Difference between revisions of "cpp/algorithm/ranges/rotate copy"
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{{cpp/algorithm/ranges/navbar}} | {{cpp/algorithm/ranges/navbar}} | ||
{{dcl begin}} | {{dcl begin}} | ||
| − | {{dcl header | algorithm}} | + | {{dcl header|algorithm}} |
| − | {{dcl h | Call signature}} | + | {{dcl h|Call signature}} |
| − | {{dcl | num=1 | since=c++20 |1= | + | {{dcl|num=1|since=c++20|1= |
| − | template< std::forward_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O > | + | template< std::forward_iterator I, std::sentinel_for<I> S, |
| − | requires | + | std::weakly_incrementable O > |
| + | requires std::indirectly_copyable<I, O> | ||
constexpr rotate_copy_result<I, O> | constexpr rotate_copy_result<I, O> | ||
| − | + | rotate_copy( I first, I middle, S last, O result ); | |
}} | }} | ||
| − | {{dcl | num=2 | since=c++20 |1= | + | {{dcl|num=2|since=c++20|1= |
template< ranges::forward_range R, std::weakly_incrementable O > | template< ranges::forward_range R, std::weakly_incrementable O > | ||
| − | requires | + | requires std::indirectly_copyable<ranges::iterator_t<R>, O> |
constexpr rotate_copy_result<ranges::borrowed_iterator_t<R>, O> | constexpr rotate_copy_result<ranges::borrowed_iterator_t<R>, O> | ||
| − | + | rotate_copy( R&& r, ranges::iterator_t<R> middle, O result ); | |
}} | }} | ||
| − | {{dcl h | Helper types}} | + | {{dcl h|Helper types}} |
| − | {{dcl | num=3 | since=c++20 |1= | + | {{dcl|num=3|since=c++20|1= |
template< class I, class O > | template< class I, class O > | ||
| − | + | using rotate_copy_result = in_out_result<I, O>; | |
}} | }} | ||
{{dcl end}} | {{dcl end}} | ||
| − | @1@ Copies the elements from the source range {{ | + | @1@ Copies the elements from the source range {{range|first|last}}, to the destination range beginning at {{c|result}} in such a way, that the element {{c|*middle}} becomes the first element of the destination range and {{c|*(middle - 1)}} becomes the last element. The result is that the destination range contains a ''left rotated'' copy of the source range. |
| − | @@ The behavior is undefined if either {{ | + | @@ The behavior is undefined if either {{range|first|middle}} or {{range|middle|last}} is not a valid range, or the source and destination ranges overlap. |
| − | @2@ Same as {{v|1}}, but uses {{ | + | @2@ Same as {{v|1}}, but uses {{c|r}} as the source range, as if using {{c|ranges::begin(r)}} as {{c|first}} and {{c|ranges::end(r)}} as {{c|last}}. |
{{cpp/ranges/niebloid}} | {{cpp/ranges/niebloid}} | ||
| Line 32: | Line 33: | ||
===Parameters=== | ===Parameters=== | ||
{{par begin}} | {{par begin}} | ||
| − | {{par | first, last | the source range of elements to copy from}} | + | {{par|first, last|the source range of elements to copy from}} |
| − | {{par | r | the source range of elements to copy from}} | + | {{par|r|the source range of elements to copy from}} |
| − | {{par | middle | the iterator to the element that should appear at the beginning of the destination range}} | + | {{par|middle|the iterator to the element that should appear at the beginning of the destination range}} |
| − | {{par | result | beginning of the destination range}} | + | {{par|result|beginning of the destination range}} |
{{par end}} | {{par end}} | ||
| Line 49: | Line 50: | ||
===Possible implementation=== | ===Possible implementation=== | ||
See also the implementations in [https://github.com/gcc-mirror/gcc/blob/14d8a5ae472ca5743016f37da2dd4770d83dea21/libstdc%2B%2B-v3/include/bits/ranges_algo.h#L1511-L1539 libstdc++] and [https://github.com/microsoft/STL/blob/472161105d596192194d4715ccad307c6c163b4a/stl/inc/algorithm#L4466-L4514 MSVC STL]. | See also the implementations in [https://github.com/gcc-mirror/gcc/blob/14d8a5ae472ca5743016f37da2dd4770d83dea21/libstdc%2B%2B-v3/include/bits/ranges_algo.h#L1511-L1539 libstdc++] and [https://github.com/microsoft/STL/blob/472161105d596192194d4715ccad307c6c163b4a/stl/inc/algorithm#L4466-L4514 MSVC STL]. | ||
| − | {{eq fun | 1= | + | {{eq fun|1= |
| − | struct rotate_copy_fn { | + | struct rotate_copy_fn |
| − | + | { | |
| + | template<std::forward_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O> | ||
requires std::indirectly_copyable<I, O> | requires std::indirectly_copyable<I, O> | ||
constexpr ranges::rotate_copy_result<I, O> | constexpr ranges::rotate_copy_result<I, O> | ||
| − | + | operator()(I first, I middle, S last, O result) const | |
| − | + | { | |
| − | + | auto c1 {ranges::copy(middle, std::move(last), std::move(result))}; | |
| − | + | auto c2 {ranges::copy(std::move(first), std::move(middle), std::move(c1.out))}; | |
| − | + | return {std::move(c1.in), std::move(c2.out)}; | |
| + | } | ||
| − | + | template<ranges::forward_range R, std::weakly_incrementable O> | |
requires std::indirectly_copyable<ranges::iterator_t<R>, O> | requires std::indirectly_copyable<ranges::iterator_t<R>, O> | ||
constexpr ranges::rotate_copy_result<ranges::borrowed_iterator_t<R>, O> | constexpr ranges::rotate_copy_result<ranges::borrowed_iterator_t<R>, O> | ||
| − | + | operator()(R&& r, ranges::iterator_t<R> middle, O result) const | |
| − | + | { | |
| − | + | return (*this)(ranges::begin(r), std::move(middle), | |
| − | + | ranges::end(r), std::move(result)); | |
| + | } | ||
}; | }; | ||
| − | inline constexpr rotate_copy_fn rotate_copy{}; | + | inline constexpr rotate_copy_fn rotate_copy {}; |
}} | }} | ||
===Example=== | ===Example=== | ||
{{example | {{example | ||
| − | + | |code= | |
#include <algorithm> | #include <algorithm> | ||
#include <iostream> | #include <iostream> | ||
| Line 87: | Line 91: | ||
std::ranges::rotate_copy(src, pivot, dest.begin()); | std::ranges::rotate_copy(src, pivot, dest.begin()); | ||
| − | for (int i : dest) | + | for (int i : dest) |
| + | std::cout << i << ' '; | ||
std::cout << '\n'; | std::cout << '\n'; | ||
| Line 95: | Line 100: | ||
std::cout << '\n'; | std::cout << '\n'; | ||
} | } | ||
| − | | output= | + | |output= |
3 4 5 1 2 | 3 4 5 1 2 | ||
1 2 3 4 5 | 1 2 3 4 5 | ||
| Line 102: | Line 107: | ||
===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/algorithm/ranges/dsc rotate}} | + | {{dsc inc|cpp/algorithm/ranges/dsc rotate}} |
| − | {{dsc inc | cpp/algorithm/ranges/dsc copy}} | + | {{dsc inc|cpp/algorithm/ranges/dsc copy}} |
| − | {{dsc inc | cpp/algorithm/dsc | + | {{dsc inc|cpp/algorithm/dsc rotate_copy}} |
{{dsc end}} | {{dsc end}} | ||
{{langlinks|de|es|fr|it|ja|pt|ru|zh}} | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 11:40, 16 April 2023
| Defined in header <algorithm>
|
||
| Call signature |
||
| template< std::forward_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O > |
(1) | (since C++20) |
| template< ranges::forward_range R, std::weakly_incrementable O > requires std::indirectly_copyable<ranges::iterator_t<R>, O> |
(2) | (since C++20) |
| Helper types |
||
| template< class I, class O > using rotate_copy_result = in_out_result<I, O>; |
(3) | (since C++20) |
1) Copies the elements from the source range
[first, last), to the destination range beginning at result in such a way, that the element *middle becomes the first element of the destination range and *(middle - 1) becomes the last element. The result is that the destination range contains a left rotated copy of the source range. The behavior is undefined if either
[first, middle) or [middle, last) is not a valid range, or the source and destination ranges overlap.2) 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 function-like entities described on this page are 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.
In practice, they may be implemented as function objects, or with special compiler extensions.
Contents |
[edit] Parameters
| first, last | - | the source range of elements to copy from |
| r | - | the source range of elements to copy from |
| middle | - | the iterator to the element that should appear at the beginning of the destination range |
| result | - | beginning of the destination range |
[edit] Return value
{last, result + N}, where N = ranges::distance(first, last).
[edit] Complexity
Linear: exactly N assignments.
[edit] Notes
If the value type is TriviallyCopyable and the iterator types satisfy contiguous_iterator, implementations of ranges::rotate_copy usually avoid multiple assignments by using a "bulk copy" function such as std::memmove.
[edit] Possible implementation
See also the implementations in libstdc++ and MSVC STL.
struct rotate_copy_fn { template<std::forward_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O> requires std::indirectly_copyable<I, O> constexpr ranges::rotate_copy_result<I, O> operator()(I first, I middle, S last, O result) const { auto c1 {ranges::copy(middle, std::move(last), std::move(result))}; auto c2 {ranges::copy(std::move(first), std::move(middle), std::move(c1.out))}; return {std::move(c1.in), std::move(c2.out)}; } template<ranges::forward_range R, std::weakly_incrementable O> requires std::indirectly_copyable<ranges::iterator_t<R>, O> constexpr ranges::rotate_copy_result<ranges::borrowed_iterator_t<R>, O> operator()(R&& r, ranges::iterator_t<R> middle, O result) const { return (*this)(ranges::begin(r), std::move(middle), ranges::end(r), std::move(result)); } }; inline constexpr rotate_copy_fn rotate_copy {}; |
[edit] 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::ranges::find(src, 3); std::ranges::rotate_copy(src, pivot, dest.begin()); for (int i : dest) std::cout << i << ' '; std::cout << '\n'; // copy the rotation result directly to the std::cout pivot = std::ranges::find(dest, 1); std::ranges::rotate_copy(dest, pivot, std::ostream_iterator<int>(std::cout, " ")); std::cout << '\n'; }
Output:
3 4 5 1 2 1 2 3 4 5
[edit] See also
| (C++20) |
rotates the order of elements in a range (niebloid) |
| (C++20)(C++20) |
copies a range of elements to a new location (niebloid) |
| copies and rotate a range of elements (function template) |
