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();
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(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() {
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_);
}
};
template<class R>
common_view(R&&) -> common_view<views::all_t<R>>;
}
constexpr explicit common_view(V base);
Effects: Initializes
base_ with
std::move(base).