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

     2 

     3 JSON (JavaScript Object Notation) <http://json.org> is a subset of

     4 JavaScript syntax (ECMA-262 3rd edition) used as a lightweight data

     5 interchange format.

     6 

     7 json exposes an API familiar to uses of the standard library

     8 marshal and pickle modules.

     9 

    10 Encoding basic Python object hierarchies::

    11 

    12     >>> import json

    13     >>> json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])

    14     '["foo", {"bar": ["baz", null, 1.0, 2]}]'

    15     >>> print json.dumps("\"foo\bar")

    16     "\"foo\bar"

    17     >>> print json.dumps(u'\u1234')

    18     "\u1234"

    19     >>> print json.dumps('\\')

    20     "\\"

    21     >>> print json.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True)

    22     {"a": 0, "b": 0, "c": 0}

    23     >>> from StringIO import StringIO

    24     >>> io = StringIO()

    25     >>> json.dump(['streaming API'], io)

    26     >>> io.getvalue()

    27     '["streaming API"]'

    28 

    29 Compact encoding::

    30 

    31     >>> import json

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

    33     '[1,2,3,{"4":5,"6":7}]'

    34 

    35 Pretty printing (using repr() because of extraneous whitespace in the output)::

    36 

    37     >>> import json

    38     >>> print repr(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4))

    39     '{\n    "4": 5, \n    "6": 7\n}'

    40 

    41 Decoding JSON::

    42 

    43     >>> import json

    44     >>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]')

    45     [u'foo', {u'bar': [u'baz', None, 1.0, 2]}]

    46     >>> json.loads('"\\"foo\\bar"')

    47     u'"foo\x08ar'

    48     >>> from StringIO import StringIO

    49     >>> io = StringIO('["streaming API"]')

    50     >>> json.load(io)

    51     [u'streaming API']

    52 

    53 Specializing JSON object decoding::

    54 

    55     >>> import json

    56     >>> def as_complex(dct):

    57     ...     if '__complex__' in dct:

    58     ...         return complex(dct['real'], dct['imag'])

    59     ...     return dct

    60     ...

    61     >>> json.loads('{"__complex__": true, "real": 1, "imag": 2}',

    62     ...     object_hook=as_complex)

    63     (1+2j)

    64     >>> import decimal

    65     >>> json.loads('1.1', parse_float=decimal.Decimal)

    66     Decimal('1.1')

    67 

    68 Extending JSONEncoder::

    69 

    70     >>> import json

    71     >>> class ComplexEncoder(json.JSONEncoder):

    72     ...     def default(self, obj):

    73     ...         if isinstance(obj, complex):

    74     ...             return [obj.real, obj.imag]

    75     ...         return json.JSONEncoder.default(self, obj)

    76     ...

    77     >>> dumps(2 + 1j, cls=ComplexEncoder)

    78     '[2.0, 1.0]'

    79     >>> ComplexEncoder().encode(2 + 1j)

    80     '[2.0, 1.0]'

    81     >>> list(ComplexEncoder().iterencode(2 + 1j))

    82     ['[', '2.0', ', ', '1.0', ']']

    83 

    84 

    85 Using json.tool from the shell to validate and

    86 pretty-print::

    87 

    88     $ echo '{"json":"obj"}' | python -mjson.tool

    89     {

    90         "json": "obj"

    91     }

    92     $ echo '{ 1.2:3.4}' | python -mjson.tool

    93     Expecting property name: line 1 column 2 (char 2)

    94 

    95 Note that the JSON produced by this module's default settings

    96 is a subset of YAML, so it may be used as a serializer for that as well.

    97 

    98 """

    99 

   100 __version__ = '1.9'

   101 __all__ = [

   102     'dump', 'dumps', 'load', 'loads',

   103     'JSONDecoder', 'JSONEncoder',

   104 ]

   105 

   106 __author__ = 'Bob Ippolito <bob@redivi.com>'

   107 

   108 from .decoder import JSONDecoder

   109 from .encoder import JSONEncoder

   110 

   111 _default_encoder = JSONEncoder(

   112     skipkeys=False,

   113     ensure_ascii=True,

   114     check_circular=True,

   115     allow_nan=True,

   116     indent=None,

   117     separators=None,

   118     encoding='utf-8',

   119     default=None,

   120 )

   121 

   122 def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,

   123         allow_nan=True, cls=None, indent=None, separators=None,

   124         encoding='utf-8', default=None, **kw):

   125     """Serialize ``obj`` as a JSON formatted stream to ``fp`` (a

   126     ``.write()``-supporting file-like object).

   127 

   128     If ``skipkeys`` is ``True`` then ``dict`` keys that are not basic types

   129     (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``)

   130     will be skipped instead of raising a ``TypeError``.

   131 

   132     If ``ensure_ascii`` is ``False``, then the some chunks written to ``fp``

   133     may be ``unicode`` instances, subject to normal Python ``str`` to

   134     ``unicode`` coercion rules. Unless ``fp.write()`` explicitly

   135     understands ``unicode`` (as in ``codecs.getwriter()``) this is likely

   136     to cause an error.

   137 

   138     If ``check_circular`` is ``False``, then the circular reference check

   139     for container types will be skipped and a circular reference will

   140     result in an ``OverflowError`` (or worse).

   141 

   142     If ``allow_nan`` is ``False``, then it will be a ``ValueError`` to

   143     serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``)

   144     in strict compliance of the JSON specification, instead of using the

   145     JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

   146 

   147     If ``indent`` is a non-negative integer, then JSON array elements and object

   148     members will be pretty-printed with that indent level. An indent level

   149     of 0 will only insert newlines. ``None`` is the most compact representation.

   150 

   151     If ``separators`` is an ``(item_separator, dict_separator)`` tuple

   152     then it will be used instead of the default ``(', ', ': ')`` separators.

   153     ``(',', ':')`` is the most compact JSON representation.

   154 

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

   156 

   157     ``default(obj)`` is a function that should return a serializable version

   158     of obj or raise TypeError. The default simply raises TypeError.

   159 

   160     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the

   161     ``.default()`` method to serialize additional types), specify it with

   162     the ``cls`` kwarg.

   163 

   164     """

   165     # cached encoder

   166     if (skipkeys is False and ensure_ascii is True and

   167         check_circular is True and allow_nan is True and

   168         cls is None and indent is None and separators is None and

   169         encoding == 'utf-8' and default is None and not kw):

   170         iterable = _default_encoder.iterencode(obj)

   171     else:

   172         if cls is None:

   173             cls = JSONEncoder

   174         iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,

   175             check_circular=check_circular, allow_nan=allow_nan, indent=indent,

   176             separators=separators, encoding=encoding,

   177             default=default, **kw).iterencode(obj)

   178     # could accelerate with writelines in some versions of Python, at

   179     # a debuggability cost

   180     for chunk in iterable:

   181         fp.write(chunk)

   182 

   183 

   184 def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,

   185         allow_nan=True, cls=None, indent=None, separators=None,

   186         encoding='utf-8', default=None, **kw):

   187     """Serialize ``obj`` to a JSON formatted ``str``.

   188 

   189     If ``skipkeys`` is ``True`` then ``dict`` keys that are not basic types

   190     (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``)

   191     will be skipped instead of raising a ``TypeError``.

   192 

   193     If ``ensure_ascii`` is ``False``, then the return value will be a

   194     ``unicode`` instance subject to normal Python ``str`` to ``unicode``

   195     coercion rules instead of being escaped to an ASCII ``str``.

   196 

   197     If ``check_circular`` is ``False``, then the circular reference check

   198     for container types will be skipped and a circular reference will

   199     result in an ``OverflowError`` (or worse).

   200 

   201     If ``allow_nan`` is ``False``, then it will be a ``ValueError`` to

   202     serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in

   203     strict compliance of the JSON specification, instead of using the

   204     JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

   205 

   206     If ``indent`` is a non-negative integer, then JSON array elements and

   207     object members will be pretty-printed with that indent level. An indent

   208     level of 0 will only insert newlines. ``None`` is the most compact

   209     representation.

   210 

   211     If ``separators`` is an ``(item_separator, dict_separator)`` tuple

   212     then it will be used instead of the default ``(', ', ': ')`` separators.

   213     ``(',', ':')`` is the most compact JSON representation.

   214 

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

   216 

   217     ``default(obj)`` is a function that should return a serializable version

   218     of obj or raise TypeError. The default simply raises TypeError.

   219 

   220     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the

   221     ``.default()`` method to serialize additional types), specify it with

   222     the ``cls`` kwarg.

   223 

   224     """

   225     # cached encoder

   226     if (skipkeys is False and ensure_ascii is True and

   227         check_circular is True and allow_nan is True and

   228         cls is None and indent is None and separators is None and

   229         encoding == 'utf-8' and default is None and not kw):

   230         return _default_encoder.encode(obj)

   231     if cls is None:

   232         cls = JSONEncoder

   233     return cls(

   234         skipkeys=skipkeys, ensure_ascii=ensure_ascii,

   235         check_circular=check_circular, allow_nan=allow_nan, indent=indent,

   236         separators=separators, encoding=encoding, default=default,

   237         **kw).encode(obj)

   238 

   239 

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

   241 

   242 

   243 def load(fp, encoding=None, cls=None, object_hook=None, parse_float=None,

   244         parse_int=None, parse_constant=None, **kw):

   245     """Deserialize ``fp`` (a ``.read()``-supporting file-like object

   246     containing a JSON document) to a Python object.

   247 

   248     If the contents of ``fp`` is encoded with an ASCII based encoding other

   249     than utf-8 (e.g. latin-1), then an appropriate ``encoding`` name must

   250     be specified. Encodings that are not ASCII based (such as UCS-2) are

   251     not allowed, and should be wrapped with

   252     ``codecs.getreader(fp)(encoding)``, or simply decoded to a ``unicode``

   253     object and passed to ``loads()``

   254 

   255     ``object_hook`` is an optional function that will be called with the

   256     result of any object literal decode (a ``dict``). The return value of

   257     ``object_hook`` will be used instead of the ``dict``. This feature

   258     can be used to implement custom decoders (e.g. JSON-RPC class hinting).

   259 

   260     To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``

   261     kwarg.

   262 

   263     """

   264     return loads(fp.read(),

   265         encoding=encoding, cls=cls, object_hook=object_hook,

   266         parse_float=parse_float, parse_int=parse_int,

   267         parse_constant=parse_constant, **kw)

   268 

   269 

   270 def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None,

   271         parse_int=None, parse_constant=None, **kw):

   272     """Deserialize ``s`` (a ``str`` or ``unicode`` instance containing a JSON

   273     document) to a Python object.

   274 

   275     If ``s`` is a ``str`` instance and is encoded with an ASCII based encoding

   276     other than utf-8 (e.g. latin-1) then an appropriate ``encoding`` name

   277     must be specified. Encodings that are not ASCII based (such as UCS-2)

   278     are not allowed and should be decoded to ``unicode`` first.

   279 

   280     ``object_hook`` is an optional function that will be called with the

   281     result of any object literal decode (a ``dict``). The return value of

   282     ``object_hook`` will be used instead of the ``dict``. This feature

   283     can be used to implement custom decoders (e.g. JSON-RPC class hinting).

   284 

   285     ``parse_float``, if specified, will be called with the string

   286     of every JSON float to be decoded. By default this is equivalent to

   287     float(num_str). This can be used to use another datatype or parser

   288     for JSON floats (e.g. decimal.Decimal).

   289 

   290     ``parse_int``, if specified, will be called with the string

   291     of every JSON int to be decoded. By default this is equivalent to

   292     int(num_str). This can be used to use another datatype or parser

   293     for JSON integers (e.g. float).

   294 

   295     ``parse_constant``, if specified, will be called with one of the

   296     following strings: -Infinity, Infinity, NaN, null, true, false.

   297     This can be used to raise an exception if invalid JSON numbers

   298     are encountered.

   299 

   300     To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``

   301     kwarg.

   302 

   303     """

   304     if (cls is None and encoding is None and object_hook is None and

   305             parse_int is None and parse_float is None and

   306             parse_constant is None and not kw):

   307         return _default_decoder.decode(s)

   308     if cls is None:

   309         cls = JSONDecoder

   310     if object_hook is not None:

   311         kw['object_hook'] = object_hook

   312     if parse_float is not None:

   313         kw['parse_float'] = parse_float

   314     if parse_int is not None:

   315         kw['parse_int'] = parse_int

   316     if parse_constant is not None:

   317         kw['parse_constant'] = parse_constant

   318     return cls(encoding=encoding, **kw).decode(s)