std::ranges::views::stride, std::ranges::stride_view
From cppreference.com
Defined in header <ranges>
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template< ranges::input_range V > requires ranges::view<V> |
(1) | (since C++23) |
namespace views { inline constexpr /* unspecified */ stride = /* unspecified */; |
(2) | (since C++23) |
Call signature |
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template< ranges::viewable_range R > constexpr ranges::view auto stride( R&& r, ranges::range_difference_t<R> n ); |
(since C++23) | |
template< class DifferenceType > constexpr /*range adaptor closure*/ stride( DifferenceType&& n ); |
(since C++23) | |
Helper templates |
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1)
stride_view
is a range adaptor that takes a view
and a number n
and produces a view, that consists of elements of the original view by advancing over n elements at a time. This means that each m
th element of the produced view is (n * i)
th element of the original view, for some non-negative index i
.
The elements of the original view, whose "index" is not a multiple of n
, are not present in the produced view. Let
S
be the size of the original view. Then the size of produced view is:
- (S / n) + (S % n ? 1 : 0), if S >= n; otherwise,
- 1, if S > 0; otherwise,
- 0, and the resulting view is empty.
2) The name views::stride denotes a RangeAdaptorObject. Given subexpressions e and n, the expression views::stride(e, n) is expression-equivalent to stride_view(e, n).
The
n
must be greater than 0, otherwise the behavior is undefined.stride_view
always models input_range
, and models forward_range
, bidirectional_range
, random_access_range
, and/or sized_range
, if adapted view
type V models the corresponding concept.
stride_view<V> models common_range
whenever the underlying view V does.
Contents |
[edit] Data members
Member object | Definition |
base_ (private)
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The underlying view of type V .(exposition-only member object*) |
stride_ (private)
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The size object (the "stride") of type ranges::range_difference_t<V>. (exposition-only member object*) |
[edit] Member functions
constructs a stride_view (public member function) | |
(C++23) |
returns the stored stride value (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) | |
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> )
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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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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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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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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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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> )
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[edit] Deduction guides
[edit] Nested classes
(C++23) |
the iterator type (exposition-only member class template*) |
[edit] Helper templates
template< class V > constexpr bool ranges::enable_borrowed_range<stride_view<V>> = |
(since C++23) | |
This specialization of ranges::enable_borrowed_range makes stride_view
satisfy borrowed_range
when the underlying view satisfies it.
[edit] Notes
Feature-test macro | Value | Std | Feature |
---|---|---|---|
__cpp_lib_ranges_stride |
202207L |
(C++23) | std::ranges::stride_view
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[edit] Example
Run this code
#include <algorithm> #include <iostream> #include <ranges> #include <string_view> using namespace std::literals; void print(std::ranges::viewable_range auto&& v, std::string_view separator = " ") { for (auto const& x : v) std::cout << x << separator; std::cout << '\n'; } int main() { print(std::views::iota(1, 13) | std::views::stride(3)); print(std::views::iota(1, 13) | std::views::stride(3) | std::views::reverse); print(std::views::iota(1, 13) | std::views::reverse | std::views::stride(3)); print("0x0!133713337*x//42/A$@"sv | std::views::stride(0B11) | std::views::transform([](char O) -> char { return 0100 | O; }), ""); }
Output:
1 4 7 10 10 7 4 1 12 9 6 3 password
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 26.7.31 Stride view [range.stride]
[edit] See also
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) | |
a range of view s that are N -sized non-overlapping successive chunks of the elements of another view (class template) (range adaptor object) | |
a view consisting of tuples of references to adjacent elements of the adapted view(class template) (range adaptor object) | |
a view that consists of the elements of a range that satisfies a predicate(class template) (range adaptor object) |