2) RangeAdaptorObject. The expression views::reverse(e) is expression-equivalent to one of the following expressions, except that e is evaluated only once:

• e.base(), if the type of e is a (possibly cv-qualified) specialization of reverse_view;
• otherwise, if the type of e is (possibly cv-qualified) ranges::subrange<std::reverse_iterator<I>, std::reverse_iterator<I>, K> for some iterator type I and value K of type ranges::subrange_kind:

• ranges::subrange<I, I, K>(e.end().base(), e.begin().base(), e.size()), if K is ranges::subrange_kind::sized;
• otherwise ranges::subrange<I, I, K>(e.end().base(), e.begin().base());

• otherwise ranges::reverse_view{e}.

In other words, views::reverse unwraps reversed views if possible.

std::ranges::reverse_view::reverse_view

1) Value-initializes base_  via its default member initializer (= V()).

2) Initializes base_  with std::move(r).

Parameters

std::ranges::reverse_view::base

Returns the underlying view.

1) Copy-constructs the result from the underlying view. Equivalent to return base_ ;.

2) Move-constructs the result from the underlying view. Equivalent to return std::move(base_ );.

std::ranges::reverse_view::begin

Deduction guides

Helper templates

This specialization of std::ranges::enable_borrowed_range makes reverse_view satisfy borrowed_range when the underlying view satisfies it.

Notes

Example

#include <iostream>
#include <ranges>

int main()
{
    static constexpr auto il = {3, 1, 4, 1, 5, 9};

    std::ranges::reverse_view rv{il};
    for (int i : rv)
        std::cout << i << ' ';
    std::cout << '\n';

    for (int i : il | std::views::reverse)
        std::cout << i << ' ';
    std::cout << '\n';

    // operator[] is inherited from std::view_interface
    for (auto i{0U}; i != rv.size(); ++i)
        std::cout << rv[i] << ' ';
    std::cout << '\n';
}

9 5 1 4 1 3
9 5 1 4 1 3
9 5 1 4 1 3

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also