class Reline::Unicode

def self.get_mbchar_width(mbchar)
  ord = mbchar.ord
  if (0x00 <= ord and ord <= 0x1F) # in EscapedPairs
    return 2
  elsif (0x20 <= ord and ord <= 0x7E) # printable ASCII chars
    return 1
  end
  m = mbchar.encode(Encoding::UTF_8).match(MBCharWidthRE)
  case
  when m.nil? then 1 # TODO should be U+FFFD � REPLACEMENT CHARACTER
  when m[:width_2_1], m[:width_2_2], m[:width_2_3] then 2
  when m[:width_3] then 3
  when m[:width_0] then 0
  when m[:width_1] then 1
  when m[:ambiguous_width] then Reline.ambiguous_width
  else
    nil
  end
end