Header <boost/text/grapheme

Header <boost/text/grapheme_iterator.hpp>

namespace boost {
  namespace text {
    template<code_point_iter I, std::sentinel_for< I > S = I> 
      struct grapheme_iterator;
    template<typename Iter1, typename Sentinel1, typename Iter2, 
             typename Sentinel2, 
             typename Enable = std::enable_if_t<            std::is_same<Sentinel1, null_sentinel_t>::value !=            std::is_same<Sentinel2, null_sentinel_t>::value> > 
      constexpr auto 
      operator==(grapheme_iterator< Iter1, Sentinel1 > const & lhs, 
                 grapheme_iterator< Iter2, Sentinel2 > const & rhs);
    template<typename Iter1, typename Sentinel1, typename Iter2, 
             typename Sentinel2, 
             typename Enable = std::enable_if_t<            std::is_same<Sentinel1, null_sentinel_t>::value !=            std::is_same<Sentinel2, null_sentinel_t>::value> > 
      constexpr auto 
      operator!=(grapheme_iterator< Iter1, Sentinel1 > const & lhs, 
                 grapheme_iterator< Iter2, Sentinel2 > const & rhs);
    template<typename CPIter, typename Sentinel> 
      constexpr auto 
      operator==(grapheme_iterator< CPIter, Sentinel > it, Sentinel s);
    template<typename CPIter, typename Sentinel> 
      constexpr auto 
      operator==(Sentinel s, grapheme_iterator< CPIter, Sentinel > it);
    template<typename CPIter, typename Sentinel> 
      constexpr auto 
      operator!=(grapheme_iterator< CPIter, Sentinel > it, Sentinel s);
    template<typename CPIter, typename Sentinel> 
      constexpr auto 
      operator!=(Sentinel s, grapheme_iterator< CPIter, Sentinel > it);
  }
}