class Reline::Unicode

def self.calculate_width(str, allow_escape_code = false)
  if allow_escape_code
    width = 0
    rest = str.encode(Encoding::UTF_8)
    in_zero_width = false
    rest.scan(WIDTH_SCANNER) do |gc|
      case
      when gc[NON_PRINTING_START_INDEX]
        in_zero_width = true
      when gc[NON_PRINTING_END_INDEX]
        in_zero_width = false
      when gc[CSI_REGEXP_INDEX], gc[OSC_REGEXP_INDEX]
      when gc[GRAPHEME_CLUSTER_INDEX]
        gc = gc[GRAPHEME_CLUSTER_INDEX]
        unless in_zero_width
          width += get_mbchar_width(gc)
        end
      end
    end
    width
  else
    str.encode(Encoding::UTF_8).grapheme_clusters.inject(0) { |w, gc|
      w + get_mbchar_width(gc)
    }
  end
end