std::ranges:: views:: slide, std::ranges:: slide_view

From cppreference.com
Ranges library
Range adaptors
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 m th element (a "window") is a view over the m th through (m + n - 1) th 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 object Definition
base_ (private) The underlying view of type V .
( exposition-only member object* )
n_ (private) The "window size" of type ranges:: range_difference_t < V > .
( exposition-only member object* )
cached_begin_ (private)
(present only if V models the slide-caches-first )
An optional-like object.
( exposition-only member object* )
cached_end_ (private)
(present only if V models the slide-caches-last )
An optional-like object.
( exposition-only member object* )

Member functions

constructs a slide_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)
Inherited from std::ranges::view_interface
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> )
(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 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 if it satisfies bidirectional_range and common_range .
(public member function of std::ranges::view_interface<D> )
returns the n th element in the derived view. Provided 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 a "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 <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

a view consisting of tuples of references to adjacent elements of the adapted view
(class template) (range adaptor object)
a range of view s that are N -sized non-overlapping successive chunks of the elements of another view
(class template) (range adaptor object)