31 Input/output library [input.output]

31.8 String-based streams [string.streams]

31.8.2 Class template basic_stringbuf [stringbuf] Assignment and swap [stringbuf.assign]

basic_stringbuf& operator=(basic_stringbuf&& rhs);
Effects: After the move assignment *this has the observable state it would have had if it had been move constructed from rhs (see [stringbuf.cons]).
Returns: *this.
void swap(basic_stringbuf& rhs) noexcept(see below);
Preconditions: allocator_traits<Allocator>​::​propagate_on_container_swap​::​value is true or get_allocator() == rhs.get_allocator() is true.
Effects: Exchanges the state of *this and rhs.
Remarks: The exception specification is equivalent to:
allocator_traits<Allocator>​::​propagate_on_container_swap​::​value ||
template<class charT, class traits, class Allocator> void swap(basic_stringbuf<charT, traits, Allocator>& x, basic_stringbuf<charT, traits, Allocator>& y) noexcept(noexcept(x.swap(y)));
Effects: Equivalent to x.swap(y).