std::ranges::views::as_input, std::ranges::as_input_view
Defined in header <ranges> | ||
|---|---|---|
template< ranges::input_range V >
requires ranges::view<V>
class as_input_view
: public ranges::view_interface<as_input_view<V>>
| (1) | (since C++26) |
namespace views {
inline constexpr /* unspecified */ as_input = /* unspecified */;
}
| (2) | (since C++26) |
| Call signature | ||
template< ranges::viewable_range R >
requires /* see below */
constexpr ranges::view auto as_input( R&& r );
| (since C++26) |
1) A range adaptor that represents a view of an underlying
2) RangeAdaptorObject. Let view as an input_range-only and not a common_range.e be a subexpression, and let T be decltype(e). Then the expression views::as_input(e) is expression-equivalent to: -
views::all(e), if it is a well-formed expression and all of the conditions below aretrue:-
Tmodelsinput_range, -
Tdoes not satisfycommon_range, and -
Tdoes not satisfyforward_range.
-
-
as_input_view{e}otherwise.
Consequently, as_input_view never models range concepts that are stronger than input_range. In particular, it does not model all of these:
Additionally, as_input_view does not model common_range. However, it does model borrowed_range, constant_range, and sized_range when the underlying view V models respective concepts.
Data members
| Member | Description |
|---|---|
V base_ (private) | the underlying view (exposition-only member object*) |
Member functions
constructs an as_input_view (public member function) |
|
| returns a copy of the underlying (adapted) view (public member function) |
|
| returns an iterator to the beginning (public member function) |
|
| returns an iterator or a sentinel to the end (public member function) |
|
returns the number of elements. Provided only if the underlying (adapted) range satisfies sized_range. (public member function) |
|
Inherited from |
|
returns whether the derived view is empty, provided only if it satisfies sized_range or forward_range (public member function of std::ranges::view_interface<D>) |
|
|
(C++23) | returns a constant iterator to the beginning of the range (public member function of std::ranges::view_interface<D>) |
|
(C++23) | returns a sentinel for the constant iterator of the range (public member function of std::ranges::view_interface<D>) |
returns whether the derived view is not empty, provided only if ranges::empty is applicable to it (public member function of std::ranges::view_interface<D>) |
|
gets the address of derived view's data, provided only if its iterator type satisfies contiguous_iterator (public member function of std::ranges::view_interface<D>) |
|
returns the first element in the derived view, provided if it satisfies forward_range (public member function of std::ranges::view_interface<D>) |
|
returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range (public member function of std::ranges::view_interface<D>) |
|
returns the nth element in the derived view, provided only if it satisfies random_access_range (public member function of std::ranges::view_interface<D>) |
|
std::ranges::as_input_view::as_input_view
as_input_view() requires std::default_initializable<V> = default; | (1) | (since C++26) |
constexpr explicit as_input_view( V base ); | (2) | (since C++26) |
1) Value-initializes
base_ via its default member initializer (= V()).
2) Initializes
base_ with std::move(base).Parameters
| base | - | a view |
std::ranges::as_input_view::base
constexpr V base() const& requires std::copy_constructible<V>; | (1) | (since C++26) |
constexpr V base() &&; | (2) | (since C++26) |
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_input_view::begin
constexpr auto begin() requires (!__simple_view<V>); | (1) | (since C++26) |
constexpr auto begin() const requires ranges::range<const V>; | (2) | (since C++26) |
1) Equivalent to
return /*iterator*/<false>(ranges::begin(base_));
2) Equivalent to
return /*iterator*/<true>(ranges::begin(base_));
std::ranges::as_input_view::end
constexpr auto end() requires (!__simple_view<V>); | (1) | (since C++26) |
constexpr auto end() const requires ranges::range<const V>; | (2) | (since C++26) |
1,2) Equivalent to
return ranges::end(base_);
std::ranges::as_input_view::size
constexpr auto size() requires ranges::sized_range<V>; | (1) | (since C++26) |
constexpr auto size() const requires ranges::sized_range<const V>; | (2) | (since C++26) |
1,2) Equivalent to
return ranges::size(base_);
Deduction guides
template< class R > as_input_view( R&& ) -> as_input_view<views::all_t<R>>; | (since C++26) |
Nested classes
| the iterator type (exposition-only member class template*) |
Helper templates
template< class T >
constexpr bool enable_borrowed_range<std::ranges::as_input_view<T>> =
ranges::enable_borrowed_range<T>;
| (since C++26) |
This specialization of std::ranges::enable_borrowed_range makes as_input_view satisfy borrowed_range when the underlying view satisfies it.
Notes
as_input_view can be useful to avoid the overhead necessary to provide support for the operations needed for greater iterator strength.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_ranges_as_input | 202502L | (C++26) |
std::ranges::as_input_view |
Example
See also
|
(C++20) | specifies a range whose iterator type satisfies input_iterator (concept) |
|
(C++20) | converts a view into a common_range(class template) (range adaptor object) |
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