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std::experimental::optional::swap

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Technical specifications
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals 2 TS)
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Special mathematical functions (special math TR)
 
 
 
void swap( optional& other );
(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 other un), the contained value of un is direct-initialized from std::move(*in), followed by destruction of the contained value of in as if by in.val->T::~T(). After this call, in does not contain a value un 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(is_nothrow_move_constructible<T>::value &&
           noexcept(swap(declval<T&>(), 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) [edit]