Defined in header <ranges> | ||
|---|---|---|
template< ranges::forward_range V, std::size_t N >
requires ranges::view<V> && (N > 0)
class adjacent_view : public ranges::view_interface<adjacent_view<V, N>>
| (1) | (since C++23) |
namespace views {
template< std::size_t N >
inline constexpr /* unspecified */ adjacent = /* unspecified */ ;
}
| (2) | (since C++23) |
namespace views {
inline constexpr auto pairwise = adjacent<2>;
}
| (3) | (since C++23) |
| Call signature | ||
template< ranges::viewable_range R >
requires /* see below */
constexpr ranges::view auto adjacent<N>( R&& r );
| (since C++23) |
adjacent_view is a range adaptor that takes a view, and produces a view whose ith element (a "window") is a std::tuple that holds N references to the elements of the original view, from ith up to i + N - 1th inclusively.S be the size of the original view. Then the size of produced view is: S - N + 1, if S >= N, 0 otherwise, and the resulting view is empty.views::adjacent<N> denotes a RangeAdaptorObject. Given a subexpression e and a constant expression N, the expression views::adjacent<N>(e) is expression-equivalent to ((void)e, auto(views::empty<tuple<>>)) if N is equal to 0, adjacent_view<views::all_t<decltype((e))>, N>(e) otherwise.adjacent_view always models forward_range, and models bidirectional_range, random_access_range, or sized_range if adapted view type models the corresponding concept.
Typical implementations of adjacent_view hold only one non-static data member base_ of type V. The name is for exposition only.
|
(C++23) | constructs a adjacent_view (public member function) |
|
(C++23) | returns an iterator to the beginning (public member function) |
|
(C++23) | returns an iterator or a sentinel to the end (public member function) |
|
(C++23) | returns the number of elements. Provided only if the underlying (adapted) range satisfies sized_range. (public member function) |
Inherited from |
|
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(C++20) | returns whether the derived view is empty. Provided if it satisfies sized_range or forward_range. (public member function of std::ranges::view_interface<D>) |
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(C++23) | returns a constant iterator to the beginning of the range. (public member function of std::ranges::view_interface<D>) |
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(C++23) | returns a sentinel for the constant iterator of the range. (public member function of std::ranges::view_interface<D>) |
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(C++20) | returns whether the derived view is not empty. Provided if ranges::empty is applicable to it. (public member function of std::ranges::view_interface<D>) |
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(C++20) | returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>) |
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(C++20) | returns the last element in the derived view. Provided if it satisfies bidirectional_range and common_range. (public member function of std::ranges::view_interface<D>) |
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(C++20) | returns the nth element in the derived view. Provided if it satisfies random_access_range. (public member function of std::ranges::view_interface<D>) |
(none).
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(C++23) | the iterator type (exposition-only member class template) |
|
(C++23) | the sentinel type used when adjacent_view is not a common_range (exposition-only member class template) |
template< class V, size_t N >
inline constexpr bool ranges::enable_borrowed_range<adjacent_view<V, N>> =
ranges::enable_borrowed_range<V>;
| (since C++23) |
This specialization of ranges::enable_borrowed_range makes adjacent_view satisfy borrowed_range when the underlying view satisfies it.
There is a similarity between ranges::adjacent_view and ranges::slide_view — they both produce a "sliding window" of the size N, and, given a view of the size S, where S >= N > 0, they both will have the same size: S - N + 1. The difference between these view adaptors are:
| View adaptor | value_type | The window size N |
|---|---|---|
ranges::adjacent_view | a tuple-like object | a template parameter |
ranges::slide_view | a range
| a runtime parameter |
| Feature-test macro | Value | Std | Comment |
|---|---|---|---|
__cpp_lib_ranges_zip | 202110L | (C++23) |
|
#include <array>
#include <cstddef>
#include <iostream>
#include <ranges>
#include <string>
#include <tuple>
int main()
{
constexpr std::size_t window{3};
constexpr std::array v {1, 2, 3, 4, 5, 6};
std::cout << "v = [1 2 3 4 5 6]\n";
for (int i{}; auto const e: v | std::views::adjacent<window>)
{
std::cout << "e = " << std::string(2 * i++, ' ') << '['
<< std::get<0>(e) << ' '
<< std::get<1>(e) << ' '
<< std::get<2>(e) << "]\n";
}
}Output:
v = [1 2 3 4 5 6] e = [1 2 3] e = [2 3 4] e = [3 4 5] e = [4 5 6]
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(C++23) | a view consisting of tuples of results of application of a transformation function to adjacent elements of the adapted view (class template) (range adaptor object) |
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(C++23) | a view whose Mth element is a view over the Mth through (M + N - 1)th elements of another view (class template) (range adaptor object) |
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(C++23) | a range of views that are N-sized non-overlapping successive chunks of the elements of another view (class template) (range adaptor object) |
|
(C++23) | a view consisting of elements of another view, advancing over N elements at a time (class template) (range adaptor object) |
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