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Pure Python CBOR (de)serializer with extensive tag support

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This library provides encoding and decoding for the Concise Binary Object Representation (CBOR) (RFC 7049) serialization format.


from cbor2 import *

# Serialize an object as a bytestring
data = dumps(['hello', 'world'])

# Deserialize a bytestring
obj = loads(data)

# Efficiently deserialize from a file
with open('input.cbor', 'rb') as fp:
    obj = load(fp)

# Efficiently serialize an object to a file
with open('output.cbor', 'wb') as fp:
    dump(obj, fp)

# Iteratively decode a datastream
for chunk in CBORDecoder().decode(data):

String/bytes handling on Python 2

Bytestrings are encoded as binary strings on Python 2. If you want to encode strings as text on Python 2, use unicode strings instead.

Date/time handling

CBOR does not support naïve datetimes (that is, datetimes where tzinfo is missing). When the encoder encounters such a datetime, it needs to know which timezone it belongs to. To this end, you can specify a default timezone by passing a datetime.tzinfo instance to dump()/dumps() call as the timezone argument. Decoded datetimes are always timezone aware.

By default, datetimes are serialized in a manner that retains their timezone offsets. You can optimize the data stream size by passing datetime_as_timestamp=False to dump()/dumps(), but this causes the timezone offset information to be lost.

Cyclic (recursive) data structures

By default, both the encoder and decoder support cyclic data structures (ie. containers that contain references to themselves). When serializing, this requires some extra space in the data stream. If you know you won’t have cyclic structures in your data, you can turn off the value sharing feature by passing the value_sharing=False option to dump()/dumps().

Tag support

In addition to all standard CBOR tags, this library supports many extended tags:

Tag Semantics Python type(s)
0 Standard date/time string / datetime.datetime
1 Epoch-based date/time / datetime.datetime
2 Positive bignum int / long
3 Negative bignum int / long
4 Decimal fraction decimal.Decimal
5 Bigfloat decimal.Decimal
28 Mark shared value N/A
29 Reference shared value N/A
30 Rational number fractions.Fraction
35 Regular expression _sre.SRE_Pattern (result of re.compile(...))
36 MIME message email.message.Message
37 Binary UUID uuid.UUID

Customizing encoding/decoding

The encoder allows you to specify a mapping of types to callables that handle the encoding of some otherwise unsupported type. The decoder, on the other hand, allows you to specify a mapping of semantic tag numbers to callables that implement custom transformation logic for tagged values.

See the docstrings of cbor2.CBOREncoder and cbor2.CBORDecoder for details.

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