class Sass::Tree::RuleNode

def to_s(tabs, super_rules = nil)
  attributes = []
  sub_rules = []
  rule_split = /\s*,\s*/
  rule_separator = @style == :compressed ? ',' : ', '
  line_separator = [:nested, :expanded].include?(@style) ? ",\n" : rule_separator
  rule_indent = '  ' * (tabs - 1)
  total_rule = if super_rules
    super_rules.split(",\n").map do |super_line|
      super_line.strip.split(rule_split).map do |super_rule|
        self.rules.map do |line|
          rule_indent + line.gsub(/,$/, '').split(rule_split).map do |rule|
            if rule.include?(PARENT)
              rule.gsub(PARENT, super_rule)
            else
              "#{super_rule} #{rule}"
            end
          end.join(rule_separator)
        end.join(line_separator)
      end.join(rule_separator)
    end.join(line_separator)
  elsif self.rules.any? { |r| r.include?(PARENT) }
    raise Sass::SyntaxError.new("Base-level rules cannot contain the parent-selector-referencing character '#{PARENT}'.", line)
  else
    per_rule_indent, total_indent = [:nested, :expanded].include?(@style) ? [rule_indent, ''] : ['', rule_indent]
    total_indent + self.rules.map do |r|
      per_rule_indent + r.gsub(/,$/, '').gsub(rule_split, rule_separator).rstrip
    end.join(line_separator)
  end
  children.each do |child|
    if child.is_a? RuleNode
      sub_rules << child
    else
      attributes << child
    end
  end
  to_return = ''
  if !attributes.empty?
    old_spaces = '  ' * (tabs - 1)
    spaces = '  ' * tabs
    if @style == :compact
      attributes = attributes.map { |a| a.to_s(1) }.join(' ')
      to_return << "#{total_rule} { #{attributes} }\n"
    elsif @style == :compressed
      attributes = attributes.map { |a| a.to_s(1) }.join(';')
      to_return << "#{total_rule}{#{attributes}}"
    else
      attributes = attributes.map { |a| a.to_s(tabs + 1) }.join("\n")
      end_attrs = (@style == :expanded ? "\n" + old_spaces : ' ')
      to_return << "#{total_rule} {\n#{attributes}#{end_attrs}}\n"
    end
  end
  tabs += 1 unless attributes.empty? || @style != :nested
  sub_rules.each do |sub|
    to_return << sub.to_s(tabs, total_rule)
  end
  to_return
end