NAME¶

std::swappable,std::swappable_with - std::swappable,std::swappable_with

Synopsis¶

Defined in header <concepts>
template< class T >

concept swappable =
requires(T& a, T& b) { (1) (since C++20)
ranges::swap(a, b);

};
template< class T, class U >

concept swappable_with =
std::common_reference_with<T, U> &&
requires(T&& t, U&& u) {
ranges::swap(std::forward<T>(t), std::forward<T>(t)); (2) (since C++20)
ranges::swap(std::forward<U>(u), std::forward<U>(u));
ranges::swap(std::forward<T>(t), std::forward<U>(u));
ranges::swap(std::forward<U>(u), std::forward<T>(t));

};

The concept swappable<T> specifies that lvalues of type T are swappable.

The concept swappable_with<T, U> specifies that expressions of the type and value
category encoded by T and U are swappable with each other. swappable_with<T, U> is
satisfied only if a call to ranges::swap(t, u) exchanges the value of t and u, that
is, given distinct objects t2 equal to t and u2 equal to u, after evaluating either
ranges::swap(t, u) or ranges::swap(u, t), t2 is equal to u and u2 is equal to t.

Equality preservation

Expressions declared in requires expressions of the standard library concepts are
required to be equality-preserving (except where stated otherwise).