24 Ranges library [ranges]

24.7 Range adaptors [range.adaptors]

24.7.6 Transform view [range.transform]

24.7.6.3 Class template transform_­view​::​iterator [range.transform.iterator]

namespace std::ranges { template<input_­range V, copy_­constructible F> requires view<V> && is_object_v<F> && regular_invocable<F&, range_reference_t<V>> && can-reference<invoke_result_t<F&, range_reference_t<V>>> template<bool Const> class transform_view<V, F>::iterator { private: using Parent = // exposition only conditional_t<Const, const transform_view, transform_view>; using Base = // exposition only conditional_t<Const, const V, V>; iterator_t<Base> current_ = // exposition only iterator_t<Base>(); Parent* parent_ = nullptr; // exposition only public: using iterator_concept = see below; using iterator_category = see below; using value_type = remove_cvref_t<invoke_result_t<F&, range_reference_t<Base>>>; using difference_type = range_difference_t<Base>; iterator() = default; constexpr iterator(Parent& parent, 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 invoke(*parent_->fun_, *current_); } constexpr iterator& operator++(); constexpr void operator++(int); 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 n) requires random_­access_­range<Base>; constexpr iterator& operator-=(difference_type n) requires random_­access_­range<Base>; constexpr decltype(auto) operator[](difference_type n) const requires random_­access_­range<Base> { return invoke(*parent_->fun_, 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+(iterator i, difference_type n) requires random_­access_­range<Base>; friend constexpr iterator operator+(difference_type n, iterator i) requires random_­access_­range<Base>; friend constexpr iterator operator-(iterator i, difference_type n) requires random_­access_­range<Base>; friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires random_­access_­range<Base>; friend constexpr decltype(auto) iter_move(const iterator& i) noexcept(noexcept(invoke(*i.parent_->fun_, *i.current_))) { if constexpr (is_lvalue_reference_v<decltype(*i)>) return std::move(*i); else return *i; } friend constexpr void iter_swap(const iterator& x, const iterator& y) noexcept(noexcept(ranges::iter_swap(x.current_, y.current_))) requires indirectly_­swappable<iterator_t<Base>>; }; }
1
#
iterator​::​iterator_­concept is defined as follows:
2
#
iterator​::​iterator_­category is defined as follows: Let C denote the type iterator_­traits<iterator_­t<Base>>​::​iterator_­category.
  • (2.1)
    If is_­lvalue_­reference_­v<invoke_­result_­t<F&, range_­reference_­t<Base>>> is true, then
    • (2.1.1)
      if C models derived_­from<contiguous_­iterator_­tag>, iterator_­category denotes random_­access_­iterator_­tag;
    • (2.1.2)
      otherwise, iterator_­category denotes C.
  • (2.2)
    Otherwise, iterator_­category denotes input_­iterator_­tag.
🔗
constexpr iterator(Parent& parent, iterator_t<Base> current);
3
#
Effects: Initializes current_­ with std​::​move(current) and parent_­ with addressof(parent).
🔗
constexpr iterator(iterator<!Const> i) requires Const && convertible_­to<iterator_t<V>, iterator_t<Base>>;
4
#
Effects: Initializes current_­ with std​::​move(i.current_­) and parent_­ with i.parent_­.
🔗
constexpr iterator_t<Base> base() const & requires copyable<iterator_t<Base>>;
5
#
Effects: Equivalent to: return current_­;
🔗
constexpr iterator_t<Base> base() &&;
6
#
Effects: Equivalent to: return std​::​move(current_­);
🔗
constexpr iterator& operator++();
7
#
Effects: Equivalent to: ++current_; return *this;
🔗
constexpr void operator++(int);
8
#
Effects: Equivalent to ++current_­.
🔗
constexpr iterator operator++(int) requires forward_­range<Base>;
9
#
Effects: Equivalent to: auto tmp = *this; ++*this; return tmp;
🔗
constexpr iterator& operator--() requires bidirectional_­range<Base>;
10
#
Effects: Equivalent to: --current_; return *this;
🔗
constexpr iterator operator--(int) requires bidirectional_­range<Base>;
11
#
Effects: Equivalent to: auto tmp = *this; --*this; return tmp;
🔗
constexpr iterator& operator+=(difference_type n) requires random_­access_­range<Base>;
12
#
Effects: Equivalent to: current_ += n; return *this;
🔗
constexpr iterator& operator-=(difference_type n) requires random_­access_­range<Base>;
13
#
Effects: Equivalent to: current_ -= n; return *this;
🔗
friend constexpr bool operator==(const iterator& x, const iterator& y) requires equality_comparable<iterator_t<Base>>;
14
#
Effects: Equivalent to: return x.current_­ == y.current_­;
🔗
friend constexpr bool operator<(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
15
#
Effects: Equivalent to: return x.current_­ < y.current_­;
🔗
friend constexpr bool operator>(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
16
#
Effects: Equivalent to: return y < x;
🔗
friend constexpr bool operator<=(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
17
#
Effects: Equivalent to: return !(y < x);
🔗
friend constexpr bool operator>=(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
18
#
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>>;
19
#
Effects: Equivalent to: return x.current_­ <=> y.current_­;
🔗
friend constexpr iterator operator+(iterator i, difference_type n) requires random_­access_­range<Base>; friend constexpr iterator operator+(difference_type n, iterator i) requires random_­access_­range<Base>;
20
#
Effects: Equivalent to: return iterator{*i.parent_­, i.current_­ + n};
🔗
friend constexpr iterator operator-(iterator i, difference_type n) requires random_­access_­range<Base>;
21
#
Effects: Equivalent to: return iterator{*i.parent_­, i.current_­ - n};
🔗
friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires random_­access_­range<Base>;
22
#
Effects: Equivalent to: return x.current_­ - y.current_­;
🔗
friend constexpr void iter_swap(const iterator& x, const iterator& y) noexcept(noexcept(ranges::iter_swap(x.current_­, y.current_­))) requires indirectly_­swappable<iterator_t<Base>>;
23
#
Effects: Equivalent to ranges​::​iter_­swap(x.current_­, y.current_­).