143 lines
5.2 KiB
Python
143 lines
5.2 KiB
Python
"""Wraps the best available JSON implementation available in a common
|
|
interface"""
|
|
|
|
import sys
|
|
|
|
VERSION = (0, 3, 3)
|
|
__version__ = ".".join(map(str, VERSION[0:3])) + "".join(VERSION[3:])
|
|
__author__ = "Rune Halvorsen"
|
|
__contact__ = "runefh@gmail.com"
|
|
__homepage__ = "http://bitbucket.org/runeh/anyjson/"
|
|
__docformat__ = "restructuredtext"
|
|
|
|
# -eof meta-
|
|
|
|
#: 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``.
|
|
implementation = None
|
|
|
|
# json.loads does not support buffer() objects,
|
|
# so we load() and StringIO instead, and it won't copy.
|
|
if sys.version_info[0] == 3:
|
|
from io import StringIO
|
|
else:
|
|
try:
|
|
from cStringIO import StringIO # noqa
|
|
except ImportError:
|
|
from StringIO import StringIO # noqa
|
|
|
|
#: List of known json modules, and the names of their loads/dumps
|
|
#: methods, as well as the exceptions they throw. Exception can be either
|
|
#: an exception class or a string.
|
|
_modules = [("yajl", "dumps", TypeError, "loads", ValueError, "load"),
|
|
("jsonlib2", "write", "WriteError", "read", "ReadError", None),
|
|
("jsonlib", "write", "WriteError", "read", "ReadError", None),
|
|
("simplejson", "dumps", TypeError, "loads", ValueError, "load"),
|
|
("json", "dumps", TypeError, "loads", ValueError, "load"),
|
|
("django.utils.simplejson", "dumps", TypeError, "loads", ValueError, "load"),
|
|
("cjson", "encode", "EncodeError", "decode", "DecodeError", None)
|
|
]
|
|
|
|
_fields = ("modname", "encoder", "encerror",
|
|
"decoder", "decerror", "filedecoder")
|
|
|
|
|
|
class _JsonImplementation(object):
|
|
"""Incapsulates a JSON implementation"""
|
|
|
|
def __init__(self, modspec):
|
|
modinfo = dict(zip(_fields, modspec))
|
|
|
|
if modinfo["modname"] == "cjson":
|
|
import warnings
|
|
warnings.warn("cjson is deprecated! See http://pypi.python.org/pypi/python-cjson/1.0.5", DeprecationWarning)
|
|
|
|
# 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"])
|
|
fdec = modinfo["filedecoder"]
|
|
self._filedecode = fdec and getattr(module, fdec)
|
|
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 __repr__(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 dumps(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, TypeError(*exc.args), sys.exc_info()[2]
|
|
serialize = dumps
|
|
|
|
def loads(self, s):
|
|
"""deserialize the string to python data types. Raises
|
|
ValueError if the string could not be parsed."""
|
|
# uses StringIO to support buffer objects.
|
|
try:
|
|
if self._filedecode and not isinstance(s, basestring):
|
|
return self._filedecode(StringIO(s))
|
|
return self._decode(s)
|
|
except self._decode_error, exc:
|
|
raise ValueError, ValueError(*exc.args), sys.exc_info()[2]
|
|
deserialize = loads
|
|
|
|
|
|
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")
|
|
|
|
|
|
def loads(value):
|
|
"""Serialize the object to JSON."""
|
|
return implementation.loads(value)
|
|
deserialize = loads # compat
|
|
|
|
|
|
def dumps(value):
|
|
"""Deserialize JSON-encoded object to a Python object."""
|
|
return implementation.dumps(value)
|
|
serialize = dumps
|