Two functions to work with unicode whitespaces. See: http://php.net/manual/en/regexp.reference.unicode.php

whitespaces.php

<?php

$compactWhitespace = function ($string) {
    return preg_replace('/[\pZ\pC]+/u', ' ', $string);
};

$trim = function ($string) {
    return preg_replace('/^[\pZ\pC]+|[\pZ\pC]+$/u', '', $string);
};