Defined in header <algorithm> | ||
---|---|---|
template< class I, class T > struct in_value_result; | (since C++23) |
ranges::in_value_result
is a class template that provides a way to store an iterator and a value as a single unit.
This class template has no base classes or declared members other than those shown below. Thus it is suitable for use with structured bindings.
All special member functions of this class template are implicitly declared, which makes specializations be aggregate classes, and propagate triviality, potentially-throwing-ness, and constexpr-ness of corresponding operations on data members.
I, T | - | the types of the objects that the ranges::in_value_result stores. |
[[no_unique_address]] I in; |
a value (that is supposed to be an iterator).
[[no_unique_address]] T value; |
a value (that is supposed to be a stored value).
template<class I2, class T2> requires convertible_to<const I&, I2> && convertible_to<const T&, T2> constexpr operator in_value_result<I2, T2>() const &; | (1) | |
template<class I2, class T2> requires convertible_to<I, I2> && convertible_to<T, T2> constexpr operator in_value_result<I2, T2>() &&; | (2) |
Converts *this
to the result by constructing every data member of the result from the corresponding member of *this
.
return {in, value};
.return {std::move(in), std::move(value)};
. The following standard library functions use ranges::in_value_result
as the return type:
Algorithm functions |
|
(C++23) | left-folds a range of elements, and returns a pair (iterator, value) (niebloid) |
(C++23) | left-folds a range of elements using the first element as an initial value, and returns a pair (iterator, optional) (niebloid) |
namespace std::ranges { template<class I, class T> struct in_value_result { [[no_unique_address]] I in; [[no_unique_address]] T value; template<class I2, class T2> requires convertible_to<const I&, I2> && convertible_to<const T&, T2> constexpr operator in_value_result<I2, T2>() const & { return {in, value}; } template<class I2, class T2> requires convertible_to<I, I2> && convertible_to<T, T2> constexpr operator in_value_result<I2, T2>() && { return {std::move(in), std::move(value)}; } }; }
Each standard library algorithm that uses this family of return types declares a new alias type, e.g. using merge_result = in_in_out_result<I1, I2, O>;
.
The names for such aliases are formed by adding the suffix "_result
" to the algorithm's name. So, the return type of std::ranges::merge
can be named as std::ranges::merge_result
.
Unlike std::pair
and std::tuple
, this class template has data members of meaningful names.
implements binary tuple, i.e. a pair of values (class template) |
|
(C++11) | implements fixed size container, which holds elements of possibly different types (class template) |
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