class Nokogiri::CSS::XPathVisitor

def visit_attribute_condition(node)
  attribute = node.value.first.accept(self)
  return attribute if node.value.length == 1
  value = node.value.last
  value = "'#{value}'" unless /^['"]/.match?(value)
  # quoted values - see test_attribute_value_with_quotes in test/css/test_parser.rb
  if (value[0] == value[-1]) && %q{"'}.include?(value[0])
    str_value = value[1..-2]
    if str_value.include?(value[0])
      value = 'concat("' + str_value.split('"', -1).join(%q{",'"',"}) + '","")'
    end
  end
  case node.value[1]
  when :equal
    attribute + "=" + value.to_s
  when :not_equal
    attribute + "!=" + value.to_s
  when :substring_match
    "contains(#{attribute},#{value})"
  when :prefix_match
    "starts-with(#{attribute},#{value})"
  when :dash_match
    "#{attribute}=#{value} or starts-with(#{attribute},concat(#{value},'-'))"
  when :includes
    value = value[1..-2] # strip quotes
    css_class(attribute, value)
  when :suffix_match
    "substring(#{attribute},string-length(#{attribute})-string-length(#{value})+1,string-length(#{value}))=#{value}"
  else
    attribute + " #{node.value[1]} " + value.to_s
  end
end