std::ranges::owning_view
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C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Ranges library
(exposition-only member object*)
returns the approximate size of the stored
(public member function)
returns a constant iterator to the beginning of the range
(public member function of
returns a sentinel for the constant iterator of the range
(public member function of
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++26)(C++26)
owning_view
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)
(C++23)(C++23)
(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)
Defined in header
<ranges>
template< ranges::range R >
(since C++20)
requires std::movable <R> && (!/*is-initializer-list*/<R>)
class owning_view
owning_view is a view that has unique ownership of a range. It is move-only and stores that range within it.
The constant /*is-initializer-list*/<R> in the requires clause is true if and only if std::remove_cvref_t <R> is a specialization of std::initializer_list .
Contents
- 1 Data members
- 2 Member functions
- 3 std::ranges::owning_view::owning_view
- 4 std::ranges::owning_view::operator=
- 5 std::ranges::owning_view::base
- 6 std::ranges::owning_view::begin
- 7 std::ranges::owning_view::end
- 8 std::ranges::owning_view::empty
- 9 std::ranges::owning_view::size
- 10 std::ranges::owning_view::reserve_hint
- 11 std::ranges::owning_view::data
[edit] Data members
Member
Description
R r_
the underlying range(exposition-only member object*)
[edit] Member functions
constructs an
(public member function)
owning_view by value-initializing or move-constructing the stored range (public member function)
(C++26)
approximately_sized_range (public member function)
Inherited from std::ranges::view_interface
(C++23)
(public member function of
std::ranges::view_interface<D>) [edit]
(C++23)
(public member function of
std::ranges::view_interface<D>) [edit]
returns whether the derived view is not empty, provided only if ranges::empty is applicable to it
(public member function of
(public member function of
std::ranges::view_interface<D>) [edit]
returns the first element in the derived view, provided if it satisfies
(public member function of
forward_range (public member function of
std::ranges::view_interface<D>) [edit]
returns the last element in the derived view, provided only if it satisfies
(public member function of
bidirectional_range and common_range (public member function of
std::ranges::view_interface<D>) [edit]
returns the
(public member function of
nth element in the derived view, provided only if it satisfies random_access_range (public member function of
std::ranges::view_interface<D>) [edit]
std::ranges::owning_view::owning_view
owning_view() requires std::default_initializable <R> = default;
(1)
(since C++20)
owning_view( owning_view&& other ) = default;
(2)
(since C++20)
constexpr owning_view( R&& t );
(3)
(since C++20)
Parameters
other
-
another
owning_view to move from
t
-
range to move from
Notes
owning_view does not explicitly define a copy constructor. owning_view is move-only.
std::ranges::owning_view::operator=
owning_view& operator=( owning_view&& other ) = default;
(since C++20)
Move assignment operator. Move assigns r_ from that of other.
Parameters
other
-
another
owning_view to move from
Return value
*this
Notes
owning_view does not explicitly define a copy assignment operator. owning_view is move-only.
std::ranges::owning_view::base
constexpr R& base() & noexcept;
(1)
(since C++20)
constexpr const R& base() const & noexcept;
(2)
(since C++20)
constexpr R&& base() && noexcept;
(3)
(since C++20)
constexpr const R&& base() const && noexcept;
(4)
(since C++20)
Returns a reference to the stored range, keeping value category and const-qualification.
Return value
1,2)
r_ 3,4) std::move(
r_ )
std::ranges::owning_view::begin
constexpr ranges::iterator_t <R> begin();
(1)
(since C++20)
constexpr auto begin() const requires ranges::range <const R>;
(2)
(since C++20)
Returns ranges::begin (r_ ).
std::ranges::owning_view::end
constexpr ranges::sentinel_t <R> end();
(1)
(since C++20)
constexpr auto end() const requires ranges::range <const R>;
(2)
(since C++20)
Returns ranges::end (r_ ).
std::ranges::owning_view::empty
constexpr bool empty() requires requires { ranges::empty (r_); };
(1)
(since C++20)
constexpr bool empty() const requires requires { ranges::empty (r_); };
(2)
(since C++20)
Returns ranges::empty (r_ ).
std::ranges::owning_view::size
constexpr auto size() requires ranges::sized_range <R>;
(1)
(since C++20)
constexpr auto size() const requires ranges::sized_range <const R>;
(2)
(since C++20)
Returns ranges::size (r_ ).
std::ranges::owning_view::reserve_hint
constexpr auto reserve_hint()
requires ranges::approximately_sized_range<R>;
(1)
(since C++26)
requires ranges::approximately_sized_range<R>;
constexpr auto reserve_hint() const
requires ranges::approximately_sized_range<const R>;
(2)
(since C++26)
requires ranges::approximately_sized_range<const R>;
Returns ranges::reserve_hint(r_ ).
std::ranges::owning_view::data
constexpr auto data() requires ranges::contiguous_range <R>;
(1)
(since C++20)
constexpr auto data() const requires ranges::contiguous_range <const R>;
(2)
(since C++20)
Returns ranges::data (r_ ).
[edit] Helper templates
template< class T >
(since C++20)
constexpr bool enable_borrowed_range<std::ranges::owning_view<T>> =
This specialization of ranges::enable_borrowed_range makes owning_view satisfy borrowed_range when the underlying range satisfies it.
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_ranges_reserve_hint |
202502L |
(C++26) | ranges::approximately_sized_range and reserve_hint
|
[edit] Example
Run this code
#include <cassert> #include <iostream> #include <ranges> #include <string> int main() { using namespace std::literals; std::ranges::owning_view ov{"cosmos"s}; // the deduced type of R is std::string; // "ov" is the only owner of this string assert ( ov.empty() == false && ov.size() == 6 && ov.size() == ov.base().size() && ov.front() == 'c' && ov.front() == *ov.begin() && ov.back() == 's' && ov.back() == *(ov.end() - 1) && ov.data() == ov.base() ); std::cout << "sizeof(ov): " << sizeof ov << '\n' // typically equal to sizeof(R) << "range-for: "; for (const char ch : ov) std::cout << ch; std::cout << '\n'; std::ranges::owning_view<std::string > ov2; assert (ov2.empty()); // ov2 = ov; // compile-time error: copy assignment operator is deleted ov2 = std::move(ov); // OK assert (ov2.size() == 6); }
Possible output:
sizeof(ov): 32 range-for: cosmos