From cppreference.com
Defined in header
template<ranges::viewV>requiresranges::input_range<V>classas_rvalue_view:publicranges::view_interface<as_rvalue_view<V>> (1) (since C++23)namespaceviews{inlineconstexpr/* unspecified */as_rvalue=/* unspecified */;} (2) (since C++23)Call signature
template<ranges::viewable_rangeR>requires/* see below */constexprranges::viewautoas_rvalue(R&&r);(since C++23)1) A range adaptor that represents a view of underlying
whose elements are rvalues.
2)
. Let e be a subexpression and let T be decltype((e)). Then the expression views::as_rvalue(e) is
to:
views::all(e), if it is a well-formed expression, T models
, and std::same_as<ranges::range_rvalue_reference_t<T>,ranges::range_reference_t<T>> is true;
as_rvalue_view{e} otherwise.
Data members
Member Description Vbase_(private)the underlying view
(exposition-only member object*)Member functions
constructs an as_rvalue_view
(public member function)
returns the underlying view V
(public member function)
returns the beginning iterator of the as_rvalue_view
(public member function)
returns the end iterator of the as_rvalue_view
(public member function)
returns the size of the view if it is bounded
(public member function)
(C++26)
returns the approximate size of the underlying
(public member function) Inherited from
returns whether the derived view is empty, provided only if it satisfies
or
(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
is applicable to it
(public member function of std::ranges::view_interface<D>)
returns the first element in the derived view, provided if it satisfies
(public member function of std::ranges::view_interface<D>)
returns the last element in the derived view, provided only if it satisfies
and
(public member function of std::ranges::view_interface<D>)
returns the nth element in the derived view, provided only if it satisfies
(public member function of std::ranges::view_interface<D>)
std::ranges::as_rvalue_view::as_rvalue_view
as_rvalue_view()requiresstd::default_initializable<V>=default; (1) (since C++23)constexprexplicitas_rvalue_view(Vbase); (2) (since C++23)1) Value-initializes
via its default member initializer (=V()).
2) Initializes
with std::move(base).
Parameters
base - a view std::ranges::as_rvalue_view::base
constexprVbase()const&requiresstd::copy_constructible<V>; (1) (since C++23)constexprVbase()&&; (2) (since C++23)Returns the underlying view.
1) Copy-constructs the result from the underlying view. Equivalent to return
;.
2) Move-constructs the result from the underlying view. Equivalent to returnstd::move(
);.
std::ranges::as_rvalue_view::begin
constexprautobegin()requires(!/*simple-view*/<V>); (1) (since C++23)constexprautobegin()constrequiresranges::range<constV>; (2) (since C++23)Returns std::move_iterator(ranges::begin(
)).
std::ranges::as_rvalue_view::end
constexprautoend()requires(!/*simple-view*/<V>); (1) (since C++23)constexprautoend()constrequiresranges::range<constV>; (2) (since C++23)Returns std::move_iterator(ranges::end(
)) if (1)V or (2)constV models
.
Returns std::move_sentinel(ranges::end(
)) otherwise.
std::ranges::as_rvalue_view::size
constexprautosize()requiresranges::sized_range<V>; (1) (since C++23)constexprautosize()constrequiresranges::sized_range<constV>; (2) (since C++23)Returns the size of the view if the view is bounded. Equivalent to returnranges::size(
);.
std::ranges::as_rvalue_view::reserve_hint
constexprautoreserve_hint()requiresranges::approximately_sized_range<V>; (1) (since C++26)constexprautoreserve_hint()constrequiresranges::approximately_sized_range<constV>; (2) (since C++26)Returns ranges::reserve_hint(
).
Deduction guides
template<classR>as_rvalue_view(R&&)->as_rvalue_view<views::all_t<R>>;(since C++23)Helper templates
template<classT>constexprboolenable_borrowed_range<std::ranges::as_rvalue_view<T>>=ranges::enable_borrowed_range<T>;(since C++23)This specialization of
makes as_rvalue_view satisfy
when the underlying view satisfies it.
Notes
macro ValueStdFeature
(C++23)std::ranges::as_rvalue_view
(C++26)ranges::approximately_sized_range and
Example
Run this code
#include<algorithm>#include<iostream>#include<ranges>#include<string>#include<vector>intmain(){std::vector<std::string>words={"Quick","red","\N{FOX FACE}","jumped","over","a","pterodactyl"};std::vector<std::string>new_words;std::ranges::copy(words|std::views::as_rvalue,std::back_inserter(new_words));// move string from words into new_wordsautoquoted=std::views::transform([](auto&&s){return"“"+s+"”";});std::cout<<"Old words: ";for(auto&&word:words|std::views::as_rvalue|quoted)std::cout<<word<<' ';std::cout<<"\nNew words: ";for(auto&&word:new_words|std::views::as_rvalue|quoted)std::cout<<word<<' ';}Possible output:
Old words: “” “” “” “” “” “” “” New words: “Quick” “red” “🦊” “jumped” “over” “a” “pterodactyl” Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
C++23 views::as_rvalue used to accept non-input ranges made rejected See also