223 lines
7.2 KiB
Python
223 lines
7.2 KiB
Python
# Copyright 2009-2010 10gen, 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 creating and manipulating SON, the Serialized Ocument Notation.
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Regular dictionaries can be used instead of SON objects, but not when the order
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of keys is important. A SON object can be used just like a normal Python
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dictionary."""
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import copy
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class SON(dict):
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"""SON data.
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A subclass of dict that maintains ordering of keys and provides a
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few extra niceties for dealing with SON. SON objects can be
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converted to and from BSON.
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The mapping from Python types to BSON types is as follows:
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=================================== ============= ===================
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Python Type BSON Type Supported Direction
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=================================== ============= ===================
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None null both
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bool boolean both
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int [#int]_ int32 / int64 py -> bson
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long int64 both
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float number (real) both
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string string py -> bson
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unicode string both
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list array both
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dict / `SON` object both
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datetime.datetime [#dt]_ [#dt2]_ date both
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compiled re regex both
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`bson.binary.Binary` binary both
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`bson.objectid.ObjectId` oid both
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`bson.dbref.DBRef` dbref both
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None undefined bson -> py
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unicode code bson -> py
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`bson.code.Code` code py -> bson
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unicode symbol bson -> py
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=================================== ============= ===================
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Note that to save binary data it must be wrapped as an instance of
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`bson.binary.Binary`. Otherwise it will be saved as a BSON string
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and retrieved as unicode.
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.. [#int] A Python int will be saved as a BSON int32 or BSON int64 depending
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on its size. A BSON int32 will always decode to a Python int. A BSON int64
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will always decode to a Python long.
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.. [#dt] datetime.datetime instances will be rounded to the nearest
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millisecond when saved
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.. [#dt2] all datetime.datetime instances are treated as *naive*. clients
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should always use UTC.
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"""
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def __init__(self, data=None, **kwargs):
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self.__keys = []
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dict.__init__(self)
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self.update(data)
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self.update(kwargs)
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def __new__(cls, *args, **kwargs):
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instance = super(SON, cls).__new__(cls, *args, **kwargs)
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instance.__keys = []
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return instance
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def __repr__(self):
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result = []
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for key in self.__keys:
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result.append("(%r, %r)" % (key, self[key]))
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return "SON([%s])" % ", ".join(result)
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def __setitem__(self, key, value):
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if key not in self:
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self.__keys.append(key)
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dict.__setitem__(self, key, value)
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def __delitem__(self, key):
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self.__keys.remove(key)
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dict.__delitem__(self, key)
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def keys(self):
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return list(self.__keys)
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def copy(self):
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other = SON()
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other.update(self)
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return other
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# TODO this is all from UserDict.DictMixin. it could probably be made more
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# efficient.
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# second level definitions support higher levels
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def __iter__(self):
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for k in self.keys():
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yield k
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def has_key(self, key):
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return key in self.keys()
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def __contains__(self, key):
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return key in self.keys()
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# third level takes advantage of second level definitions
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def iteritems(self):
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for k in self:
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yield (k, self[k])
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def iterkeys(self):
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return self.__iter__()
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# fourth level uses definitions from lower levels
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def itervalues(self):
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for _, v in self.iteritems():
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yield v
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def values(self):
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return [v for _, v in self.iteritems()]
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def items(self):
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return list(self.iteritems())
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def clear(self):
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for key in self.keys():
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del self[key]
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def setdefault(self, key, default=None):
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try:
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return self[key]
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except KeyError:
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self[key] = default
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return default
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def pop(self, key, *args):
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if len(args) > 1:
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raise TypeError("pop expected at most 2 arguments, got "\
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+ repr(1 + len(args)))
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try:
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value = self[key]
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except KeyError:
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if args:
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return args[0]
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raise
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del self[key]
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return value
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def popitem(self):
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try:
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k, v = self.iteritems().next()
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except StopIteration:
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raise KeyError('container is empty')
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del self[k]
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return (k, v)
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def update(self, other=None, **kwargs):
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# Make progressively weaker assumptions about "other"
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if other is None:
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pass
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elif hasattr(other, 'iteritems'): # iteritems saves memory and lookups
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for k, v in other.iteritems():
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self[k] = v
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elif hasattr(other, 'keys'):
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for k in other.keys():
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self[k] = other[k]
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else:
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for k, v in other:
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self[k] = v
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if kwargs:
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self.update(kwargs)
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def get(self, key, default=None):
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try:
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return self[key]
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except KeyError:
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return default
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def __cmp__(self, other):
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if isinstance(other, SON):
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return cmp((dict(self.iteritems()), self.keys()),
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(dict(other.iteritems()), other.keys()))
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return cmp(dict(self.iteritems()), other)
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def __len__(self):
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return len(self.keys())
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def to_dict(self):
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"""Convert a SON document to a normal Python dictionary instance.
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This is trickier than just *dict(...)* because it needs to be
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recursive.
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"""
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def transform_value(value):
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if isinstance(value, list):
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return [transform_value(v) for v in value]
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if isinstance(value, SON):
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value = dict(value)
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if isinstance(value, dict):
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for k, v in value.iteritems():
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value[k] = transform_value(v)
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return value
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return transform_value(dict(self))
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def __deepcopy__(self, memo):
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out = SON()
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for k, v in self.iteritems():
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out[k] = copy.deepcopy(v, memo)
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return out
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