kopia lustrzana https://github.com/dsblank/activitypub
318 wiersze
10 KiB
Python
318 wiersze
10 KiB
Python
# Copyright 2009-2015 MongoDB, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Tools for working with MongoDB `ObjectIds
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<http://dochub.mongodb.org/core/objectids>`_.
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"""
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import binascii
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import calendar
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import datetime
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import os
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import random
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import socket
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import struct
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import threading
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import time
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from .errors import InvalidId
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from .py3compat import PY3, bytes_from_hex, string_type, text_type
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from .tz_util import utc
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if PY3:
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_ord = lambda x: x
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else:
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_ord = ord
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# http://isthe.com/chongo/tech/comp/fnv/index.html#FNV-1a
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def _fnv_1a_24(data, _ord=_ord):
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"""FNV-1a 24 bit hash"""
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# http://www.isthe.com/chongo/tech/comp/fnv/index.html#xor-fold
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# Start with FNV-1a 32 bit.
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hash_size = 2 ** 32
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fnv_32_prime = 16777619
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fnv_1a_hash = 2166136261 # 32-bit FNV-1 offset basis
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for elt in data:
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fnv_1a_hash = fnv_1a_hash ^ _ord(elt)
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fnv_1a_hash = (fnv_1a_hash * fnv_32_prime) % hash_size
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# xor-fold the result to 24 bit.
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return (fnv_1a_hash >> 24) ^ (fnv_1a_hash & 0xffffff)
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def _machine_bytes():
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"""Get the machine portion of an ObjectId.
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"""
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# gethostname() returns a unicode string in python 3.x
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# We only need 3 bytes, and _fnv_1a_24 returns a 24 bit integer.
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# Remove the padding byte.
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return struct.pack("<I", _fnv_1a_24(socket.gethostname().encode()))[:3]
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def _raise_invalid_id(oid):
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raise InvalidId(
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"%r is not a valid ObjectId, it must be a 12-byte input"
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" or a 24-character hex string" % oid)
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class ObjectId(object):
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"""A MongoDB ObjectId.
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"""
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_inc = random.randint(0, 0xFFFFFF)
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_inc_lock = threading.Lock()
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_machine_bytes = _machine_bytes()
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__slots__ = ('__id')
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_type_marker = 7
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def __init__(self, oid=None):
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"""Initialize a new ObjectId.
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An ObjectId is a 12-byte unique identifier consisting of:
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- a 4-byte value representing the seconds since the Unix epoch,
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- a 3-byte machine identifier,
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- a 2-byte process id, and
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- a 3-byte counter, starting with a random value.
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By default, ``ObjectId()`` creates a new unique identifier. The
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optional parameter `oid` can be an :class:`ObjectId`, or any 12
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:class:`bytes` or, in Python 2, any 12-character :class:`str`.
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For example, the 12 bytes b'foo-bar-quux' do not follow the ObjectId
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specification but they are acceptable input::
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>>> ObjectId(b'foo-bar-quux')
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ObjectId('666f6f2d6261722d71757578')
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`oid` can also be a :class:`unicode` or :class:`str` of 24 hex digits::
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>>> ObjectId('0123456789ab0123456789ab')
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ObjectId('0123456789ab0123456789ab')
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>>>
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>>> # A u-prefixed unicode literal:
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>>> ObjectId(u'0123456789ab0123456789ab')
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ObjectId('0123456789ab0123456789ab')
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Raises :class:`~bson.errors.InvalidId` if `oid` is not 12 bytes nor
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24 hex digits, or :class:`TypeError` if `oid` is not an accepted type.
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:Parameters:
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- `oid` (optional): a valid ObjectId.
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.. mongodoc:: objectids
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"""
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if oid is None:
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self.__generate()
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elif isinstance(oid, bytes) and len(oid) == 12:
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self.__id = oid
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else:
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self.__validate(oid)
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@classmethod
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def from_datetime(cls, generation_time):
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"""Create a dummy ObjectId instance with a specific generation time.
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This method is useful for doing range queries on a field
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containing :class:`ObjectId` instances.
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.. warning::
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It is not safe to insert a document containing an ObjectId
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generated using this method. This method deliberately
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eliminates the uniqueness guarantee that ObjectIds
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generally provide. ObjectIds generated with this method
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should be used exclusively in queries.
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`generation_time` will be converted to UTC. Naive datetime
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instances will be treated as though they already contain UTC.
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An example using this helper to get documents where ``"_id"``
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was generated before January 1, 2010 would be:
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>>> import datetime
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>>> gen_time = datetime.datetime(2010, 1, 1)
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>>> early = ObjectId.from_datetime(gen_time)
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>>> from activitypub.manager import Manager
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>>> from activitypub.database import ListDatabase
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>>> m = Manager(database=ListDatabase())
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>>> n = m.Note(_id=early, attributedTo="alyssa")
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>>> m.database.activities.insert_one(n.to_dict())
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>>> gen_time = datetime.datetime(2011, 1, 1)
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>>> later = ObjectId.from_datetime(gen_time)
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>>> result = m.database.activities.find({"_id": {"$lt": later}})
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>>> result # doctest: +ELLIPSIS
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[{'@context': 'https://www.w3.org/ns/activitystreams', '_id': ObjectId('...'), 'attributedTo': 'alyssa', 'type': 'Note'}]
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:Parameters:
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- `generation_time`: :class:`~datetime.datetime` to be used
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as the generation time for the resulting ObjectId.
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"""
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if generation_time.utcoffset() is not None:
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generation_time = generation_time - generation_time.utcoffset()
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timestamp = calendar.timegm(generation_time.timetuple())
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oid = struct.pack(
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">i", int(timestamp)) + b"\x00\x00\x00\x00\x00\x00\x00\x00"
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return cls(oid)
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@classmethod
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def is_valid(cls, oid):
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"""Checks if a `oid` string is valid or not.
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:Parameters:
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- `oid`: the object id to validate
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.. versionadded:: 2.3
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"""
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if not oid:
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return False
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try:
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ObjectId(oid)
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return True
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except (InvalidId, TypeError):
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return False
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def __generate(self):
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"""Generate a new value for this ObjectId.
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"""
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# 4 bytes current time
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oid = struct.pack(">i", int(time.time()))
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# 3 bytes machine
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oid += ObjectId._machine_bytes
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# 2 bytes pid
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oid += struct.pack(">H", os.getpid() % 0xFFFF)
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# 3 bytes inc
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with ObjectId._inc_lock:
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oid += struct.pack(">i", ObjectId._inc)[1:4]
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ObjectId._inc = (ObjectId._inc + 1) % 0xFFFFFF
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self.__id = oid
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def __validate(self, oid):
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"""Validate and use the given id for this ObjectId.
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Raises TypeError if id is not an instance of
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(:class:`basestring` (:class:`str` or :class:`bytes`
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in python 3), ObjectId) and InvalidId if it is not a
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valid ObjectId.
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:Parameters:
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- `oid`: a valid ObjectId
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"""
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if isinstance(oid, ObjectId):
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self.__id = oid.binary
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# bytes or unicode in python 2, str in python 3
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elif isinstance(oid, string_type):
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if len(oid) == 24:
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try:
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self.__id = bytes_from_hex(oid)
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except (TypeError, ValueError):
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_raise_invalid_id(oid)
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else:
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_raise_invalid_id(oid)
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else:
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raise TypeError("id must be an instance of (bytes, %s, ObjectId), "
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"not %s" % (text_type.__name__, type(oid)))
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@property
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def binary(self):
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"""12-byte binary representation of this ObjectId.
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"""
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return self.__id
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@property
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def generation_time(self):
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"""A :class:`datetime.datetime` instance representing the time of
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generation for this :class:`ObjectId`.
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The :class:`datetime.datetime` is timezone aware, and
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represents the generation time in UTC. It is precise to the
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second.
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"""
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timestamp = struct.unpack(">i", self.__id[0:4])[0]
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return datetime.datetime.fromtimestamp(timestamp, utc)
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def __getstate__(self):
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"""return value of object for pickling.
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needed explicitly because __slots__() defined.
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"""
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return self.__id
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def __setstate__(self, value):
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"""explicit state set from pickling
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"""
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# Provide backwards compatability with OIDs
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# pickled with pymongo-1.9 or older.
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if isinstance(value, dict):
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oid = value["_ObjectId__id"]
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else:
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oid = value
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# ObjectIds pickled in python 2.x used `str` for __id.
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# In python 3.x this has to be converted to `bytes`
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# by encoding latin-1.
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if PY3 and isinstance(oid, text_type):
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self.__id = oid.encode('latin-1')
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else:
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self.__id = oid
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def __str__(self):
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if PY3:
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return binascii.hexlify(self.__id).decode()
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return binascii.hexlify(self.__id)
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def __repr__(self):
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return "ObjectId('%s')" % (str(self),)
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def __eq__(self, other):
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if isinstance(other, ObjectId):
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return self.__id == other.binary
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return NotImplemented
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def __ne__(self, other):
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if isinstance(other, ObjectId):
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return self.__id != other.binary
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return NotImplemented
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def __lt__(self, other):
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if isinstance(other, ObjectId):
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return self.__id < other.binary
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return NotImplemented
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def __le__(self, other):
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if isinstance(other, ObjectId):
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return self.__id <= other.binary
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return NotImplemented
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def __gt__(self, other):
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if isinstance(other, ObjectId):
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return self.__id > other.binary
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return NotImplemented
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def __ge__(self, other):
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if isinstance(other, ObjectId):
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return self.__id >= other.binary
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return NotImplemented
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def __hash__(self):
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"""Get a hash value for this :class:`ObjectId`."""
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return hash(self.__id)
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