[tab:cpp17.allocator]

Table 36: Cpp17Allocator requirements [tab:cpp17.allocator]

🔗	Expression	Return type	Assertion/note	Default
🔗			pre-/post-condition
🔗	X::pointer			T*
🔗	X::const_pointer		X::pointer is convertible to X::const_pointer	pointer_traits<X::pointer>::rebind<const T>
🔗	X::void_pointer Y::void_pointer		X::pointer is convertible to X::void_pointer. X::void_pointer and Y::void_pointer are the same type.	pointer_traits<X::pointer>::rebind<void>
🔗	X::const_void_pointer Y::const_void_pointer		X::pointer, X::const_pointer, and X::void_pointer are convertible to X::const_void_pointer. X::const_void_pointer and Y::const_void_pointer are the same type.	pointer_traits<X::pointer>::rebind<const void>
🔗	X::value_type	Identical to T
🔗	X::size_type	unsigned integer type	a type that can represent the size of the largest object in the allocation model	make_unsigned_t<X::difference_type>
🔗	X::difference_type	signed integer type	a type that can represent the difference between any two pointers in the allocation model	pointer_traits<X::pointer>::difference_type
🔗	typename X::template rebind<U>::other	Y	For all U (including T), Y::template rebind<T>::other is X.	See Note A, below.
🔗	*p	T&
🔗	*q	const T&	q refers to the same object as p.
🔗	p->m	type of T::m	Preconditions: (p).m is well-defined. equivalent to (p).m
🔗	q->m	type of T::m	Preconditions: (q).m is well-defined. equivalent to (q).m
🔗	static_cast<X::pointer>(w)	X::pointer	static_cast<X::pointer>(w) == p
🔗	static_cast<X::const_pointer>(x)	X::const_pointer	static_cast< X::const_pointer>(x) == q
🔗	pointer_traits<X::pointer>::pointer_to(r)	X::pointer	same as p
🔗	a.allocate(n)	X::pointer	Memory is allocated for an array of n T and such an object is created but array elements are not constructed. [Example 1: When reusing storage denoted by some pointer value p, launder(reinterpret_cast<T>(new (p) byte[n sizeof(T)])) can be used to implicitly create a suitable array object and obtain a pointer to it. — end example] allocate may throw an appropriate exception.176 [Note 1: If n == 0, the return value is unspecified. — end note]
🔗	a.allocate(n, y)	X::pointer	Same as a.allocate(n). The use of y is unspecified, but it is intended as an aid to locality.	a.allocate(n)
🔗	a.deallocate(p,n)	(not used)	Preconditions: p is a value returned by an earlier call to allocate that has not been invalidated by an intervening call to deallocate. n matches the value passed to allocate to obtain this memory. Throws: Nothing.
🔗	a.max_size()	X::size_type	the largest value that can meaningfully be passed to X::allocate()	numeric_limits<size_type>::max() / sizeof(value_type)
🔗	a1 == a2	bool	Returns true only if storage allocated from each can be deallocated via the other. operator== shall be reflexive, symmetric, and transitive, and shall not exit via an exception.
🔗	a1 != a2	bool	same as !(a1 == a2)
🔗	a == b	bool	same as a == Y::rebind<T>::other(b)
🔗	a != b	bool	same as !(a == b)
🔗	X u(a); X u = a;		Shall not exit via an exception. Postconditions: u == a
🔗	X u(b);		Shall not exit via an exception. Postconditions: Y(u) == b, u == X(b)
🔗	X u(std::move(a)); X u = std::move(a);		Shall not exit via an exception. Postconditions: The value of a is unchanged and is equal to u.
🔗	X u(std::move(b));		Shall not exit via an exception. Postconditions: u is equal to the prior value of X(b).
🔗	a.construct(c, args)	(not used)	Effects: Constructs an object of type C at c.	construct_at(c, std::forward<Args>(args)...)
🔗	a.destroy(c)	(not used)	Effects: Destroys the object at c	destroy_at(c)
🔗	a.select_on_container_copy_construction()	X	Typically returns either a or X().	return a;
🔗	X::propagate_on_container_copy_assignment	Identical to or derived from true_type or false_type	true_type only if an allocator of type X should be copied when the client container is copy-assigned. See Note B, below.	false_type
🔗	X::propagate_on_container_move_assignment	Identical to or derived from true_type or false_type	true_type only if an allocator of type X should be moved when the client container is move-assigned. See Note B, below.	false_type
🔗	X::propagate_on_- container_swap	Identical to or derived from true_type or false_type	true_type only if an allocator of type X should be swapped when the client container is swapped. See Note B, below.	false_type
🔗	X::is_always_equal	Identical to or derived from true_type or false_type	true_type only if the expression a1 == a2 is guaranteed to be true for any two (possibly const) values a1, a2 of type X.	is_empty<X>::type

16 Library introduction [library]

16.4 Library-wide requirements [requirements]

16.4.4 Requirements on types and expressions [utility.requirements]

16.4.4.6 Cpp17Allocator requirements [allocator.requirements]

16.4.4.6.1 General [allocator.requirements.general]