26 Ranges library [ranges]

26.7 Range adaptors [range.adaptors]

26.7.23 Enumerate view [range.enumerate]

26.7.23.3 Class template enumerate_view​::​iterator [range.enumerate.iterator]

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namespace std::ranges { template<view V> requires range-with-movable-references<V> template<bool Const> class enumerate_view<V>::iterator { using Base = maybe-const<Const, V>; // exposition only public: using iterator_category = input_iterator_tag; using iterator_concept = see below; using difference_type = range_difference_t<Base>; using value_type = tuple<difference_type, range_value_t<Base>>; private: using reference-type = // exposition only tuple<difference_type, range_reference_t<Base>>; iterator_t<Base> current_ = iterator_t<Base>(); // exposition only difference_type pos_ = 0; // exposition only constexpr explicit iterator(iterator_t<Base> current, difference_type pos); // exposition only public: iterator() requires default_initializable<iterator_t<Base>> = default; constexpr iterator(iterator<!Const> i) requires Const && convertible_to<iterator_t<V>, iterator_t<Base>>; constexpr const iterator_t<Base>& base() const & noexcept; constexpr iterator_t<Base> base() &&; constexpr difference_type index() const noexcept; constexpr auto operator*() const { return reference-type(pos_, *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 x) requires random_access_range<Base>; constexpr iterator& operator-=(difference_type x) requires random_access_range<Base>; constexpr auto operator[](difference_type n) const requires random_access_range<Base> { return reference-type(pos_ + n, current_[n]); } friend constexpr bool operator==(const iterator& x, const iterator& y) noexcept; friend constexpr strong_ordering operator<=>(const iterator& x, const iterator& y) noexcept; 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); friend constexpr auto iter_move(const iterator& i) noexcept(noexcept(ranges::iter_move(i.current_)) && is_nothrow_move_constructible_v<range_rvalue_reference_t<Base>>) { return tuple<difference_type, range_rvalue_reference_t<Base>>(i.pos_, ranges::iter_move(i.current_)); } }; }
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The member typedef-name iterator​::​iterator_concept is defined as follows:
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constexpr explicit iterator(iterator_t<Base> current, difference_type pos);
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Effects: Initializes current_ with std​::​move(current) and pos_ with pos.
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constexpr iterator(iterator<!Const> i) requires Const && convertible_to<iterator_t<V>, iterator_t<Base>>;
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Effects: Initializes current_ with std​::​move(i.current_) and pos_ with i.pos_.
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constexpr const iterator_t<Base>& base() const & noexcept;
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Effects: Equivalent to: return current_;
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constexpr iterator_t<Base> base() &&;
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Effects: Equivalent to: return std​::​move(current_);
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constexpr difference_type index() const noexcept;
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Effects: Equivalent to: return pos_;
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constexpr iterator& operator++();
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Effects: Equivalent to: ++current_; ++pos_; 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 temp = *this; ++*this; return temp;
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constexpr iterator& operator--() requires bidirectional_range<Base>;
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Effects: Equivalent to: --current_; --pos_; return *this;
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constexpr iterator operator--(int) requires bidirectional_range<Base>;
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Effects: Equivalent to: auto temp = *this; --*this; return temp;
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constexpr iterator& operator+=(difference_type n) requires random_access_range<Base>;
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Effects: Equivalent to: current_ += n; pos_ += n; return *this;
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constexpr iterator& operator-=(difference_type n) requires random_access_range<Base>;
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Effects: Equivalent to: current_ -= n; pos_ -= n; return *this;
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friend constexpr bool operator==(const iterator& x, const iterator& y) noexcept;
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Effects: Equivalent to: return x.pos_ == y.pos_;
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friend constexpr strong_ordering operator<=>(const iterator& x, const iterator& y) noexcept;
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Effects: Equivalent to: return x.pos_ <=> y.pos_;
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friend constexpr iterator operator+(const iterator& x, difference_type y) requires random_access_range<Base>;
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Effects: Equivalent to: auto temp = x; temp += y; return temp;
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friend constexpr iterator operator+(difference_type 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 iterator operator-(const iterator& x, difference_type y) requires random_access_range<Base>;
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Effects: Equivalent to: auto temp = x; temp -= y; return temp;
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friend constexpr difference_type operator-(const iterator& x, const iterator& y);
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Effects: Equivalent to: return x.pos_ - y.pos_;