25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.6 All view [range.all]

25.7.6.1 General [range.all.general]

views::all returns a view that includes all elements of its range argument.

The name views::all denotes a range adaptor object ([range.adaptor.object]).

Given a subexpression E, the expression views::all(E) is expression-equivalent to:

(2.1)
decay-copy(E) if the decayed type of E models view .
(2.2)
Otherwise, ref_view{E} if that expression is well-formed.
(2.3)
Otherwise, owning_view{E}.

25.7.6.2 Class template ref_view [range.ref.view]

ref_view is a view of the elements of some other range.

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namespace std::ranges { template<range R> requires is_object_v<R> class ref_view : public view_interface<ref_view<R>> { private: R* r_; // exposition only public: template<different-from<ref_view> T> requires see below constexpr ref_view(T&& t); constexpr R& base() const { return *r_; } constexpr iterator_t<R> begin() const { return ranges::begin(*r_); } constexpr sentinel_t<R> end() const { return ranges::end(*r_); } constexpr bool empty() const requires requires { ranges::empty(*r_); } { return ranges::empty(*r_); } constexpr auto size() const requires sized_range<R> { return ranges::size(*r_); } constexpr auto data() const requires contiguous_range<R> { return ranges::data(*r_); } }; template<class R> ref_view(R&) -> ref_view<R>; }

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template<different-from<ref_view> T>
  requires see below
constexpr ref_view(T&& t);

Effects: Initializes r_ with addressof(static_cast<R&>(std::forward<T>(t))).

Remarks: Let FUN denote the exposition-only functions void FUN(R&); void FUN(R&&) = delete;

The expression in the requires-clause is equivalent to: convertible_to<T, R&> && requires { FUN(declval<T>()); }

25.7.6.3 Class template owning_view [range.owning.view]

owning_view is a move-only view of the elements of some other range.

namespace std::ranges { template<range R> requires movable<R> && (!is-initializer-list<R>) // see [range.refinements] class owning_view : public view_interface<owning_view<R>> { private: R r_ = R(); // exposition only public: owning_view() requires default_initializable<R> = default; constexpr owning_view(R&& t); owning_view(owning_view&&) = default; owning_view& operator=(owning_view&&) = default; constexpr R& base() & noexcept { return r_; } constexpr const R& base() const & noexcept { return r_; } constexpr R&& base() && noexcept { return std::move(r_); } constexpr const R&& base() const && noexcept { return std::move(r_); } constexpr iterator_t<R> begin() { return ranges::begin(r_); } constexpr sentinel_t<R> end() { return ranges::end(r_); } constexpr auto begin() const requires range<const R> { return ranges::begin(r_); } constexpr auto end() const requires range<const R> { return ranges::end(r_); } constexpr bool empty() requires requires { ranges::empty(r_); } { return ranges::empty(r_); } constexpr bool empty() const requires requires { ranges::empty(r_); } { return ranges::empty(r_); } constexpr auto size() requires sized_range<R> { return ranges::size(r_); } constexpr auto size() const requires sized_range<const R> { return ranges::size(r_); } constexpr auto data() requires contiguous_range<R> { return ranges::data(r_); } constexpr auto data() const requires contiguous_range<const R> { return ranges::data(r_); } }; }

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constexpr owning_view(R&& t);

Effects: Initializes r_ with std::move(t).