class Regexp::Scanner

def emit_options(text)
  token = nil
  # Ruby allows things like '(?-xxxx)' or '(?xx-xx--xx-:abc)'.
  text =~ /\(\?([mixdau]*)(-(?:[mix]*))*(:)?/
  positive, negative, group_local = $1,$2,$3
  if positive.include?('x')
    self.free_spacing = true
  end
  # If the x appears in both, treat it like ruby does, the second cancels
  # the first.
  if negative && negative.include?('x')
    self.free_spacing = false
  end
  if group_local
    spacing_stack << {:free_spacing => free_spacing, :depth => group_depth}
    token = :options
  else
    # switch for parent group level
    spacing_stack.last[:free_spacing] = free_spacing
    token = :options_switch
  end
  emit(:group, token, text)
end