Truncate string on word break

TruncateString.php

<?php

/**
 * @param string $string Subject
 * @param int $length Max string length
 * @param bool $exactLength Truncate string with exact $length
 * @param string $append Ellipsis string
 * @return string
 */
class TruncateString
{
    public static function truncate($string, $length, $exactLength = false, $append = '…')
    {
        if (mb_strlen($string) < $length) {
            return $string;
        }

        if ($exactLength) {
            return mb_substr($string, 0, $length) . $append;
        } else {
            $string = mb_substr($string, 0, $length);
            $replaced = preg_replace("/\\s+?(\\S+)?$/u", '', $string);
            return $replaced . $append;
        }
    }
}