app/django/utils/simplejson/__init__.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sat, 22 Nov 2008 13:59:34 +0000
changeset 553 c0cc20b4afc9
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Make redirect generic using the new Lists object This makes it possible (and easier) to have the list view redirect to any page specially tailored to the current item. Patch by: Sverre Rabbelier

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)
    >>> import decimal
    >>> simplejson.loads('1.1', parse_float=decimal.Decimal)
    Decimal("1.1")

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', ']']
    

Using simplejson from the shell to validate and
pretty-print::
    
    $ echo '{"json":"obj"}' | python -msimplejson.tool
    {
        "json": "obj"
    }
    $ echo '{ 1.2:3.4}' | python -msimplejson.tool
    Expecting property name: line 1 column 2 (char 2)

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__ = '1.9.2'
__all__ = [
    'dump', 'dumps', 'load', 'loads',
    'JSONDecoder', 'JSONEncoder',
]

if __name__ == '__main__':
    import warnings
    warnings.warn('python -msimplejson is deprecated, use python -msiplejson.tool', DeprecationWarning)
    from django.utils.simplejson.decoder import JSONDecoder
    from django.utils.simplejson.encoder import JSONEncoder
else:
    from decoder import JSONDecoder
    from encoder import JSONEncoder

_default_encoder = JSONEncoder(
    skipkeys=False,
    ensure_ascii=True,
    check_circular=True,
    allow_nan=True,
    indent=None,
    separators=None,
    encoding='utf-8',
    default=None,
)

def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, separators=None,
        encoding='utf-8', default=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.

    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.

    ``encoding`` is the character encoding for str instances, default is UTF-8.

    ``default(obj)`` is a function that should return a serializable version
    of obj or raise TypeError. The default simply raises TypeError.

    To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
    ``.default()`` method to serialize additional types), specify it with
    the ``cls`` kwarg.
    """
    # cached encoder
    if (skipkeys is False and ensure_ascii is True and
        check_circular is True and allow_nan is True and
        cls is None and indent is None and separators is None and
        encoding == 'utf-8' and default is None and not kw):
        iterable = _default_encoder.iterencode(obj)
    else:
        if cls is None:
            cls = JSONEncoder
        iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,
            check_circular=check_circular, allow_nan=allow_nan, indent=indent,
            separators=separators, encoding=encoding,
            default=default, **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,
        encoding='utf-8', default=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.

    ``encoding`` is the character encoding for str instances, default is UTF-8.

    ``default(obj)`` is a function that should return a serializable version
    of obj or raise TypeError. The default simply raises TypeError.

    To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
    ``.default()`` method to serialize additional types), specify it with
    the ``cls`` kwarg.
    """
    # cached encoder
    if (skipkeys is False and ensure_ascii is True and
        check_circular is True and allow_nan is True and
        cls is None and indent is None and separators is None and
        encoding == 'utf-8' and default is None and not kw):
        return _default_encoder.encode(obj)
    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, encoding=encoding, default=default,
        **kw).encode(obj)


_default_decoder = JSONDecoder(encoding=None, object_hook=None)


def load(fp, encoding=None, cls=None, object_hook=None, parse_float=None,
        parse_int=None, parse_constant=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.
    """
    return loads(fp.read(),
        encoding=encoding, cls=cls, object_hook=object_hook,
        parse_float=parse_float, parse_int=parse_int,
        parse_constant=parse_constant, **kw)


def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None,
        parse_int=None, parse_constant=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).

    ``parse_float``, if specified, will be called with the string
    of every JSON float to be decoded. By default this is equivalent to
    float(num_str). This can be used to use another datatype or parser
    for JSON floats (e.g. decimal.Decimal).

    ``parse_int``, if specified, will be called with the string
    of every JSON int to be decoded. By default this is equivalent to
    int(num_str). This can be used to use another datatype or parser
    for JSON integers (e.g. float).

    ``parse_constant``, if specified, will be called with one of the
    following strings: -Infinity, Infinity, NaN, null, true, false.
    This can be used to raise an exception if invalid JSON numbers
    are encountered.

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


#
# Compatibility cruft from other libraries
#


def decode(s):
    """
    demjson, python-cjson API compatibility hook. Use loads(s) instead.
    """
    import warnings
    warnings.warn("simplejson.loads(s) should be used instead of decode(s)",
        DeprecationWarning)
    return loads(s)


def encode(obj):
    """
    demjson, python-cjson compatibility hook. Use dumps(s) instead.
    """
    import warnings
    warnings.warn("simplejson.dumps(s) should be used instead of encode(s)",
        DeprecationWarning)
    return dumps(obj)


def read(s):
    """
    jsonlib, JsonUtils, python-json, 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):
    """
    jsonlib, JsonUtils, python-json, 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)


if __name__ == '__main__':
    import simplejson.tool
    simplejson.tool.main()