std::swappable,std::swappable_with

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Concepts library

Core language concepts
same_as (C++20)
derived_from (C++20)
convertible_to (C++20)
common_reference_with (C++20)
common_with (C++20)
integral (C++20)
signed_integral (C++20)
unsigned_integral (C++20)
floating_point (C++20)
swappableswappable_with (C++20)(C++20)
destructible (C++20)
constructible_from (C++20)
default_initializable (C++20)
move_constructible (C++20)
copy_constructible (C++20)
assignable_from (C++20)

Comparison concepts
equality_comparableequality_comparable_with (C++20)(C++20)
totally_orderedtotally_ordered_with (C++20)(C++20)
Object concepts
movable (C++20)
copyable (C++20)
semiregular (C++20)
regular (C++20)
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invocableregular_invocable (C++20)(C++20)
predicate (C++20)
relation (C++20)
equivalence_relation (C++20)
strict_weak_order (C++20)

Exposition-only concepts
boolean-testable (C++20)

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Defined in header`<concepts>`
template<class T> concept swappable= requires(T& a, T& b){ ranges::swap(a, b); };	(1)	(since C++20)
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)); 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)); };	(2)	(since C++20)

The conceptswappable<T> specifies that lvalues of typeT are swappable.

The conceptswappable_with<T, U> specifies that expressions of the type and value category encoded byT andU are swappable with each other.swappable_with<T, U> is satisfied only if a call toranges::swap(t, u) exchanges the value oft andu, that is, given distinct objectst2 equal tot andu2 equal tou, after evaluating eitherranges::swap(t, u) orranges::swap(u, t),t2 is equal tou andu2 is equal tot.