30 Input/output library [input.output]

30.8 String-based streams [string.streams]

30.8.2 Class template basic_­stringbuf [stringbuf]

30.8.2.2 Assign 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);
Effects: Exchanges the state of *this and rhs.
template<class charT, class traits, class Allocator> void swap(basic_stringbuf<charT, traits, Allocator>& x, basic_stringbuf<charT, traits, Allocator>& y);
Effects: As if by x.swap(y).