PHP笛卡爾積算法

//笛卡爾積
    private function _dicaer($data)
    {
        $rr = array_shift($data);
        $result = [];
        while($arr2 = array_shift($data)){
            $arr1 = $rr;
            $result = array();
            foreach($arr1 as $v){
                foreach($arr2 as $v2){
                    if(!is_array($v))$v = array($v);
                    if(!is_array($v2))$v2 = array($v2);
                    $result[] = array_merge_recursive($v,$v2);
                }
            }
        }
        return $result;
    }