code: private static function createBuilder($isXhtml = false)
      {
          // @codeCoverageIgnoreStart
          static $breakControl = null;
          if (!isset($breakControl)) {
              $breakControl = new NameBreakControl(
                  array("html", "head", "body", "ul", "ol", "dl", "table"),
                  array("pre", "code", "textarea")
              );
          }
          // @codeCoverageIgnoreEnd
          
          $renderer = $isXhtml ? XmlRenderer::getInstance() : SgmlRenderer::getInstance();
          $builder  = new DefaultBuilder();
          $builder->setBreakControl($breakControl);
          $builder->setRenderer($renderer);
          return $builder;
      }
docs: 新しい DefaultBuilder を生成します.
  @param  bool $isXhtml XHTML 形式の場合は true, HTML 形式の場合は false
  @return DefaultBuilder