std::experimental::ranges::is_swappable_with, std::experimental::ranges::is_swappable, std::experimental::ranges::is_nothrow_swappable_with, std::experimental::ranges::is_nothrow_swappable

< cpp‎ | experimental‎ | ranges

Defined in header `<experimental/ranges/type_traits>`
template <class T, class U> struct is_swappable_with;	(1)	(ranges TS)
template <class T> struct is_swappable;	(2)	(ranges TS)
template <class T, class U> struct is_nothrow_swappable_with;	(3)	(ranges TS)
template <class T> struct is_nothrow_swappable;	(4)	(ranges TS)

1) If the expressions ranges::swap(std::declval<T>(), std::declval<U>()) and ranges::swap(std::declval<U>(), std::declval<T>()) are both well-formed when treated as an unevaluated operand, provides the member constant value equal true. Otherwise, value is false. Access checks are performed as if from a context unrelated to either type.

2) If T is not a referenceable type (i.e., possibly cv-qualified void or a function type with a cv-qualifier-seq or a ref-qualifier), provides a member constant value equal to false. Otherwise, provides a member constant value equal to ranges::is_swappable_with<T&, T&>::value.

3) Same as (1), but evaluations of both expressions from (1) are known not to throw exceptions.

4) Same as (2), but uses is_nothrow_swappable_with.

T and U shall each be a complete type, (possibly cv-qualified) void, or an array of unknown bound. Otherwise, the behavior is undefined.

Helper variable templates

template <class T, class U> constexpr bool is_swappable_with_v = is_swappable_with<T, U>::value;	(1)	(ranges TS)
template <class T> constexpr bool is_swappable_v = is_swappable<T>::value;	(2)	(ranges TS)
template <class T, class U> constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<T, U>::value;	(3)	(ranges TS)
template <class T> constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<T>::value;	(4)	(ranges TS)

Inherited from std::integral_constant

Member constants

value

[static]

true if T is swappable with U , false otherwise
(public static member constant)

Member functions

operator bool	converts the object to bool, returns `value` (public member function)
operator() (C++14)	returns `value` (public member function)

Member types

Type	Definition
`value_type`	`bool`
`type`	std::integral_constant<bool, value>

Notes

This trait does not check anything outside the immediate context of the swap expressions: if the use of T or U would trigger template specializations, generation of implicitly-defined special member functions etc, and those have errors, the actual swap may not compile even if ranges::is_swappable_with<T,U>::value compiles and evaluates to true.

Examples

This section is incomplete
Reason: no example

SwappableSwappableWith	specifies that a type can be swapped or that two types can be swapped with each other (concept)
is_swappable_withis_swappableis_nothrow_swappable_withis_nothrow_swappable (C++17)(C++17)(C++17)(C++17)	checks if objects of a type can be swapped with objects of same or different type (class template)