<xstd/bits/ext/boost/bit_small_vector.hpp>

basic_bit_small_vector, bit_small_vector

template<unsigned_integer Block, size_t N, class Alloc = boost::container::new_allocator<Block>>
  requires see below
using basic_bit_small_vector = basic_bit_vector<boost::container::small_vector<Block, see below, Alloc>>;

template<size_t N>
using bit_small_vector = basic_bit_small_vector<size_t, N>;

A basic_bit_vector over boost::container::small_vector, with:

• bit_small_vector<N> holds its bools in size_t blocks, the ceil(N / D) blocks that hold N bits inline and the rest on the heap. The requires-clause admits Block as basic_bit_vector's does, and Alloc defaults to Boost's own, as small_vector's does.
• The inline part is whole blocks, so bit_small_vector<N> and bit_small_vector<M> are one type wherever ceil(N / D) == ceil(M / D), and bit_rebind and bit_resize keep the bits the inline blocks hold.
• allocator_type is the small vector's, which wraps Alloc, and every allocator argument is of that type. Constructing from an allocator does not throw, inline blocks allocating nothing.
• capacity(), reserve and shrink_to_fit are the small vector's.
• Every exception is a standard one: std::length_error past max_size(), before the small vector would throw Boost's own, and std::bad_alloc from the allocator. Blocks taken out with extract are the small vector itself, and throw boost::container exceptions unless BOOST_CONTAINER_USE_STD_EXCEPTIONS is defined.
• The header also brings std::hash and Boost's is_range and is_tuple_like for it, which basic_bit_vector's headers declare. The Hash2 hook's model is vector<bool>.