MongoLite\UtilArrayQuery::buildCondition PHP Method

    public static function buildCondition($criteria, $concat = " && ")
    {
        $fn = array();
        foreach ($criteria as $key => $value) {
            switch ($key) {
                case '$and':
                    $_fn = array();
                    foreach ($value as $v) {
                        $_fn[] = '(' . self::buildCondition($v, ' && ') . ')';
                    }
                    $fn[] = implode(' || ', $_fn);
                    break;
                case '$or':
                    $_fn = array();
                    foreach ($value as $v) {
                        $_fn[] = '(' . self::buildCondition($v, ' || ') . ')';
                    }
                    $fn[] = implode(' || ', $_fn);
                    break;
                default:
                    $d = '$document';
                    if (strpos($key, ".") !== false) {
                        $keys = explode('.', $key);
                        foreach ($keys as $k) {
                            $d .= '["' . $k . '"]';
                        }
                    } else {
                        $d .= '["' . $key . '"]';
                    }
                    $fn[] = is_array($value) ? "\\MongoLite\\UtilArrayQuery::check((isset({$d}) ? {$d} : null), " . var_export($value, true) . ")" : "(isset({$d}) && {$d}==" . (is_string($value) ? "'{$value}'" : var_export($value, true)) . ")";
            }
        }
        return count($fn) ? trim(implode($concat, $fn)) : 'true';
    }