class RuboCop::Cop::Style::RedundantRegexpArgument

def on_send(node)
  return unless (regexp_node = node.first_argument)
  return unless regexp_node.regexp_type?
  return if !regexp_node.regopt.children.empty? || regexp_node.content == ' '
  return unless determinist_regexp?(regexp_node)
  prefer = preferred_argument(regexp_node)
  message = format(MSG, prefer: prefer, current: regexp_node.source)
  add_offense(regexp_node, message: message) do |corrector|
    corrector.replace(regexp_node, prefer)
  end
end