25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.29 Chunk view [range.chunk]

25.7.29.7 Class template chunk_view​::​iterator for forward ranges [range.chunk.fwd.iter]

namespace std::ranges { template<view V> requires forward_range<V> template<bool Const> class chunk_view<V>::iterator { using Parent = maybe-const<Const, chunk_view>; // exposition only using Base = maybe-const<Const, V>; // exposition only iterator_t<Base> current_ = iterator_t<Base>(); // exposition only sentinel_t<Base> end_ = sentinel_t<Base>(); // exposition only range_difference_t<Base> n_ = 0; // exposition only range_difference_t<Base> missing_ = 0; // exposition only constexpr iterator(Parent* parent, iterator_t<Base> current, // exposition only range_difference_t<Base> missing = 0); public: using iterator_category = input_iterator_tag; using iterator_concept = see below; using value_type = decltype(views::take(subrange(current_, end_), n_)); using difference_type = range_difference_t<Base>; iterator() = default; constexpr iterator(iterator<!Const> i) requires Const && convertible_to<iterator_t<V>, iterator_t<Base>> && convertible_to<sentinel_t<V>, sentinel_t<Base>>; constexpr iterator_t<Base> base() const; constexpr value_type operator*() const; constexpr iterator& operator++(); constexpr iterator operator++(int); 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 value_type operator[](difference_type n) const requires random_access_range<Base>; friend constexpr bool operator==(const iterator& x, const iterator& y); friend constexpr bool operator==(const iterator& x, default_sentinel_t); 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& 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<iterator_t<Base>, iterator_t<Base>>; friend constexpr difference_type operator-(default_sentinel_t y, const iterator& x) requires sized_sentinel_for<sentinel_t<Base>, iterator_t<Base>>; friend constexpr difference_type operator-(const iterator& x, default_sentinel_t y) requires sized_sentinel_for<sentinel_t<Base>, iterator_t<Base>>; }; }
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iterator​::​iterator_concept is defined as follows:
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constexpr iterator(Parent* parent, iterator_t<Base> current, range_difference_t<Base> missing = 0);
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Effects: Initializes current_ with current, end_ with ranges​::​end(parent->base_), n_ with parent->n_, and missing_ with missing.
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constexpr iterator(iterator<!Const> i) requires Const && convertible_to<iterator_t<V>, iterator_t<Base>> && convertible_to<sentinel_t<V>, sentinel_t<Base>>;
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Effects: Initializes current_ with std​::​move(i.current_), end_ with std​::​move(i.end_), n_ with i.n_, and missing_ with i.missing_.
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constexpr iterator_t<Base> base() const;
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Returns: current_.
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constexpr value_type operator*() const;
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Preconditions: current_ != end_ is true.
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Returns: views​::​take(subrange(current_, end_), n_).
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constexpr iterator& operator++();
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Preconditions: current_ != end_ is true.
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Effects: Equivalent to: missing_ = ranges::advance(current_, n_, end_); return *this;
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constexpr iterator operator++(int);
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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: ranges::advance(current_, missing_ - n_); missing_ = 0; 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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Preconditions: If x is positive, ranges​::​distance(current_, end_) > n_ * (x - 1) is true.
[Note 1: 
If x is negative, the Effects paragraph implies a precondition.
— end note]
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Effects: Equivalent to: if (x > 0) { ranges::advance(current_, n_ * (x - 1)); missing_ = ranges::advance(current_, n_, end_); } else if (x < 0) { ranges::advance(current_, n_ * x + missing_); missing_ = 0; } return *this;
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constexpr iterator& operator-=(difference_type x) requires random_access_range<Base>;
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Effects: Equivalent to: return *this += -x;
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constexpr value_type operator[](difference_type n) const requires random_access_range<Base>;
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Returns: *(*this + n).
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friend constexpr bool operator==(const iterator& x, const iterator& y);
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Returns: x.current_ == y.current_.
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friend constexpr bool operator==(const iterator& x, default_sentinel_t);
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Returns: x.current_ == x.end_.
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friend constexpr bool operator<(const iterator& x, const iterator& y) requires random_access_range<Base>;
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Returns: x.current_ < y.current_.
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friend constexpr bool operator>(const iterator& x, const iterator& y) requires random_access_range<Base>;
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Effects: Equivalent to: return y < x;
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friend constexpr bool operator<=(const iterator& x, const iterator& y) requires random_access_range<Base>;
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Effects: Equivalent to: return !(y < x);
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friend constexpr bool operator>=(const iterator& x, const iterator& y) requires random_access_range<Base>;
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Effects: Equivalent to: return !(x < y);
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friend constexpr auto operator<=>(const iterator& x, const iterator& y) requires random_access_range<Base> && three_way_comparable<iterator_t<Base>>;
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Returns: x.current_ <=> y.current_.
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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: auto r = i; r += n; return r;
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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: auto r = i; r -= n; return r;
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friend constexpr difference_type operator-(const iterator& x, const iterator& y) requires sized_sentinel_for<iterator_t<Base>, iterator_t<Base>>;
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Returns: (x.current_ - y.current_ + x.missing_ - y.missing_) / x.n_.
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friend constexpr difference_type operator-(default_sentinel_t y, const iterator& x) requires sized_sentinel_for<sentinel_t<Base>, iterator_t<Base>>;
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Returns: div-ceil(x.end_ - x.current_, x.n_).
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friend constexpr difference_type operator-(const iterator& x, default_sentinel_t y) requires sized_sentinel_for<sentinel_t<Base>, iterator_t<Base>>;
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Effects: Equivalent to: return -(y - x);