vendorization!

github3/packages/anyjson.py

@@ -0,0 +1,117 @@
+"""
+Wraps the best available JSON implementation available in a common interface
+"""
+
+__version__ = "0.2.0"
+__author__ = "Rune Halvorsen <runefh@gmail.com>"
+__homepage__ = "http://bitbucket.org/runeh/anyjson/"
+__docformat__ = "restructuredtext"
+
+"""
+
+.. 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`.
+"""
+
+import sys
+
+implementation = None
+
+"""
+.. 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"),
+            ("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(list(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"], str):
+            self._encode_error = getattr(module, modinfo["encerror"])
+        if isinstance(modinfo["decerror"], str):
+            self._decode_error = getattr(module, modinfo["decerror"])
+
+        self.name = modinfo["modname"]
+
+    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 as 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 as 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)
+
+
+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)