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# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
class JsonEncodedObject:
"""A common base class for defining protocol units that are represented
as JSON.
Attributes:
unrecognized_keys (dict): A dict containing all the key/value pairs we
don't recognize.
"""
valid_keys = [] # keys we will store
"""A list of strings that represent keys we know about
and can handle. If we have values for these keys they will be
included in the `dictionary` instance variable.
"""
internal_keys = [] # keys to ignore while building dict
"""A list of strings that should *not* be encoded into JSON.
"""
required_keys = []
"""A list of strings that we require to exist. If they are not given upon
construction it raises an exception.
"""
def __init__(self, **kwargs):
"""Takes the dict of `kwargs` and loads all keys that are *valid*
(i.e., are included in the `valid_keys` list) into the dictionary`
instance variable.
Any keys that aren't recognized are added to the `unrecognized_keys`
attribute.
Args:
**kwargs: Attributes associated with this protocol unit.
"""
for required_key in self.required_keys:
if required_key not in kwargs:
raise RuntimeError("Key %s is required" % required_key)
self.unrecognized_keys = {} # Keys we were given not listed as valid
for k, v in kwargs.items():
if k in self.valid_keys or k in self.internal_keys:
self.__dict__[k] = v
else:
self.unrecognized_keys[k] = v
def get_dict(self):
"""Converts this protocol unit into a :py:class:`dict`, ready to be
encoded as JSON.
The keys it encodes are: `valid_keys` - `internal_keys`
Returns
dict
"""
d = {
k: _encode(v)
for (k, v) in self.__dict__.items()
if k in self.valid_keys and k not in self.internal_keys
}
d.update(self.unrecognized_keys)
return d
def get_internal_dict(self):
d = {
k: _encode(v, internal=True)
for (k, v) in self.__dict__.items()
if k in self.valid_keys
}
d.update(self.unrecognized_keys)
return d
def __str__(self):
return "(%s, %s)" % (self.__class__.__name__, repr(self.__dict__))
def _encode(obj, internal=False):
if type(obj) is list:
return [_encode(o, internal=internal) for o in obj]
if isinstance(obj, JsonEncodedObject):
if internal:
return obj.get_internal_dict()
else:
return obj.get_dict()
return obj
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