24 Ranges library [ranges]

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"}; split_view sentence{str, ' '}; for (auto word : sentence) { for (char ch : word) cout << ch; cout << '*'; } // The above prints: the*quick*brown*fox* — end example]

24.7.12.2 Class template split_view [range.split.view]

namespace std::ranges { template<auto> struct require-constant; // exposition only template<class R> concept tiny-range = // exposition only sized_range<R> && requires { typename require-constant<remove_reference_t<R>::size()>; } && (remove_reference_t<R>::size() <= 1); template<input_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> && (forward_range<V> || tiny-range<Pattern>) class split_view : public view_interface<split_view<V, Pattern>> { private: V base_ = V(); // exposition only Pattern pattern_ = Pattern(); // exposition only iterator_t<V> current_ = iterator_t<V>(); // exposition only, present only if !forward_range<V> // [range.split.outer], class template split_view::outer-iterator template<bool> struct outer-iterator; // exposition only // [range.split.inner], class template split_view::inner-iterator template<bool> struct inner-iterator; // exposition only public: split_view() = default; constexpr split_view(V base, Pattern pattern); template<input_range R> requires constructible_from<V, views::all_t<R>> && constructible_from<Pattern, single_view<range_value_t<R>>> constexpr 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 auto begin() { if constexpr (forward_range<V>) return outer-iterator<simple-view<V>>{*this, ranges::begin(base_)}; else { current_ = ranges::begin(base_); return outer-iterator<false>{*this}; } } constexpr auto begin() const requires forward_range<V> && forward_range<const V> { return outer-iterator<true>{*this, ranges::begin(base_)}; } constexpr auto end() requires forward_range<V> && common_range<V> { return outer-iterator<simple-view<V>>{*this, ranges::end(base_)}; } constexpr auto end() const { if constexpr (forward_range<V> && forward_range<const V> && common_range<const V>) return outer-iterator<true>{*this, ranges::end(base_)}; else return default_sentinel; } }; template<class R, class P> split_view(R&&, P&&) -> split_view<views::all_t<R>, views::all_t<P>>; template<input_range R> split_view(R&&, range_value_t<R>) -> split_view<views::all_t<R>, single_view<range_value_t<R>>>; }

constexpr split_view(V base, Pattern pattern);

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

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

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

24.7.12.3 Class template split_view::outer-iterator [range.split.outer]

namespace std::ranges { template<input_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> && (forward_range<V> || tiny-range<Pattern>) template<bool Const> struct split_view<V, Pattern>::outer-iterator { private: using Parent = // exposition only conditional_t<Const, const split_view, split_view>; using Base = // exposition only conditional_t<Const, const V, V>; Parent* parent_ = nullptr; // exposition only iterator_t<Base> current_ = // exposition only, present only if V models forward_range iterator_t<Base>(); public: using iterator_concept = conditional_t<forward_range<Base>, forward_iterator_tag, input_iterator_tag>; using iterator_category = input_iterator_tag; // [range.split.outer.value], class split_view::outer-iterator::value_type struct value_type; using difference_type = range_difference_t<Base>; outer-iterator() = default; constexpr explicit outer-iterator(Parent& parent) requires (!forward_range<Base>); constexpr outer-iterator(Parent& parent, iterator_t<Base> current) requires forward_range<Base>; constexpr outer-iterator(outer-iterator<!Const> i) requires Const && convertible_to<iterator_t<V>, iterator_t<Base>>; constexpr value_type operator*() const; constexpr outer-iterator& operator++(); constexpr decltype(auto) operator++(int) { if constexpr (forward_range<Base>) { auto tmp = *this; ++*this; return tmp; } else ++*this; } friend constexpr bool operator==(const outer-iterator& x, const outer-iterator& y) requires forward_range<Base>; friend constexpr bool operator==(const outer-iterator& x, default_sentinel_t); }; }

Many of the following specifications refer to the notional member current of outer-iterator.

current is equivalent to current_ if V models forward_range, and parent_->current_ otherwise.

constexpr explicit outer-iterator(Parent& parent)
  requires (!forward_range<Base>);

Effects: Initializes parent_ with addressof(parent).

constexpr outer-iterator(Parent& parent, iterator_t<Base> current)
  requires forward_range<Base>;

Effects: Initializes parent_ with addressof(parent) and current_ with std::move(current).

constexpr outer-iterator(outer-iterator<!Const> i)
  requires Const && convertible_to<iterator_t<V>, iterator_t<Base>>;

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Effects: Initializes parent_ with i.parent_ and current_ with std::move(i.current_).

constexpr value_type operator*() const;

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Effects: Equivalent to: return value_type{*this};

constexpr outer-iterator& operator++();

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Effects: Equivalent to: const auto end = ranges::end(parent_->base_); if (current == end) return *this; const auto [pbegin, pend] = subrange{parent_->pattern_}; if (pbegin == pend) ++current; else { do { auto [b, p] = ranges::mismatch(std::move(current), end, pbegin, pend); current = std::move(b); if (p == pend) { break; // The pattern matched; skip it } } while (++current != end); } return *this;

friend constexpr bool operator==(const outer-iterator& x, const outer-iterator& y)
  requires forward_range<Base>;

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Effects: Equivalent to: return x.current_ == y.current_;

friend constexpr bool operator==(const outer-iterator& x, default_sentinel_t);

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Effects: Equivalent to: return x.current == ranges::end(x.parent_->base_);

24.7.12.4 Class split_view::outer-iterator::value_type [range.split.outer.value]

namespace std::ranges { template<input_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> && (forward_range<V> || tiny-range<Pattern>) template<bool Const> struct split_view<V, Pattern>::outer-iterator<Const>::value_type : view_interface<value_type> { private: outer-iterator i_ = outer-iterator(); // exposition only public: value_type() = default; constexpr explicit value_type(outer-iterator i); constexpr inner-iterator<Const> begin() const requires copyable<outer-iterator>; constexpr inner-iterator<Const> begin() requires (!copyable<outer-iterator>); constexpr default_sentinel_t end() const; }; }

constexpr explicit value_type(outer-iterator i);

Effects: Initializes i_ with std::move(i).

constexpr inner-iterator<Const> begin() const requires copyable<outer-iterator>;

Effects: Equivalent to: return inner-iterator<Const>{i_};

constexpr inner-iterator<Const> begin() requires (!copyable<outer-iterator>);

Effects: Equivalent to: return inner-iterator<Const>{std::move(i_)};

constexpr default_sentinel_t end() const;

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Effects: Equivalent to: return default_sentinel;

24.7.12.5 Class template split_view::inner-iterator [range.split.inner]

namespace std::ranges { template<input_range V, forward_range Pattern> requires view<V> && view<Pattern> && indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> && (forward_range<V> || tiny-range<Pattern>) template<bool Const> struct split_view<V, Pattern>::inner-iterator { private: using Base = conditional_t<Const, const V, V>; // exposition only outer-iterator<Const> i_ = outer-iterator<Const>(); // exposition only bool incremented_ = false; // exposition only public: using iterator_concept = typename outer-iterator<Const>::iterator_concept; using iterator_category = see below; using value_type = range_value_t<Base>; using difference_type = range_difference_t<Base>; inner-iterator() = default; constexpr explicit inner-iterator(outer-iterator<Const> i); constexpr decltype(auto) operator*() const { return *i_.current; } constexpr inner-iterator& operator++(); constexpr decltype(auto) operator++(int) { if constexpr (forward_range<V>) { auto tmp = *this; ++*this; return tmp; } else ++*this; } friend constexpr bool operator==(const inner-iterator& x, const inner-iterator& y) requires forward_range<Base>; friend constexpr bool operator==(const inner-iterator& x, default_sentinel_t); friend constexpr decltype(auto) iter_move(const inner-iterator& i) noexcept(noexcept(ranges::iter_move(i.i_.current))) { return ranges::iter_move(i.i_.current); } friend constexpr void iter_swap(const inner-iterator& x, const inner-iterator& y) noexcept(noexcept(ranges::iter_swap(x.i_.current, y.i_.current))) requires indirectly_swappable<iterator_t<Base>>; }; }

The typedef-name iterator_category denotes:

(1.1)
forward_iterator_tag if iterator_traits<iterator_t<Base>>::iterator_category models
derived_from<forward_iterator_tag>;
(1.2)
otherwise, iterator_traits<iterator_t<Base>>::iterator_category.

constexpr explicit inner-iterator(outer-iterator<Const> i);

Effects: Initializes i_ with std::move(i).

constexpr inner-iterator& operator++();

Effects: Equivalent to: incremented_ = true; if constexpr (!forward_range<Base>) { if constexpr (Pattern::size() == 0) { return *this; } } ++i_.current; return *this;

friend constexpr bool operator==(const inner-iterator& x, const inner-iterator& y)
  requires forward_range<Base>;

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Effects: Equivalent to: return x.i_.current == y.i_.current;

friend constexpr bool operator==(const inner-iterator& x, default_sentinel_t);

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Effects: Equivalent to: auto [pcur, pend] = subrange{x.i_.parent_->pattern_}; auto end = ranges::end(x.i_.parent_->base_); if constexpr (tiny-range<Pattern>) { const auto & cur = x.i_.current; if (cur == end) return true; if (pcur == pend) return x.incremented_; return *cur == *pcur; } else { auto cur = x.i_.current; if (cur == end) return true; if (pcur == pend) return x.incremented_; do { if (*cur != *pcur) return false; if (++pcur == pend) return true; } while (++cur != end); return false; }

friend constexpr void iter_swap(const inner-iterator& x, const inner-iterator& y)
  noexcept(noexcept(ranges::iter_swap(x.i_.current, y.i_.current)))
  requires indirectly_swappable<iterator_t<Base>>;

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