class ERB::Compiler

def prepare_trim_mode(mode) # :nodoc:
  case mode
  when 1
    return [false, '>']
  when 2
    return [false, '<>']
  when 0, nil
    return [false, nil]
  when String
    unless mode.match?(/\A(%|-|>|<>){1,2}\z/)
      warn_invalid_trim_mode(mode, uplevel: 5)
    end
    perc = mode.include?('%')
    if mode.include?('-')
      return [perc, '-']
    elsif mode.include?('<>')
      return [perc, '<>']
    elsif mode.include?('>')
      return [perc, '>']
    else
      [perc, nil]
    end
  else
    warn_invalid_trim_mode(mode, uplevel: 5)
    return [false, nil]
  end
end