24 Ranges library [ranges]

24.6 Range factories [range.factories]

24.6.4 Istream view [range.istream]

24.6.4.3 Class template basic_­istream_­view​::​iterator [range.istream.iterator]

namespace std::ranges {
  template<movable Val, class CharT, class Traits>
    requires default_initializable<Val> &&
             stream-extractable<Val, CharT, Traits>
  class basic_istream_view<Val, CharT, Traits>::iterator {      // exposition only
  public:
    using iterator_concept = input_iterator_tag;
    using difference_type = ptrdiff_t;
    using value_type = Val;

    iterator() = default;
    constexpr explicit iterator(basic_istream_view& parent) noexcept;

    iterator(const iterator&) = delete;
    iterator(iterator&&) = default;

    iterator& operator=(const iterator&) = delete;
    iterator& operator=(iterator&&) = default;

    iterator& operator++();
    void operator++(int);

    Val& operator*() const;

    friend bool operator==(const iterator& x, default_sentinel_t);

  private:
    basic_istream_view* parent_ = nullptr;                      // exposition only
  };
}

*parent_->stream_>> parent_->object_;
return *this;