public static function highlightText($str, $style = null)
    {
        $html     = '';
        $prevTag  = 0;
        $prevWord = '';
        
        $taggedText = self::tagText($str);
        
        foreach ($taggedText as $wordTag) {
            list($word, $tag) = $wordTag;
            
            if ($prevTag == 1) {
                if (in_array($word, self::$_particlePreNouns)) {
                    $prevWord = $word;
                    continue;
                }
                
                if ($tag == 0) {
                    $html .= "</span> \r\n";
                }
            } else {
                // if ($tag == 1 && !in_array($word, $this->_commonWords)) {
                if ($tag == 1) {
                    $html .= " \r\n<span class=\"" . $style ."\">";
                }
            }
            
            $html .= ' ' . $prevWord . ' ' . $word;
            
            if ($prevWord != '') {
                $prevWord = '';
            }
            $prevTag = $tag;
        }
        
        if ($prevTag == 1) {
            $html .= "</span> \r\n";
        }
        
        return $html;
    }