360 lines
14 KiB
Python
360 lines
14 KiB
Python
r"""JSON (JavaScript Object Notation) <http://json.org> is a subset of
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JavaScript syntax (ECMA-262 3rd edition) used as a lightweight data
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interchange format.
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:mod:`json` exposes an API familiar to users of the standard library
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:mod:`marshal` and :mod:`pickle` modules. It is derived from a
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version of the externally maintained simplejson library.
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Encoding basic Python object hierarchies::
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>>> import json
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>>> json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])
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'["foo", {"bar": ["baz", null, 1.0, 2]}]'
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>>> print(json.dumps("\"foo\bar"))
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"\"foo\bar"
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>>> print(json.dumps('\u1234'))
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"\u1234"
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>>> print(json.dumps('\\'))
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"\\"
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>>> print(json.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True))
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{"a": 0, "b": 0, "c": 0}
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>>> from io import StringIO
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>>> io = StringIO()
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>>> json.dump(['streaming API'], io)
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>>> io.getvalue()
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'["streaming API"]'
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Compact encoding::
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>>> import json
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>>> mydict = {'4': 5, '6': 7}
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>>> json.dumps([1,2,3,mydict], separators=(',', ':'))
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'[1,2,3,{"4":5,"6":7}]'
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Pretty printing::
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>>> import json
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>>> print(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4))
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{
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"4": 5,
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"6": 7
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}
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Decoding JSON::
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>>> import json
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>>> obj = ['foo', {'bar': ['baz', None, 1.0, 2]}]
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>>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]') == obj
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True
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>>> json.loads('"\\"foo\\bar"') == '"foo\x08ar'
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True
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>>> from io import StringIO
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>>> io = StringIO('["streaming API"]')
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>>> json.load(io)[0] == 'streaming API'
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True
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Specializing JSON object decoding::
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>>> import json
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>>> def as_complex(dct):
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... if '__complex__' in dct:
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... return complex(dct['real'], dct['imag'])
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... return dct
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...
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>>> json.loads('{"__complex__": true, "real": 1, "imag": 2}',
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... object_hook=as_complex)
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(1+2j)
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>>> from decimal import Decimal
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>>> json.loads('1.1', parse_float=Decimal) == Decimal('1.1')
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True
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Specializing JSON object encoding::
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>>> import json
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>>> def encode_complex(obj):
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... if isinstance(obj, complex):
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... return [obj.real, obj.imag]
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... raise TypeError(f'Object of type {obj.__class__.__name__} '
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... f'is not JSON serializable')
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...
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>>> json.dumps(2 + 1j, default=encode_complex)
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'[2.0, 1.0]'
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>>> json.JSONEncoder(default=encode_complex).encode(2 + 1j)
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'[2.0, 1.0]'
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>>> ''.join(json.JSONEncoder(default=encode_complex).iterencode(2 + 1j))
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'[2.0, 1.0]'
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Using json.tool from the shell to validate and pretty-print::
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$ echo '{"json":"obj"}' | python -m json.tool
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{
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"json": "obj"
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}
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$ echo '{ 1.2:3.4}' | python -m json.tool
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Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
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"""
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__version__ = '2.0.9'
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__all__ = [
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'dump', 'dumps', 'load', 'loads',
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'JSONDecoder', 'JSONDecodeError', 'JSONEncoder',
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]
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__author__ = 'Bob Ippolito <bob@redivi.com>'
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from .decoder import JSONDecoder, JSONDecodeError
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from .encoder import JSONEncoder
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import codecs
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_default_encoder = JSONEncoder(
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skipkeys=False,
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ensure_ascii=True,
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check_circular=True,
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allow_nan=True,
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indent=None,
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separators=None,
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default=None,
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)
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def dump(obj, fp, *, skipkeys=False, ensure_ascii=True, check_circular=True,
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allow_nan=True, cls=None, indent=None, separators=None,
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default=None, sort_keys=False, **kw):
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"""Serialize ``obj`` as a JSON formatted stream to ``fp`` (a
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``.write()``-supporting file-like object).
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If ``skipkeys`` is true then ``dict`` keys that are not basic types
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(``str``, ``int``, ``float``, ``bool``, ``None``) will be skipped
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instead of raising a ``TypeError``.
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If ``ensure_ascii`` is false, then the strings written to ``fp`` can
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contain non-ASCII characters if they appear in strings contained in
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``obj``. Otherwise, all such characters are escaped in JSON strings.
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If ``check_circular`` is false, then the circular reference check
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for container types will be skipped and a circular reference will
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result in an ``OverflowError`` (or worse).
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If ``allow_nan`` is false, then it will be a ``ValueError`` to
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serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``)
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in strict compliance of the JSON specification, instead of using the
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JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).
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If ``indent`` is a non-negative integer, then JSON array elements and
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object members will be pretty-printed with that indent level. An indent
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level of 0 will only insert newlines. ``None`` is the most compact
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representation.
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If specified, ``separators`` should be an ``(item_separator, key_separator)``
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tuple. The default is ``(', ', ': ')`` if *indent* is ``None`` and
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``(',', ': ')`` otherwise. To get the most compact JSON representation,
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you should specify ``(',', ':')`` to eliminate whitespace.
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``default(obj)`` is a function that should return a serializable version
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of obj or raise TypeError. The default simply raises TypeError.
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If *sort_keys* is true (default: ``False``), then the output of
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dictionaries will be sorted by key.
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To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
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``.default()`` method to serialize additional types), specify it with
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the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
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"""
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# cached encoder
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if (not skipkeys and ensure_ascii and
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check_circular and allow_nan and
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cls is None and indent is None and separators is None and
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default is None and not sort_keys and not kw):
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iterable = _default_encoder.iterencode(obj)
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else:
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if cls is None:
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cls = JSONEncoder
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iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,
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check_circular=check_circular, allow_nan=allow_nan, indent=indent,
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separators=separators,
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default=default, sort_keys=sort_keys, **kw).iterencode(obj)
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# could accelerate with writelines in some versions of Python, at
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# a debuggability cost
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for chunk in iterable:
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fp.write(chunk)
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def dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True,
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allow_nan=True, cls=None, indent=None, separators=None,
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default=None, sort_keys=False, **kw):
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"""Serialize ``obj`` to a JSON formatted ``str``.
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If ``skipkeys`` is true then ``dict`` keys that are not basic types
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(``str``, ``int``, ``float``, ``bool``, ``None``) will be skipped
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instead of raising a ``TypeError``.
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If ``ensure_ascii`` is false, then the return value can contain non-ASCII
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characters if they appear in strings contained in ``obj``. Otherwise, all
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such characters are escaped in JSON strings.
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If ``check_circular`` is false, then the circular reference check
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for container types will be skipped and a circular reference will
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result in an ``OverflowError`` (or worse).
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If ``allow_nan`` is false, then it will be a ``ValueError`` to
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serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
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strict compliance of the JSON specification, instead of using the
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JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).
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If ``indent`` is a non-negative integer, then JSON array elements and
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object members will be pretty-printed with that indent level. An indent
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level of 0 will only insert newlines. ``None`` is the most compact
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representation.
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If specified, ``separators`` should be an ``(item_separator, key_separator)``
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tuple. The default is ``(', ', ': ')`` if *indent* is ``None`` and
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``(',', ': ')`` otherwise. To get the most compact JSON representation,
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you should specify ``(',', ':')`` to eliminate whitespace.
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``default(obj)`` is a function that should return a serializable version
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of obj or raise TypeError. The default simply raises TypeError.
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If *sort_keys* is true (default: ``False``), then the output of
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dictionaries will be sorted by key.
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To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
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``.default()`` method to serialize additional types), specify it with
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the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
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"""
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# cached encoder
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if (not skipkeys and ensure_ascii and
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check_circular and allow_nan and
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cls is None and indent is None and separators is None and
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default is None and not sort_keys and not kw):
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return _default_encoder.encode(obj)
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if cls is None:
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cls = JSONEncoder
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return cls(
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skipkeys=skipkeys, ensure_ascii=ensure_ascii,
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check_circular=check_circular, allow_nan=allow_nan, indent=indent,
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separators=separators, default=default, sort_keys=sort_keys,
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**kw).encode(obj)
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_default_decoder = JSONDecoder(object_hook=None, object_pairs_hook=None)
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def detect_encoding(b):
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bstartswith = b.startswith
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if bstartswith((codecs.BOM_UTF32_BE, codecs.BOM_UTF32_LE)):
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return 'utf-32'
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if bstartswith((codecs.BOM_UTF16_BE, codecs.BOM_UTF16_LE)):
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return 'utf-16'
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if bstartswith(codecs.BOM_UTF8):
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return 'utf-8-sig'
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if len(b) >= 4:
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if not b[0]:
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# 00 00 -- -- - utf-32-be
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# 00 XX -- -- - utf-16-be
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return 'utf-16-be' if b[1] else 'utf-32-be'
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if not b[1]:
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# XX 00 00 00 - utf-32-le
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# XX 00 00 XX - utf-16-le
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# XX 00 XX -- - utf-16-le
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return 'utf-16-le' if b[2] or b[3] else 'utf-32-le'
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elif len(b) == 2:
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if not b[0]:
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# 00 XX - utf-16-be
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return 'utf-16-be'
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if not b[1]:
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# XX 00 - utf-16-le
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return 'utf-16-le'
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# default
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return 'utf-8'
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def load(fp, *, cls=None, object_hook=None, parse_float=None,
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parse_int=None, parse_constant=None, object_pairs_hook=None, **kw):
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"""Deserialize ``fp`` (a ``.read()``-supporting file-like object containing
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a JSON document) to a Python object.
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``object_hook`` is an optional function that will be called with the
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result of any object literal decode (a ``dict``). The return value of
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``object_hook`` will be used instead of the ``dict``. This feature
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can be used to implement custom decoders (e.g. JSON-RPC class hinting).
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``object_pairs_hook`` is an optional function that will be called with the
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result of any object literal decoded with an ordered list of pairs. The
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return value of ``object_pairs_hook`` will be used instead of the ``dict``.
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This feature can be used to implement custom decoders. If ``object_hook``
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is also defined, the ``object_pairs_hook`` takes priority.
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To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``
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kwarg; otherwise ``JSONDecoder`` is used.
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"""
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return loads(fp.read(),
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cls=cls, object_hook=object_hook,
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parse_float=parse_float, parse_int=parse_int,
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parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
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def loads(s, *, cls=None, object_hook=None, parse_float=None,
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parse_int=None, parse_constant=None, object_pairs_hook=None, **kw):
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"""Deserialize ``s`` (a ``str``, ``bytes`` or ``bytearray`` instance
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containing a JSON document) to a Python object.
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``object_hook`` is an optional function that will be called with the
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result of any object literal decode (a ``dict``). The return value of
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``object_hook`` will be used instead of the ``dict``. This feature
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can be used to implement custom decoders (e.g. JSON-RPC class hinting).
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``object_pairs_hook`` is an optional function that will be called with the
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result of any object literal decoded with an ordered list of pairs. The
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return value of ``object_pairs_hook`` will be used instead of the ``dict``.
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This feature can be used to implement custom decoders. If ``object_hook``
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is also defined, the ``object_pairs_hook`` takes priority.
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``parse_float``, if specified, will be called with the string
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of every JSON float to be decoded. By default this is equivalent to
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float(num_str). This can be used to use another datatype or parser
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for JSON floats (e.g. decimal.Decimal).
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``parse_int``, if specified, will be called with the string
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of every JSON int to be decoded. By default this is equivalent to
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int(num_str). This can be used to use another datatype or parser
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for JSON integers (e.g. float).
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``parse_constant``, if specified, will be called with one of the
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following strings: -Infinity, Infinity, NaN.
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This can be used to raise an exception if invalid JSON numbers
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are encountered.
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To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``
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kwarg; otherwise ``JSONDecoder`` is used.
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"""
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if isinstance(s, str):
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if s.startswith('\ufeff'):
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raise JSONDecodeError("Unexpected UTF-8 BOM (decode using utf-8-sig)",
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s, 0)
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else:
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if not isinstance(s, (bytes, bytearray)):
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raise TypeError(f'the JSON object must be str, bytes or bytearray, '
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f'not {s.__class__.__name__}')
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s = s.decode(detect_encoding(s), 'surrogatepass')
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if (cls is None and object_hook is None and
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parse_int is None and parse_float is None and
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parse_constant is None and object_pairs_hook is None and not kw):
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return _default_decoder.decode(s)
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if cls is None:
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cls = JSONDecoder
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if object_hook is not None:
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kw['object_hook'] = object_hook
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if object_pairs_hook is not None:
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kw['object_pairs_hook'] = object_pairs_hook
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if parse_float is not None:
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kw['parse_float'] = parse_float
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if parse_int is not None:
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kw['parse_int'] = parse_int
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if parse_constant is not None:
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kw['parse_constant'] = parse_constant
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return cls(**kw).decode(s)
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