快速JSON编码器
metamagic.json的Python项目详细描述
为python对象设计的json编码器的超高速python 3实现 与各种web浏览器中的本地json解码器兼容。
可以编码为python字符串（请参见dumps）或序列 字节数（请参阅dumpb）。保证dumps（）返回的字符串 只有7位ascii字符[1]和dumps(obj).encode('ascii') = dumpb(obj)。
支持一个特殊的编码器类方法encode_hook(obj)，如果存在的话，它将应用于
输入对象和其余处理将应用于encode_hook（）的输出。
注意：encode_hook（）应该始终返回一个对象；对于不应该
特殊编码的encode_hook（）应该返回原始对象。
通过使用对象__mm_json__()或^{tt5}支持自定义编码器$ 方法（如果可用）。对于所有非本机类型__mm_json__和 然后__mm_serialize__将在尝试对对象[2]进行编码之前进行尝试。 __mm_serialize__的输出依次编码为任何其他对象（并可能依次具有 是否支持__mm_serialize__方法）。
本机支持字符串、整数、浮点、真、假、无、列表、元组， dicts，sets，frozensets，collections.ordereddicts，colections.set，集合，集合 collections.sequence[3]，collections.mapping，uuid.uuids[4]，decimal.decimals， DateTime.DateTime和从所有列出的对象派生的对象。
对于所有不能以任何其他方式编码的对象 试图使用^{tt10}将对象转换为可编码对象$ 方法。如果Encoder.default成功，则输出将再次编码为任何其他对象。
如果需要自定义处理本机支持的基元类型，则 {TT12} $方法存在。
示例
编码自定义对象：
>>> from metamagic.json import dumps, dumpb
>>> class Foo:
... def __mm_serialize__(self):
... return "Im foo"
...
>>> dumps(Foo())
'"Im foo"'
>>> dumps({Foo(): 123})
'{"Im foo":123}'
直接转储到字节：
>>> dumpb(Foo()) b'"Im foo"'
绕过json缓冲区的序列化：
>>> class JSONData:
... def __init__(self, data):
... self.data = data
...
... def __mm_json__(self):
... return self.data
>>> a = JSONData('["abc", "def"]')
>>> dumps([1,2,3,a])
'[1,2,3,["abc", "def"]]'
引发异常
- dumps()和dumpb()都会引发不支持对象的类型错误，并且 对于不是字符串（或uuid[5]）的所有字典键 它们的__mm_serialize__方法不能表示为字符串（或uuid）。
- default()为所有不支持的对象引发typeerror，并覆盖default() 还应为它不支持的所有对象引发Typeerror。
- 当编码整数时，dumps()和dumpb()如果整数 值大于JavaScript支持的最大整型值 （9007199254740992，请参阅http://ecma262-5.com/ELS5_HTML.htm#Section_8.5）。
- 对嵌套对象进行编码时，如果深度超过 允许的嵌套级别（默认为100，可以通过传递 作为dumps()和dumpb()方法的第二个参数的所需值
基准
Array with 256 short ascii strings:
std json: 2.6581 sec, 11286 req/sec
mm c json: 0.90321 sec, 33214 req/sec ( 2.9x )
mm c 1ini: 0.85578 sec, 35055 req/sec ( 3.1x )
mm c dumpb: 0.84517 sec, 35495 req/sec ( 3.1x )
marshal: 1.77567 sec, 16895 req/sec
Array with 2048 3-char ascii strings:
std json: 0.47259 sec, 4231 req/sec
mm c json: 0.12481 sec, 16024 req/sec ( 3.8x )
mm c 1ini: 0.12261 sec, 16311 req/sec ( 3.9x )
mm c dumpb: 0.11732 sec, 17047 req/sec ( 4.0x )
marshal: 0.41334 sec, 4838 req/sec
Array with 256 long ascii strings:
std json: 1.30821 sec, 3822 req/sec
mm c json: 0.47144 sec, 10605 req/sec ( 2.8x )
mm c 1ini: 0.44159 sec, 11322 req/sec ( 3.0x )
mm c dumpb: 0.4346 sec, 11504 req/sec ( 3.0x )
marshal: 0.85593 sec, 5841 req/sec
Array with 256 long utf-8 strings:
std json: 1.52419 sec, 1312 req/sec
mm c json: 1.4438 sec, 1385 req/sec ( 1.1x )
mm c 1ini: 1.43666 sec, 1392 req/sec ( 1.1x )
mm c dumpb: 1.40142 sec, 1427 req/sec ( 1.1x )
marshal: 1.3413 sec, 1491 req/sec
Medium complex object:
std json: 3.5078 sec, 2850 req/sec
mm c json: 1.45764 sec, 6860 req/sec ( 2.4x )
mm c 1ini: 1.43357 sec, 6975 req/sec ( 2.4x )
mm c dumpb: 1.47626 sec, 6773 req/sec ( 2.4x )
marshal: 1.04175 sec, 9599 req/sec
Array with 256 doubles:
std json: 3.37919 sec, 2959 req/sec
mm c json: 2.23615 sec, 4471 req/sec ( 1.5x )
mm c 1ini: 2.48201 sec, 4028 req/sec ( 1.4x )
mm c dumpb: 2.23184 sec, 4480 req/sec ( 1.5x )
marshal: 0.14098 sec, 70932 req/sec
Array with 256 ints:
std json: 1.0185 sec, 19636 req/sec
mm c json: 0.2752 sec, 72674 req/sec ( 3.7x )
mm c 1ini: 0.25349 sec, 78898 req/sec ( 4.0x )
mm c dumpb: 0.28252 sec, 70791 req/sec ( 3.6x )
marshal: 0.15442 sec, 129516 req/sec
Array with 256 small ints:
std json: 1.04397 sec, 191576 req/sec
mm c json: 0.28152 sec, 710429 req/sec ( 3.7x )
mm c 1ini: 0.09222 sec, 2168726 req/sec ( 11.3x )
mm c dumpb: 0.27627 sec, 723929 req/sec ( 3.8x )
marshal: 0.08306 sec, 2407897 req/sec
Array with 256 Decimals:
std json: failed to serialize
mm c json: 0.77161 sec, 10367 req/sec ( 0.0x )
mm c 1ini: 0.76022 sec, 10523 req/sec ( 0.0x )
mm c dumpb: 0.78671 sec, 10168 req/sec ( 0.0x )
marshal: failed to serialize
Array with 256 True values:
std json: 2.08432 sec, 38381 req/sec
mm c json: 0.47159 sec, 169638 req/sec ( 4.4x )
mm c 1ini: 0.39814 sec, 200934 req/sec ( 5.2x )
mm c dumpb: 0.45191 sec, 177026 req/sec ( 4.6x )
marshal: 0.24776 sec, 322893 req/sec
Array with 256 False values:
std json: 2.0099 sec, 39802 req/sec
mm c json: 0.50992 sec, 156887 req/sec ( 3.9x )
mm c 1ini: 0.43001 sec, 186042 req/sec ( 4.7x )
mm c dumpb: 0.50839 sec, 157359 req/sec ( 4.0x )
marshal: 0.25551 sec, 313099 req/sec
Array with 256 dict{string, int} pairs:
std json: 1.96227 sec, 4076 req/sec
mm c json: 0.36569 sec, 21876 req/sec ( 5.4x )
mm c 1ini: 0.34565 sec, 23144 req/sec ( 5.7x )
mm c dumpb: 0.36583 sec, 21868 req/sec ( 5.4x )
marshal: 0.51862 sec, 15425 req/sec
Array with 256 dict-based{string, int} pairs:
std json: 4.20194 sec, 1903 req/sec
mm c json: 3.74071 sec, 2138 req/sec ( 1.1x )
mm c 1ini: 3.70554 sec, 2158 req/sec ( 1.1x )
mm c dumpb: 3.77039 sec, 2121 req/sec ( 1.1x )
marshal: failed to serialize
Array with 256 orderedDict{string, int} pairs:
std json: 2.31765 sec, 431 req/sec
mm c json: 0.70724 sec, 1413 req/sec ( 3.3x )
mm c 1ini: 0.69506 sec, 1438 req/sec ( 3.3x )
mm c dumpb: 0.70373 sec, 1420 req/sec ( 3.3x )
marshal: failed to serialize
Dict with 256 arrays with 256 dict{string, int} pairs:
std json: 3.78828 sec, 13 req/sec
mm c json: 0.69496 sec, 71 req/sec ( 5.5x )
mm c 1ini: 0.69522 sec, 71 req/sec ( 5.4x )
mm c dumpb: 0.68382 sec, 73 req/sec ( 5.5x )
marshal: 1.02776 sec, 48 req/sec
测试
^运行测试需要{tt23}$。
| [1] | All characters required to be escaped by the JSON spec @ http://json.org are escaped |
| [2] | If present, encode_hook() is applied before and independently of all other encoders |
| [3] | To avoid errors in the metamagic framework ^{tt24}$, ^{tt25}$ and derived classes are deliberately not encoded using the built-in sequence encoder; the only way to encode these objects is to either overwrite the encoders’ default() method or to provide __mm_serialize__ method in the object being serialized. |
| [4] | UUIDs and Decimals are encoded as strings. |
| [5] | JSON specification only supports string dictionary keys; since UUIDs are also encoded to strings and are a common key in the metamagic framework, this encoder also supports UUIDs as dictionary keys. |
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