class RDoc::Markup::Attributes

def as_string bitmap
  return 'none' if bitmap.zero?
  res = []
  @name_to_bitmap.each do |name, bit|
    res << name if (bitmap & bit) != 0
  end
  res.join ','
end

def bitmap_for name
  bitmap = @name_to_bitmap.assoc name
  unless bitmap then
    bitmap = @next_bitmap
    @next_bitmap <<= 1
    @name_to_bitmap << [name, bitmap]
  else
    bitmap = bitmap.last
  end
  bitmap
end

def each_name_of bitmap
  return enum_for __method__, bitmap unless block_given?
  @name_to_bitmap.each do |name, bit|
    next if bit == @special
    yield name.to_s if (bitmap & bit) != 0
  end
end

def initialize
  @special = 1
  @name_to_bitmap = [
    [:_SPECIAL_, @special],
  ]
  @next_bitmap = @special << 1
end