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"""Wraps the best available JSON implementation available in a common
interface"""
import sys
VERSION = (0, 3, 2)
__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
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