Escaping Method for filter Expressions

[staabm]

we built filter expressions like

        $searchParams = [
            'returnProperties' => true,
            'filter' => '(
                           (\'adaid\' == '.(int) $user->adaid.') AND
                           ( \'active\') 
                        )',
        ];

        $result = $this->client->send(new SearchItems($userid, $searchQuery, self::COUNT_SEARCH_ITEMS, $searchParams));

for this case we need to escape user-input so we can use it in the filter query.
atm this is easy because we just have this int here. but image we would have to pass in a string value.. how should this value be escaped for the filter-expression?

IMO the SDK should provide a escaping method, so we can use whatever variable inside the expresssion without security risks