cpp-lazy-stream/include/stream/detail/sentinal.h

//
//  sentinal.h
//  stream
//
//  Created by Sam Jaffe on 3/30/23.
//

#pragma once

namespace stream::detail {
struct sentinal_type {
  template <typename It>
  friend bool operator==(It const & iter, sentinal_type) {
    return iter.at_end();
  }
  template <typename It>
  friend bool operator!=(It const & iter, sentinal_type) {
    return !iter.at_end();
  }
};
}

namespace stream::ranges {
constexpr inline detail::sentinal_type sentinal;
}