public static function tagText($str)
    {
        $text     = array();
        $words    = explode(' ', $str);
        $prevWord = '';
        
        foreach ($words as $word) {
            if ($word == '') {
                continue;
            }

            if (self::isNoun($word, $prevWord)) {
                $text[] = array($word, 1);
            } else {
                $text[] = array($word, 0);
            }
            
            $prevWord = $word;
        }

        return $text;
    }