std::ranges::swap_ranges, std::ranges::swap_ranges_result
Defined in header <algorithm> |
||
|---|---|---|
| Call signature | ||
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 swap_ranges_result<I1, I2>
swap_ranges( I1 first1, S1 last1, I2 first2, S2 last2 ); |
(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>>
constexpr swap_ranges_result<ranges::borrowed_iterator_t<R1>,
ranges::borrowed_iterator_t<R2>>
swap_ranges( R1&& r1, R2&& r2 ); |
(2) | (since C++20) |
| Helper types | ||
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), 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 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
| 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
#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) |
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https://en.cppreference.com/w/cpp/algorithm/ranges/swap_ranges
