namespace boost {
  namespace text {
    template<typename CPIter> struct bidirectional_cp_subrange;
    template<typename CPIter> struct bidirectional_grapheme_subrange;
    template<typename CPIter, typename Sentinel, typename ResultType, 
             typename NextLineBreakFunc = detail::bidi_next_hard_line_break_callable> 
      struct lazy_bidi_segment_range;
    bidi_property bidi_prop(uint32_t);
    namespace v1 {
      template<code_point_iter I, std::sentinel_for< I > S> 
        unspecified bidirectional_subranges(I, S, int = -1);
      template<code_point_range R> 
        unspecified bidirectional_subranges(R &&, int = -1);
      template<grapheme_range R> unspecified bidirectional_subranges(int);
      template<code_point_iter I, std::sentinel_for< I > S, typename Extent, 
               line_break_cp_extent_func< I, Extent > Func> 
        unspecified bidirectional_subranges(I, S, Extent, Func, int = -1, 
                                            bool = true);
      template<code_point_range R, typename Extent, 
               line_break_cp_extent_func< std::ranges::iterator_t< R >, Extent > Func> 
        unspecified bidirectional_subranges(R &&, Extent, Func, int = -1, 
                                            bool = true);
      template<typename Extent, typename Func> 
        unspecified bidirectional_subranges(Extent, Func, int = -1, 
                                            bool = true);
    }
  }
}namespace std {
  namespace ranges {
  }
}