24 Ranges library [ranges]

24.7 Range adaptors [range.adaptors]

24.7.16 Elements view [range.elements]

24.7.16.3 Class template elements_­view​::​iterator [range.elements.iterator]

namespace std::ranges { template<input_­range V, size_t N> requires view<V> && has-tuple-element<range_value_t<V>, N> && has-tuple-element<remove_reference_t<range_reference_t<V>>, N> template<bool Const> class elements_view<V, N>::iterator { // exposition only using Base = maybe-const<Const, V>; // exposition only iterator_t<Base> current_ = iterator_t<Base>(); public: using iterator_category = typename iterator_traits<iterator_t<Base>>::iterator_category; using value_type = remove_cvref_t<tuple_element_t<N, range_value_t<Base>>>; using difference_type = range_difference_t<Base>; iterator() = default; constexpr explicit iterator(iterator_t<Base> current); constexpr iterator(iterator<!Const> i) requires Const && convertible_­to<iterator_t<V>, iterator_t<Base>>; constexpr iterator_t<Base> base() const& requires copyable<iterator_t<Base>>; constexpr iterator_t<Base> base() &&; constexpr decltype(auto) operator*() const { return get<N>(*current_); } constexpr iterator& operator++(); constexpr void operator++(int) requires (!forward_­range<Base>); constexpr iterator operator++(int) requires forward_­range<Base>; constexpr iterator& operator--() requires bidirectional_­range<Base>; constexpr iterator operator--(int) requires bidirectional_­range<Base>; constexpr iterator& operator+=(difference_type x) requires random_­access_­range<Base>; constexpr iterator& operator-=(difference_type x) requires random_­access_­range<Base>; constexpr decltype(auto) operator[](difference_type n) const requires random_­access_­range<Base> { return get<N>(*(current_ + n)); } friend constexpr bool operator==(const iterator& x, const iterator& y) requires equality_­comparable<iterator_t<Base>>; friend constexpr bool operator<(const iterator& x, const iterator& y) requires random_­access_­range<Base>; friend constexpr bool operator>(const iterator& x, const iterator& y) requires random_­access_­range<Base>; friend constexpr bool operator<=(const iterator& x, const iterator& y) requires random_­access_­range<Base>; friend constexpr bool operator>=(const iterator& x, const iterator& y) requires random_­access_­range<Base>; friend constexpr auto operator<=>(const iterator& x, const iterator& y) requires random_­access_­range<Base> && three_­way_­comparable<iterator_t<Base>>; friend constexpr iterator operator+(const iterator& x, difference_type y) requires random_­access_­range<Base>; friend constexpr iterator operator+(difference_type x, const iterator& y) requires random_­access_­range<Base>; friend constexpr iterator operator-(const iterator& x, difference_type y) requires random_­access_­range<Base>; friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires sized_­sentinel_­for<iterator_t<Base>, iterator_t<Base>>; }; }
constexpr explicit iterator(iterator_t<Base> current);
Effects: Initializes current_­ with std​::​move(current).
constexpr iterator(iterator<!Const> i) requires Const && convertible_­to<iterator_t<V>, iterator_t<Base>>;
Effects: Initializes current_­ with std​::​move(i.current_­).
constexpr iterator_t<Base> base() const& requires copyable<iterator_t<Base>>;
Effects: Equivalent to: return current_­;
constexpr iterator_t<Base> base() &&;
Effects: Equivalent to: return std​::​move(current_­);
constexpr iterator& operator++();
Effects: Equivalent to: ++current_; return *this;
constexpr void operator++(int) requires (!forward_­range<Base>);
Effects: Equivalent to: ++current_­.
constexpr iterator operator++(int) requires forward_­range<Base>;
Effects: Equivalent to: auto temp = *this; ++current_; return temp;
constexpr iterator& operator--() requires bidirectional_­range<Base>;
Effects: Equivalent to: --current_; return *this;
constexpr iterator operator--(int) requires bidirectional_­range<Base>;
Effects: Equivalent to: auto temp = *this; --current_; return temp;
constexpr iterator& operator+=(difference_type n); requires random_­access_­range<Base>;
Effects: Equivalent to: current_ += n; return *this;
constexpr iterator& operator-=(difference_type n) requires random_­access_­range<Base>;
Effects: Equivalent to: current_ -= n; return *this;
friend constexpr bool operator==(const iterator& x, const iterator& y) requires equality_comparable<Base>;
Effects: Equivalent to: return x.current_­ == y.current_­;
friend constexpr bool operator<(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
Effects: Equivalent to: return x.current_­ < y.current_­;
friend constexpr bool operator>(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
Effects: Equivalent to: return y < x;
friend constexpr bool operator<=(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
Effects: Equivalent to: return !(y < x);
friend constexpr bool operator>=(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
Effects: Equivalent to: return !(x < y);
friend constexpr auto operator<=>(const iterator& x, const iterator& y) requires random_­access_­range<Base> && three_­way_­comparable<iterator_t<Base>>;
Effects: Equivalent to: return x.current_­ <=> y.current_­;
friend constexpr iterator operator+(const iterator& x, difference_type y) requires random_­access_­range<Base>;
Effects: Equivalent to: return iterator{x} += y;
friend constexpr iterator operator+(difference_type x, const iterator& y) requires random_­access_­range<Base>;
Effects: Equivalent to: return y + x;
friend constexpr iterator operator-(const iterator& x, difference_type y) requires random_­access_­range<Base>;
Effects: Equivalent to: return iterator{x} -= y;
friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires sized_­sentinel_­for<iterator_t<Base>, iterator_t<Base>>;
Effects: Equivalent to: return x.current_­ - y.current_­;