GUMP::validate_contains PHP Method

    protected function validate_contains($field, $input, $param = null)
    {
        if (!isset($input[$field])) {
            return;
        }
        $param = trim(strtolower($param));
        $value = trim(strtolower($input[$field]));
        if (preg_match_all('#\'(.+?)\'#', $param, $matches, PREG_PATTERN_ORDER)) {
            $param = $matches[1];
        } else {
            $param = explode(chr(32), $param);
        }
        if (in_array($value, $param)) {
            // valid, return nothing
            return;
        }
        return array('field' => $field, 'value' => $value, 'rule' => __FUNCTION__, 'param' => $param);
    }