std::ranges::views::elements, std::ranges::elements_view - cppreference.com (original) (raw)

std::ranges::elements_view

1. Accepts a view of tuple-like values, and issues a view with a value type of the Nth element of the adapted view's value-type.

2. Every specialization of views::elements is a RangeAdaptorObject. The expression views::elements<M>(e) is expression-equivalent to elements_view<views::all_t<decltype((e))>, M>{e} for any suitable subexpression e and constant expression M.

3. Ensures that the elements of the underlying view are tuple-like values, see tuple-like(since C++23).

4. Ensures that dangling references cannot be returned.

elements_view models the concepts random_access_range, bidirectional_range, forward_range, input_range, common_range, and sized_range when the underlying view V models respective concepts.

Contents

• 1 Data members
• 2 Member functions
  • 2.1 Inherited from std::ranges::view_interface
• 3 Nested classes
• 4 Helper templates
• 5 Example
• 6 Defect reports
• 7 See also

[edit] Data members

[edit] Member functions

[edit] Nested classes

| | the iterator type(exposition-only member class template*) | | ------------------------------------------------------------- | | | the sentinel type(exposition-only member class template*) |

[edit] Helper templates

This specialization of ranges::enable_borrowed_range makes elements_view satisfy borrowed_range when the underlying view satisfies it.

[edit] Example

#include #include #include #include #include   int main() { const std::vector<std::tuple<int, char, std::string>> vt { {1, 'A', "α"}, {2, 'B', "β"}, {3, 'C', "γ"}, {4, 'D', "δ"}, {5, 'E', "ε"}, };   for (int const e : std::views::elements<0>(vt)) std::cout << e << ' '; std::cout << '\n';   for (char const e : vt | std::views::elements<1>) std::cout << e << ' '; std::cout << '\n';   for (std::string const& e : std::views::elements<2>(vt)) std::cout << e << ' '; std::cout << '\n'; }

Output:

1 2 3 4 5 A B C D E α β γ δ ε

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also