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<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> && regular_invocable<F&, range_reference_t<Views>...> && can-reference<invoke_result_t<F&, range_reference_t<Views>...>> template<bool Const> class zip_transform_view<F, Views...>::iterator { using Parent = maybe-const<Const, zip_transform_view>; // exposition only using Base = maybe-const<Const, InnerView>; // exposition only Parent* parent_ = nullptr; // exposition only ziperator<Const> inner_; // exposition only constexpr iterator(Parent& parent, ziperator<Const> inner); // exposition only public: using iterator_category = see below; // not always present using iterator_concept = typename ziperator<Const>::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<!Const> i) requires Const && convertible_to<ziperator<false>, ziperator<Const>>; 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) const requires random_access_range<Base>; friend constexpr bool operator==(const iterator& x, const iterator& y) requires equality_comparable<ziperator<Const>>; 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<Const>, ziperator<Const>>; }; }
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The member typedef-name iterator​::​iterator_category is defined if and only if Base models forward_range.
In that case, iterator​::​iterator_category is defined as follows:
  • (1.1)
    If invoke_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 types iterator_traits<iterator_t<maybe-const<Const, Views>>>​::​iterator_category....
    • (1.2.1)
      If (derived_from<Cs, random_access_iterator_tag> && ...) is true, iterator_category denotes random_access_iterator_tag.
    • (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.
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constexpr iterator(Parent& parent, ziperator<Const> inner);
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Effects: Initializes parent_ with addressof(parent) and inner_ with std​::​move(inner).
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constexpr iterator(iterator<!Const> i) requires Const && convertible_to<ziperator<false>, ziperator<Const>>;
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Effects: Initializes parent_ with i.parent_ and inner_ with std​::​move(i.inner_).
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constexpr decltype(auto) operator*() const noexcept(see below);
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Effects: Equivalent to: return apply([&](const auto&... iters) -> decltype(auto) { return invoke(*parent_->fun_, *iters...); }, inner_.current_);
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Remarks: Let Is be the pack 0, 1, …, (sizeof...(Views)-1).
The exception specification is equivalent to: noexcept(invoke(*parent_->fun_, *std​::​get<Is>(inner_.current_)...)).
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constexpr iterator& operator++();
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Effects: Equivalent to: ++inner_; return *this;
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constexpr void operator++(int);
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Effects: Equivalent to: ++*this.
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constexpr iterator operator++(int) requires forward_range<Base>;
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Effects: Equivalent to: auto tmp = *this; ++*this; return tmp;
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constexpr iterator& operator--() requires bidirectional_range<Base>;
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Effects: Equivalent to: --inner_; return *this;
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constexpr iterator operator--(int) requires bidirectional_range<Base>;
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Effects: Equivalent to: auto tmp = *this; --*this; return tmp;
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constexpr iterator& operator+=(difference_type x) requires random_access_range<Base>;
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Effects: Equivalent to: inner_ += x; return *this;
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constexpr iterator& operator-=(difference_type x) requires random_access_range<Base>;
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Effects: Equivalent to: inner_ -= x; return *this;
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constexpr decltype(auto) operator[](difference_type n) const requires random_access_range<Base>;
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Effects: Equivalent to: return apply([&]<class... Is>(const Is&... iters) -> decltype(auto) { return invoke(*parent_->fun_, iters[iter_difference_t<Is>(n)]...); }, inner_.current_);
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friend constexpr bool operator==(const iterator& x, const iterator& y) requires equality_comparable<ziperator<Const>>; friend constexpr auto operator<=>(const iterator& x, const iterator& y) requires random_access_range<Base>;
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Let op be the operator.
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Effects: Equivalent to: return x.inner_ op y.inner_;
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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>;
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Effects: Equivalent to: return iterator(*i.parent_, i.inner_ + n);
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friend constexpr iterator operator-(const iterator& i, difference_type n) requires random_access_range<Base>;
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Effects: Equivalent to: return iterator(*i.parent_, i.inner_ - n);
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friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires sized_sentinel_for<ziperator<Const>, ziperator<Const>>;
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Effects: Equivalent to: return x.inner_ - y.inner_;