std::ranges..._rvalue_view(3)

📦 version 2024.07.05, in nixpkgs unstable, opensuse-leap 16.0

✨ NAME ✨

std::ranges::views::as_rvalue,std::ranges::as_rvalue_view — okay bestie, that’s the whole name, and yes it’s a mouthful. This is the C++ Standard Library manual page for std::ranges..._rvalue_view(3), and it’s all about std::ranges::views::as_rvalue and std::ranges::as_rvalue_view. It’s giving “a view whose elements are rvalues” energy. 💅

🌸 Synopsis 🌸

Defined in header <ranges>.

template< ranges::view V >
    requires ranges::input_range<V>
class as_rvalue_view
    : public ranges::view_interface<as_rvalue_view<V>>

(1) (since C++23)

namespace views {
    inline constexpr /* unspecified */ as_rvalue = /* unspecified */;
}

(2) (since C++23)

💬 Call signature 💬

template< ranges::viewable_range R >
    requires /* see below */
constexpr ranges::view auto as_rvalue( R&& r );

(since C++23)

  1. A range adaptor that represents a view of underlying view whose elements are rvalues.
  2. RangeAdaptorObject. Let e be a subexpression and let T be decltype((e)). Then the expression views::as_rvalue(e) is expression-equivalent to:
    • views::all(e), if it is a well-formed expression and std::same_as<ranges::range_rvalue_reference_t<T>, ranges::range_reference_t<T>> is true;
    • as_rvalue_view{e} otherwise.

💅 Member functions 💅

  • constructor — constructs an as_rvalue_view (public member function)
  • base — returns the underlying view V (public member function)
  • begin — returns the beginning iterator of the as_rvalue_view (public member function)
  • end — returns the end iterator of the as_rvalue_view (public member function)
  • size — returns the size of the view if it is bounded (public member function)

🫶 Inherited from std::ranges::view_interface 🫶

  • empty (C++20) — 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>)
  • cbegin (C++23) — returns a constant iterator to the beginning of the range. (public member function of std::ranges::view_interface<D>)
  • cend (C++23) — returns a sentinel for the constant iterator of the range. (public member function of std::ranges::view_interface<D>)
  • operator bool (C++20) — 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>)
  • front (C++20) — returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>)
  • back (C++20) — 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>)
  • operator[] (C++20) — 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>)

🎀 std::ranges::as_rvalue_view::as_rvalue_view 🎀

as_rvalue_view() requires std::default_initializable<V> = default;

(1) (since C++23)

constexpr explicit as_rvalue_view( V base );

(2) (since C++23)

  1. Value-initializes base_ via its default member initializer (= V()).
  2. Initializes base_ with std::move(base).

🍓 Parameters 🍓

  • base — a view

🦋 std::ranges::as_rvalue_view::base 🦋

constexpr V base() const& requires std::copy_constructible<V>;

(1) (since C++23)

constexpr V base() &&;

(2) (since C++23)

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::as_rvalue_view::begin 🌈

constexpr auto begin() requires (!__simple_view<V>);

(1) (since C++23)

constexpr auto begin() const requires ranges::range<const V>;

(2) (since C++23)

1,2) Returns std::move_iterator(ranges::begin(base_)).

🔥 std::ranges::as_rvalue_view::end 🔥

constexpr auto end() requires (!__simple_view<V>);

(1) (since C++23)

constexpr auto end() const requires ranges::range<const V>;

(2) (since C++23)

  1. Returns std::move_iterator(ranges::end(base_)) if V models common_range, otherwise std::move_sentinel(ranges::end(base_)).
  2. Returns std::move_iterator(ranges::end(base_)) if const V models common_range, otherwise std::move_sentinel(ranges::end(base_)).

⭐ std::ranges::as_rvalue_view::size ⭐

constexpr auto size() requires ranges::sized_range<V>;

(1) (since C++23)

constexpr auto size() const requires ranges::sized_range<const V>;

(2) (since C++23)

Returns the size of the view if the view is bounded.

1,2) Equivalent to return ranges::size(base_);

🧚 Deduction guides 🧚

template< class R >
as_rvalue_view( R&& ) -> as_rvalue_view<views::all_t<R>>;

(since C++23)

👑 Helper templates 👑

template< class T >
inline constexpr bool enable_borrowed_range<std::ranges::as_rvalue_view<T>>
    = std::ranges::enable_borrowed_range<T>;

(since C++23)

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

💀 Notes 💀

  • Feature-test macro: __cpp_lib_ranges_as_rvalue — value 202207L, Std (C++23), feature std::ranges::as_rvalue_view.

🙈 Example 🙈

This section is incomplete.

Reason: example.

🎀 See also 🎀

  • move_iterator (C++11) — iterator adaptor which dereferences to an rvalue (class template)
  • move_sentinel (C++20) — sentinel adaptor for use with std::move_iterator (class template)
  • ranges::as_const_view — converts a view into a constant_range
  • views::as_const (C++23) — (class template) (range adaptor object)

🏷️ Category 🏷️

  • Todo with reason

source/version: cppreference.com · date: 2024.06.10 · manual page: std::ranges..._rvalue_view(3) — that’s the whole vibe, bestie, slay and bye 💅✨

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