std::ranges::move, std::ranges::move_result

template< std::input_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O >
requires  std::indirectly_movable<I, O>
constexpr move_result<I, O>
          move( I first, S last, O result );

template< ranges::input_range R, std::weakly_incrementable O >
requires  std::indirectly_movable<ranges::iterator_t<R>, O>
constexpr move_result<ranges::borrowed_iterator_t<R>, O>
          move( R&& r, O result );

template< class I, class O >
  using move_result = ranges::in_out_result<I, O>;

The elements in the moved-from range will still contain valid values of the appropriate type, but not necessarily the same values as before the move.

The function-like entities described on this page are niebloids, that is:

• Explicit template argument lists may not be specified when calling any of them.
• None of them is visible to argument-dependent lookup.
• When one of them is found by normal unqualified lookup for the name to the left of the function-call operator, it inhibits argument-dependent lookup.

In practice, they may be implemented as function objects, or with special compiler extensions.

Parameters

Return value

{last, result + N}, where.

Complexity

Exactly N move assignments.

Notes

When moving overlapping ranges, ranges::move is appropriate when moving to the left (beginning of the destination range is outside the source range) while ranges::move_backward is appropriate when moving to the right (end of the destination range is outside the source range).

Possible implementation

struct move_fn {
  template<std::input_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O>
    requires std::indirectly_movable<I, O>
      constexpr ranges::move_result<I, O>
        operator()( I first, S last, O result ) const {
          for (; first != last; ++first, ++result)
            *result = ranges::iter_move(first);
          return {std::move(first), std::move(result)};
        }
  template<ranges::input_range R, std::weakly_incrementable O>
    requires std::indirectly_movable<ranges::iterator_t<R>, O>
      constexpr ranges::move_result<ranges::borrowed_iterator_t<R>, O>
        operator()( R&& r, O result ) const {
          return (*this)(ranges::begin(r), ranges::end(r), std::move(result));
        }
};
 
inline constexpr move_fn move{};

Example

#include <algorithm>
#include <iostream>
#include <vector>
#include <list>
#include <iterator>
#include <thread>
#include <chrono>
using namespace std::literals::chrono_literals;
 
void f(std::chrono::milliseconds n)
{
    std::this_thread::sleep_for(n);
    std::cout << "thread with n=" << n.count() << "ms ended" << std::endl;
}
 
int main()
{
    std::vector<std::jthread> v;
    v.emplace_back(f, 400ms);
    v.emplace_back(f, 600ms);
    v.emplace_back(f, 800ms);
 
    std::list<std::jthread> l;
 
    // std::ranges::copy() would not compile, because std::jthread is non-copyable
    std::ranges::move(v, std::back_inserter(l));
}

thread with n=400ms ended
thread with n=600ms ended
thread with n=800ms ended

See also