std::ranges::views::slide, std::ranges::slide_view
Defined in header <ranges> | ||
|---|---|---|
template< ranges::forward_range V >
requires ranges::view<V>
class slide_view
: public ranges::view_interface<slide_view<V>>
| (1) | (since C++23) |
namespace views {
inline constexpr /* unspecified */ slide = /* unspecified */;
}
| (2) | (since C++23) |
| Call signature | ||
template< ranges::viewable_range R > constexpr ranges::view auto slide( R&& r, ranges::range_difference_t<R> n ); | (since C++23) | |
template< class DifferenceType > constexpr /* range adaptor object */ slide( DifferenceType&& n ); | (since C++23) | |
| Helper concepts | ||
template< class V >
concept /*slide-caches-nothing*/ =
ranges::random_access_range<V> && ranges::sized_range<V>;
| (3) | (exposition only*) |
template< class V >
concept /*slide-caches-last*/ =
!/*slide-caches-nothing*/<V> &&
ranges::bidirectional_range<V> && ranges::common_range<V>;
| (4) | (exposition only*) |
template< class V >
concept /*slide-caches-first*/ =
!/*slide-caches-nothing*/<V> && !/*slide-caches-last*/<V>;
| (5) | (exposition only*) |
1)
Let slide_view is a range adaptor that takes a view and a number n and produces a view whose mth element (a “window”) is a view over [m, m + n - 1] elements of the original view.s be the size of the original view. Then the size of produced view is: -
s - n + 1, ifs >= n, -
0otherwise, and the resulting view is empty.
2) The name
views::slide denotes a RangeAdaptorObject. Given subexpressions e and n, the expression views::slide(e, n) is expression-equivalent to slide_view(e, n).If n is not greater than 0, the behavior is undefined.
slide_view always models forward_range, and models bidirectional_range, random_access_range, or sized_range if adapted view type models the corresponding concept.
Data members
| Member | Description |
|---|---|
V base_ | the underlying view (exposition-only member object*) |
ranges::range_difference_t<V> n_ | the “window” size (exposition-only member object*) |
non-propagating-cache<ranges::iterator_t<V>> cached_begin_ (present only if V models the slide-caches-first) | an object that caches the result of begin()(exposition-only member object*) |
non-propagating-cache<ranges::iterator_t<V>> cached_end_ (present only if V models the slide-caches-last) | an object that caches the result of end()(exposition-only member object*) |
Member functions
constructs a slide_view (public member function) |
|
| returns a copy of the underlying (adapted) view (public member function) |
|
| returns an iterator to the beginning (public member function) |
|
| returns an iterator or a sentinel to the end (public member function) |
|
returns the number of elements, provided only if the underlying (adapted) range satisfies sized_range (public member function) |
|
|
(C++26) | returns the approximate size of the resulting approximately_sized_range (public member function) |
Inherited from |
|
returns whether the derived view is empty, provided only if it satisfies sized_range or forward_range (public member function of std::ranges::view_interface<D>) |
|
|
(C++23) | returns a constant iterator to the beginning of the range (public member function of std::ranges::view_interface<D>) |
|
(C++23) | returns a sentinel for the constant iterator of the range (public member function of std::ranges::view_interface<D>) |
returns whether the derived view is not empty, provided only if ranges::empty is applicable to it (public member function of std::ranges::view_interface<D>) |
|
returns the first element in the derived view, provided if it satisfies forward_range (public member function of std::ranges::view_interface<D>) |
|
returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range (public member function of std::ranges::view_interface<D>) |
|
returns the nth element in the derived view, provided only if it satisfies random_access_range (public member function of std::ranges::view_interface<D>) |
|
Deduction guides
Nested classes
|
(C++23) | the iterator type (exposition-only member class template*) |
|
(C++23) | the sentinel type used when slide_view is not a common_range(exposition-only member class template*) |
Helper templates
template< class V >
constexpr bool ranges::enable_borrowed_range<slide_view<V>> =
ranges::enable_borrowed_range<V>;
| (since C++23) |
This specialization of ranges::enable_borrowed_range makes slide_view satisfy borrowed_range when the underlying view satisfies it.
Notes
There are similarities between ranges::adjacent_view and ranges::slide_view:
- Both create “sliding window” of size
N. - Both have the same size
S - N + 1, whereSis the size of an adaptedviewsuch thatS >= N > 0.
The following table shows the differences between these adaptors:
| View adaptor | value_type | The window size N |
|---|---|---|
| ranges::adjacent_view | std::tuple | A template parameter |
| ranges::slide_view | ranges::range | A runtime argument |
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_ranges_slide | 202202L | (C++23) |
std::ranges::slide_view |
Example
#include <initializer_list>
#include <print>
#include <ranges>
int main()
{
const auto v = {1, 2, 3, 4, 5, 6};
std::println("All sliding windows of width:");
for (const unsigned width : std::views::iota(1U, 1U + v.size()))
{
auto const windows = v | std::views::slide(width);
std::println("W = {}: {}", width, windows);
}
}
Output:
All sliding windows of width: W = 1: [[1], [2], [3], [4], [5], [6]] W = 2: [[1, 2], [2, 3], [3, 4], [4, 5], [5, 6]] W = 3: [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]] W = 4: [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5, 6]] W = 5: [[1, 2, 3, 4, 5], [2, 3, 4, 5, 6]] W = 6: [[1, 2, 3, 4, 5, 6]]
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3848 | C++23 |
slide_view does not provide a base() accessor | added |
References
- C++23 standard (ISO/IEC 14882:2024):
- 26.7.29 Slide view [range.slide]
See also
|
(C++23) | a view consisting of tuples of references to adjacent elements of the adapted view(class template) (range adaptor object) |
|
(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) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/cpp/ranges/slide_view
