app/django/utils/simplejson/__init__.py
author Todd Larsen <tlarsen@google.com>
Mon, 29 Sep 2008 15:46:42 +0000
changeset 208 e076aee6e90f
parent 54 03e267d67478
child 323 ff1a9aa48cfd
permissions -rw-r--r--
Take advantage of the Model inheritance provided by polymodel.PolyModel to have Club, School, Sponsor, and Organization actually inherit from the Group Model class, rather than being composed via ReferenceProperties. Patch by: Todd Larsen Review by: Pawel Solyga, Sverre Rabbelier, Augie Fackler Review URL: http://codereviews.googleopensourceprograms.com/606

r"""
A simple, fast, extensible JSON encoder and decoder

JSON (JavaScript Object Notation) <http://json.org> is a subset of
JavaScript syntax (ECMA-262 3rd edition) used as a lightweight data
interchange format.

simplejson exposes an API familiar to uses of the standard library
marshal and pickle modules.

Encoding basic Python object hierarchies::
    
    >>> import simplejson
    >>> simplejson.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])
    '["foo", {"bar": ["baz", null, 1.0, 2]}]'
    >>> print simplejson.dumps("\"foo\bar")
    "\"foo\bar"
    >>> print simplejson.dumps(u'\u1234')
    "\u1234"
    >>> print simplejson.dumps('\\')
    "\\"
    >>> print simplejson.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True)
    {"a": 0, "b": 0, "c": 0}
    >>> from StringIO import StringIO
    >>> io = StringIO()
    >>> simplejson.dump(['streaming API'], io)
    >>> io.getvalue()
    '["streaming API"]'

Compact encoding::

    >>> import simplejson
    >>> simplejson.dumps([1,2,3,{'4': 5, '6': 7}], separators=(',',':'))
    '[1,2,3,{"4":5,"6":7}]'

Pretty printing::

    >>> import simplejson
    >>> print simplejson.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4)
    {
        "4": 5, 
        "6": 7
    }

Decoding JSON::
    
    >>> import simplejson
    >>> simplejson.loads('["foo", {"bar":["baz", null, 1.0, 2]}]')
    [u'foo', {u'bar': [u'baz', None, 1.0, 2]}]
    >>> simplejson.loads('"\\"foo\\bar"')
    u'"foo\x08ar'
    >>> from StringIO import StringIO
    >>> io = StringIO('["streaming API"]')
    >>> simplejson.load(io)
    [u'streaming API']

Specializing JSON object decoding::

    >>> import simplejson
    >>> def as_complex(dct):
    ...     if '__complex__' in dct:
    ...         return complex(dct['real'], dct['imag'])
    ...     return dct
    ... 
    >>> simplejson.loads('{"__complex__": true, "real": 1, "imag": 2}',
    ...     object_hook=as_complex)
    (1+2j)

Extending JSONEncoder::
    
    >>> import simplejson
    >>> class ComplexEncoder(simplejson.JSONEncoder):
    ...     def default(self, obj):
    ...         if isinstance(obj, complex):
    ...             return [obj.real, obj.imag]
    ...         return simplejson.JSONEncoder.default(self, obj)
    ... 
    >>> dumps(2 + 1j, cls=ComplexEncoder)
    '[2.0, 1.0]'
    >>> ComplexEncoder().encode(2 + 1j)
    '[2.0, 1.0]'
    >>> list(ComplexEncoder().iterencode(2 + 1j))
    ['[', '2.0', ', ', '1.0', ']']
    

Note that the JSON produced by this module's default settings
is a subset of YAML, so it may be used as a serializer for that as well.
"""
__version__ = '1.5'
__all__ = [
    'dump', 'dumps', 'load', 'loads',
    'JSONDecoder', 'JSONEncoder',
]

from django.utils.simplejson.decoder import JSONDecoder
from django.utils.simplejson.encoder import JSONEncoder

def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, **kw):
    """
    Serialize ``obj`` as a JSON formatted stream to ``fp`` (a
    ``.write()``-supporting file-like object).

    If ``skipkeys`` is ``True`` then ``dict`` keys that are not basic types
    (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``) 
    will be skipped instead of raising a ``TypeError``.

    If ``ensure_ascii`` is ``False``, then the some chunks written to ``fp``
    may be ``unicode`` instances, subject to normal Python ``str`` to
    ``unicode`` coercion rules.  Unless ``fp.write()`` explicitly
    understands ``unicode`` (as in ``codecs.getwriter()``) this is likely
    to cause an error.

    If ``check_circular`` is ``False``, then the circular reference check
    for container types will be skipped and a circular reference will
    result in an ``OverflowError`` (or worse).

    If ``allow_nan`` is ``False``, then it will be a ``ValueError`` to
    serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``)
    in strict compliance of the JSON specification, instead of using the
    JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

    If ``indent`` is a non-negative integer, then JSON array elements and object
    members will be pretty-printed with that indent level.  An indent level
    of 0 will only insert newlines.  ``None`` is the most compact representation.

    To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
    ``.default()`` method to serialize additional types), specify it with
    the ``cls`` kwarg.
    """
    if cls is None:
        cls = JSONEncoder
    iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,
        check_circular=check_circular, allow_nan=allow_nan, indent=indent,
        **kw).iterencode(obj)
    # could accelerate with writelines in some versions of Python, at
    # a debuggability cost
    for chunk in iterable:
        fp.write(chunk)

def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, separators=None, **kw):
    """
    Serialize ``obj`` to a JSON formatted ``str``.

    If ``skipkeys`` is ``True`` then ``dict`` keys that are not basic types
    (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``) 
    will be skipped instead of raising a ``TypeError``.

    If ``ensure_ascii`` is ``False``, then the return value will be a
    ``unicode`` instance subject to normal Python ``str`` to ``unicode``
    coercion rules instead of being escaped to an ASCII ``str``.

    If ``check_circular`` is ``False``, then the circular reference check
    for container types will be skipped and a circular reference will
    result in an ``OverflowError`` (or worse).

    If ``allow_nan`` is ``False``, then it will be a ``ValueError`` to
    serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
    strict compliance of the JSON specification, instead of using the
    JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

    If ``indent`` is a non-negative integer, then JSON array elements and
    object members will be pretty-printed with that indent level.  An indent
    level of 0 will only insert newlines.  ``None`` is the most compact
    representation.

    If ``separators`` is an ``(item_separator, dict_separator)`` tuple
    then it will be used instead of the default ``(', ', ': ')`` separators.
    ``(',', ':')`` is the most compact JSON representation.

    To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
    ``.default()`` method to serialize additional types), specify it with
    the ``cls`` kwarg.
    """
    if cls is None:
        cls = JSONEncoder
    return cls(
        skipkeys=skipkeys, ensure_ascii=ensure_ascii,
        check_circular=check_circular, allow_nan=allow_nan, indent=indent,
        separators=separators,
        **kw).encode(obj)

def load(fp, encoding=None, cls=None, object_hook=None, **kw):
    """
    Deserialize ``fp`` (a ``.read()``-supporting file-like object containing
    a JSON document) to a Python object.

    If the contents of ``fp`` is encoded with an ASCII based encoding other
    than utf-8 (e.g. latin-1), then an appropriate ``encoding`` name must
    be specified.  Encodings that are not ASCII based (such as UCS-2) are
    not allowed, and should be wrapped with
    ``codecs.getreader(fp)(encoding)``, or simply decoded to a ``unicode``
    object and passed to ``loads()``

    ``object_hook`` is an optional function that will be called with the
    result of any object literal decode (a ``dict``).  The return value of
    ``object_hook`` will be used instead of the ``dict``.  This feature
    can be used to implement custom decoders (e.g. JSON-RPC class hinting).
    
    To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``
    kwarg.
    """
    if cls is None:
        cls = JSONDecoder
    if object_hook is not None:
        kw['object_hook'] = object_hook
    return cls(encoding=encoding, **kw).decode(fp.read())

def loads(s, encoding=None, cls=None, object_hook=None, **kw):
    """
    Deserialize ``s`` (a ``str`` or ``unicode`` instance containing a JSON
    document) to a Python object.

    If ``s`` is a ``str`` instance and is encoded with an ASCII based encoding
    other than utf-8 (e.g. latin-1) then an appropriate ``encoding`` name
    must be specified.  Encodings that are not ASCII based (such as UCS-2)
    are not allowed and should be decoded to ``unicode`` first.

    ``object_hook`` is an optional function that will be called with the
    result of any object literal decode (a ``dict``).  The return value of
    ``object_hook`` will be used instead of the ``dict``.  This feature
    can be used to implement custom decoders (e.g. JSON-RPC class hinting).

    To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``
    kwarg.
    """
    if cls is None:
        cls = JSONDecoder
    if object_hook is not None:
        kw['object_hook'] = object_hook
    return cls(encoding=encoding, **kw).decode(s)

def read(s):
    """
    json-py API compatibility hook.  Use loads(s) instead.
    """
    import warnings
    warnings.warn("simplejson.loads(s) should be used instead of read(s)",
        DeprecationWarning)
    return loads(s)

def write(obj):
    """
    json-py API compatibility hook.  Use dumps(s) instead.
    """
    import warnings
    warnings.warn("simplejson.dumps(s) should be used instead of write(s)",
        DeprecationWarning)
    return dumps(obj)