function highlight_keywords($text, $keywords, $highlighter = '<strong class="highlight">%s</strong>')
{
    $h = new sfSolrHighlighter($text);
    $h->addKeywordSlug($keywords);
    $h->addHighlighter($highlighter);
    $h->hasBody(false);
    return $h->highlight();
}
 protected function doHighlight($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());
 }