class ActiveModel::Validations::FormatValidator

def check_options_validity(name)
  if option = options[name]
    if option.is_a?(Regexp)
      if options[:multiline] != true && regexp_using_multiline_anchors?(option)
        raise ArgumentError, "The provided regular expression is using multiline anchors (^ or $), " \
        "which may present a security risk. Did you mean to use \\A and \\z, or forgot to add the " \
        ":multiline => true option?"
      end
    elsif !option.respond_to?(:call)
      raise ArgumentError, "A regular expression or a proc or lambda must be supplied as :#{name}"
    end
  end
end