class RuboCop::Cop::Performance::StringReplacement

def on_send(node)
  _string, method, first_param, second_param = *node
  return unless GSUB_METHODS.include?(method)
  return unless string?(second_param)
  return unless DETERMINISTIC_TYPES.include?(first_param.type)
  first_source, options = first_source(first_param)
  second_source, = *second_param
  return if first_source.nil?
  if regex?(first_param)
    return unless first_source =~ DETERMINISTIC_REGEX
    return if options
    # This must be done after checking DETERMINISTIC_REGEX
    # Otherwise things like \s will trip us up
    first_source = interpret_string_escapes(first_source)
  end
  return if first_source.length != 1
  return unless second_source.length <= 1
  message = message(method, first_source, second_source)
  add_offense(node, range(node), message)
end