Adapts a given
view
with different types for iterator/sentinel pair into a
view
that is also a
common_range
. A
common_view
always has the same iterator/sentinel type.
[edit] Data members Member DescriptionV base_ (private) the underlying view
common_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] gets the address of derived view's data, provided only if its iterator type satisfies contiguous_iterator
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] Helper templates
This specialization of ranges::enable_borrowed_range makes common_view satisfy borrowed_range when the underlying view satisfies it.
common_view can be useful for working with legacy algorithms that expect the iterator and sentinel are of the same type.
#include <initializer_list>
#include <iostream>
#include <iterator>
#include <list>
#include <numeric>
#include <ranges>
int main()
{
auto v1 = {1, 2, 3, 4, 5};
auto i1 = std::counted_iterator{v1.begin(), std::ssize(v1)};
auto r1 = std::ranges::subrange{i1, std::default_sentinel};
// auto e1 = std::accumulate(r1.begin(), r1.end(), 0); // error: "common range" required
auto c1 = std::ranges::common_view{r1};
std::cout << "accumulate: " << std::accumulate(c1.begin(), c1.end(), 0) << '\n';
// inherited from ranges::view_interface:
std::cout << "c1.front(): " << c1.front() << '\n';
std::cout << "c1.back(): " << c1.back() << '\n';
std::cout << "c1.data(): " << c1.data() << '\n';
std::cout << "c1[0]: " << c1[0] << '\n';
auto v2 = std::list{1, 2, 3, 4, 5};
auto i2 = std::counted_iterator{v2.begin(), std::ssize(v2)};
auto r2 = std::ranges::subrange{i2, std::default_sentinel};
// auto e2 = std::accumulate(r2.begin(), r2.end(), 0); // error: "common range" required
auto c2 = std::ranges::common_view{ r2 };
std::cout << "accumulate: " << std::accumulate(c2.begin(), c2.end(), 0) << '\n';
// inherited from ranges::view_interface:
std::cout << "c2.front(): " << c2.front() << '\n';
// auto e3 = c2.back(); // error: "bidirectional range" required
// auto e4 = c2.data(); // error: "contiguous range" required
// auto e5 = c2[0]; // error: "random access range" required
}
Possible output:
accumulate: 15 c1.front(): 1 c1.back(): 5 c1.data(): 0x7f19937f00d0 c1[0]: 1 accumulate: 15 c2.front(): 1[edit] 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 3494 C++20common_view was never a borrowed_range it is a borrowed_range if its underlying view is [edit] See also
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