/usr/lib/python2.7/dist-packages/jsonpickle/backend.py is in python-jsonpickle 0.6.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 | from jsonpickle.compat import PY32
class JSONBackend(object):
"""Manages encoding and decoding using various backends.
It tries these modules in this order:
simplejson, json, demjson
simplejson is a fast and popular backend and is tried first.
json comes with python2.6 and is tried second.
demjson is the most permissive backend and is tried last.
"""
def __init__(self):
## The names of backends that have been successfully imported
self._backend_names = []
## A dictionary mapping backend names to encode/decode functions
self._encoders = {}
self._decoders = {}
## Options to pass to specific encoders
json_opts = ((), {'sort_keys': True})
self._encoder_options = {
'json': json_opts,
'simplejson': json_opts,
'django.util.simplejson': json_opts,
}
## The exception class that is thrown when a decoding error occurs
self._decoder_exceptions = {}
## Whether we've loaded any backends successfully
self._verified = False
if not PY32:
self.load_backend('simplejson', 'dumps', 'loads', ValueError)
self.load_backend('json', 'dumps', 'loads', ValueError)
self.load_backend('demjson', 'encode', 'decode', 'JSONDecodeError')
self.load_backend('jsonlib', 'write', 'read', 'ReadError')
self.load_backend('yajl', 'dumps', 'loads', ValueError)
self.load_backend('ujson', 'dumps', 'loads', ValueError)
def _verify(self):
"""Ensures that we've loaded at least one JSON backend."""
if self._verified:
return
raise AssertionError('jsonpickle requires at least one of the '
'following:\n'
' python2.6, simplejson, or demjson')
def load_backend(self, name, encode_name, decode_name, decode_exc):
"""
Load a JSON backend by name.
This method loads a backend and sets up references to that
backend's encode/decode functions and exception classes.
:param encode_name: is the name of the backend's encode method.
The method should take an object and return a string.
:param decode_name: names the backend's method for the reverse
operation -- returning a Python object from a string.
:param decode_exc: can be either the name of the exception class
used to denote decoding errors, or it can be a direct reference
to the appropriate exception class itself. If it is a name,
then the assumption is that an exception class of that name
can be found in the backend module's namespace.
"""
try:
## Load the JSON backend
mod = __import__(name)
except ImportError:
return
try:
## Handle submodules, e.g. django.utils.simplejson
components = name.split('.')
for comp in components[1:]:
mod = getattr(mod, comp)
except AttributeError:
return
try:
## Setup the backend's encode/decode methods
self._encoders[name] = getattr(mod, encode_name)
self._decoders[name] = getattr(mod, decode_name)
except AttributeError:
self.remove_backend(name)
return
try:
if type(decode_exc) is str:
## This backend's decoder exception is part of the backend
self._decoder_exceptions[name] = getattr(mod, decode_exc)
else:
## simplejson uses the ValueError exception
self._decoder_exceptions[name] = decode_exc
except AttributeError:
self.remove_backend(name)
return
## Setup the default args and kwargs for this encoder
self._encoder_options[name] = ([], {})
## Add this backend to the list of candidate backends
self._backend_names.append(name)
## Indicate that we successfully loaded a JSON backend
self._verified = True
def remove_backend(self, name):
"""Remove all entries for a particular backend."""
self._encoders.pop(name, None)
self._decoders.pop(name, None)
self._decoder_exceptions.pop(name, None)
self._encoder_options.pop(name, None)
if name in self._backend_names:
self._backend_names.remove(name)
self._verified = bool(self._backend_names)
def encode(self, obj):
"""
Attempt to encode an object into JSON.
This tries the loaded backends in order and passes along the last
exception if no backend is able to encode the object.
"""
self._verify()
for idx, name in enumerate(self._backend_names):
try:
optargs, optkwargs = self._encoder_options[name]
encoder_kwargs = optkwargs.copy()
encoder_args = (obj,) + tuple(optargs)
return self._encoders[name](*encoder_args, **encoder_kwargs)
except Exception:
if idx == len(self._backend_names) - 1:
raise
def decode(self, string):
"""
Attempt to decode an object from a JSON string.
This tries the loaded backends in order and passes along the last
exception if no backends are able to decode the string.
"""
self._verify()
for idx, name in enumerate(self._backend_names):
try:
return self._decoders[name](string)
except self._decoder_exceptions[name] as e:
if idx == len(self._backend_names) - 1:
raise e
else:
pass # and try a more forgiving encoder, e.g. demjson
def set_preferred_backend(self, name):
"""
Set the preferred json backend.
If a preferred backend is set then jsonpickle tries to use it
before any other backend.
For example::
set_preferred_backend('simplejson')
If the backend is not one of the built-in jsonpickle backends
(json/simplejson, or demjson) then you must load the backend
prior to calling set_preferred_backend.
AssertionError is raised if the backend has not been loaded.
"""
if name in self._backend_names:
self._backend_names.remove(name)
self._backend_names.insert(0, name)
else:
errmsg = 'The "%s" backend has not been loaded.' % name
raise AssertionError(errmsg)
def set_encoder_options(self, name, *args, **kwargs):
"""
Associate encoder-specific options with an encoder.
After calling set_encoder_options, any calls to jsonpickle's
encode method will pass the supplied args and kwargs along to
the appropriate backend's encode method.
For example::
set_encoder_options('simplejson', sort_keys=True, indent=4)
set_encoder_options('demjson', compactly=False)
See the appropriate encoder's documentation for details about
the supported arguments and keyword arguments.
"""
self._encoder_options[name] = (args, kwargs)
|