namespace std::ranges {
template<view V>
requires range-with-movable-references<V>
class enumerate_view : public view_interface<enumerate_view<V>> {
V base_ = V();
template<bool Const>
class iterator;
template<bool Const>
class sentinel;
public:
constexpr enumerate_view() requires default_initializable<V> = default;
constexpr explicit enumerate_view(V base);
constexpr auto begin() requires (!simple-view<V>)
{ return iterator<false>(ranges::begin(base_), 0); }
constexpr auto begin() const requires range-with-movable-references<const V>
{ return iterator<true>(ranges::begin(base_), 0); }
constexpr auto end() requires (!simple-view<V>) {
if constexpr (common_range<V> && sized_range<V>)
return iterator<false>(ranges::end(base_), ranges::distance(base_));
else
return sentinel<false>(ranges::end(base_));
}
constexpr auto end() const requires range-with-movable-references<const V> {
if constexpr (common_range<const V> && sized_range<const V>)
return iterator<true>(ranges::end(base_), ranges::distance(base_));
else
return sentinel<true>(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 V base() const & requires copy_constructible<V> { return base_; }
constexpr V base() && { return std::move(base_); }
};
template<class R>
enumerate_view(R&&) -> enumerate_view<views::all_t<R>>;
}
constexpr explicit enumerate_view(V base);
Effects: Initializes
base_ with
std::move(base).