    # File lib/nokogiri/xml/document.rb, line 19
          def self.parse string_or_io, url = nil, encoding = nil, options = ParseOptions::DEFAULT_XML, &block

            options = Nokogiri::XML::ParseOptions.new(options) if Fixnum === options
            # Give the options to the user
            yield options if block_given?

            if string_or_io.respond_to?(:read)
              url ||= string_or_io.respond_to?(:path) ? string_or_io.path : nil
              return read_io(string_or_io, url, encoding, options.to_i)
            end

            # read_memory pukes on empty docs
            return new if string_or_io.nil? or string_or_io.empty?

            read_memory(string_or_io, url, encoding, options.to_i)
          end