std::unordered_set::swap

From cppreference.com

void swap( unordered_set& other );
(since C++11)
(until C++17)
void swap( unordered_set& other ) noexcept(/* see below */);
(since C++17)

Exchanges the contents of the container with those of other. Does not invoke any move, copy, or swap operations on individual elements.

All iterators and references remain valid. The past-the-end iterator is invalidated.

The Hash and KeyEqual objects must be Swappable, and they are exchanged using unqualified calls to non-member swap.

If std::allocator_traits<allocator_type>::propagate_on_container_swap::value is true, then the allocators are exchanged using an unqualified call to non-member swap. Otherwise, they are not swapped (and if get_allocator() != other.get_allocator(), the behavior is undefined). (since C++11)

Parameters

other - container to exchange the contents with

Return value

(none)

Exceptions

Any exception thrown by the swap of the Hash or KeyEqual objects.

(until C++17)
noexcept specification:
noexcept(std::allocator_traits<Allocator>::is_always_equal::value

&& std::is_nothrow_swappable<Hash>::value

&& std::is_nothrow_swappable<KeyEqual>::value)
(since C++17)

Complexity

Constant.

See also

specializes the std::swap algorithm
(function template)