cppdraft_translate/cppdraft/range/zip/transform/iterator.md

[range.zip.transform.iterator]

25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.26 Zip transform view [range.zip.transform]

25.7.26.3 Class template zip_transform_view​::​iterator [range.zip.transform.iterator]

🔗

namespace std::ranges {template<move_constructible F, input_range... Views>requires (view && ...) && (sizeof...(Views) > 0) && is_object_v &&regular_invocable<F&, range_reference_t...> &&can-reference<invoke_result_t<F&, range_reference_t...>>templateclass zip_transform_view<F, Views...>::iterator {using Parent = maybe-const<Const, zip_transform_view>; // exposition onlyusing Base = maybe-const<Const, InnerView>; // exposition onlyParent parent_ = nullptr; // exposition only**ziperator inner_; // exposition onlyconstexpr iterator(Parent& parent, ziperator inner); // exposition onlypublic:using iterator_category = see below; // not always presentusing iterator_concept = typename ziperator::iterator_concept; using value_type = remove_cvref_t<invoke_result_t<maybe-const<Const, F>&, range_reference_t<maybe-const<Const, Views>>...>>; using difference_type = range_difference_t<Base>; iterator() = default; constexpr iterator(iterator i)requires Const && convertible_to<ziperator, ziperator>; constexpr decltype(auto) operator() const noexcept(see below); 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 x) requires random_access_range<Base>; constexpr iterator& operator-=(difference_type x) requires random_access_range<Base>; constexpr decltype(auto) operator[](difference_type n) constrequires random_access_range<Base>; friend constexpr bool operator==(const iterator& x, const iterator& y)requires equality_comparable<ziperator>; friend constexpr auto operator<=>(const iterator& x, const iterator& y)requires random_access_range<Base>; friend constexpr iterator operator+(const iterator& i, difference_type n)requires random_access_range<Base>; friend constexpr iterator operator+(difference_type n, const iterator& i)requires random_access_range<Base>; friend constexpr iterator operator-(const iterator& i, difference_type n)requires random_access_range<Base>; friend constexpr difference_type operator-(const iterator& x, const iterator& y)requires sized_sentinel_for<ziperator, ziperator>; };}

1

#

The member typedef-nameiterator​::​iterator_category is defined if and only if Base models forward_range.

In that case,iterator​::​iterator_category is defined as follows:

• (1.1)

Ifinvoke_result_t<maybe-const<Const, F>&, range_reference_t<maybe-const<Const, Views>>...> is not a reference,iterator_category denotes input_iterator_tag.

• (1.2)

Otherwise, let Cs denote the pack of typesiterator_traits<iterator_t<maybe-const<Const, Views>>>​::​iterator_category.... * (1.2.1)

  If ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, random_access_iterator_tag> && ...) is true,iterator_category denotes random_access_iterator_tag[.](#1.2.1.sentence-1)

• (1.2.2)

  Otherwise, if (derived_from<Cs, bidirectional_iterator_tag> && ...) is true,iterator_category denotes bidirectional_iterator_tag.

• (1.2.3)

  Otherwise, if (derived_from<Cs, forward_iterator_tag> && ...) is true,iterator_category denotes forward_iterator_tag.

• (1.2.4)

  Otherwise, iterator_category denotes input_iterator_tag.

🔗

constexpr iterator(Parent& parent, ziperator<Const> inner);

2

#

Effects: Initializes parent_ with addressof(parent) andinner_ with std​::​move(inner).

🔗

constexpr iterator(iterator<!Const> i) requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<ziperator<false>, ziperator<Const>>;

3

#

Effects: Initializes parent_ with i.parent_ andinner_ with std​::​move(i.inner_).

🔗

constexpr decltype(auto) operator*() const noexcept(see below);

4

#

Effects: Equivalent to:return apply([&](const auto&... iters) -> decltype(auto) {return invoke(**parent_*->fun_, *iters...);}, inner_.current_);

5

#

Remarks: Let Is be the pack 0, 1, …, (sizeof...(Views) - 1).

The exception specification is equivalent to:noexcept(invoke(**parent_*->fun_, *std​::​get(inner_.current_)...)).

🔗

constexpr iterator& operator++();

6

#

Effects: Equivalent to:++inner_;return *this;

🔗

constexpr void operator++(int);

7

#

Effects: Equivalent to: ++*this.

🔗

constexpr iterator operator++(int) requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<Base>;

8

#

Effects: Equivalent to:auto tmp = *this;++*this;return tmp;

🔗

constexpr iterator& operator--() requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base>;

9

#

Effects: Equivalent to:--inner_;return *this;

🔗

constexpr iterator operator--(int) requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base>;

10

#

Effects: Equivalent to:auto tmp = *this;--*this;return tmp;

🔗

constexpr iterator& operator+=(difference_type x) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;

11

#

Effects: Equivalent to:inner_ += x;return *this;

🔗

constexpr iterator& operator-=(difference_type x) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;

12

#

Effects: Equivalent to:inner_ -= x;return *this;

🔗

constexpr decltype(auto) operator[](difference_type n) const requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;

13

#

Effects: Equivalent to:return apply([&]<class... Is>(const Is&... iters) -> decltype(auto) {return invoke(**parent_*->fun_, iters[iter_difference_t(n)]...);}, inner_.current_);

🔗

friend constexpr bool operator==(const iterator& x, const iterator& y) requires [equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<ziperator<Const>>; friend constexpr auto operator<=>(const iterator& x, const iterator& y) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;

14

#

Let op be the operator.

15

#

Effects: Equivalent to:return x.inner_ op y.inner_;

🔗

friend constexpr iterator operator+(const iterator& i, difference_type n) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>; friend constexpr iterator operator+(difference_type n, const iterator& i) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;

16

#

Effects: Equivalent to:return iterator(*i.parent_, i.inner_ + n);

🔗

friend constexpr iterator operator-(const iterator& i, difference_type n) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;

17

#

Effects: Equivalent to:return iterator(*i.parent_, i.inner_ - n);

🔗

friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<ziperator<Const>, ziperator<Const>>;

18

#

Effects: Equivalent to:return x.inner_ - y.inner_;