cpp-useful-iterators/include/iterator/sentinel.h

//
//  sentinel.h
//  iterator
//
//  Created by Sam Jaffe on 3/31/23.
//  Copyright © 2023 Sam Jaffe. All rights reserved.
//

#pragma once

namespace iterator {
struct sentinel_t {};
inline constexpr sentinel_t sentinel;

template <typename It> bool operator==(It const & iter, sentinel_t) {
  return iter.at_end();
}
template <typename It> bool operator!=(It const & iter, sentinel_t) {
  return !iter.at_end();
}
}