std::tuple_element<std::ranges::subrange>
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std::ranges::subrange
tuple_element<std::ranges::subrange>
Defined in header
<ranges>
template< class I, class S, ranges::subrange_kind K >
struct tuple_element<0, ranges::subrange <I, S, K>>;
(1)
(since C++20)
struct tuple_element<0, ranges::subrange <I, S, K>>;
template< class I, class S, ranges::subrange_kind K >
struct tuple_element<0, const ranges::subrange <I, S, K>>;
(2)
(since C++20)
struct tuple_element<0, const ranges::subrange <I, S, K>>;
template< class I, class S, ranges::subrange_kind K >
struct tuple_element<1, ranges::subrange <I, S, K>>;
(3)
(since C++20)
struct tuple_element<1, ranges::subrange <I, S, K>>;
template< class I, class S, ranges::subrange_kind K >
struct tuple_element<1, const ranges::subrange <I, S, K>>;
(4)
(since C++20)
struct tuple_element<1, const ranges::subrange <I, S, K>>;
The partial specializations of std::tuple_element for std::ranges::subrange provide compile-time access to the iterator or sentinel type of a subrange, using tuple-like syntax. They are provided for structured binding support.
1,2) Obtains the iterator type, i.e.
I.3,4) Obtains the sentinel type, i.e.
S.Contents
[edit] Member types
Member type
Definition
type
(1,2) I(3,4)
S
[edit] Notes
As get functions for subrange return iterators and sentinels by value, const qualifier is not added to the result types when the subrange is const-qualified (but not volatile-qualified).
If the subrange is volatile-qualified, the result types are also volatile-qualified because the partial specialization for volatile or const volatile types are used. Such usage is deprecated.
[edit] Example
Run this code
#include <iterator> #include <list> #include <ranges> #include <type_traits> int main() { std::list <int> list{3, 1, 4, 1, 5, 9, 2, 6}; std::ranges::subrange subrange { std::counted_iterator {std::begin (list), 4}, std::default_sentinel }; static_assert( std::is_same_v < std::tuple_element_t <0, decltype(subrange)>, // implementation-defined type: std::counted_iterator <std::_List_iterator<int>> >); static_assert( std::is_same_v < std::tuple_element_t <1, decltype(subrange)>, std::default_sentinel_t >); }
[edit] See also
Structured binding (C++17)
binds the specified names to sub-objects or tuple elements of the initializer[edit]