25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.20 Common view [range.common]

25.7.20.2 Class template common_view [range.common.view]

namespace std::ranges { template<view V> requires (!common_range<V> && copyable<iterator_t<V>>) class common_view : public view_interface<common_view<V>> { private: V base_ = V(); // exposition only public: common_view() requires default_initializable<V> = default; constexpr explicit common_view(V r); constexpr V base() const & requires copy_constructible<V> { return base_; } constexpr V base() && { return std::move(base_); } constexpr auto begin() requires (!simple-view<V>) { if constexpr (random_access_range<V> && sized_range<V>) return ranges::begin(base_); else return common_iterator<iterator_t<V>, sentinel_t<V>>(ranges::begin(base_)); } constexpr auto begin() const requires range<const V> { if constexpr (random_access_range<const V> && sized_range<const V>) return ranges::begin(base_); else return common_iterator<iterator_t<const V>, sentinel_t<const V>>(ranges::begin(base_)); } constexpr auto end() requires (!simple-view<V>) { if constexpr (random_access_range<V> && sized_range<V>) return ranges::begin(base_) + ranges::distance(base_); else return common_iterator<iterator_t<V>, sentinel_t<V>>(ranges::end(base_)); } constexpr auto end() const requires range<const V> { if constexpr (random_access_range<const V> && sized_range<const V>) return ranges::begin(base_) + ranges::distance(base_); else return common_iterator<iterator_t<const V>, sentinel_t<const V>>(ranges::end(base_)); } constexpr auto size() requires sized_range<V> { return ranges::size(base_); } constexpr auto size() const requires sized_range<const V> { return ranges::size(base_); } constexpr auto reserve_hint() requires approximately_sized_range<V> { return ranges::reserve_hint(base_); } constexpr auto reserve_hint() const requires approximately_sized_range<const V> { return ranges::reserve_hint(base_); } }; template<class R> common_view(R&&) -> common_view<views::all_t<R>>; }

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constexpr explicit common_view(V base);

Effects: Initializes base_ with std::move(base).