namespace std { template <class Iterator> class move_iterator { public: using iterator_type = Iterator; using iterator_category = typename iterator_traits<Iterator>::iterator_category; using value_type = typename iterator_traits<Iterator>::value_type; using difference_type = typename iterator_traits<Iterator>::difference_type; using pointer = Iterator; using reference = see below; constexpr move_iterator(); constexpr explicit move_iterator(Iterator i); template <class U> constexpr move_iterator(const move_iterator<U>& u); template <class U> constexpr move_iterator& operator=(const move_iterator<U>& u); constexpr iterator_type base() const; constexpr reference operator*() const; constexpr pointer operator->() const; constexpr move_iterator& operator++(); constexpr move_iterator operator++(int); constexpr move_iterator& operator--(); constexpr move_iterator operator--(int); constexpr move_iterator operator+(difference_type n) const; constexpr move_iterator& operator+=(difference_type n); constexpr move_iterator operator-(difference_type n) const; constexpr move_iterator& operator-=(difference_type n); constexpr unspecified operator[](difference_type n) const; private: Iterator current; // exposition only }; template <class Iterator1, class Iterator2> constexpr bool operator==( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y); template <class Iterator1, class Iterator2> constexpr bool operator!=( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y); template <class Iterator1, class Iterator2> constexpr bool operator<( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y); template <class Iterator1, class Iterator2> constexpr bool operator<=( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y); template <class Iterator1, class Iterator2> constexpr bool operator>( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y); template <class Iterator1, class Iterator2> constexpr bool operator>=( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y); template <class Iterator1, class Iterator2> constexpr auto operator-( const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base()); template <class Iterator> constexpr move_iterator<Iterator> operator+( typename move_iterator<Iterator>::difference_type n, const move_iterator<Iterator>& x); template <class Iterator> constexpr move_iterator<Iterator> make_move_iterator(Iterator i); }
Let R denote iterator_traits<Iterator>::reference. If is_reference_v<R> is true, the template specialization move_iterator<Iterator> shall define the nested type named reference as a synonym for remove_reference_t<R>&&, otherwise as a synonym for R.