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);
      };
    }

####  [ [ edit
](/mwiki/index.php?title=Template:cpp/synopsis/ranges&action=edit&section=T-55
"Template:cpp/synopsis/ranges") ]  Class template  std::ranges::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() {
          if constexpr (random_access_range<V> && sized_range<V>)
            return [ranges::begin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/begin)(base_);
          else
            return common_iterator<iterator_t<V>, sentinel_t<V>>([ranges::begin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/begin)(base_));
        }
     
        constexpr auto begin() const requires range<const V> {
          if constexpr (random_access_range<const V> && sized_range<const V>)
            return [ranges::begin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/begin)(base_);
          else
            return common_iterator<iterator_t<const V>, sentinel_t<const V>>(
              [ranges::begin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/begin)(base_));
        }
     
        constexpr auto end() {
          if constexpr (random_access_range<V> && sized_range<V>)
            return [ranges::begin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/begin)(base_) + [ranges::size](http://en.cppreference.com/w/cpp/ranges/size)(base_);
          else
            return common_iterator<iterator_t<V>, sentinel_t<V>>([ranges::end](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/end)(base_));
        }
     
        constexpr auto end() const requires range<const V> {
          if constexpr (random_access_range<const V> && sized_range<const V>)
            return [ranges::begin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/begin)(base_) + [ranges::size](http://en.cppreference.com/w/cpp/ranges/size)(base_);
          else
            return common_iterator<iterator_t<const V>, sentinel_t<const V>>(
              [ranges::end](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/end)(base_));
        }
     
        constexpr auto size() requires sized_range<V> {
          return [ranges::size](http://en.cppreference.com/w/cpp/ranges/size)(base_);
        }
        constexpr auto size() const requires sized_range<const V> {
          return [ranges::size](http://en.cppreference.com/w/cpp/ranges/size)(base_);
        }
      };
     
      template<class R>
        common_view(R&&) -> common_view<[views::all_t](http://en.cppreference.com/w/cpp/ranges/all_view)<R>>;
    }

####  [ [ edit
](/mwiki/index.php?title=Template:cpp/synopsis/ranges&action=edit&section=T-56
"Template:cpp/synopsis/ranges") ]  Class template  [ std::ranges::reverse_view
](/w/cpp/ranges/reverse_view "cpp/ranges/reverse view")

    
    
    namespace std::ranges {
      template<view V>
        requires bidirectional_range<V>
      class reverse_view : public view_interface<reverse_view<V>> {
      private:
        V base_ = V();  // exposition only
      public:
        reverse_view() requires default_initializable<V> = default;
     
        constexpr explicit reverse_view(V r);
     
        constexpr V base() const & requi