92 lines
3.0 KiB
Python
92 lines
3.0 KiB
Python
"""
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PRIVATE MODULE: do not import (from) it directly.
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This module contains functionality for supporting the compatibility of jsons
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with multiple Python versions.
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"""
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import sys
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import typing
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from enum import Enum
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from jsons._cache import cached
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class Flag(Enum):
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"""
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This is a light version of the Flag enum type that was introduced in
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Python3.6. It supports the use of pipes for members (Flag.A | Flag.B).
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"""
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@classmethod
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def _get_inst(cls, value):
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try:
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result = cls(value)
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except ValueError:
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pseudo_member = object.__new__(cls)
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pseudo_member._value_ = value
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contained = [elem.name for elem in cls if elem in pseudo_member]
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pseudo_member._name_ = '|'.join(contained)
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result = pseudo_member
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return result
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def __or__(self, other: 'Flag') -> 'Flag':
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new_value = other.value | self.value
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return self._get_inst(new_value)
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def __contains__(self, item: 'Flag') -> bool:
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return item.value == self.value & item.value
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__ror__ = __or__
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@cached
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def tuple_with_ellipsis(tup: type) -> bool:
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# Python3.5: Tuples have __tuple_use_ellipsis__
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# Python3.7: Tuples have __args__
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use_el = getattr(tup, '__tuple_use_ellipsis__', None)
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if use_el is None:
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use_el = tup.__args__[-1] is ...
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return use_el
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@cached
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def get_union_params(un: type) -> list:
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# Python3.5: Unions have __union_params__
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# Python3.7: Unions have __args__
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return getattr(un, '__union_params__', getattr(un, '__args__', None))
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@cached
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def get_naked_class(cls: type) -> type:
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# Python3.5: typing classes have __extra__
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# Python3.6: typing classes have __extra__
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# Python3.7: typing classes have __origin__
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# Return the non-generic class (e.g. dict) of a generic type (e.g. Dict).
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return getattr(cls, '__extra__', getattr(cls, '__origin__', cls))
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@cached
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def get_type_hints(callable_: callable, fallback_ns=None):
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# Python3.5: get_type_hints raises on classes without explicit constructor.
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# Python3.10: get_type_hints on classes does not take the constructor.
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try:
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result = typing.get_type_hints(callable_)
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except AttributeError:
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result = {}
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except NameError:
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# attempt to resolve in global namespace - this works around an
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# issue in 3.7 whereby __init__ created by dataclasses fails
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# to find it's context. See https://bugs.python.org/issue34776
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if fallback_ns is not None:
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context_dict = sys.modules[fallback_ns].__dict__
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result = typing.get_type_hints(callable_, globalns=context_dict)
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if sys.version_info.minor >= 10 and type(callable_) is type:
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annotations_from_init = typing.get_type_hints(callable_.__init__)
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if 'return' in annotations_from_init:
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# Python3.10: 'return' is a key that holds the returning type.
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del annotations_from_init['return']
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result = {**result, **annotations_from_init}
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return result
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