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std::ranges::views::slide, std::ranges::slide_view - cppreference.com

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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) 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.

Let 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.

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) [edit]
returns an iterator to the beginning
(public member function) [edit]
returns an iterator or a sentinel to the end
(public member function) [edit]
returns the number of elements, provided only if the underlying (adapted) range satisfies sized_range
(public member function) [edit]
returns the approximate size of the resulting approximately_sized_range
(public member function) [edit]
Inherited from ranges::view_interface
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>) [edit]

(C++23)

 returns a constant iterator to the beginning of the range
(public member function of std::ranges::view_interface<D>) [edit]

(C++23)

 returns a sentinel for the constant iterator of the range
(public member function of std::ranges::view_interface<D>) [edit]
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>) [edit]
returns the first element in the derived view, provided if it satisfies forward_range
(public member function of std::ranges::view_interface<D>) [edit]
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>) [edit]
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>) [edit]

Deduction guides

Nested classes

the iterator type
(exposition-only member class template*)
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, where S is the size of an adapted view such that S >= 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 <algorithm>
#include <initializer_list>
#include <iostream>
#include <ranges>

auto print_subrange = [](std::ranges::viewable_range auto&& r)
{
    std::cout << '[';
    for (char space[]{0,0}; auto elem : r)
        std::cout << space << elem, *space = ' ';
    std::cout << "] ";
};

int main()
{
    const auto v = {1, 2, 3, 4, 5, 6};
    
    std::cout << "All sliding windows of width:\n";
    for (const unsigned width : std::views::iota(1U, 1U + v.size()))
    {
        auto const windows = v | std::views::slide(width);
        std::cout << "W = " << width << ": ";
        std::ranges::for_each(windows, print_subrange);
        std::cout << '\n';
    }
}

Output: 

All sliding windows of width W:
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]

References

  • C++23 standard (ISO/IEC 14882:2024):
  • 26.7.29 Slide view [range.slide]

See also