const_sentinel_t.md

const_sentinel_t

• ranges[meta header]
• std::ranges[meta namespace]
• type-alias[meta id-type]
• cpp23[meta cpp]

namespace std::ranges {
  template<range R>
  using const_sentinel_t = decltype(ranges::cend(declval<R&>()));
}

• range[link range.md]
• cend[link cend.md]
• declval[link /reference/utility/declval.md]

概要

任意のRange型Rの定数イテレータ（const_iterator_t<R>）に対応する番兵の型を取得する。

例

#include <ranges>
#include <vector>

int main() {
  static_assert(std::same_as<std::ranges::const_sentinel_t<      std::vector<int>>, std::basic_const_iterator<std::vector<int>::iterator>>);
  static_assert(std::same_as<std::ranges::const_sentinel_t<const std::vector<int>>, std::vector<int>::const_iterator>);

  static_assert(std::same_as<std::ranges::const_sentinel_t<std::ranges::repeat_view<int>>, std::unreachable_sentinel_t>);
}

• std::ranges::const_sentinel_t[color ff0000]
• repeat_view[link repeat_view.md]
• std::unreachable_sentinel_t[link /reference/iterator/unreachable_sentinel_t.md]

出力

バージョン

言語

• C++23

処理系

• Clang: ??
• GCC: 13.1 [mark verified]
• Visual C++: 2022 Update 6 [mark verified]

参照

• P2278R4 cbegin should always return a constant iterator
• LWG Issue 3946. The definition of const_iterator_t should be reworked