std::ranges::swap_ranges, std::ranges::swap_ranges_result
From cppreference.com
| Defined in header <algorithm>
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| Call signature |
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| template< std::input_iterator I1, std::sentinel_for<I1> S1, std::input_iterator I2, std::sentinel_for<I2> S2 > |
(1) | (since C++20) |
| template< ranges::input_range R1, ranges::input_range R2 > requires std::indirectly_swappable<ranges::iterator_t<R1>, ranges::iterator_t<R2>> |
(2) | (since C++20) |
| Helper types |
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| template< class I1, class I2 > using swap_ranges_result = ranges::in_in_result<I1, I2>; |
(3) | (since C++20) |
1) Exchanges elements between first range
[first1, first1 + M) and second range [first2, first2 + M) via ranges::iter_swap(first1 + i, first2 + i), where M = ranges::min(ranges::distance(first1, last1), ranges::distance(first2, last2)). The ranges
[first1, last1) and [first2, last2) must not overlap.2) Same as (1), but uses r1 as the first range and r2 as the second range, as if using ranges::begin(r1) as first1, ranges::end(r1) as last1, ranges::begin(r2) as first2, and ranges::end(r2) as last2.
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.
Parameters
| first1, last1 | - | the first range of elements to swap |
| first2, last2 | - | the second range of elements to swap |
| r1 | - | the first range of elements to swap |
| r2 | - | the second range of elements to swap. |
Return value
{first1 + M, first2 + M}.
Complexity
Exactly M swaps.
Notes
Implementations (e.g. MSVC STL) may enable vectorization when the iterator type models contiguous_iterator and swapping its value type calls neither non-trivial special member function nor ADL-found swap.
Possible implementation
struct swap_ranges_fn { template<std::input_iterator I1, std::sentinel_for<I1> S1, std::input_iterator I2, std::sentinel_for<I2> S2> requires std::indirectly_swappable<I1, I2> constexpr ranges::swap_ranges_result<I1, I2> operator()(I1 first1, S1 last1, I2 first2, S2 last2) const { for (; !(first1 == last1 or first2 == last2); ++first1, ++first2) ranges::iter_swap(first1, first2); return {std::move(first1), std::move(first2)}; } template<ranges::input_range R1, ranges::input_range R2> requires std::indirectly_swappable<ranges::iterator_t<R1>, ranges::iterator_t<R2>> constexpr ranges::swap_ranges_result<ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>> operator()(R1&& r1, R2&& r2) const { return (*this)(ranges::begin(r1), ranges::end(r1), ranges::begin(r2), ranges::end(r2)); } }; inline constexpr swap_ranges_fn swap_ranges {}; |
Example
Run this code
#include <algorithm> #include <iostream> #include <list> #include <string_view> #include <vector> auto print(std::string_view name, auto const& seq, std::string_view term = "\n") { std::cout << name << " : "; for (const auto& elem : seq) std::cout << elem << ' '; std::cout << term; } int main() { std::vector<char> p {'A', 'B', 'C', 'D', 'E'}; std::list<char> q {'1', '2', '3', '4', '5', '6'}; print("p", p); print("q", q, "\n\n"); // swap p[0, 2) and q[1, 3): std::ranges::swap_ranges(p.begin(), p.begin() + 4, std::ranges::next(q.begin(), 1), std::ranges::next(q.begin(), 3)); print("p", p); print("q", q, "\n\n"); // swap p[0, 5) and q[0, 5): std::ranges::swap_ranges(p, q); print("p", p); print("q", q); }
Output:
p : A B C D E q : 1 2 3 4 5 6 p : 2 3 C D E q : 1 A B 4 5 6 p : 1 A B 4 5 q : 2 3 C D E 6
See also
| (C++20) |
swaps the values referenced by two dereferenceable objects (customization point object) |
| (C++20) |
swaps the values of two objects (customization point object) |
| swaps two ranges of elements (function template) | |
| swaps the elements pointed to by two iterators (function template) | |
| swaps the values of two objects (function template) |