24 Ranges library [ranges]

24.5 Range utilities [range.utility]

24.5.3 Sub-ranges [range.subrange]

24.5.3.2 Accessors [range.subrange.access]

constexpr I begin() const requires copyable<I>;

Effects: Equivalent to: return begin_;

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[[nodiscard]] constexpr I begin() requires (!copyable<I>);

Effects: Equivalent to: return std::move(begin_);

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constexpr S end() const;

Effects: Equivalent to: return end_;

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constexpr bool empty() const;

Effects: Equivalent to: return begin_ == end_;

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constexpr make-unsigned-like-t<iter_difference_t<I>> size() const
  requires (K == subrange_kind::sized);

Effects:

(5.1)
If StoreSize is true, equivalent to: return size_;
(5.2)
Otherwise, equivalent to: return to-unsigned-like(end_ - begin_);

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[[nodiscard]] constexpr subrange next(iter_difference_t<I> n = 1) const &
  requires forward_iterator<I>;

Effects: Equivalent to:

auto tmp = *this;
tmp.advance(n);
return tmp;

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[[nodiscard]] constexpr subrange next(iter_difference_t<I> n = 1) &&;

Effects: Equivalent to:

advance(n);
return std::move(*this);

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[[nodiscard]] constexpr subrange prev(iter_difference_t<I> n = 1) const
  requires bidirectional_iterator<I>;

Effects: Equivalent to:

auto tmp = *this;
tmp.advance(-n);
return tmp;

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constexpr subrange& advance(iter_difference_t<I> n);

Effects: Equivalent to:

(9.1)

If StoreSize is true,

auto d = n - ranges::advance(begin_, n, end_);
if (d >= 0)
  size_ -= to-unsigned-like(d);
else
  size_ += to-unsigned-like(-d);
return *this;

(9.2)

Otherwise,

ranges::advance(begin_, n, end_);
return *this;

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template<size_t N, class I, class S, subrange_kind K>
  requires (N < 2)
  constexpr auto get(const subrange<I, S, K>& r);
template<size_t N, class I, class S, subrange_kind K>
  requires (N < 2)
  constexpr auto get(subrange<I, S, K>&& r);

Effects: Equivalent to:

if constexpr (N == 0)
  return r.begin();
else
  return r.end();