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

NAME
     std::ranges::in_in_out_result - std::ranges::in_in_out_result

Synopsis
	Defined in header <algorithm>
	template< class I1, class I2, class O >  (since C++20)
	struct in_in_out_result;

	ranges::in_in_out_result  is  a  class	template  that provides a way to
     store three
	iterators 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
	I1, I2, O - the types of the iterators that the ranges::in_in_out_result
     stores.

	Data members

	Member name Definition
	in1	    a value (that is supposed to be an iterator) of type I1.
		    (public member object)
	in2	    a value (that is supposed to be an iterator) of type I2.
		    (public member object)
	out	    a value (that is supposed to be an iterator) of type O.
		    (public member object)

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

Member functions
     std::ranges::in_in_out_result::operator in_in_out_result<II1, II2, OO>

	template<class II1, class II2, class OO>

	requires std::convertible_to<const I1&, II1> &&
		 std::convertible_to<const I2&, II2> && 	     (1)
		 std::convertible_to<const O&, OO>

	constexpr operator in_in_out_result<II1, II2, OO>() const &;
	template<class II1, class II2, class OO>

	requires std::convertible_to<I1, II1> &&
		 std::convertible_to<I2, II2> &&		     (2)
		 std::convertible_to<O, OO>

	constexpr operator in_in_out_result<II1, II2, OO>() &&;

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

	1) Equivalent to return {in1, in2, out};.
	2)    Equivalent    to	  return    {std::move(in1),	 std::move(in2),
     std::move(out)};.

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

	      Algorithm functions
	ranges::transform		  applies  a function to a range of ele-
     ments
	(C++20) 			 (niebloid)
	ranges::merge			 merges two sorted ranges
	(C++20) 			 (niebloid)
	ranges::set_union		 computes the union of two sets
	(C++20) 			 (niebloid)
	ranges::set_intersection	 computes the intersection of two sets
	(C++20) 			 (niebloid)
	ranges::set_symmetric_difference computes the symmetric  difference  be-
     tween two sets
	(C++20) 			 (niebloid)

Synopsis
      namespace std::ranges
      {
	  template<class I1, class I2, class O>
	  struct in_in_out_result
	  {
	      [[no_unique_address]] I1 in1;
	      [[no_unique_address]] I2 in2;
	      [[no_unique_address]] O  out;

	      template<class II1, class II2, class OO>
	      requires std::convertible_to<const I1&, II1> &&
		       std::convertible_to<const I2&, II2> &&
		       std::convertible_to<const O&, OO>
	      constexpr operator in_in_out_result<II1, II2, OO>() const &
	      {
		  return {in1, in2, out};
	      }

	      template<class II1, class II2, class OO>
	      requires std::convertible_to<I1, II1> &&
		       std::convertible_to<I2, II2> &&
		       std::convertible_to<O, OO>
	      constexpr operator in_in_out_result<II1, II2, OO>() &&
	      {
		  return {std::move(in1), std::move(in2), std::move(out)};
	      }
	  };
      }

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 <iostream>
      #include <iterator>
      #include <ranges>

      void print(auto rem, auto first, auto last)
      {
	  for (std::cout << rem << ": "; first != last; ++first)
	      std::cout << *first << ' ';
	  std::cout << '\n';
      }

      int main()
      {
	  constexpr static auto in1 = {1, 2, 3, 4, 5, 5};
	  constexpr static auto in2 = {3, 4, 5, 6, 7};
	  std::array<int, std::size(in1) + std::size(in2)> out;

	  const auto result = std::ranges::merge(in1, in2, out.begin());
	  print("in1", in1.begin(), result.in1);
	  print("in2", in2.begin(), result.in2);
	  print("out", out.begin(), result.out);
      }

Output:
      in1: 1 2 3 4 5 5
      in2: 3 4 5 6 7
      out: 1 2 3 3 4 4 5 5 5 6 7

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...n_out_result(3)
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