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

NAME
     std::ranges::in_out_out_result - std::ranges::in_out_out_result

Synopsis
	Defined in header <algorithm>
	template< class I, class O1, class O2 >  (since C++20)
	struct in_out_out_result;

	ranges::in_out_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
	I,  O1, O2 - the types of the objects that the ranges::in_out_out_result
     stores.

	Data members

	Member name Definition
	in	    a value (that is supposed to be an iterator) of type I.
		    (public member object)
	out1	    a value (that is supposed to be an iterator) of type O1.
		    (public member object)
	out2	    a value (that is supposed to be an iterator) of type O2.
		    (public member object)

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

Member functions
     std::ranges::in_out_out_result::operator in_out_out_result<II, OO1, OO2>

	template<class II, class OO1, class OO2>

	requires std::convertible_to<const I&, II> &&
		 std::convertible_to<const O1&, OO1> && 	      (1)
		 std::convertible_to<const O2&, OO2>

	constexpr operator in_out_out_result<II, OO1, OO2>() const &;
	template<class II, class OO1, class OO2>

	requires std::convertible_to<I, II> &&
		 std::convertible_to<O1, OO1> &&		      (2)
		 std::convertible_to<O2, OO2>

	constexpr operator in_out_out_result<II, OO1, OO2>() &&;

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

	1) Equivalent to return {in, out1, out2};.
	2)     Equivalent    to    return    {std::move(in),	std::move(out1),
     std::move(out2)};.

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

	      Algorithm functions
	ranges::partition_copy	copies	a  range  dividing the elements into two
     groups
	(C++20) 	       (niebloid)

Synopsis
      namespace std::ranges
      {
	  template<class I, class O1, class O2>
	  struct in_out_out_result
	  {
	      [[no_unique_address]] I  in;
	      [[no_unique_address]] O1 out1;
	      [[no_unique_address]] O2 out2;

	      template<class II, class OO1, class OO2>
	      requires std::convertible_to<const I&, II> &&
		       std::convertible_to<const O1&, OO1> &&
		       std::convertible_to<const O2&, OO2>
	      constexpr operator in_out_out_result<II, OO1, OO2>() const &
	      {
		  return {in, out1, out2};
	      }

	      template<class II, class OO1, class OO2>
	      requires std::convertible_to<I, II> &&
		       std::convertible_to<O1, OO1> &&
		       std::convertible_to<O2, OO2>
	      constexpr operator in_out_out_result<II, OO1, OO2>() &&
	      {
		  return {std::move(in), std::move(out1), std::move(out2)};
	      }
	  };
      }

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 <cctype>
      #include <iostream>
      #include <iterator>
      #include <ranges>
      #include <string_view>

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

      int main()
      {
	  constexpr std::string_view in {"TvEeNcStOoRr"};
	  std::array<char, in.size()> o1, o2;

	  const auto result = std::ranges::partition_copy(in, o1.begin(), o2.be-
     gin(),
	      [](char c) { return std::isupper(c); });

	  print("in", in.begin(), result.in);
	  print("o1", o1.begin(), result.out1);
	  print("o2", o2.begin(), result.out2);
      }

Output:
      in: { T v E e N c S t O o R r }
      o1: { T E N S O R }
      o2: { v e c t o r }

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..._out_result(3)
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