std::experimental::optional::swap

 

C++

Language

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Utilities library

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Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals 2 TS)

Extensions for parallelism (parallelism TS)

Concepts (concepts TS)

Extensions for concurrency (concurrency TS)

 

Library fundamentals

experimental::optional

experimental::any

experimental::basic_string_view

experimental::sample

experimental::apply

experimental::search

experimental::default_searcher experimental::make_default_searcher

experimental::boyer_moore_searcher experimental::make_boyer_moore_searcher

experimental::boyer_moore_horspool_searcher experimental::make_boyer_moore_horspool_searcher

type-erased and polymorphic allocators

variable templates for type traits

 

std::experimental::optional

Member functions

optional::optional

optional::~optional

optional::operator=

Observers

optional::operator->optional::operator*

optional::operator bool

optional::value

optional::value_or

Modifiers

optional::emplace

optional::swap

Non-member functions

operator==operator<

make_optional

swap

Helper classes

hash

nullopt_t

in_place_t

bad_optional_access

Helper objects

nullopt

in_place

 

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.

Parameters

other

-

the optional object to exchange the contents with

Return value

(none)

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.

See also

std::swap(std::experimental::optional)

specializes the std::swap algorithm (function)