protected function doHighlight($terms)
 {
     $content = $this->getContext()->getResponse()->getContent();
     $lighter = new sfSolrHighlighter($content);
     $lighter->addKeywords($terms);
     $lighter->addHighlighters($this->getHighlightStrings());
     $lighter->hasBody(true);
     $this->getContext()->getResponse()->setContent($lighter->highlight());
 }