std::experimental::optional<T>::swap
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< cpp | experimental | optional
void swap( optional& other ) noexcept(/* see below */); |
(library fundamentals TS) | |
Swaps the contents with those of other.
- If neither *this nor other contain a value, the function has no effect.
- If only one of *this and other contains a value (let's call this object
in
and the otherun
), the contained value ofun
is direct-initialized from std::move(*in), followed by destruction of the contained value ofin
as if by in.val->T::~T(). After this call,in
does not contain a valueun
contains a value.
- If both *this and other contain values, the contained values are exchanged by calling using std::swap; swap(**this, *other).
T
lvalues must satisfy Swappable.
Contents |
[edit] Parameters
other | - | the optional object to exchange the contents with
|
[edit] Return value
(none)
[edit] Exceptions
noexcept specification:
noexcept(std::is_nothrow_move_constructible<T>::value &&
noexcept(swap(std::declval<T&>(), std::declval<T&>())))
noexcept(swap(std::declval<T&>(), std::declval<T&>())))
In the case of thrown exception, the states of the contained values of *this and other are determined by the exception safety guarantees of swap
of type T
or T
's move constructor, whichever is called. For both *this and other, if the object contained a value, it is left containing a value, and the other way round.
[edit] See also
specializes the std::swap algorithm (function) |