PHP contagem de palavras árabe

if (!function_exists('mb_str_word_count'))
{
    function mb_str_word_count($string, $format = 0, $charlist = '[]') {
        $string=trim($string);
        if(empty($string))
            $words = array();
        else
            $words = preg_split('~[^\p{L}\p{N}\']+~u',$string);
        switch ($format) {
            case 0:
                return count($words);
                break;
            case 1:
            case 2:
                return $words;
                break;
            default:
                return $words;
                break;
        }
    }
}
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