jsons._main_impl._get_cls_and_meta() - Code Metrics - Inspection of "Release/0.8.4" - ramonhagenaars/jsons - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Pull Request — master (#38)

by Ramon

created 2019-04-02 20:24 UTC

jsons._main_impl._get_cls_and_meta() A

↳ Parent: Project

Complexity

Conditions

Size

Total Lines	8
Code Lines	8

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
eloc	8
dl	0
loc	8
rs	10
c	0
b	0
f	0
cc	3
nop	2

"""
PRIVATE MODULE: do not import (from) it directly.

This module contains the implementation of the main functions of jsons, such
as `load` and `dump`.
"""
from __future__ import annotations
import json
from json import JSONDecodeError
from typing import Dict, Callable, Optional, Union, Tuple, Sequence

from jsons._common_impl import (
    get_class_name,
    get_parents,
    StateHolder,
    get_cls_from_str, get_cls_and_meta, determine_precedence
)
from jsons.exceptions import (
    DecodeError,
    DeserializationError,
    JsonsError,
    SerializationError
)

VALID_TYPES = (str, int, float, bool, list, tuple, set, dict, type(None))
RFC3339_DATETIME_PATTERN = '%Y-%m-%dT%H:%M:%S'


def dump(obj: object,
         cls: Optional[type] = None,
         fork_inst: Optional[type] = StateHolder,
         **kwargs) -> object:
    """
    Serialize the given ``obj`` to a JSON equivalent type (e.g. dict, list,
    int, ...).

    The way objects are serialized can be finetuned by setting serializer
    functions for the specific type using ``set_serializer``.

    You can also provide ``cls`` to specify that ``obj`` needs to be serialized
    as if it was of type ``cls`` (meaning to only take into account attributes
    from ``cls``). The type ``cls`` must have a ``__slots__`` defined. Any type
    will do, but in most cases you may want ``cls`` to be a base class of
    ``obj``.
    :param obj: a Python instance of any sort.
    :param cls: if given, ``obj`` will be dumped as if it is of type ``type``.
    :param fork_inst: if given, it uses this fork of ``JsonSerializable``.
    :param kwargs: the keyword args are passed on to the serializer function.
    :return: the serialized obj as a JSON type.
    """
    if cls and not hasattr(cls, '__slots__'):
        raise SerializationError('Invalid type: "{}". Only types that have a '
                                 '__slots__ defined are allowed when '
                                 'providing "cls".'
                         .format(get_class_name(cls, fork_inst=fork_inst,
                                                fully_qualified=True)))
    cls_ = cls or obj.__class__
    serializer = _get_serializer(cls_, fork_inst)
    kwargs_ = {
        'fork_inst': fork_inst,
        **kwargs
    }
    announce_class(cls_, fork_inst=fork_inst)
    try:
        return serializer(obj, cls=cls, **kwargs_)
    except Exception as err:
        raise SerializationError(str(err))


def load(json_obj: object,
         cls: Optional[type] = None,
         strict: bool = False,
         fork_inst: Optional[type] = StateHolder,
         attr_getters: Optional[Dict[str, Callable[[], object]]] = None,
         **kwargs) -> object:
    """
    Deserialize the given ``json_obj`` to an object of type ``cls``. If the
    contents of ``json_obj`` do not match the interface of ``cls``, a
    DeserializationError is raised.

    If ``json_obj`` contains a value that belongs to a custom class, there must
    be a type hint present for that value in ``cls`` to let this function know
    what type it should deserialize that value to.


    **Example**:

    >>> from typing import List
    >>> import jsons
    >>> class Person:
    ...     # No type hint required for name
    ...     def __init__(self, name):
    ...         self.name = name
    >>> class Family:
    ...     # Person is a custom class, use a type hint
    ...         def __init__(self, persons: List[Person]):
    ...             self.persons = persons
    >>> loaded = jsons.load({'persons': [{'name': 'John'}]}, Family)
    >>> loaded.persons[0].name
    'John'

    If no ``cls`` is given, a dict is simply returned, but contained values
    (e.g. serialized ``datetime`` values) are still deserialized.

    If `strict` mode is off and the type of `json_obj` exactly matches `cls`
    then `json_obj` is simply returned.

    :param json_obj: the dict that is to be deserialized.
    :param cls: a matching class of which an instance should be returned.
    :param strict: a bool to determine if the deserializer should be strict
    (i.e. fail on a partially deserialized `json_obj` or on `None`).
    :param fork_inst: if given, it uses this fork of ``JsonSerializable``.
    :param attr_getters: a ``dict`` that may hold callables that return values
    for certain attributes.
    :param kwargs: the keyword args are passed on to the deserializer function.
    :return: an instance of ``cls`` if given, a dict otherwise.
    """
    if _should_skip(json_obj, cls, strict):
        return json_obj
    if isinstance(cls, str):
        cls = get_cls_from_str(cls, json_obj, fork_inst)
    cls, meta_hints = _check_and_get_cls_and_meta_hints(
        json_obj, cls, fork_inst, kwargs.get('_inferred_cls', False))

    deserializer = _get_deserializer(cls, fork_inst)
    kwargs_ = {
        'strict': strict,
        'fork_inst': fork_inst,
        'attr_getters': attr_getters,
        'meta_hints': meta_hints,
        **kwargs
    }
    try:
        return deserializer(json_obj, cls, **kwargs_)
    except Exception as err:
        if isinstance(err, JsonsError):
            raise
        raise DeserializationError(str(err), json_obj, cls)


def _should_skip(json_obj: object, cls: type, strict: bool):
    if not strict and (json_obj is None or type(json_obj) == cls):
        return True


def _get_serializer(cls: type,
                    fork_inst: Optional[type] = StateHolder) -> callable:
    serializer = _get_lizer(cls, fork_inst._serializers,
                            fork_inst._classes_serializers, fork_inst)
    return serializer


def _get_deserializer(cls: type,
                      fork_inst: Optional[type] = StateHolder) -> callable:
    deserializer = _get_lizer(cls, fork_inst._deserializers,
                              fork_inst._classes_deserializers, fork_inst)
    return deserializer


def _get_lizer(cls: type,
               lizers: Dict[str, callable],
               classes_lizers: list,
               fork_inst: type) -> callable:
    cls_name = get_class_name(cls, str.lower, fork_inst=fork_inst,
                              fully_qualified=True)
    lizer = lizers.get(cls_name, None)
    if not lizer:
        parents = get_parents(cls, classes_lizers)
        if parents:
            pname = get_class_name(parents[0], str.lower, fork_inst=fork_inst,
                                   fully_qualified=True)
            lizer = lizers[pname]
    return lizer


def dumps(obj: object,
          jdkwargs: Optional[Dict[str, object]] = None,
          *args,
          **kwargs) -> str:
    """
    Extend ``json.dumps``, allowing any Python instance to be dumped to a
    string. Any extra (keyword) arguments are passed on to ``json.dumps``.

    :param obj: the object that is to be dumped to a string.
    :param jdkwargs: extra keyword arguments for ``json.dumps`` (not
    ``jsons.dumps``!)
    :param args: extra arguments for ``jsons.dumps``.
    :param kwargs: Keyword arguments that are passed on through the
    serialization process.
    passed on to the serializer function.
    :return: ``obj`` as a ``str``.
    """
    jdkwargs = jdkwargs or {}
    dumped = dump(obj, *args, **kwargs)
    return json.dumps(dumped, **jdkwargs)


def loads(str_: str,
          cls: Optional[type] = None,
          jdkwargs: Optional[Dict[str, object]] = None,
          *args,
          **kwargs) -> object:
    """
    Extend ``json.loads``, allowing a string to be loaded into a dict or a
    Python instance of type ``cls``. Any extra (keyword) arguments are passed
    on to ``json.loads``.

    :param str_: the string that is to be loaded.
    :param cls: a matching class of which an instance should be returned.
    :param jdkwargs: extra keyword arguments for ``json.loads`` (not
    ``jsons.loads``!)
    :param args: extra arguments for ``jsons.loads``.
    :param kwargs: extra keyword arguments for ``jsons.loads``.
    :return: a JSON-type object (dict, str, list, etc.) or an instance of type
    ``cls`` if given.
    """
    jdkwargs = jdkwargs or {}
    try:
        obj = json.loads(str_, **jdkwargs)
    except JSONDecodeError as err:
        raise DecodeError('Could not load a dict; the given string is not '
                          'valid JSON.', str_, cls, err)
    else:
        return load(obj, cls, *args, **kwargs)


def dumpb(obj: object,
          encoding: str = 'utf-8',
          jdkwargs: Optional[Dict[str, object]] = None,
          *args,
          **kwargs) -> bytes:
    """
    Extend ``json.dumps``, allowing any Python instance to be dumped to bytes.
    Any extra (keyword) arguments are passed on to ``json.dumps``.

    :param obj: the object that is to be dumped to bytes.
    :param encoding: the encoding that is used to transform to bytes.
    :param jdkwargs: extra keyword arguments for ``json.dumps`` (not
    ``jsons.dumps``!)
    :param args: extra arguments for ``jsons.dumps``.
    :param kwargs: Keyword arguments that are passed on through the
    serialization process.
    passed on to the serializer function.
    :return: ``obj`` as ``bytes``.
    """
    jdkwargs = jdkwargs or {}
    dumped_dict = dump(obj, *args, **kwargs)
    dumped_str = json.dumps(dumped_dict, **jdkwargs)
    return dumped_str.encode(encoding=encoding)


def loadb(bytes_: bytes,
          cls: Optional[type] = None,
          encoding: str = 'utf-8',
          jdkwargs: Optional[Dict[str, object]] = None,
          *args,
          **kwargs) -> object:
    """
    Extend ``json.loads``, allowing bytes to be loaded into a dict or a Python
    instance of type ``cls``. Any extra (keyword) arguments are passed on to
    ``json.loads``.

    :param bytes_: the bytes that are to be loaded.
    :param cls: a matching class of which an instance should be returned.
    :param encoding: the encoding that is used to transform from bytes.
    :param jdkwargs: extra keyword arguments for ``json.loads`` (not
    ``jsons.loads``!)
    :param args: extra arguments for ``jsons.loads``.
    :param kwargs: extra keyword arguments for ``jsons.loads``.
    :return: a JSON-type object (dict, str, list, etc.) or an instance of type
    ``cls`` if given.
    """
    if not isinstance(bytes_, bytes):
        raise DeserializationError('loadb accepts bytes only, "{}" was given'
                                   .format(type(bytes_)), bytes_, cls)
    jdkwargs = jdkwargs or {}
    str_ = bytes_.decode(encoding=encoding)
    return loads(str_, cls, jdkwargs=jdkwargs, *args, **kwargs)


def set_serializer(func: callable,
                   cls: Union[type, Sequence[type]],
                   high_prio: bool = True,
                   fork_inst: type = StateHolder) -> None:
    """
    Set a serializer function for the given type. You may override the default
    behavior of ``jsons.load`` by setting a custom serializer.

    The ``func`` argument must take one argument (i.e. the object that is to be
    serialized) and also a ``kwargs`` parameter. For example:

    >>> def func(obj, **kwargs):
    ...    return dict()

    You may ask additional arguments between ``cls`` and ``kwargs``.

    :param func: the serializer function.
    :param cls: the type or sequence of types this serializer can handle.
    :param high_prio: determines the order in which is looked for the callable.
    :param fork_inst: if given, it uses this fork of ``JsonSerializable``.
    :return: None.
    """
    if isinstance(cls, Sequence):
        for cls_ in cls:
            set_serializer(func, cls_, high_prio, fork_inst)
    elif cls:
        index = 0 if high_prio else len(fork_inst._classes_serializers)
        fork_inst._classes_serializers.insert(index, cls)
        cls_name = get_class_name(cls, fork_inst=fork_inst,
                                  fully_qualified=True)
        fork_inst._serializers[cls_name.lower()] = func
    else:
        fork_inst._serializers['nonetype'] = func


def set_deserializer(func: callable,
                     cls: Union[type, Sequence[type]],
                     high_prio: bool = True,
                     fork_inst: type = StateHolder) -> None:
    """
    Set a deserializer function for the given type. You may override the
    default behavior of ``jsons.dump`` by setting a custom deserializer.

    The ``func`` argument must take two arguments (i.e. the dict containing the
    serialized values and the type that the values should be deserialized into)
    and also a ``kwargs`` parameter. For example:

    >>> def func(dict_, cls, **kwargs):
    ...    return cls()

    You may ask additional arguments between ``cls`` and ``kwargs``.

    :param func: the deserializer function.
    :param cls: the type or sequence of types this serializer can handle.
    :param high_prio: determines the order in which is looked for the callable.
    :param fork_inst: if given, it uses this fork of ``JsonSerializable``.
    :return: None.
    """
    if isinstance(cls, Sequence):
        for cls_ in cls:
            set_deserializer(func, cls_, high_prio, fork_inst)
    elif cls:
        index = 0 if high_prio else len(fork_inst._classes_deserializers)
        fork_inst._classes_deserializers.insert(index, cls)
        cls_name = get_class_name(cls, fork_inst=fork_inst,
                                  fully_qualified=True)
        fork_inst._deserializers[cls_name.lower()] = func
    else:
        fork_inst._deserializers['nonetype'] = func


def suppress_warnings(
        do_suppress: Optional[bool] = True,
        fork_inst: Optional[type] = StateHolder):
    """
    Suppress (or stop suppressing) warnings.
    :param do_suppress: if ``True``, warnings will be suppressed from now on.
    :param fork_inst: if given, it uses this fork of ``JsonSerializable``.
    :return: None.
    """
    fork_inst._suppress_warnings = do_suppress


def announce_class(
        cls: type,
        cls_name: Optional[str] = None,
        fork_inst: type = StateHolder):
    """
    Announce the given cls to jsons to allow jsons to deserialize a verbose
    dump into that class.
    :param cls: the class that is to be announced.
    :param cls_name: a custom name for that class.
    :param fork_inst: if given, it uses this fork of ``JsonSerializable``.
    :return: None.
    """
    cls_name = cls_name or get_class_name(cls, fully_qualified=True,
                                          fork_inst=fork_inst)
    fork_inst._announced_classes[cls] = cls_name
    fork_inst._announced_classes[cls_name] = cls


def _check_and_get_cls_and_meta_hints(
        json_obj: object,
        cls: type,
        fork_inst: type,
        inferred_cls: bool) -> Tuple[type, Optional[dict]]:
    # Check if json_obj is of a valid type and return the cls.
    if type(json_obj) not in VALID_TYPES:
        invalid_type = get_class_name(type(json_obj), fork_inst=fork_inst,
                                      fully_qualified=True)
        valid_types = [get_class_name(typ, fork_inst=fork_inst,
                                      fully_qualified=True)
                       for typ in VALID_TYPES]
        msg = ('Invalid type: "{}", only arguments of the following types are '
               'allowed: {}'.format(invalid_type, ", ".join(valid_types)))
        raise DeserializationError(msg, json_obj, cls)
    if json_obj is None:
        raise DeserializationError('Cannot load None with strict=True',
                                   json_obj, cls)

    cls_from_meta, meta = get_cls_and_meta(json_obj, fork_inst)
    meta_hints = meta.get('classes', {}) if meta else {}
    return determine_precedence(
        cls, cls_from_meta, type(json_obj), inferred_cls), meta_hints


1			"""
2			PRIVATE MODULE: do not import (from) it directly.
3
4			This module contains the implementation of the main functions of jsons, such
5			as `load` and `dump`.
6			"""
7			from __future__ import annotations
8			import json
9			from json import JSONDecodeError
10			from typing import Dict, Callable, Optional, Union, Tuple, Sequence
11
12			from jsons._common_impl import (
13			get_class_name,
14			get_parents,
15			StateHolder,
16			get_cls_from_str, get_cls_and_meta, determine_precedence
17			)
18			from jsons.exceptions import (
19			DecodeError,
20			DeserializationError,
21			JsonsError,
22			SerializationError
23			)
24
25			VALID_TYPES = (str, int, float, bool, list, tuple, set, dict, type(None))
26			RFC3339_DATETIME_PATTERN = '%Y-%m-%dT%H:%M:%S'
27
28
29			def dump(obj: object,
30			cls: Optional[type] = None,
31			fork_inst: Optional[type] = StateHolder,
32			**kwargs) -> object:
33			"""
34			Serialize the given ``obj`` to a JSON equivalent type (e.g. dict, list,
35			int, ...).
36
37			The way objects are serialized can be finetuned by setting serializer
38			functions for the specific type using ``set_serializer``.
39
40			You can also provide ``cls`` to specify that ``obj`` needs to be serialized
41			as if it was of type ``cls`` (meaning to only take into account attributes
42			from ``cls``). The type ``cls`` must have a ``__slots__`` defined. Any type
43			will do, but in most cases you may want ``cls`` to be a base class of
44			``obj``.
45			:param obj: a Python instance of any sort.
46			:param cls: if given, ``obj`` will be dumped as if it is of type ``type``.
47			:param fork_inst: if given, it uses this fork of ``JsonSerializable``.
48			:param kwargs: the keyword args are passed on to the serializer function.
49			:return: the serialized obj as a JSON type.
50			"""
51			if cls and not hasattr(cls, '__slots__'):
52			raise SerializationError('Invalid type: "{}". Only types that have a '
53			'__slots__ defined are allowed when '
54			'providing "cls".'
55			.format(get_class_name(cls, fork_inst=fork_inst,
56			fully_qualified=True)))
57			cls_ = cls or obj.__class__
58			serializer = _get_serializer(cls_, fork_inst)
59			kwargs_ = {
60			'fork_inst': fork_inst,
61			**kwargs
62			}
63			announce_class(cls_, fork_inst=fork_inst)
64			try:
65			return serializer(obj, cls=cls, **kwargs_)
66			except Exception as err:
67			raise SerializationError(str(err))
68
69
70			def load(json_obj: object,
71			cls: Optional[type] = None,
72			strict: bool = False,
73			fork_inst: Optional[type] = StateHolder,
74			attr_getters: Optional[Dict[str, Callable[[], object]]] = None,
75			**kwargs) -> object:
76			"""
77			Deserialize the given ``json_obj`` to an object of type ``cls``. If the
78			contents of ``json_obj`` do not match the interface of ``cls``, a
79			DeserializationError is raised.
80
81			If ``json_obj`` contains a value that belongs to a custom class, there must
82			be a type hint present for that value in ``cls`` to let this function know
83			what type it should deserialize that value to.
84
85
86			Example:
87
88			>>> from typing import List
89			>>> import jsons
90			>>> class Person:
91			... # No type hint required for name
92			... def __init__(self, name):
93			... self.name = name
94			>>> class Family:
95			... # Person is a custom class, use a type hint
96			... def __init__(self, persons: List[Person]):
97			... self.persons = persons
98			>>> loaded = jsons.load({'persons': [{'name': 'John'}]}, Family)
99			>>> loaded.persons[0].name
100			'John'
101
102			If no ``cls`` is given, a dict is simply returned, but contained values
103			(e.g. serialized ``datetime`` values) are still deserialized.
104
105			If `strict` mode is off and the type of `json_obj` exactly matches `cls`
106			then `json_obj` is simply returned.
107
108			:param json_obj: the dict that is to be deserialized.
109			:param cls: a matching class of which an instance should be returned.
110			:param strict: a bool to determine if the deserializer should be strict
111			(i.e. fail on a partially deserialized `json_obj` or on `None`).
112			:param fork_inst: if given, it uses this fork of ``JsonSerializable``.
113			:param attr_getters: a ``dict`` that may hold callables that return values
114			for certain attributes.
115			:param kwargs: the keyword args are passed on to the deserializer function.
116			:return: an instance of ``cls`` if given, a dict otherwise.
117			"""
118			if _should_skip(json_obj, cls, strict):
119			return json_obj
120			if isinstance(cls, str):
121			cls = get_cls_from_str(cls, json_obj, fork_inst)
122			cls, meta_hints = _check_and_get_cls_and_meta_hints(
123			json_obj, cls, fork_inst, kwargs.get('_inferred_cls', False))
124
125			deserializer = _get_deserializer(cls, fork_inst)
126			kwargs_ = {
127			'strict': strict,
128			'fork_inst': fork_inst,
129			'attr_getters': attr_getters,
130			'meta_hints': meta_hints,
131			**kwargs
132			}
133			try:
134			return deserializer(json_obj, cls, **kwargs_)
135			except Exception as err:
136			if isinstance(err, JsonsError):
137			raise
138			raise DeserializationError(str(err), json_obj, cls)
139
140
141			def _should_skip(json_obj: object, cls: type, strict: bool):
142			if not strict and (json_obj is None or type(json_obj) == cls):
143			return True
144
145
146			def _get_serializer(cls: type,
147			fork_inst: Optional[type] = StateHolder) -> callable:
148			serializer = _get_lizer(cls, fork_inst._serializers,
149			fork_inst._classes_serializers, fork_inst)
150			return serializer
151
152
153			def _get_deserializer(cls: type,
154			fork_inst: Optional[type] = StateHolder) -> callable:
155			deserializer = _get_lizer(cls, fork_inst._deserializers,
156			fork_inst._classes_deserializers, fork_inst)
157			return deserializer
158
159
160			def _get_lizer(cls: type,
161			lizers: Dict[str, callable],
162			classes_lizers: list,
163			fork_inst: type) -> callable:
164			cls_name = get_class_name(cls, str.lower, fork_inst=fork_inst,
165			fully_qualified=True)
166			lizer = lizers.get(cls_name, None)
167			if not lizer:
168			parents = get_parents(cls, classes_lizers)
169			if parents:
170			pname = get_class_name(parents[0], str.lower, fork_inst=fork_inst,
171			fully_qualified=True)
172			lizer = lizers[pname]
173			return lizer
174
175
176			def dumps(obj: object,
177			jdkwargs: Optional[Dict[str, object]] = None,
178			*args,
179			**kwargs) -> str:
180			"""
181			Extend ``json.dumps``, allowing any Python instance to be dumped to a
182			string. Any extra (keyword) arguments are passed on to ``json.dumps``.
183
184			:param obj: the object that is to be dumped to a string.
185			:param jdkwargs: extra keyword arguments for ``json.dumps`` (not
186			``jsons.dumps``!)
187			:param args: extra arguments for ``jsons.dumps``.
188			:param kwargs: Keyword arguments that are passed on through the
189			serialization process.
190			passed on to the serializer function.
191			:return: ``obj`` as a ``str``.
192			"""
193			jdkwargs = jdkwargs or {}
194			dumped = dump(obj, args, *kwargs)
195			return json.dumps(dumped, **jdkwargs)
196
197
198			def loads(str_: str,
199			cls: Optional[type] = None,
200			jdkwargs: Optional[Dict[str, object]] = None,
201			*args,
202			**kwargs) -> object:
203			"""
204			Extend ``json.loads``, allowing a string to be loaded into a dict or a
205			Python instance of type ``cls``. Any extra (keyword) arguments are passed
206			on to ``json.loads``.
207
208			:param str_: the string that is to be loaded.
209			:param cls: a matching class of which an instance should be returned.
210			:param jdkwargs: extra keyword arguments for ``json.loads`` (not
211			``jsons.loads``!)
212			:param args: extra arguments for ``jsons.loads``.
213			:param kwargs: extra keyword arguments for ``jsons.loads``.
214			:return: a JSON-type object (dict, str, list, etc.) or an instance of type
215			``cls`` if given.
216			"""
217			jdkwargs = jdkwargs or {}
218			try:
219			obj = json.loads(str_, **jdkwargs)
220			except JSONDecodeError as err:
221			raise DecodeError('Could not load a dict; the given string is not '
222			'valid JSON.', str_, cls, err)
223			else:
224			return load(obj, cls, args, *kwargs)
225
226
227			def dumpb(obj: object,
228			encoding: str = 'utf-8',
229			jdkwargs: Optional[Dict[str, object]] = None,
230			*args,
231			**kwargs) -> bytes:
232			"""
233			Extend ``json.dumps``, allowing any Python instance to be dumped to bytes.
234			Any extra (keyword) arguments are passed on to ``json.dumps``.
235
236			:param obj: the object that is to be dumped to bytes.
237			:param encoding: the encoding that is used to transform to bytes.
238			:param jdkwargs: extra keyword arguments for ``json.dumps`` (not
239			``jsons.dumps``!)
240			:param args: extra arguments for ``jsons.dumps``.
241			:param kwargs: Keyword arguments that are passed on through the
242			serialization process.
243			passed on to the serializer function.
244			:return: ``obj`` as ``bytes``.
245			"""
246			jdkwargs = jdkwargs or {}
247			dumped_dict = dump(obj, args, *kwargs)
248			dumped_str = json.dumps(dumped_dict, **jdkwargs)
249			return dumped_str.encode(encoding=encoding)
250
251
252			def loadb(bytes_: bytes,
253			cls: Optional[type] = None,
254			encoding: str = 'utf-8',
255			jdkwargs: Optional[Dict[str, object]] = None,
256			*args,
257			**kwargs) -> object:
258			"""
259			Extend ``json.loads``, allowing bytes to be loaded into a dict or a Python
260			instance of type ``cls``. Any extra (keyword) arguments are passed on to
261			``json.loads``.
262
263			:param bytes_: the bytes that are to be loaded.
264			:param cls: a matching class of which an instance should be returned.
265			:param encoding: the encoding that is used to transform from bytes.
266			:param jdkwargs: extra keyword arguments for ``json.loads`` (not
267			``jsons.loads``!)
268			:param args: extra arguments for ``jsons.loads``.
269			:param kwargs: extra keyword arguments for ``jsons.loads``.
270			:return: a JSON-type object (dict, str, list, etc.) or an instance of type
271			``cls`` if given.
272			"""
273			if not isinstance(bytes_, bytes):
274			raise DeserializationError('loadb accepts bytes only, "{}" was given'
275			.format(type(bytes_)), bytes_, cls)
276			jdkwargs = jdkwargs or {}
277			str_ = bytes_.decode(encoding=encoding)
278			return loads(str_, cls, jdkwargs=jdkwargs, args, *kwargs)
279
280
281			def set_serializer(func: callable,
282			cls: Union[type, Sequence[type]],
283			high_prio: bool = True,
284			fork_inst: type = StateHolder) -> None:
285			"""
286			Set a serializer function for the given type. You may override the default
287			behavior of ``jsons.load`` by setting a custom serializer.
288
289			The ``func`` argument must take one argument (i.e. the object that is to be
290			serialized) and also a ``kwargs`` parameter. For example:
291
292			>>> def func(obj, **kwargs):
293			... return dict()
294
295			You may ask additional arguments between ``cls`` and ``kwargs``.
296
297			:param func: the serializer function.
298			:param cls: the type or sequence of types this serializer can handle.
299			:param high_prio: determines the order in which is looked for the callable.
300			:param fork_inst: if given, it uses this fork of ``JsonSerializable``.
301			:return: None.
302			"""
303			if isinstance(cls, Sequence):
304			for cls_ in cls:
305			set_serializer(func, cls_, high_prio, fork_inst)
306			elif cls:
307			index = 0 if high_prio else len(fork_inst._classes_serializers)
308			fork_inst._classes_serializers.insert(index, cls)
309			cls_name = get_class_name(cls, fork_inst=fork_inst,
310			fully_qualified=True)
311			fork_inst._serializers[cls_name.lower()] = func
312			else:
313			fork_inst._serializers['nonetype'] = func
314
315
316			def set_deserializer(func: callable,
317			cls: Union[type, Sequence[type]],
318			high_prio: bool = True,
319			fork_inst: type = StateHolder) -> None:
320			"""
321			Set a deserializer function for the given type. You may override the
322			default behavior of ``jsons.dump`` by setting a custom deserializer.
323
324			The ``func`` argument must take two arguments (i.e. the dict containing the
325			serialized values and the type that the values should be deserialized into)
326			and also a ``kwargs`` parameter. For example:
327
328			>>> def func(dict_, cls, **kwargs):
329			... return cls()
330
331			You may ask additional arguments between ``cls`` and ``kwargs``.
332
333			:param func: the deserializer function.
334			:param cls: the type or sequence of types this serializer can handle.
335			:param high_prio: determines the order in which is looked for the callable.
336			:param fork_inst: if given, it uses this fork of ``JsonSerializable``.
337			:return: None.
338			"""
339			if isinstance(cls, Sequence):
340			for cls_ in cls:
341			set_deserializer(func, cls_, high_prio, fork_inst)
342			elif cls:
343			index = 0 if high_prio else len(fork_inst._classes_deserializers)
344			fork_inst._classes_deserializers.insert(index, cls)
345			cls_name = get_class_name(cls, fork_inst=fork_inst,
346			fully_qualified=True)
347			fork_inst._deserializers[cls_name.lower()] = func
348			else:
349			fork_inst._deserializers['nonetype'] = func
350
351
352			def suppress_warnings(
353			do_suppress: Optional[bool] = True,
354			fork_inst: Optional[type] = StateHolder):
355			"""
356			Suppress (or stop suppressing) warnings.
357			:param do_suppress: if ``True``, warnings will be suppressed from now on.
358			:param fork_inst: if given, it uses this fork of ``JsonSerializable``.
359			:return: None.
360			"""
361			fork_inst._suppress_warnings = do_suppress
362
363
364			def announce_class(
365			cls: type,
366			cls_name: Optional[str] = None,
367			fork_inst: type = StateHolder):
368			"""
369			Announce the given cls to jsons to allow jsons to deserialize a verbose
370			dump into that class.
371			:param cls: the class that is to be announced.
372			:param cls_name: a custom name for that class.
373			:param fork_inst: if given, it uses this fork of ``JsonSerializable``.
374			:return: None.
375			"""
376			cls_name = cls_name or get_class_name(cls, fully_qualified=True,
377			fork_inst=fork_inst)
378			fork_inst._announced_classes[cls] = cls_name
379			fork_inst._announced_classes[cls_name] = cls
380
381
382			def _check_and_get_cls_and_meta_hints(
383			json_obj: object,
384			cls: type,
385			fork_inst: type,
386			inferred_cls: bool) -> Tuple[type, Optional[dict]]:
387			# Check if json_obj is of a valid type and return the cls.
388			if type(json_obj) not in VALID_TYPES:
389			invalid_type = get_class_name(type(json_obj), fork_inst=fork_inst,
390			fully_qualified=True)
391			valid_types = [get_class_name(typ, fork_inst=fork_inst,
392			fully_qualified=True)
393			for typ in VALID_TYPES]
394			msg = ('Invalid type: "{}", only arguments of the following types are '
395			'allowed: {}'.format(invalid_type, ", ".join(valid_types)))
396			raise DeserializationError(msg, json_obj, cls)
397			if json_obj is None:
398			raise DeserializationError('Cannot load None with strict=True',
399			json_obj, cls)
400
401			cls_from_meta, meta = get_cls_and_meta(json_obj, fork_inst)
402			meta_hints = meta.get('classes', {}) if meta else {}
403			return determine_precedence(
404			cls, cls_from_meta, type(json_obj), inferred_cls), meta_hints
405

ramonhagenaars / jsons

Pull Request — master (#38)

jsons._main_impl._get_cls_and_meta() A

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