<xstd/bits/bit_valarray/bit_gslice.hpp>

bit_gslice

class bit_gslice {
public:
  bit_gslice();
  bit_gslice(size_t start, const valarray<size_t>& lengths, const valarray<size_t>& strides);
  explicit bit_gslice(const gslice& g);

  auto start() const noexcept -> size_t;
  auto size() const -> valarray<size_t>;
  auto stride() const -> valarray<size_t>;
};

• As [class.gslice], with its positions worked out once, in its constructor, and kept for every subscript that reuses it: as one bit per position where they ascend, and as the positions themselves where they repeat or turn back.
• It selects what the gslice of the same numbers selects, over every owner and block.
• Copies share the positions, and a proxy holds a copy, so a bit_gslice_array outlives the bit_gslice it was made from.