class Addressable::Template

def ordered_variable_defaults
  @ordered_variable_defaults ||= begin
    expansions, _ = parse_template_pattern(pattern)
    expansions.map do |capture|
      _, _, varlist = *capture.match(EXPRESSION)
      varlist.split(',').map do |varspec|
        varspec[VARSPEC, 1]
      end
    end.flatten
  end
end