class Cucumber::RbSupport::RegexpArgumentMatcher

def self.arguments_from(regexp, step_name)
  match = regexp.match(step_name)
  if match
    n = 0
    match.captures.map do |val|
      n += 1
      start = match.offset(n)[0]
      StepArgument.new(val, start)
    end
  else
    nil
  end
end