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std::ranges...value_result(3)  C++ Standard Libary std::ranges...value_result(3)

NAME
     std::ranges::out_value_result - std::ranges::out_value_result

Synopsis
	Defined in header <algorithm>
	template< class O, class T >   (since C++23)
	struct out_value_result;

	ranges::out_value_result  is  a  class	template  that provides a way to
     store an
	iterator and a value as a single unit.

	This class template has no base classes or declared members  other  than
     those shown
	below. Thus it is suitable for use with structured bindings.

	All  special  member functions of this class template are implicitly de-
     clared, which
	makes specializations be aggregate classes, and propagate triviality,
	potentially-throwing-ness, and constexpr-ness  of  corresponding  opera-
     tions on data
	members.

Template parameters
	O,  T  -  the  types  of  the  objects that the ranges::out_value_result
     stores.

	Data members

	Member name Definition
	out	    a value (that is supposed to be an iterator) of type O.
		    (public member object)
	value	    a value (that is supposed to be a stored value) of type T.
		    (public member object)

	All these members are declared with [[no_unique_address]] attribute.

Member functions
     std::ranges::out_value_result::operator out_value_result<O2, T2>

	template<class O2, class T2>

	requires convertible_to<const O&, O2> &&  convertible_to<const	T&,  T2>
     (1)

	constexpr operator out_value_result<O2, T2>() const &;
	template<class O2, class T2>

	requires     convertible_to<O,	   O2>	  &&	convertible_to<T,    T2>
     (2)

	constexpr operator out_value_result<O2, T2>() &&;

	Converts *this to the result by constructing every data  member  of  the
     result from
	the corresponding member of *this.

	1) Equivalent to return {out, value};.
	2) Equivalent to return {std::move(out), std::move(value)};.

Standard library
	The following standard library functions use ranges::out_value_result as
     the return
	type:

	      Algorithm functions
	ranges::iota  fills  a	range with successive increments of the starting
     value
	(C++23)      (niebloid)

Synopsis
      namespace std::ranges
      {
	  template<class O, class T>
	  struct out_value_result
	  {
	      [[no_unique_address]] O out;
	      [[no_unique_address]] T value;

	      template<class O2, class T2>
	      requires convertible_to<const O&, O2> && convertible_to<const  T&,
     T2>
	      constexpr operator out_value_result<O2, T2>() const &
	      {
		  return {out, value};
	      }

	      template<class O2, class T2>
	      requires convertible_to<O, O2> && convertible_to<T, T2>
	      constexpr operator out_value_result<O2, T2>() &&
	      {
		  return {std::move(out), std::move(value)};
	      }
	  };
      }

Notes
	Each  standard	library  algorithm that uses this family of return types
     declares a new
	alias type, e.g. using merge_result = in_in_out_result<I1, I2, O>;.

	The names for such aliases are formed by adding the suffix "_result"  to
     the
	algorithm's name. So, the return type of std::ranges::merge can be named
     as
	std::ranges::merge_result.

	Unlike std::pair and std::tuple, this class template has data members of
     meaningful
	names.

Example
     // Run this code

      #include <algorithm>
      #include <array>
      #include <cassert>
      #include <numeric>
      #include <ranges>

      int main()
      {
	  std::array<int, 4> a{};
	  constexpr std::array expected{2, 3, 4, 5};
	  const auto result = std::ranges::iota(a, 2);
	  assert(std::ranges::distance(a.cbegin(), result.out) == 4);
	  assert(result.value == 6);
	  assert(a == expected);
      }

See also
	pair	implements binary tuple, i.e. a pair of values
		(class template)
	tuple	 implements fixed size container, which holds elements of possi-
     bly different
	(C++11) types
		(class template)

http://cppreference.com 	   2024.06.10	   std::ranges...value_result(3)
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