operator=(const _Optional_base&) = default;
+ _Optional_base& operator=(_Optional_base&&) = default;
- return *this;
- }
-
- _Optional_base&
- operator=(_Optional_base&& __other)
- noexcept(__and_<is_nothrow_move_constructible<_Tp>,
- is_nothrow_move_assignable<_Tp>>())
- {
- if (this->_M_payload._M_engaged && __other._M_payload._M_engaged)
- this->_M_get() = std::move(__other._M_get());
- else
- {
- if (__other._M_payload._M_engaged)
- this->_M_construct(std::move(__other._M_get()));
- else
- this->_M_reset();
- }
- return *this;
- }
- // The following functionality is also needed by optional, hence the
- // protected accessibility.
- protected:
- constexpr bool _M_is_engaged() const noexcept
- { return this->_M_payload._M_engaged; }
+ _Optional_payload<_Tp> _M_payload;
+ };
- // The _M_get operations have _M_engaged as a precondition.
- constexpr _Tp&
- _M_get() noexcept
- {
- __glibcxx_assert(_M_is_engaged());
- return this->_M_payload._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;
- constexpr const _Tp&
- _M_get() const noexcept
- {
- __glibcxx_assert(_M_is_engaged());
- return this->_M_payload._M_payload;
- }
+ // 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)...) { }
- // 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<_Stored_type, _Args...>())
- {
- ::new (std::__addressof(this->_M_payload._M_payload))
- _Stored_type(std::forward<_Args>(__args)...);
- this->_M_payload._M_engaged = true;
- }
+ 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)...)
+ { }
- void
- _M_destruct()
- {
- this->_M_payload._M_engaged = false;
- this->_M_payload._M_payload.~_Stored_type();
- }
+ // Copy and move constructors.
+ constexpr _Optional_base(const _Optional_base& __other) = default;
+ constexpr _Optional_base(_Optional_base&& __other) = default;
- // _M_reset is a 'safe' operation with no precondition.
- void
- _M_reset()
- {
- if (this->_M_payload._M_engaged)
- this->_M_destruct();
- }
+ // Assignment operators.
+ _Optional_base& operator=(const _Optional_base&) = default;
+ _Optional_base& operator=(_Optional_base&&) = default;
- private:
_Optional_payload<_Tp> _M_payload;
};
class optional
: private _Optional_base<_Tp>,
private _Enable_copy_move<
- // Copy constructor.
- is_copy_constructible<_Tp>::value,
- // Copy assignment.
- __and_<is_copy_constructible<_Tp>, is_copy_assignable<_Tp>>::value,
- // Move constructor.
- is_move_constructible<_Tp>::value,
- // Move assignment.
- __and_<is_move_constructible<_Tp>, is_move_assignable<_Tp>>::value,
- // Unique tag type.
- optional<_Tp>>
+ // 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>);
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() = default;
- constexpr optional(nullopt_t) noexcept
- : _Base(nullopt) { }
+ constexpr optional(nullopt_t) noexcept { }
// Converting constructors for engaged optionals.
- template <typename _Up = _Tp,
- enable_if_t<__and_<
- __not_<is_same<optional<_Tp>, decay_t<_Up>>>,
- __not_<is_same<in_place_t, decay_t<_Up>>>,
- is_constructible<_Tp, _Up&&>,
- is_convertible<_Up&&, _Tp>
- >::value, bool> = true>
- constexpr optional(_Up&& __t)
- : _Base(std::in_place, std::forward<_Up>(__t)) { }
-
- template <typename _Up = _Tp,
- enable_if_t<__and_<
- __not_<is_same<optional<_Tp>, decay_t<_Up>>>,
- __not_<is_same<in_place_t, decay_t<_Up>>>,
- is_constructible<_Tp, _Up&&>,
- __not_<is_convertible<_Up&&, _Tp>>
- >::value, bool> = false>
- explicit constexpr optional(_Up&& __t)
+ template<typename _Up = _Tp,
+ _Requires<__not_self<_Up>, __not_tag<_Up>,
+ is_constructible<_Tp, _Up&&>,
+ is_convertible<_Up&&, _Tp>> = true>
+ constexpr
+ optional(_Up&& __t)
+ : _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)
: _Base(std::in_place, std::forward<_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)
- {
- if (__t)
- emplace(*__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)
+ {
+ if (__t)
+ emplace(*__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>
- explicit constexpr optional(const optional<_Up>& __t)
- {
- 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)
+ {
+ if (__t)
+ emplace(*__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)
- {
- if (__t)
- emplace(std::move(*__t));
- }
+ _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)
+ {
+ if (__t)
+ emplace(std::move(*__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>
- explicit constexpr optional(optional<_Up>&& __t)
- {
- if (__t)
- emplace(std::move(*__t));
- }
+ _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)
+ {
+ if (__t)
+ emplace(std::move(*__t));
+ }
template<typename... _Args,
- enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
- explicit constexpr optional(in_place_t, _Args&&... __args)
- : _Base(std::in_place, std::forward<_Args>(__args)...) { }
+ _Requires<is_constructible<_Tp, _Args&&...>> = false>
+ explicit constexpr
+ optional(in_place_t, _Args&&... __args)
+ : _Base(std::in_place, std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
- enable_if_t<is_constructible_v<_Tp,
- initializer_list<_Up>&,
- _Args&&...>, bool> = false>
- explicit constexpr optional(in_place_t,
- initializer_list<_Up> __il,
- _Args&&... __args)
- : _Base(std::in_place, __il, std::forward<_Args>(__args)...) { }
+ _Requires<is_constructible<_Tp,
+ initializer_list<_Up>&,
+ _Args&&...>> = false>
+ explicit constexpr
+ optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args)
+ : _Base(std::in_place, __il, std::forward<_Args>(__args)...) { }
// Assignment operators.
optional&
operator=(nullopt_t) noexcept
{
- this->_M_reset();
- return *this;
+ this->_M_reset();
+ return *this;
}
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,
+ 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)
- {
- if (this->_M_is_engaged())
- this->_M_get() = std::forward<_Up>(__u);
- else
- this->_M_construct(std::forward<_Up>(__u));
+ operator=(_Up&& __u)
+ {
+ if (this->_M_is_engaged())
+ this->_M_get() = std::forward<_Up>(__u);
+ else
+ this->_M_construct(std::forward<_Up>(__u));
- return *this;
- }
+ return *this;
+ }
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,
+ enable_if_t<__and_v<__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>>>,
optional&>
- operator=(const optional<_Up>& __u)
- {
- if (__u)
- {
- if (this->_M_is_engaged())
- this->_M_get() = *__u;
- else
- this->_M_construct(*__u);
- }
- else
- {
- this->_M_reset();
- }
- return *this;
- }
+ operator=(const optional<_Up>& __u)
+ {
+ 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_<
- __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,
+ 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)
- {
- 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;
- }
+ operator=(optional<_Up>&& __u)
+ {
+ 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<_Tp, _Args&&...>::value, _Tp&>
+ enable_if_t<is_constructible_v<_Tp, _Args&&...>, _Tp&>
emplace(_Args&&... __args)
{
this->_M_reset();
}
template<typename _Up, typename... _Args>
- enable_if_t<is_constructible<_Tp, initializer_list<_Up>&,
- _Args&&...>::value, _Tp&>
+ enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&,
+ _Args&&...>, _Tp&>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
this->_M_reset();
// Swap.
void
swap(optional& __other)
- noexcept(is_nothrow_move_constructible<_Tp>()
- && is_nothrow_swappable_v<_Tp>)
+ noexcept(is_nothrow_move_constructible_v<_Tp>
+ && is_nothrow_swappable_v<_Tp>)
{
- using std::swap;
+ 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())
+ 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())
+ else if (__other._M_is_engaged())
{
this->_M_construct(std::move(__other._M_get()));
__other._M_destruct();
operator->() const
{ return std::__addressof(this->_M_get()); }
- _Tp*
+ constexpr _Tp*
operator->()
{ return std::__addressof(this->_M_get()); }
value() const&
{
return this->_M_is_engaged()
- ? this->_M_get()
- : (__throw_bad_optional_access(),
- this->_M_get());
+ ? this->_M_get()
+ : (__throw_bad_optional_access(), this->_M_get());
}
constexpr _Tp&
value()&
{
return this->_M_is_engaged()
- ? this->_M_get()
- : (__throw_bad_optional_access(),
- this->_M_get());
+ ? this->_M_get()
+ : (__throw_bad_optional_access(), this->_M_get());
}
constexpr _Tp&&
value()&&
{
return this->_M_is_engaged()
- ? std::move(this->_M_get())
- : (__throw_bad_optional_access(),
- std::move(this->_M_get()));
+ ? std::move(this->_M_get())
+ : (__throw_bad_optional_access(), std::move(this->_M_get()));
}
constexpr const _Tp&&
value() const&&
{
return this->_M_is_engaged()
- ? std::move(this->_M_get())
- : (__throw_bad_optional_access(),
- std::move(this->_M_get()));
+ ? std::move(this->_M_get())
+ : (__throw_bad_optional_access(), std::move(this->_M_get()));
}
template<typename _Up>
static_assert(is_convertible_v<_Up&&, _Tp>);
return this->_M_is_engaged()
- ? this->_M_get()
- : static_cast<_Tp>(std::forward<_Up>(__u));
+ ? this->_M_get() : static_cast<_Tp>(std::forward<_Up>(__u));
}
template<typename _Up>
- _Tp
+ constexpr _Tp
value_or(_Up&& __u) &&
{
static_assert(is_move_constructible_v<_Tp>);
? std::move(this->_M_get())
: 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>;
+ enable_if_t<is_convertible<_Tp, bool>::value, bool>;
// Comparisons between optional values.
template<typename _Tp, typename _Up>
/// @}
+#if __cpp_deduction_guides >= 201606
template <typename _Tp> optional(_Tp) -> optional<_Tp>;
+#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
projects / thirdparty / gcc.git / blobdiff