比JSON更好的序列化格式？ 快速查找和保存键的顺序？ [重复]

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I am using PHP, but question is not entirely PHP specific.

I've got a need to serialize object, current I am using JSON format and this could be example of serialized object: {"22":{"val":"e","gIds":["48"]},"23":{"val":"e","gIds":["235"]}}

Given this format I can simply use PHP's : $array = json_decode($string, true), then I can use either isset($array[22]) or array_key_exists(22, $array) for quick lookups, which I think would be equivalent to hashmap / dictionary in different languages.

Unfortunately the JSON format by default doesn't keep the order of properties within the object (https://stackoverflow.com/a/7214312/2263395). The order might be consistent in the same version of PHP, but it's not guaranteed behavior according to JSON standard.

I could make it a list of nested objects: [{"22":{"val":"e","gIds":["48"]}},{"23":{"val":"e","gIds":["235"]}}] or even move the id inside: [{"id": "22","val":"e","gIds":["48"]},{"id": "23","val":"e","gIds":["235"]}] That way I can preserve order, however each I can no longer use the quick lookup functions like: isset or array_key_exists before I create a hashmap. For JSONs having thousands of items, I would have to iterate that many times in order to prepare a hashmap, so I can use the quick lookup function.

Can I have the both order and speed, is there any format that could do that?

Speaking of PHP options is there any performant competitor?

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