std::ranges...sentinel_t,(3)

🌸 NAME 🌸

okay so bestie, welcome to the C++ Standard Library manual page std::ranges...sentinel_t,(3) — yes the title is a little cursed but we move 💅. This page is the group chat for std::ranges::iterator_t, std::ranges::const_iterator_t, and std::ranges::sentinel_t. The original NAME line repeats the squad after the dash too: std::ranges::iterator_t, std::ranges::const_iterator_t, std::ranges::sentinel_t. No cap, that's the name zone.

✨ Synopsis ✨

also hanging at the top of the synopsis: std::ranges::range_value_t, std::ranges::range_reference_t.

Defined in header <ranges>.

template< class T >
using iterator_t = decltype(ranges::begin(std::declval<T&>()));

template< ranges::range R >
using const_iterator_t = decltype(ranges::cbegin(std::declval<R&>()));

template< ranges::range R >
using sentinel_t = decltype(ranges::end(std::declval<R&>()));

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

template< ranges::sized_range R >
using range_size_t = decltype(ranges::size(std::declval<R&>()));

template< ranges::range R >
using range_difference_t = std::iter_difference_t<ranges::iterator_t<R>>;

template< ranges::range R >
using range_value_t = std::iter_value_t<ranges::iterator_t<R>>;

template< ranges::range R >
using range_reference_t = std::iter_reference_t<ranges::iterator_t<R>>;

template< ranges::range R >
using range_const_reference_t = std::iter_const_reference_t<ranges::iterator_t<R>>;

template< ranges::range R >
using range_rvalue_reference_t = std::iter_rvalue_reference_t<ranges::iterator_t<R>>;

template< ranges::range R >
using range_common_reference_t = std::iter_common_reference_t<ranges::iterator_t<R>>;

1. (1) — since C++20 — used to obtain the iterator type of the type T.
2. (2) — since C++23 — used to obtain the constant iterator type of the range type R.
3. (3) — since C++20 — used to obtain the sentinel type of the range type R.
4. (4) — since C++23 — used to obtain the constant sentinel type of the range type R.
5. (5) — since C++20 — used to obtain the size type of the sized_range type R.
6. (6) — since C++20 — used to obtain the difference type of the iterator type of range type R.
7. (7) — since C++20 — used to obtain the value type of the iterator type of range type R.
8. (8) — since C++20 — used to obtain the reference type of the iterator type of range type R.
9. (9) — since C++23 — used to obtain the constant reference type of the iterator type of range type R.
10. (10) — since C++20 — used to obtain the rvalue reference type of the iterator type of range type R.
11. (11) — since C++20 — used to obtain the common reference type of the iterator type of range type R.

🧚 Template parameters 🧚

• T — a type that can be used in std::ranges::begin.
• R — a range type or a sized_range type.

💜 Notes 💜

important note, bestie: iterator_t can be applied to non-range types, e.g. arrays with unknown bound. That's the whole note and it's lowkey iconic.

💀 Defect reports 💀

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

• DR: LWG 3860 — Applied to: C++20 — behavior as published: range_common_reference_t was missing → correct behavior: added.
• DR: LWG 3946 — Applied to: C++23 — behavior as published: const_iterator_t and const_sentinel_t were inconsistent with the result of ranges::cbegin and ranges::cend respectively → correct behavior: tweaked.

🫶 See also 🫶

The See also crew, with their standards tags:

• iter_value_t (C++20) (alias template)
• iter_reference_t (C++20)
• iter_const_reference_t (C++23)
• iter_difference_t (C++20)
• iter_rvalue_reference_t (C++20)
• iter_common_reference_t (C++20)

They compute the associated types of an iterator. iykyk ✨

mwah 💋 source/version/date: http://cppreference.com · 2024.06.10 · std::ranges...sentinel_t,(3). periodt 🎀