short_id.py 文件源码

def get_id(source_uuid):
    """Derive a short (12 character) id from a random UUID.

    The supplied UUID must be a version 4 UUID object.
    """

    if isinstance(source_uuid, six.string_types):
        source_uuid = uuid.UUID(source_uuid)
    if source_uuid.version != 4:
        raise ValueError(_('Invalid UUID version (%d)') % source_uuid.version)

    # The "time" field of a v4 UUID contains 60 random bits
    # (see RFC4122, Section 4.4)
    random_bytes = _to_byte_string(source_uuid.time, 60)
    # The first 12 bytes (= 60 bits) of base32-encoded output is our data
    encoded = base64.b32encode(six.b(random_bytes))[:12]

    if six.PY3:
        return encoded.lower().decode('utf-8')
    else:
        return encoded.lower()