public static function splitFilter($filter_type, $value)
    {
        $pattern = $filter_type === Datasource::FILTER_AND ? '\+' : '(?<!\\\\),';
        $value = preg_split('/\s*' . $pattern . '\s*/', $value, -1, PREG_SPLIT_NO_EMPTY);
        $value = array_map('trim', $value);
        $value = array_map(array('Datasource', 'removeEscapedCommas'), $value);
        return $value;
    }