| Current Path : /usr/lib64/python2.6/json/ |
| Current File : //usr/lib64/python2.6/json/__init__.py |
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.
json exposes an API familiar to uses of the standard library
marshal and pickle modules.
Encoding basic Python object hierarchies::
>>> import json
>>> json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])
'["foo", {"bar": ["baz", null, 1.0, 2]}]'
>>> print json.dumps("\"foo\bar")
"\"foo\bar"
>>> print json.dumps(u'\u1234')
"\u1234"
>>> print json.dumps('\\')
"\\"
>>> print json.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True)
{"a": 0, "b": 0, "c": 0}
>>> from StringIO import StringIO
>>> io = StringIO()
>>> json.dump(['streaming API'], io)
>>> io.getvalue()
'["streaming API"]'
Compact encoding::
>>> import json
>>> json.dumps([1,2,3,{'4': 5, '6': 7}], sort_keys=True, separators=(',',':'))
'[1,2,3,{"4":5,"6":7}]'
Pretty printing (using repr() because of extraneous whitespace in the output)::
>>> import json
>>> print repr(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4))
'{\n "4": 5, \n "6": 7\n}'
Decoding JSON::
>>> import json
>>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]')
[u'foo', {u'bar': [u'baz', None, 1.0, 2]}]
>>> json.loads('"\\"foo\\bar"')
u'"foo\x08ar'
>>> from StringIO import StringIO
>>> io = StringIO('["streaming API"]')
>>> json.load(io)
[u'streaming API']
Specializing JSON object decoding::
>>> import json
>>> def as_complex(dct):
... if '__complex__' in dct:
... return complex(dct['real'], dct['imag'])
... return dct
...
>>> json.loads('{"__complex__": true, "real": 1, "imag": 2}',
... object_hook=as_complex)
(1+2j)
>>> import decimal
>>> json.loads('1.1', parse_float=decimal.Decimal)
Decimal('1.1')
Extending JSONEncoder::
>>> import json
>>> class ComplexEncoder(json.JSONEncoder):
... def default(self, obj):
... if isinstance(obj, complex):
... return [obj.real, obj.imag]
... return json.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 json.tool from the shell to validate and
pretty-print::
$ echo '{"json":"obj"}' | python -mjson.tool
{
"json": "obj"
}
$ echo '{ 1.2:3.4}' | python -mjson.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'
__all__ = [
'dump', 'dumps', 'load', 'loads',
'JSONDecoder', 'JSONEncoder',
]
__author__ = 'Bob Ippolito <bob@redivi.com>'
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)
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