chunk_view takes a view and a number n and produces a range of views (the chunks ) of the original view, such that each chunk , except maybe the last one, has the size n. These chunks are non-overlapping, successive sub-ranges of the elements of the original view, in order.
Let s be the size of the original view. If s is not the multiple of n, the size of the last produced view is exactly s % n (the remainder). Otherwise, the size of each chunk , including the last one, is n.
The size of produced view is /*div-ceil*/(s).
If the n is not greater than â0â the behavior is undefined.
1)An implementation that supports the underlying view
V
that models only
input_range
.
4)Computes the smallest integer value that is not less than the quotient of dividing
numby
denom. Equivalent to:
I r = num / denom;
if (num % denom)
++r;
return r;[edit] Data members Member Description V base_ the underlying view
n_ the âchunkâ size
chunk_view
sized_range
approximately_sized_range
sized_range or forward_range
std::ranges::view_interface<D>) [edit] returns a constant iterator to the beginning of the range
std::ranges::view_interface<D>) [edit] returns a sentinel for the constant iterator of the range
std::ranges::view_interface<D>) [edit] returns whether the derived view is not empty, provided only if ranges::empty is applicable to it
std::ranges::view_interface<D>) [edit] returns the first element in the derived view, provided if it satisfies forward_range
std::ranges::view_interface<D>) [edit] returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range
std::ranges::view_interface<D>) [edit] returns the nth element in the derived view, provided only if it satisfies random_access_range
std::ranges::view_interface<D>) [edit] [edit] Deduction guides [edit] Nested classes [edit] Helper templates
This specialization of ranges::enable_borrowed_range makes chunk_view satisfy borrowed_range when the underlying view V satisfies both, the forward_range and the borrowed_range.
If V models input_range (1), chunk_view's iterator has a dedicated type: outer_iterator::value_type that is itself an input view.
If V models forward_range or stronger (2), chunk_view defers to views::take for its value_type.
If V models bidirectional_range or stronger ranges (2), the need to calculate size the last chunk correctly (from the end iterator) requires the underlying range type V to be sized_range.
#include <algorithm>
#include <initializer_list>
#include <iostream>
#include <ranges>
auto print_subrange = [](std::ranges::viewable_range auto&& r)
{
std::cout << '[';
for (int pos{}; auto elem : r)
std::cout << (pos++ ? " " : "") << elem;
std::cout << "] ";
};
int main()
{
const auto v = {1, 2, 3, 4, 5, 6};
for (const unsigned width : std::views::iota(1U, 2U + v.size()))
{
auto const chunks = v | std::views::chunk(width);
std::cout << "chunk(" << width << "): ";
std::ranges::for_each(chunks, print_subrange);
std::cout << '\n';
}
}
Output:
chunk(1): [1] [2] [3] [4] [5] [6] chunk(2): [1 2] [3 4] [5 6] chunk(3): [1 2 3] [4 5 6] chunk(4): [1 2 3 4] [5 6] chunk(5): [1 2 3 4 5] [6] chunk(6): [1 2 3 4 5 6] chunk(7): [1 2 3 4 5 6][edit] References
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