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std::rotate_copy(3)	      C++ Standard Libary	   std::rotate_copy(3)

NAME
       std::rotate_copy	- std::rotate_copy

Synopsis
	  Defined in header <algorithm>
	  template< class ForwardIt, class OutputIt >

	  OutputIt rotate_copy(	ForwardIt first, ForwardIt
	  n_first,						   (1) (const-
       expr since C++20)

				ForwardIt last,	OutputIt d_first
	  );
	  template< class ExecutionPolicy,

		    class ForwardIt1, class ForwardIt2 >
	  ForwardIt2 rotate_copy( ExecutionPolicy&& policy,
				  ForwardIt1  first, ForwardIt1	    (2)	(since
       C++17)
	  n_first,

				  ForwardIt1 last, ForwardIt2
	  d_first );

	  1) Copies the	elements from the  range  [first,  last),  to  another
       range beginning at
	  d_first in such a way, that the element *(n_first) becomes the first
       element of the
	  new range and	*(n_first - 1) becomes the last	element.
	  2) Same as (1), but executed according to policy.
	  This overload	participates in	overload resolution only if

	  std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>  is	 true.
       (until
										    C++20)
	  std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>  is
       true. (since
										    C++20)

	  If any of the	following conditions is	satisfied, the behavior	is un-
       defined:

	    * [first, n_first) or [n_first, last) is not a valid range.
	    * The source and destination ranges	overlap.

Parameters
	  first, last -	the range of elements to copy
	  n_first     -	an iterator to an element in [first, last) that	should
       appear at the
			beginning of the new range
	  d_first     -	beginning of the destination range
	  policy       - the execution policy to use. See execution policy for
       details.

Type requirements
	  -
	  ForwardIt, ForwardIt1, ForwardIt2 must meet the requirements of
	  LegacyForwardIterator.
	  -
	  OutputIt must	meet the requirements of LegacyOutputIterator.

Return value
	  Output iterator to the element past the last element copied.

Complexity
	  Exactly std::distance(first, last) assignments.

Exceptions
	  The overload with a template parameter named ExecutionPolicy reports
       errors as
	  follows:

	    * If execution of a	function invoked  as  part  of	the  algorithm
       throws an exception
	      and ExecutionPolicy is one of the	standard policies, std::termi-
       nate is called.
	      For  any	other ExecutionPolicy, the behavior is implementation-
       defined.
	    * If the algorithm fails to	 allocate  memory,  std::bad_alloc  is
       thrown.

Possible implementation
	  See also the implementations in libstdc++, libc++, and MSVC STL.

	  template<class ForwardIt, class OutputIt>
	  constexpr // since C++20
	  OutputIt rotate_copy(ForwardIt first,	ForwardIt n_first,
			       ForwardIt last, OutputIt	d_first)
	  {
	      d_first =	std::copy(n_first, last, d_first);
	      return std::copy(first, n_first, d_first);
	  }

Example
       // Run this code

	#include <algorithm>
	#include <iostream>
	#include <iterator>
	#include <vector>

	int main()
	{
	    std::vector<int> src{1, 2, 3, 4, 5};
	    std::vector<int> dest(src.size());
	    auto pivot = std::find(src.begin(),	src.end(), 3);

	    std::rotate_copy(src.begin(), pivot, src.end(), dest.begin());
	    for	(int i : dest)
		std::cout << i << ' ';
	    std::cout << '\n';

	    // copy the	rotation result	directly to the	std::cout
	    pivot = std::find(dest.begin(), dest.end(),	1);
	    std::rotate_copy(dest.begin(), pivot, dest.end(),
			     std::ostream_iterator<int>(std::cout, " "));
	    std::cout << '\n';
	}

Output:
	3 4 5 1	2
	1 2 3 4	5

See also
	  rotate	      rotates the order	of elements in a range
			      (function	template)
	  ranges::rotate_copy copies and rotate	a range	of elements
	  (C++20)	      (niebloid)

http://cppreference.com		  2024.06.10		   std::rotate_copy(3)

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