Apparently there's no mb_trim in the mb_* family, so I'm trying to implement one for my own.

I recently found this regex in a comment in php.net:

/(^\s+)|(\s+$)/u

So, I'd implement it in the following way:

function multibyte_trim($str)
{
    if (!function_exists("mb_trim") || !extension_loaded("mbstring")) {
        return preg_replace("/(^\s+)|(\s+$)/u", "", $str);
    } else {
        return mb_trim($str);
    }
}

The regex seems correct to me, but I'm extremely noob with regular expressions. Will this effectively remove any Unicode space in the beginning/end of a string?