std::ranges::owning_view
Defined in header <ranges>
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||
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template
<
ranges::range R >
requires std::movable
<R>
&&
(
!
/*is-initializer-list*/
<R>
)
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(since C++20) | |
owning_view is a view that has unique ownership of a range. It is move-only and stores that range
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
Data members
| Member name | Definition |
r_ (private)
|
The underlying range of type R.(exposition-only member object* |
Member functions
constructs an owning_view by value-initializing or move-constructing the stored range (public member function) |
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| move-assigns the stored range (public member function) |
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| returns a reference to the stored range (public member function) |
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| returns the beginning iterator of the stored range (public member function) |
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| returns the sentinel of the stored range (public member function) |
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| checks whether the stored range is empty (public member function) |
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returns the size of the stored sized_range (public member function) |
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returns the pointer to the beginning of the stored contiguous_range (public member function) |
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Inherited from std::ranges::view_interface |
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(C++23)
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returns a constant iterator to the beginning of the range. (public member function of std::ranges::view_interface<D>) |
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(C++23)
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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 if ranges::empty is applicable to it. (public member function of std::ranges::view_interface<D>)
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returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>)
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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>)
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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>)
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std::ranges::owning_view::owning_view
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owning_view(
) requires std::default_initializable
<R>
=
default
;
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(1) | (since C++20) |
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owning_view( owning_view&& other ) = default;
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(2) | (since C++20) |
constexpr owning_view( R&& t ); |
(3) | (since C++20) |
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owning_view( const owning_view& ) = delete;
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(4) | (since C++20) |
owning_view is move-only.Parameters
| other | - | another owning_view to move from
|
| t | - | range to move from |
std::ranges::owning_view::operator=
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owning_view& operator=
( owning_view&& other )
=
default
;
|
(1) | (since C++20) |
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owning_view& operator=
(
const owning_view&
)
= delete;
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(2) | (since C++20) |
owning_view is move-only.Parameters
| other | - | another owning_view to move from
|
Return value
*this
std::ranges::owning_view::base
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constexpr R& base(
)
&
noexcept
;
|
(1) | (since C++20) |
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constexpr
const R& base(
)
const
&
noexcept
;
|
(2) | (since C++20) |
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constexpr R&& base(
)
&&
noexcept
;
|
(3) | (since C++20) |
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constexpr
const R&& base(
)
const
&&
noexcept
;
|
(4) | (since C++20) |
Returns a reference to the stored range, keeping value category and const-qualification.
std::ranges::owning_view::begin
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constexpr
ranges::iterator_t
<R> begin(
)
;
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(1) | (since C++20) |
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constexpr
auto begin(
)
const requires ranges::range
<
const R>
;
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(2) | (since C++20) |
Equivalent to return ranges::begin(r_);
std::ranges::owning_view::end
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constexpr
ranges::sentinel_t
<R> end(
)
;
|
(1) | (since C++20) |
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constexpr
auto end(
)
const requires ranges::range
<
const R>
;
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(2) | (since C++20) |
Equivalent to return ranges::end(r_);
std::ranges::owning_view::empty
|
constexpr
bool empty(
) requires requires {
ranges::empty
(r_)
;
}
;
|
(1) | (since C++20) |
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constexpr
bool empty(
)
const requires requires {
ranges::empty
(r_)
;
}
;
|
(2) | (since C++20) |
Equivalent to return ranges::empty(r_);
std::ranges::owning_view::size
|
constexpr
auto size(
) requires ranges::sized_range
<R>
;
|
(1) | (since C++20) |
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constexpr
auto size(
)
const requires ranges::sized_range
<
const R>
;
|
(2) | (since C++20) |
Equivalent to return ranges::size(r_);
std::ranges::owning_view::data
|
constexpr
auto data(
) requires ranges::contiguous_range
<R>
;
|
(1) | (since C++20) |
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constexpr
auto data(
)
const requires ranges::contiguous_range
<
const R>
;
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(2) | (since C++20) |
Equivalent to return ranges::data(r_);
Helper templates
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template
<
class T >
constexpr
bool enable_borrowed_range<std::
ranges
::
owning_view
<T>>
=
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(since C++20) | |
This specialization of ranges::enable_borrowed_range makes owning_view satisfy borrowed_range
Example
#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
See also
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(C++20)
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a view of the elements of some other range (class template) |
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(C++20)
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a view that includes all elements of a range
(alias template) (range adaptor object) |