mirror of
https://github.com/kennethreitz-archive/python-convore.git
synced 2026-06-05 23:40:18 +00:00
Kenneth Reitz
128 lines
4.4 KiB
Python
128 lines
4.4 KiB
Python
"""Wraps the best available JSON implementation available in a common
|
|
interface"""
|
|
|
|
import sys
|
|
|
|
__version__ = "0.3"
|
|
__author__ = "Rune Halvorsen <runefh@gmail.com>"
|
|
__homepage__ = "http://bitbucket.org/runeh/anyjson/"
|
|
__docformat__ = "restructuredtext"
|
|
|
|
implementation = None
|
|
|
|
"""
|
|
.. function:: serialize(obj)
|
|
|
|
Serialize the object to JSON.
|
|
|
|
.. function:: deserialize(str)
|
|
|
|
Deserialize JSON-encoded object to a Python object.
|
|
|
|
.. function:: force_implementation(name)
|
|
|
|
Load a specific json module. This is useful for testing and not much else
|
|
|
|
.. attribute:: implementation
|
|
|
|
The json implementation object. This is probably not useful to you,
|
|
except to get the name of the implementation in use. The name is
|
|
available through `implementation.name`.
|
|
|
|
.. data:: _modules
|
|
|
|
List of known json modules, and the names of their serialize/unserialize
|
|
methods, as well as the exception they throw. Exception can be either
|
|
an exception class or a string.
|
|
"""
|
|
_modules = [("cjson", "encode", "EncodeError", "decode", "DecodeError"),
|
|
("yajl", "dumps", TypeError, "loads", ValueError),
|
|
("jsonlib2", "write", "WriteError", "read", "ReadError"),
|
|
("jsonlib", "write", "WriteError", "read", "ReadError"),
|
|
("simplejson", "dumps", TypeError, "loads", ValueError),
|
|
("json", "dumps", TypeError, "loads", ValueError),
|
|
("django.utils.simplejson", "dumps", TypeError, "loads",
|
|
ValueError)]
|
|
_fields = ("modname", "encoder", "encerror", "decoder", "decerror")
|
|
|
|
|
|
class _JsonImplementation(object):
|
|
"""Incapsulates a JSON implementation"""
|
|
|
|
def __init__(self, modspec):
|
|
modinfo = dict(zip(_fields, modspec))
|
|
|
|
# No try block. We want importerror to end up at caller
|
|
module = self._attempt_load(modinfo["modname"])
|
|
|
|
self.implementation = modinfo["modname"]
|
|
self._encode = getattr(module, modinfo["encoder"])
|
|
self._decode = getattr(module, modinfo["decoder"])
|
|
self._encode_error = modinfo["encerror"]
|
|
self._decode_error = modinfo["decerror"]
|
|
|
|
if isinstance(modinfo["encerror"], basestring):
|
|
self._encode_error = getattr(module, modinfo["encerror"])
|
|
if isinstance(modinfo["decerror"], basestring):
|
|
self._decode_error = getattr(module, modinfo["decerror"])
|
|
|
|
self.name = modinfo["modname"]
|
|
|
|
def __str__(self):
|
|
return "<_JsonImplementation instance using %s>" % self.name
|
|
|
|
def _attempt_load(self, modname):
|
|
"""Attempt to load module name modname, returning it on success,
|
|
throwing ImportError if module couldn't be imported"""
|
|
__import__(modname)
|
|
return sys.modules[modname]
|
|
|
|
def serialize(self, data):
|
|
"""Serialize the datastructure to json. Returns a string. Raises
|
|
TypeError if the object could not be serialized."""
|
|
try:
|
|
return self._encode(data)
|
|
except self._encode_error, exc:
|
|
raise TypeError(*exc.args)
|
|
|
|
def deserialize(self, s):
|
|
"""deserialize the string to python data types. Raises
|
|
ValueError if the string vould not be parsed."""
|
|
try:
|
|
return self._decode(s)
|
|
except self._decode_error, exc:
|
|
raise ValueError(*exc.args)
|
|
|
|
|
|
def force_implementation(modname):
|
|
"""Forces anyjson to use a specific json module if it's available"""
|
|
global implementation
|
|
for name, spec in [(e[0], e) for e in _modules]:
|
|
if name == modname:
|
|
implementation = _JsonImplementation(spec)
|
|
return
|
|
raise ImportError("No module named: %s" % modname)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
# If run as a script, we do nothing but print an error message.
|
|
# We do NOT try to load a compatible module because that may throw an
|
|
# exception, which renders the package uninstallable with easy_install
|
|
# (It trys to execfile the script when installing, to make sure it works)
|
|
print "Running anyjson as a stand alone script is not supported"
|
|
sys.exit(1)
|
|
else:
|
|
for modspec in _modules:
|
|
try:
|
|
implementation = _JsonImplementation(modspec)
|
|
break
|
|
except ImportError:
|
|
pass
|
|
else:
|
|
raise ImportError("No supported JSON module found")
|
|
|
|
serialize = lambda value: implementation.serialize(value)
|
|
deserialize = lambda value: implementation.deserialize(value)
|
|
dumps = serialize
|
|
loads = deserialize
|