24 Ranges library [ranges]

24.7 Range adaptors [range.adaptors]

24.7.10 Drop while view [range.drop.while]

24.7.10.2 Class template drop_­while_­view [range.drop.while.view]

namespace std::ranges { template<view V, class Pred> requires input_­range<V> && is_object_v<Pred> && indirect_­unary_­predicate<const Pred, iterator_t<V>> class drop_while_view : public view_interface<drop_while_view<V, Pred>> { public: drop_while_view() = default; constexpr drop_while_view(V base, Pred pred); constexpr V base() const& requires copy_constructible<V> { return base_; } constexpr V base() && { return std::move(base_); } constexpr const Pred& pred() const; constexpr auto begin(); constexpr auto end() { return ranges::end(base_); } private: V base_ = V(); // exposition only semiregular-box<Pred> pred_; // exposition only }; template<class R, class Pred> drop_while_view(R&&, Pred) -> drop_while_view<views::all_t<R>, Pred>; }
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constexpr drop_while_view(V base, Pred pred);
1
#
Effects: Initializes base_­ with std​::​move(base) and pred_­ with std​::​move(pred).
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constexpr const Pred& pred() const;
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Effects: Equivalent to: return *pred_­;
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constexpr auto begin();
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Returns: ranges​::​find_­if_­not(base_­, cref(*pred_­)).
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Remarks: In order to provide the amortized constant-time complexity required by the range concept when drop_­while_­view models forward_­range, the first call caches the result within the drop_­while_­view for use on subsequent calls.
[Note 1:
Without this, applying a reverse_­view over a drop_­while_­view would have quadratic iteration complexity.
— end note]