std::indirect<T, Allocator>::indirect

 

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std::indirect

Member functions

indirect::indirect

indirect::~indirect

indirect::operator=

Observers

indirect::operator->indirect::operator*

indirect::valueless_after_move

indirect::get_allocator

Modifiers

indirect::swap

Non-member functions

operator==operator<=>

swap(std::indirect)

Deduction guides

Helper classes

hash<std::indirect>

 

constexpr explicit indirect();	(1)	(since C++26)
constexpr explicit indirect( std::allocator_arg_t, const Allocator& a );	(2)	(since C++26)
template< class U = T > constexpr explicit indirect( U&& v );	(3)	(since C++26)
template< class U = T > constexpr explicit indirect( std::allocator_arg_t, const Allocator& a,                              U&& v );	(4)	(since C++26)
template< class... Args > constexpr explicit indirect( std::in_place_t, Args&&... args );	(5)	(since C++26)
template< class... Args > constexpr explicit indirect( std::allocator_arg_t, const Allocator& a,                              std::in_place_t, Args&&... args );	(6)	(since C++26)
template< class I, class... Args > constexpr explicit indirect( std::in_place_t, std::initializer_list<I> ilist,                              Args&&... args );	(7)	(since C++26)
template< class I, class... Args > constexpr explicit indirect( std::allocator_arg_t, const Allocator& a,                              std::in_place_t, std::initializer_list<I> ilist,                              Args&&... args );	(8)	(since C++26)
constexpr indirect( const indirect& other );	(9)	(since C++26)
constexpr indirect( std::allocator_arg_t, const Allocator& a,                     const indirect& other );	(10)	(since C++26)
constexpr indirect( indirect&& other ) noexcept;	(11)	(since C++26)
constexpr indirect( std::allocator_arg_t, const Allocator& a,                     indirect&& other ) noexcept(/* see below */);	(12)	(since C++26)

Constructs a new indirect object.

Parameters

a	-	the allocator to be associated
v	-	value with which to initialize the owned value
args	-	arguments with which to initialize the owned value
il	-	initializer list with which to initialize the owned value
other	-	another indirect object whose owned value (if exists) is copied

Effects

The construction of a new indirect object consists of the following steps:

1) Constructs the associated allocator alloc :

• If the initializer for alloc is empty, it is value-initialized.
• If the initializer for alloc is not empty, it is direct-non-list-initialized with the initializer argument.

2) Constructs the owned object:

• For overloads (1-8), initialize p with the result of calling std::allocator_traits<Allocator>::allocate, then calls std::allocator_traits<Allocator>::construct(alloc , p , args...), where args... is an expression pack containing the initializer arguments.
• For overloads (9-12):
  • If other is valueless, no owned object is constructed, and *this is also valueless after construction.
  • Otherwise, if other is an rvalue reference and alloc equals other.alloc, *this takes ownership of the owned object of other.
  • Otherwise, the owned object is constructed using alloc as described above.

Overload	Initializer for...		valueless_after_move() after construction
	alloc	the owned object
(1)	(empty)	(empty)	false
(2)	a
(3)	(empty)	std::forward<U>(v)
(4)	a
(5)	(empty)	std::forward<Args>(args)
(6)	a
(7)	(empty)	ilist, std::forward<Args>(args)
(8)	a
(9)	see below	*other (only if other owns a value)	true only if other is valueless
(10)	a
(11)	std::move(other.alloc )	takes ownership (only if other owns a value)
(12)	a	see below

9) alloc is direct-non-list-initialized with std::allocator_traits<Allocator>::
    select_on_container_copy_construction(other.alloc ).

12) The owned object is constructed as follows:

• If other is valueless, *this is also valueless.
• Otherwise, if alloc == other.alloc is true, *this takes ownership of the owned object of other.
• Otherwise, constructs an owned object with *std::move(other) using alloc .

Constraints and supplement information

1,2) If std::is_default_constructible_v<T> is false, the program is ill-formed.

1) This overload participates in overload resolution only if std::is_default_constructible_v<Allocator> is true.

3-8) These overloads participate in overload resolution only if std::is_constructible_v<T, /* argument types */> is true, where /* argument types */ are:

3,4) U

5,6) Args...

7,8) std::initializer_list<I>&, Args...

3,5,7) These overloads participate in overload resolution only if std::is_default_constructible_v<Allocator> is true.

3,4) These overloads participate in overload resolution only if the following values are all false:

• std::is_same_v<std::remove_cvref_t<U>, std::indirect>
• std::is_same_v<std::remove_cvref_t<U>, std::in_place_t>

9,10) If std::is_copy_constructible_v<T> is false, the program is ill-formed.

11,12) When the construction completes, other is valueless.

12) If std::allocator_traits<Allocator>::is_always_equal::value is false and T is an incomplete type, the program is ill-formed.

Exceptions

Throws nothing unless std::allocator_traits<Allocator>::allocate or std::allocator_traits<Allocator>::construct throws.

12)

noexcept specification:  

noexcept(std::allocator_traits<Allocator>::is_always_equal::value)

See also

allocator_arg_t (C++11)	tag type used to select allocator-aware constructor overloads (class)
in_placein_place_typein_place_indexin_place_tin_place_type_tin_place_index_t (C++17)	in-place construction tag (tag)