std::ranges::move, std::ranges::move_result - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| Call signature | ||
| 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 ); | (1) | (since C++20) |
| 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 ); | (2) | (since C++20) |
| Helper types | ||
| template< class I, class O > using move_result = ranges::in_out_result<I, O>; | (3) | (since C++20) |
Moves the elements in the range, defined by
[first,last), to another range beginning at result. The behavior is undefined if result is within the range[first,last). In such a case, ranges::move_backward may be used instead.Same as (1), but uses r as the source range, as if using ranges::begin(r) as first, and ranges::end(r) as last.
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 algorithm function objects (informally known as niebloids), that is:
- Explicit template argument lists cannot be specified when calling any of them.
- None of them are visible to argument-dependent lookup.
- When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.
Contents
[edit] Parameters
| first, last | - | the iterator-sentinel pair defining the range of elements to move |
|---|---|---|
| r | - | the range of the elements to move |
| result | - | the beginning of the destination range |
[edit] Return value
{last, result + N}, where
[edit] Complexity
Exactly N move assignments.
[edit] 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).
[edit] Possible implementation
struct move_fn { template<std::input_iterator I, std::sentinel_for 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, O> constexpr ranges::move_result<ranges::borrowed_iterator_t, O> operator()(R&& r, O result) const { return (*this)(ranges::begin(r), ranges::end(r), std::move(result)); } }; inline constexpr move_fn move {};
[edit] Example
The following code moves thread objects (which themselves are non copyable) from one container to another.
Output:
thread with n=400ms ended thread with n=600ms ended thread with n=800ms ended