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""" |
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PRIVATE MODULE: do not import (from) it directly. |
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This module contains implementations of common functionality that can be used |
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throughout `jsons`. |
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""" |
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import builtins |
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import warnings |
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from importlib import import_module |
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from typing import Callable, Optional, Tuple |
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from jsons.exceptions import UnknownClassError |
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META_ATTR = '-meta' # The name of the attribute holding meta info. |
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class StateHolder: |
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""" |
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This class holds the registered serializers and deserializers. |
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""" |
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_classes_serializers = list() |
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_classes_deserializers = list() |
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_serializers = dict() |
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_deserializers = dict() |
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_announced_classes = dict() |
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_suppress_warnings = False |
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@classmethod |
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def _warn(cls, msg, *args, **kwargs): |
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if not cls._suppress_warnings: |
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msg_ = ('{} You can suppress warnings like this using ' |
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'jsons.suppress_warnings().'.format(msg)) |
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warnings.warn(msg_, *args, **kwargs) |
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def get_class_name(cls: type, |
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transformer: Optional[Callable[[str], str]] = None, |
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fully_qualified: bool = False, |
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fork_inst: Optional[type] = StateHolder) -> Optional[str]: |
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""" |
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Return the name of a class. |
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:param cls: the class of which the name if to be returned. |
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:param transformer: any string transformer, e.g. ``str.lower``. |
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:param fully_qualified: if ``True`` return the fully qualified name (i.e. |
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complete with module name). |
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:param fork_inst if given, it uses this fork of ``JsonSerializable`` for |
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finding the class name. |
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:return: the name of ``cls``, transformed if a transformer is given. |
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""" |
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if cls in fork_inst._announced_classes: |
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return fork_inst._announced_classes[cls] |
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cls_name = _get_simple_name(cls) |
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transformer = transformer or (lambda x: x) |
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if fully_qualified: |
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module = _get_module(cls) |
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if module: |
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cls_name = '{}.{}'.format(module, cls_name) |
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cls_name = transformer(cls_name) |
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return cls_name |
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def get_cls_from_str(cls_str: str, source: object, fork_inst) -> type: |
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cls = getattr(builtins, cls_str, None) |
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if cls: |
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return cls |
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try: |
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splitted = cls_str.split('.') |
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module_name = '.'.join(splitted[:-1]) |
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cls_name = splitted[-1] |
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cls_module = import_module(module_name) |
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cls = getattr(cls_module, cls_name) |
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except (ImportError, AttributeError, ValueError): |
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cls = _lookup_announced_class(cls_str, source, fork_inst) |
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return cls |
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def determine_precedence( |
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cls: type, |
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cls_from_meta: type, |
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cls_from_type: type, |
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inferred_cls: bool): |
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order = [cls, cls_from_meta, cls_from_type] |
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if inferred_cls: |
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# The type from a verbose dumped object takes precedence over an |
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# inferred type (e.g. T in List[T]). |
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order = [cls_from_meta, cls, cls_from_type] |
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# Now to return the first element in the order that holds a value. |
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for elem in order: |
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if elem: |
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return elem |
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def get_cls_and_meta( |
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json_obj: object, |
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fork_inst: type) -> Tuple[Optional[type], Optional[dict]]: |
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if isinstance(json_obj, dict) and META_ATTR in json_obj: |
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cls_str = json_obj[META_ATTR]['classes']['/'] |
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cls = get_cls_from_str(cls_str, json_obj, fork_inst) |
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return cls, json_obj[META_ATTR] |
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return None, None |
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def get_parents(cls: type, lizers: list) -> list: |
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""" |
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Return a list of serializers or deserializers that can handle a parent |
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of ``cls``. |
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:param cls: the type that |
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:param lizers: a list of serializers or deserializers. |
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:return: a list of serializers or deserializers. |
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""" |
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parents = [] |
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for cls_ in lizers: |
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try: |
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if issubclass(cls, cls_): |
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parents.append(cls_) |
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except TypeError: |
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pass # Some types do not support `issubclass` (e.g. Union). |
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return parents |
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121
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def _lookup_announced_class( |
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cls_str: str, |
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source: object, |
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fork_inst: type) -> type: |
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cls = fork_inst._announced_classes.get(cls_str) |
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if not cls: |
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msg = ('Could not find a suitable type for "{}". Make sure it can be ' |
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'imported or that is has been announced.'.format(cls_str)) |
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raise UnknownClassError(msg, source, cls_str) |
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return cls |
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132
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133
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def _get_simple_name(cls: type) -> str: |
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if cls is None: |
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cls = type(cls) |
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cls_name = getattr(cls, '__name__', None) |
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if not cls_name: |
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cls_name = getattr(cls, '_name', None) |
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if not cls_name: |
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cls_name = repr(cls) |
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cls_name = cls_name.split('[')[0] # Remove generic types. |
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cls_name = cls_name.split('.')[-1] # Remove any . caused by repr. |
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cls_name = cls_name.split(r"'>")[0] # Remove any '>. |
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return cls_name |
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146
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147
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def _get_module(cls: type) -> Optional[str]: |
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builtin_module = str.__class__.__module__ |
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149
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module = cls.__module__ |
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150
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if module and module != builtin_module: |
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return module |
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ramonhagenaars /
jsons
