From Jason Turner

[move.iterator]

C++17 → C++20 4.8 KB 77 lines
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Archived: C++17 | C++20
Markdown: C++17 | C++20
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  1. tmp/tmpwwz8kz94/{from.md → to.md} +32 -42
tmp/tmpwwz8kz94/{from.md → to.md} RENAMED
@@ -4,72 +4,62 @@
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  namespace std {
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  template<class Iterator>
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  class move_iterator {
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  public:
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  using iterator_type = Iterator;
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- using iterator_category = typename iterator_traits<Iterator>::iterator_category;
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- using value_type = typename iterator_traits<Iterator>::value_type;
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- using difference_type = typename iterator_traits<Iterator>::difference_type;
 
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  using pointer = Iterator;
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- using reference = see below;
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  constexpr move_iterator();
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  constexpr explicit move_iterator(Iterator i);
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  template<class U> constexpr move_iterator(const move_iterator<U>& u);
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  template<class U> constexpr move_iterator& operator=(const move_iterator<U>& u);
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- constexpr iterator_type base() const;
 
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  constexpr reference operator*() const;
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- constexpr pointer operator->() const;
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  constexpr move_iterator& operator++();
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- constexpr move_iterator operator++(int);
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  constexpr move_iterator& operator--();
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  constexpr move_iterator operator--(int);
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  constexpr move_iterator operator+(difference_type n) const;
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  constexpr move_iterator& operator+=(difference_type n);
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  constexpr move_iterator operator-(difference_type n) const;
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  constexpr move_iterator& operator-=(difference_type n);
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- constexpr unspecified operator[](difference_type n) const;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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  private:
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  Iterator current; // exposition only
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  };
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-
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- template <class Iterator1, class Iterator2>
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- constexpr bool operator==(
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- const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
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- template <class Iterator1, class Iterator2>
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- constexpr bool operator!=(
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- const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
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- template <class Iterator1, class Iterator2>
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- constexpr bool operator<(
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- const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
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- template <class Iterator1, class Iterator2>
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- constexpr bool operator<=(
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- const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
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- template <class Iterator1, class Iterator2>
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- constexpr bool operator>(
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- const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
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- template <class Iterator1, class Iterator2>
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- constexpr bool operator>=(
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- const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
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-
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- template <class Iterator1, class Iterator2>
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- constexpr auto operator-(
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- const move_iterator<Iterator1>& x,
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- const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
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- template <class Iterator>
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- constexpr move_iterator<Iterator> operator+(
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- typename move_iterator<Iterator>::difference_type n, const move_iterator<Iterator>& x);
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- template <class Iterator>
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- constexpr move_iterator<Iterator> make_move_iterator(Iterator i);
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  }
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  ```
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- Let `R` denote `iterator_traits<Iterator>::reference`. If
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- `is_reference_v<R>` is `true`, the template specialization
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- `move_iterator<Iterator>` shall define the nested type named `reference`
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- as a synonym for `remove_reference_t<R>&&`, otherwise as a synonym for
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- `R`.
 
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  namespace std {
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  template<class Iterator>
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  class move_iterator {
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  public:
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  using iterator_type = Iterator;
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+ using iterator_concept = input_iterator_tag;
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+ using iterator_category = see below;
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+ using value_type = iter_value_t<Iterator>;
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+ using difference_type = iter_difference_t<Iterator>;
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  using pointer = Iterator;
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+ using reference = iter_rvalue_reference_t<Iterator>;
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  constexpr move_iterator();
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  constexpr explicit move_iterator(Iterator i);
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  template<class U> constexpr move_iterator(const move_iterator<U>& u);
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  template<class U> constexpr move_iterator& operator=(const move_iterator<U>& u);
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+ constexpr iterator_type base() const &;
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+ constexpr iterator_type base() &&;
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  constexpr reference operator*() const;
 
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  constexpr move_iterator& operator++();
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+ constexpr auto operator++(int);
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  constexpr move_iterator& operator--();
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  constexpr move_iterator operator--(int);
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  constexpr move_iterator operator+(difference_type n) const;
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  constexpr move_iterator& operator+=(difference_type n);
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  constexpr move_iterator operator-(difference_type n) const;
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  constexpr move_iterator& operator-=(difference_type n);
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+ constexpr reference operator[](difference_type n) const;
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+
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+ template<sentinel_for<Iterator> S>
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+ friend constexpr bool
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+ operator==(const move_iterator& x, const move_sentinel<S>& y);
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+ template<sized_sentinel_for<Iterator> S>
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+ friend constexpr iter_difference_t<Iterator>
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+ operator-(const move_sentinel<S>& x, const move_iterator& y);
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+ template<sized_sentinel_for<Iterator> S>
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+ friend constexpr iter_difference_t<Iterator>
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+ operator-(const move_iterator& x, const move_sentinel<S>& y);
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+ friend constexpr iter_rvalue_reference_t<Iterator>
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+ iter_move(const move_iterator& i)
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+ noexcept(noexcept(ranges::iter_move(i.current)));
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+ template<indirectly_swappable<Iterator> Iterator2>
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+ friend constexpr void
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+ iter_swap(const move_iterator& x, const move_iterator<Iterator2>& y)
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+ noexcept(noexcept(ranges::iter_swap(x.current, y.current)));
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  private:
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  Iterator current; // exposition only
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  };
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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  }
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  ```
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+ The member *typedef-name* `iterator_category` denotes
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+
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+ - `random_access_iterator_tag` if the type
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+ `iterator_traits<{}Iterator>::iterator_category` models
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+ `derived_from<random_access_iterator_tag>`, and
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+ - `iterator_traits<{}Iterator>::iterator_category` otherwise.
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