std::experimental::ranges::is_swappable_with, std::experimental::ranges::is_swappable, std::experimental::ranges::is_nothrow_swappable_with, std::experimental::ranges::is_nothrow_swappable
From cppreference.com
< cpp | experimental | ranges
| Defined in header <experimental/ranges/type_traits>
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| 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 |
See also
| specifies that a type can be swapped or that two types can be swapped with each other (concept) | |
| (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) |