class IRB::Irb

def truncate_prompt_main(str) # :nodoc:
  str = str.tr(CONTROL_CHARACTERS_PATTERN, ' ')
  if str.size <= PROMPT_MAIN_TRUNCATE_LENGTH
    str
  else
    str[0, PROMPT_MAIN_TRUNCATE_LENGTH - PROMPT_MAIN_TRUNCATE_OMISSION.size] + PROMPT_MAIN_TRUNCATE_OMISSION
  end
end