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

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< cpp‎ | experimental‎ | ranges
 
 
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General utilities library
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Metaprogramming and type traits
is_swappable_withis_swappable
is_nothrow_swappable_withis_nothrow_swappable
Tagged pairs and tuples
                          
tag specifiers
                                      
                          
 
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.

Contents

[edit] 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>

[edit] 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.

[edit] Example

[edit] See also

specifies that a type can be swapped or that two types can be swapped with each other
(concept) [edit]
checks if objects of a type can be swapped with objects of same or different type
(class template) [edit]