25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.17 Split view [range.split]

25.7.17.1 Overview [range.split.overview]

split_view takes a view and a delimiter, and splits the view into subranges on the delimiter.

The delimiter can be a single element or a view of elements.

The name views::split denotes a range adaptor object ([range.adaptor.object]).

Given subexpressions E and F, the expression views::split(E, F) is expression-equivalent to split_view(E, F).

[Example 1: string str{"the quick brown fox"}; for (auto word : views::split(str, ' ')) { cout << string_view(word) << '*'; } // The above prints the*quick*brown*fox* — end example]

25.7.17.2 Class template split_view [range.split.view]

namespace std::ranges { template<forward_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> class split_view : public view_interface<split_view<V, Pattern>> { private: V base_ = V(); // exposition only Pattern pattern_ = Pattern(); // exposition only // [range.split.iterator], class split_view::iterator struct iterator; // exposition only // [range.split.sentinel], class split_view::sentinel struct sentinel; // exposition only public: split_view() requires default_initializable<V> && default_initializable<Pattern> = default; constexpr explicit split_view(V base, Pattern pattern); template<forward_range R> requires constructible_from<V, views::all_t<R>> && constructible_from<Pattern, single_view<range_value_t<R>>> constexpr explicit split_view(R&& r, range_value_t<R> e); constexpr V base() const & requires copy_constructible<V> { return base_; } constexpr V base() && { return std::move(base_); } constexpr iterator begin(); constexpr auto end() { if constexpr (common_range<V>) { return iterator{*this, ranges::end(base_), {}}; } else { return sentinel{*this}; } } constexpr subrange<iterator_t<V>> find-next(iterator_t<V>); // exposition only }; template<class R, class P> split_view(R&&, P&&) -> split_view<views::all_t<R>, views::all_t<P>>; template<forward_range R> split_view(R&&, range_value_t<R>) -> split_view<views::all_t<R>, single_view<range_value_t<R>>>; }

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constexpr explicit split_view(V base, Pattern pattern);

Effects: Initializes base_ with std::move(base), and pattern_ with std::move(pattern).

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template<forward_range R>
  requires constructible_from<V, views::all_t<R>> &&
           constructible_from<Pattern, single_view<range_value_t<R>>>
constexpr explicit split_view(R&& r, range_value_t<R> e);

Effects: Initializes base_ with views::all(std::forward<R>(r)), and pattern_ with views::single(std::move(e)).

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constexpr iterator begin();

Returns: {*this, ranges::begin(base_), find-next(ranges::begin(base_))}.

Remarks: In order to provide the amortized constant time complexity required by the range concept, this function caches the result within the split_view for use on subsequent calls.

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constexpr subrange<iterator_t<V>> find-next(iterator_t<V> it);

Effects: Equivalent to: auto [b, e] = ranges::search(subrange(it, ranges::end(base_)), pattern_); if (b != ranges::end(base_) && ranges::empty(pattern_)) { ++b; ++e; } return {b, e};

25.7.17.3 Class split_view::iterator [range.split.iterator]

namespace std::ranges { template<forward_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> class split_view<V, Pattern>::iterator { private: split_view* parent_ = nullptr; // exposition only iterator_t<V> cur_ = iterator_t<V>(); // exposition only subrange<iterator_t<V>> next_ = subrange<iterator_t<V>>(); // exposition only bool trailing_empty_ = false; // exposition only public: using iterator_concept = forward_iterator_tag; using iterator_category = input_iterator_tag; using value_type = subrange<iterator_t<V>>; using difference_type = range_difference_t<V>; iterator() = default; constexpr iterator(split_view& parent, iterator_t<V> current, subrange<iterator_t<V>> next); constexpr iterator_t<V> base() const; constexpr value_type operator*() const; constexpr iterator& operator++(); constexpr iterator operator++(int); friend constexpr bool operator==(const iterator& x, const iterator& y); }; }

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constexpr iterator(split_view& parent, iterator_t<V> current, subrange<iterator_t<V>> next);

Effects: Initializes parent_ with addressof(parent), cur_ with std::move(current), and next_ with std::move(next).

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constexpr iterator_t<V> base() const;

Effects: Equivalent to: return cur_;

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constexpr value_type operator*() const;

Effects: Equivalent to: return {cur_, next_.begin()};

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constexpr iterator& operator++();

Effects: Equivalent to: cur_ = next_.begin(); if (cur_ != ranges::end(parent_->base_)) { cur_ = next_.end(); if (cur_ == ranges::end(parent_->base_)) { trailing_empty_ = true; next_ = {cur_, cur_}; } else { next_ = parent_->find-next(cur_); } } else { trailing_empty_ = false; } return *this;

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constexpr iterator operator++(int);

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

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friend constexpr bool operator==(const iterator& x, const iterator& y);

Effects: Equivalent to: return x.cur_ == y.cur_ && x.trailing_empty_ == y.trailing_empty_;

25.7.17.4 Class split_view::sentinel [range.split.sentinel]

namespace std::ranges { template<forward_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> struct split_view<V, Pattern>::sentinel { private: sentinel_t<V> end_ = sentinel_t<V>(); // exposition only public: sentinel() = default; constexpr explicit sentinel(split_view& parent); friend constexpr bool operator==(const iterator& x, const sentinel& y); }; }

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constexpr explicit sentinel(split_view& parent);

Effects: Initializes end_ with ranges::end(parent.base_).

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friend constexpr bool operator==(const iterator& x, const sentinel& y);

Effects: Equivalent to: return x.cur_ == y.end_ && !x.trailing_empty_;