[range.join.with.iterator] (original) (raw)
25 Ranges library [ranges]
25.7 Range adaptors [range.adaptors]
25.7.15 Join with view [range.join.with]
25.7.15.3 Class template join_with_view::iterator [range.join.with.iterator]
namespace std::ranges { template<input_range V, forward_range Pattern> requires view<V> && input_range<range_reference_t<V>> && view<Pattern> && concatable<range_reference_t<V>, Pattern> template<bool Const> class join_with_view<V, Pattern>::iterator { using Parent = maybe-const<Const, join_with_view>; using Base = maybe-const<Const, V>; using InnerBase = range_reference_t<_Base_>; using PatternBase = maybe-const<Const, Pattern>; using OuterIter = iterator_t<_Base_>; using InnerIter = iterator_t<_InnerBase_>; using PatternIter = iterator_t<_PatternBase_>; static constexpr bool ref-is-glvalue = is_reference_v<_InnerBase_>; Parent* parent_ = nullptr; OuterIter outer_it_ = OuterIter(); variant<_PatternIter_, _InnerIter_> inner_it_; constexpr iterator(Parent& parent, OuterIter outer) requires forward_range<_Base_>; constexpr explicit iterator(Parent& parent) requires (<_Base_>); constexpr OuterIter& outer(); constexpr const OuterIter& outer() const; constexpr auto& update-inner(); constexpr auto& get-inner(); constexpr void satisfy(); public: using iterator_concept = see below;using iterator_category = see below; using value_type = see below;using difference_type = see below;iterator() = default;constexpr iterator(iterator<!Const> i) requires Const && convertible_to<iterator_t<V>, _OuterIter_> && convertible_to<iterator_t<_InnerRng_>, _InnerIter_> && convertible_to<iterator_t<Pattern>, _PatternIter_>;constexpr decltype(auto) operator*() const;constexpr iterator& operator++();constexpr void operator++(int);constexpr iterator operator++(int) requires ref-is-glvalue && forward_iterator<_OuterIter_> && forward_iterator<_InnerIter_>;constexpr iterator& operator--() requires ref-is-glvalue && bidirectional_range<_Base_> && bidirectional-common<_InnerBase_> && bidirectional-common<_PatternBase_>;constexpr iterator operator--(int) requires ref-is-glvalue && bidirectional_range<_Base_> && bidirectional-common<_InnerBase_> && bidirectional-common<_PatternBase_>;friend constexpr bool operator==(const iterator& x, const iterator& y) requires ref-is-glvalue && forward_range<_Base_> && equality_comparable<_InnerIter_>;friend constexpr decltype(auto) iter_move(const iterator& x) { using rvalue_reference = common_reference_t< iter_rvalue_reference_t<_InnerIter_>, iter_rvalue_reference_t<_PatternIter_>>;return visit<rvalue_reference>(ranges::iter_move, x.inner_it_);} friend constexpr void iter_swap(const iterator& x, const iterator& y) requires indirectly_swappable<_InnerIter_, _PatternIter_> { visit(ranges::iter_swap, x.inner_it_, y.inner_it_);} };}
_iterator_::iterator_concept is defined as follows:
- Otherwise, if ref-is-glvalue is true and_Base_ and InnerBase each model forward_range, then iterator_concept denotes forward_iterator_tag.
- Otherwise, iterator_concept denotes input_iterator_tag.
The member typedef-name iterator_category is defined if and only if ref-is-glvalue is true, and_Base_ and InnerBase each model forward_range.
In that case,_iterator_::iterator_category is defined as follows:
- Let OUTERC denoteiterator_traits<_OuterIter_>::iterator_category, let INNERC denoteiterator_traits<_InnerIter_>::iterator_category, and let PATTERNC denoteiterator_traits<_PatternIter_>::iterator_category.
- Ifis_reference_v<common_reference_t<iter_reference_t<_InnerIter_>, iter_reference_t<_PatternIter_>>> is false,iterator_category denotes input_iterator_tag.
- Otherwise, if OUTERC, INNERC, and _PATTERNC_each model derived_from<bidirectional_iterator_tag>and InnerBase and _PatternBase_each model common_range,iterator_category denotes bidirectional_iterator_tag.
- Otherwise, if OUTERC, INNERC, and _PATTERNC_each model derived_from<forward_iterator_tag>,iterator_category denotes forward_iterator_tag.
- Otherwise, iterator_category denotes input_iterator_tag.
_iterator_::value_type denotes the type:common_type_t<iter_value_t<_InnerIter_>, iter_value_t<_PatternIter_>>
_iterator_::difference_type denotes the type:common_type_t< iter_difference_t<_OuterIter_>, iter_difference_t<_InnerIter_>, iter_difference_t<_PatternIter_>>
constexpr _OuterIter_& _outer_();constexpr const _OuterIter_& _outer_() const;
Returns: outer_it_ if Base models forward_range; otherwise, *_parent__->outer_it_.
constexpr auto& _update-inner_();
Effects: Equivalent to:if constexpr (ref-is-glvalue) return as-lvalue(*outer());else return _parent__->inner_.emplace-deref(outer());
constexpr auto& _get-inner_();
Effects: Equivalent to:if constexpr (ref-is-glvalue) return as-lvalue(*outer());else return *_parent__->inner_;
constexpr void _satisfy_();
Effects: Equivalent to:while (true) { if (inner_it_.index() == 0) { if (std::get<0>(inner_it_) != ranges::end(_parent__->pattern_)) break;inner_it_.template emplace<1>(ranges::begin(update-inner()));} else { if (std::get<1>(inner_it_) != ranges::end(get-inner())) break;if (++outer() == ranges::end(_parent__->base_)) { if constexpr (ref-is-glvalue) inner_it_.template emplace<0>();break;} inner_it_.template emplace<0>(ranges::begin(_parent__->pattern_));} }
[Note 1:
join_with_view iterators use the satisfy function to skip over empty inner ranges.
— _end note_]
constexpr _iterator_(_Parent_& parent, _OuterIter_ outer) requires [forward_range](range.refinements#concept:forward%5Frange "25.4.5 Other range refinements [range.refinements]")<_Base_>;constexpr explicit _iterator_(_Parent_& parent) requires (<_Base_>);
Effects: Initializes parent_ with addressof(parent).
For the first overload, also initializes_outer_it__ with std::move(outer).
Then, equivalent to:if (outer() != ranges::end(_parent__->base_)) { inner_it_.template emplace<1>(ranges::begin(update-inner()));satisfy();}
Effects: Initializes outer_it_ withstd::move(i.outer_it_) and_parent__ with i.parent_.
Then, equivalent to:if (i.inner_it_.index() == 0) inner_it_.template emplace<0>(std::get<0>(std::move(i.inner_it_)));else inner_it_.template emplace<1>(std::get<1>(std::move(i.inner_it_)));
[Note 2:
Const can only be truewhen Base models forward_range.
— _end note_]
constexpr decltype(auto) operator*() const;
Effects: Equivalent to:using reference = common_reference_t<iter_reference_t<_InnerIter_>, iter_reference_t<_PatternIter_>>;return visit([](auto& it) -> reference { return *it; }, inner_it_);
constexpr _iterator_& operator++();
Effects: Equivalent to:visit([](auto& it){ ++it; }, inner_it_);satisfy();return *this;
constexpr void operator++(int);
Effects: Equivalent to ++*this.
Effects: Equivalent to:iterator tmp = *this;++*this;return tmp;
Effects: Equivalent to:if (outer_it_ == ranges::end(_parent__->base_)) { auto&& inner = *--outer_it_;inner_it_.template emplace<1>(ranges::end(inner));} while (true) { if (inner_it_.index() == 0) { auto& it = std::get<0>(inner_it_);if (it == ranges::begin(_parent__->pattern_)) { auto&& inner = *--outer_it_;inner_it_.template emplace<1>(ranges::end(inner));} else { break;} } else { auto& it = std::get<1>(inner_it_);auto&& inner = *outer_it_;if (it == ranges::begin(inner)) { inner_it_.template emplace<0>(ranges::end(_parent__->pattern_));} else { break;} } }visit([](auto& it){ --it; }, inner_it_);return *this;
Effects: Equivalent to:iterator tmp = *this;--*this;return tmp;
Effects: Equivalent to:return x.outer_it_ == y.outer_it_ && x.inner_it_ == y.inner_it_;