class RuboCop::Cop::Style::Encoding

def offense(processed_source, line_number)
  line = processed_source[line_number]
  encoding_present = line =~ /#.*coding\s?[:=]\s?(UTF|utf)-8/
  ascii_only = processed_source.buffer.source.ascii_only?
  always_encode = style == :always
  if !encoding_present && (always_encode || !ascii_only)
    MSG_MISSING
  elsif !always_encode && ascii_only && encoding_present
    MSG_UNNECESSARY
  end
end