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std::expected::swap(3)	      C++ Standard Libary	std::expected::swap(3)

NAME
       std::expected::swap - std::expected::swap

Synopsis
	  constexpr  void  swap(  expected&  other  ) noexcept(/*see below*/);
       (since C++23)

	  Swaps	the contents with those	of other.

	    * If both this->has_value()	and other.has_value() are true:

	    * If T is (possibly	cv-qualified) void, no effects.
	    * Otherwise, equivalent to using std::swap;	swap(**this, *other);.
	    * If  both	this->has_value()  and	other.has_value()  are	false,
       equivalent to
	      using std::swap; swap(this->error(), other.error());.
	    *  If  this->has_value()  is  false	and other.has_value() is true,
       calls
	      other.swap(*this).
	    * If this->has_value() is true and other.has_value() is false,

	    * If T is (possibly	cv-qualified) void, let	 unex  be  the	member
       that represents the
	      unexpected value,	equivalent to:

	std::construct_at(std::addressof(unex),	std::move(other.unex));
	std::destroy_at(std::addressof(other.unex));

	    *  Otherwise,  let	val be the member that represents the expected
       value and unex be
	      the member that represents the unexpected	value, equivalent to:

	if constexpr (std::is_nothrow_move_constructible_v<E>) {
	    E temp(std::move(other.unex));
	    std::destroy_at(std::addressof(other.unex));
	    try	{
		std::construct_at(std::addressof(other.val), std::move(val));
		std::destroy_at(std::addressof(val));
		std::construct_at(std::addressof(unex),	std::move(temp));
	    } catch(...) {
		std::construct_at(std::addressof(other.unex),
       std::move(temp));
		throw;
	    }
	} else {
	    T temp(std::move(val));
	    std::destroy_at(std::addressof(val));
	    try	{
		std::construct_at(std::addressof(unex),
       std::move(other.unex));
		std::destroy_at(std::addressof(other.unex));
		std::construct_at(std::addressof(other.val), std::move(temp));
	    } catch(...) {
		std::construct_at(std::addressof(val), std::move(temp));
		throw;
	    }
	}

	    * In  either  case,	 if  no	 exception  was	 thrown,  after	 swap,
       this->has_value() is
	      false, and other.has_value() is true.

	  This function	participates in	overload resolution only if

	    *  either  T  is  (possibly	 cv-qualified)	void, or std::is_swap-
       pable_v<T> is true, and
	    * std::is_swappable_v<E> is	true, and
	    * either T is (possibly cv-qualified) void,	 or  std::is_move_con-
       structible_v<T> is
	      true, and
	    * std::is_move_constructible_v<E> is true, and
	    * at least one of the following is true:
		 * T is	(possibly cv-qualified)	void
		 * std::is_nothrow_move_constructible_v<T>
		 * std::is_nothrow_move_constructible_v<E>

Parameters
	  other	- the optional object to exchange the contents with

Return value
	  (none)

Exceptions
	  If T is (possibly cv-qualified) void,
	  noexcept specification:
	  noexcept(

	      std::is_nothrow_move_constructible_v<E> && std::is_nothrow_swap-
       pable_v<E>

	  )
	  Otherwise,
	  noexcept specification:
	  noexcept(

	      std::is_nothrow_move_constructible_v<T> && std::is_nothrow_swap-
       pable_v<T> &&
	      std::is_nothrow_move_constructible_v<E> && std::is_nothrow_swap-
       pable_v<E>

	  )

	  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  or
       T's and E's move
	  constructor,	whichever  is called. For both *this and other,	if the
       object contained
	  an expected value, it	is left	containing an expected value, and  the
       other way round.

Example
	   This	section	is incomplete
	   Reason: no example

See also
	  swap(std::expected) specializes the std::swap	algorithm
	  (C++23)	      (function)

Categories:
	    * conditionally noexcept
	    * Todo no example

http://cppreference.com		  2024.06.10		std::expected::swap(3)

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