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

 

C++

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Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

Technical specifications

Symbols index

External libraries

 

Algorithm library

Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
Non-modifying sequence operations     Batch operations for_each for_each_n (C++17) Search operations all_ofany_ofnone_of (C++11)(C++11)(C++11) countcount_if mismatch equal findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n Modifying sequence operations Copy operations copycopy_if (C++11) copy_backward copy_n (C++11) move (C++11) move_backward (C++11) Swap operations swap iter_swap swap_ranges Transformation operations replacereplace_if transform replace_copyreplace_copy_if Generation operations fill fill_n generate generate_n Removing operations removeremove_if unique remove_copyremove_copy_if unique_copy Order-changing operations reverse reverse_copy rotate rotate_copy random_shuffleshuffle (until C++17)(C++11) shift_leftshift_right (C++20)(C++20) Sampling operations sample (C++17)	Sorting and related operations Partitioning operations partition partition_copy (C++11)     stable_partition is_partitioned (C++11)     partition_point (C++11) Sorting operations sort stable_sort partial_sort partial_sort_copy is_sorted (C++11) is_sorted_until (C++11) nth_element Binary search operations (on partitioned ranges) lower_bound upper_bound equal_range binary_search Set operations (on sorted ranges) includes set_union set_intersection          set_difference set_symmetric_difference Merge operations (on sorted ranges) merge inplace_merge Heap operations push_heap pop_heap make_heap sort_heap is_heap (C++11) is_heap_until (C++11) Minimum/maximum operations max min minmax (C++11) clamp (C++17) max_element min_element minmax_element (C++11) Lexicographical comparison operations lexicographical_compare lexicographical_compare_three_way (C++20) Permutation operations next_permutation prev_permutation is_permutation (C++11)	Execution policies (C++17) is_execution_policy (C++17) execution::seqexecution::parexecution::par_unseqexecution::unseq (C++17)(C++17)(C++17)(C++20) execution-policy (exposition only*)(C++26) execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policyexecution::parallel_unsequenced (C++17)(C++17)(C++17)(C++20) Numeric operations iota (C++11) inner_product      reduce (C++17) accumulate adjacent_difference transform_reduce (C++17) partial_sum inclusive_scan (C++17)     exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17) Specialized <memory> algorithms Specialized <random> algorithms ranges::generate_random (C++26) C library qsort bsearch

 

Constrained algorithms

All names in this menu belong to namespace std::ranges

Non-modifying sequence operations

all_ofany_ofnone_of for_each for_each_n    countcount_if adjacent_find mismatch equal lexicographical_compare    containscontains_subrange (C++23)(C++23) findfind_iffind_if_not find_lastfind_last_iffind_last_if_not (C++23)(C++23)(C++23)   find_end find_first_of search search_n starts_with (C++23) ends_with (C++23)

Fold operations (Helper templates)

fold_left (C++23) fold_left_first (C++23)   fold_right (C++23) fold_right_last (C++23)   fold_left_with_iter (C++23) fold_left_first_with_iter (C++23)

Modifying sequence operations

copycopy_if copy_n copy_backward    move move_backward shift_leftshift_right (C++23)(C++23)   fill fill_n generate generate_n    transform swap_ranges    shuffle sample removeremove_if replacereplace_if reverse rotate remove_copyremove_copy_if    unique replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy

Partitioning operations

is_partitioned    partition_point    partition    partition_copy    stable_partition

Sorting operations

is_sorted is_sorted_until     sort stable_sort         partial_sort       nth_element partial_sort_copy

Binary search operations (on sorted ranges)

lower_bound         upper_bound         binary_search      equal_range

Set operations (on sorted ranges)

merge inplace_merge       set_difference set_intersection    set_union          includes set_symmetric_difference

Heap operations

is_heap is_heap_until       make_heap           sort_heap push_heap pop_heap

Minimum/maximum operations

max max_element         min min_element         minmax minmax_element     clamp

Permutation operations

is_permutation      next_permutation    prev_permutation

Numeric operations iota (C++23)             Specialized <random> algorithms generate_random (C++26)

Specialized <memory> algorithms

construct_at    destroy destroy_n destroy_at uninitialized_copy    uninitialized_move uninitialized_fill uninitialized_copy_n    uninitialized_move_n uninitialized_fill_n uninitialized_default_construct uninitialized_default_construct_n uninitialized_value_construct uninitialized_value_construct_n

Return types

in_fun_result in_in_result in_found_result    in_out_result in_in_out_result    in_out_out_result    min_max_result out_value_result (C++23) in_value_result (C++23)

 

Defined in header <algorithm>
Call signature
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> move( I first, S last, O d_first );	(1)	(since C++20)
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> move( R&& r, O d_first );	(2)	(since C++20)
template< /*execution-policy*/ Ep, std::random_access_iterator I, std::sized_sentinel_for<I> S, std::random_access_iterator O, std::sized_sentinel_for<O> OutS > requires std::indirectly_movable<I, O> ranges::move_result<I, O> move( Ep&& policy, I first, S last, O d_first, OutS d_last );	(3)	(since C++26)
template< /*execution-policy*/ Ep, /*sized-random-access-range*/ R, /*sized-random-access-range*/ OutR > requires std::indirectly_movable<ranges::iterator_t<R>, ranges::iterator_t<OutR>> ranges::move_result<ranges::borrowed_iterator_t<R>, ranges::borrowed_iterator_t<OutR>> move( Ep&& policy, R&& r, OutR&& d_r );	(4)	(since C++26)
Helper types
template< class I, class O > using move_result = ranges::in_out_result<I, O>;	(5)	(since C++20)

For the definition of /*execution-policy*/, see this page; for the definition of /*sized-random-access-range*/, see this page.

Moves the elements in the source range [first, last) or r to the destination range.

1,2) Moves all elements in the source range, starting from the beginning and proceeding to the end.

1) The destination range is [d_first, ranges::next(d_first, ranges::distance(first, last))).

2) The destination range is [d_first, ranges::next(d_first, ranges::distance(r))).

If d_first is in the source range, the behavior is undefined.

3,4) Same as (1,2), but the move order is determined by policy. If the destination range is exhausted before reaching the end of the source range, the remaining elements in the source range will not be moved.

3) The destination range is [d_first, d_last).

4) The destination range is d_r.

If the source and destination ranges overlap, the behavior is undefined.

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.

Parameters

first, last	-	the iterator-sentinel pair defining the source range
r	-	the source range
d_first	-	the beginning of the destination range
d_last	-	the sentinel of the destination range
d_r	-	the destination range
policy	-	the execution policy to use

Return value

A ranges::move_result object where:

• The data member in holds the an iterator past the last moved element in the source range, or an iterator to the beginning of the source range if no element is moved.
• The data member out holds and an iterator past the last move-assigned element in the destination range, or an iterator to the beginning of the destination range if no element is moved.

Complexity

Given

• \(\scriptsize N_1\)N1 as ranges::distance(first, last) or ranges::distance(r), and
• \(\scriptsize N_2\)N2 as ranges::distance(d_first, d_last) or ranges::distance(d_r):

1,2) Exactly \(\scriptsize N_1\)N1 assignments.

3,4) Exactly \(\scriptsize \min(N_1,N_2)\)min(N1,N2) assignments.

Exceptions

3,4) During the execution process:

• If the temporary memory resources required for parallelization are not available, std::bad_alloc is thrown.
• If an uncaught exception is thrown while accessing objects via an algorithm argument, the behavior is determined by the execution policy (for standard policies, std::terminate is invoked).

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)); } template<ranges::forward_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::next(ranges::begin(r), ranges::end(r)), std::move(result)); } }; inline constexpr move_fn move{};

Example

The following code moves thread objects (which themselves are not copyable) from one container to another.

Run this code

#include <algorithm>
#include <chrono>
#include <iostream>
#include <iterator>
#include <list>
#include <thread>
#include <vector>

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));
}

Output:

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

See also

move (C++11)	moves a range of elements to a new location (function template)
ranges::move_backward (C++20)	moves a range of elements to a new location in backwards order (algorithm function object)
ranges::copyranges::copy_if (C++20)(C++20)	copies a range of elements to a new location (algorithm function object)
ranges::copy_backward (C++20)	copies a range of elements in backwards order (algorithm function object)
move (C++11)	converts the argument to an xvalue (function template)