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https://github.com/kennethreitz/python-github3.git
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Kenneth Reitz
118 lines
3.7 KiB
Python
118 lines
3.7 KiB
Python
"""
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Wraps the best available JSON implementation available in a common interface
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"""
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__version__ = "0.2.0"
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__author__ = "Rune Halvorsen <runefh@gmail.com>"
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__homepage__ = "http://bitbucket.org/runeh/anyjson/"
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__docformat__ = "restructuredtext"
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"""
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.. function:: serialize(obj)
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Serialize the object to JSON.
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.. function:: deserialize(str)
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Deserialize JSON-encoded object to a Python object.
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.. function:: force_implementation(name)
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Load a specific json module. This is useful for testing and not much else
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.. attribute:: implementation
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The json implementation object. This is probably not useful to you,
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except to get the name of the implementation in use. The name is
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available through `implementation.name`.
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"""
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import sys
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implementation = None
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"""
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.. data:: _modules
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List of known json modules, and the names of their serialize/unserialize
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methods, as well as the exception they throw. Exception can be either
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an exception class or a string.
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"""
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_modules = [("cjson", "encode", "EncodeError", "decode", "DecodeError"),
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("jsonlib2", "write", "WriteError", "read", "ReadError"),
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("jsonlib", "write", "WriteError", "read", "ReadError"),
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("simplejson", "dumps", TypeError, "loads", ValueError),
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("json", "dumps", TypeError, "loads", ValueError),
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("django.utils.simplejson", "dumps", TypeError, "loads",
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ValueError)]
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_fields = ("modname", "encoder", "encerror", "decoder", "decerror")
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class _JsonImplementation(object):
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"""Incapsulates a JSON implementation"""
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def __init__(self, modspec):
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modinfo = dict(list(zip(_fields, modspec)))
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# No try block. We want importerror to end up at caller
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module = self._attempt_load(modinfo["modname"])
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self.implementation = modinfo["modname"]
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self._encode = getattr(module, modinfo["encoder"])
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self._decode = getattr(module, modinfo["decoder"])
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self._encode_error = modinfo["encerror"]
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self._decode_error = modinfo["decerror"]
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if isinstance(modinfo["encerror"], str):
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self._encode_error = getattr(module, modinfo["encerror"])
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if isinstance(modinfo["decerror"], str):
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self._decode_error = getattr(module, modinfo["decerror"])
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self.name = modinfo["modname"]
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def _attempt_load(self, modname):
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"""Attempt to load module name modname, returning it on success,
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throwing ImportError if module couldn't be imported"""
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__import__(modname)
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return sys.modules[modname]
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def serialize(self, data):
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"""Serialize the datastructure to json. Returns a string. Raises
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TypeError if the object could not be serialized."""
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try:
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return self._encode(data)
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except self._encode_error as exc:
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raise TypeError(*exc.args)
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def deserialize(self, s):
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"""deserialize the string to python data types. Raises
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ValueError if the string vould not be parsed."""
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try:
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return self._decode(s)
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except self._decode_error as exc:
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raise ValueError(*exc.args)
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def force_implementation(modname):
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"""Forces anyjson to use a specific json module if it's available"""
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global implementation
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for name, spec in [(e[0], e) for e in _modules]:
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if name == modname:
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implementation = _JsonImplementation(spec)
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return
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raise ImportError("No module named: %s" % modname)
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for modspec in _modules:
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try:
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implementation = _JsonImplementation(modspec)
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break
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except ImportError:
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pass
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else:
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raise ImportError("No supported JSON module found")
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serialize = lambda value: implementation.serialize(value)
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deserialize = lambda value: implementation.deserialize(value)
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