dualfroz
88a0720c67
BaseDict._get_dict_or_value() recursively unwraps nested benedict values with no cycle detection, so assigning a benedict into its own nested descendant a second time recurses forever and crashes with RecursionError. Track ids of mappings currently being unwrapped and raise a clear ValueError as soon as a self-reference is detected, instead of recursing into unrelated, equally unprotected traversal code until the interpreter stack overflows.
244 lines
8.4 KiB
Python
244 lines
8.4 KiB
Python
from __future__ import annotations
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from collections.abc import (
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ItemsView,
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Iterator,
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KeysView,
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Mapping,
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MutableMapping,
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ValuesView,
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)
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from typing import Any, cast
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from typing_extensions import Self, TypeVar
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from benedict.core.clone import clone as _clone
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_K = TypeVar("_K", default=str)
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_V = TypeVar("_V", default=Any)
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class BaseDict(dict[_K, _V]):
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_dict: dict[_K, _V] | None
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_frozen: bool
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# ids of mappings currently being unwrapped by `_get_dict_or_value`,
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# anywhere on the current call stack (not just in directly nested calls
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# of this method: unwrapping a value can re-enter this method through
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# __init__/__setitem__/_cast). Used to detect self-referential
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# (cyclic) structures and abort unwrapping them instead of recursing
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# forever. fix #592
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_unwrapping_ids: set[int] = set()
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@classmethod
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def _get_dict_or_value(cls, value: Any) -> Any:
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value = value.dict() if isinstance(value, cls) else value
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if isinstance(value, MutableMapping):
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value_id = id(value)
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if value_id in cls._unwrapping_ids:
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# value is already being unwrapped higher up the call stack,
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# ie. it (directly or indirectly) contains itself. Raise
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# immediately instead of unwrapping it again, to unwind the
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# whole unwrap/cast chain before the still-cyclic structure
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# can reach unrelated code with no cycle protection of its
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# own (eg. keypath separator validation), which would also
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# recurse infinitely but with an uncontrolled RecursionError.
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raise ValueError(
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"Cannot assign a dict that contains itself "
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"(directly or indirectly): self-referential "
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"(cyclic) structures are not supported."
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)
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cls._unwrapping_ids.add(value_id)
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try:
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for key in value.keys():
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key_val = value[key]
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if isinstance(key_val, cls):
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key_val = cls._get_dict_or_value(value[key])
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value[key] = key_val
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finally:
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cls._unwrapping_ids.discard(value_id)
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return value
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def __new__(cls, *args: Any, **kwargs: Any) -> Self:
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obj = super().__new__(cls)
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# bypass subclass __setattr__ (e.g. KeyattrDict) which may access _dict before it exists
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object.__setattr__(obj, "_dict", None)
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object.__setattr__(obj, "_frozen", False)
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return obj
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def __init__(self, *args: Any, **kwargs: Any) -> None:
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if len(args) == 1 and isinstance(args[0], Mapping):
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# bypass subclass __setattr__ (e.g. KeyattrDict) which may treat _dict as a key
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d = self._get_dict_or_value(args[0])
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object.__setattr__(self, "_dict", d)
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super().__init__(d)
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return
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super().__init__(*args, **kwargs)
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def __bool__(self) -> bool:
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if self._dict is not None:
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return bool(self._dict)
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return len(self.keys()) > 0
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def __contains__(self, o: object) -> bool:
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if self._dict is not None:
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return o in self._dict
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return super().__contains__(o)
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def __deepcopy__(self, memo: dict[int, Any]) -> Self:
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obj = self.__class__()
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for key, value in self.items():
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obj[key] = _clone(value, memo=memo)
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if self._frozen:
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obj.freeze()
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return obj
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def __delitem__(self, key: _K) -> None:
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self._check_frozen()
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if self._dict is not None:
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del self._dict[key]
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return
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super().__delitem__(key)
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def __eq__(self, other: object) -> bool:
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if self._dict is not None:
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return self._dict == other
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return super().__eq__(other)
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def __getitem__(self, key: _K) -> _V:
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if self._dict is not None:
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return self._dict[key]
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return super().__getitem__(key)
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def __ior__(self, other: Any) -> Self: # type: ignore[misc,override]
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self._check_frozen()
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if self._dict is not None:
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return cast("Self", self._dict.__ior__(other))
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return super().__ior__(other)
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def __iter__(self) -> Iterator[_K]:
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if self._dict is not None:
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return iter(self._dict)
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return super().__iter__()
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def __len__(self) -> int:
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if self._dict is not None:
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return len(self._dict)
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return super().__len__()
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def __or__(self, other: dict[_K, _V]) -> Self: # type: ignore[override]
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if self._dict is not None:
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return cast("Self", self._dict.__or__(other))
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return cast("Self", super().__or__(other))
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def __repr__(self) -> str:
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if self._dict is not None:
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return repr(self._dict)
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return super().__repr__()
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def __setitem__(self, key: _K, value: _V) -> None:
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self._check_frozen()
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value = self._get_dict_or_value(value)
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if self._dict is not None:
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is_dict_item = key in self._dict and isinstance(self._dict[key], dict)
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is_dict_value = isinstance(value, dict)
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if is_dict_item and is_dict_value:
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if self._dict[key] is value:
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# prevent clearing dict instance when assigning value to itself. fix #294
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return
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self._dict[key].clear() # type: ignore[attr-defined]
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self._dict[key].update(value) # type: ignore[attr-defined]
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return
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self._dict[key] = value
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return
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super().__setitem__(key, value)
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def __setstate__(self, state: Mapping[str, Any]) -> None:
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object.__setattr__(self, "_dict", state.get("_dict", None))
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object.__setattr__(self, "_frozen", state.get("_frozen", False))
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def __str__(self) -> str:
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if self._dict is not None:
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return str(self._dict)
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return super().__str__()
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def _check_frozen(self) -> None:
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if self._frozen:
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raise TypeError(
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f"{self.__class__.__name__!r} object is frozen and cannot be modified."
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)
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@property
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def frozen(self) -> bool:
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return self._frozen
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def freeze(self) -> Self:
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object.__setattr__(self, "_frozen", True)
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return self
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def unfreeze(self) -> Self:
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object.__setattr__(self, "_frozen", False)
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return self
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def clear(self) -> None:
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self._check_frozen()
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if self._dict is not None:
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self._dict.clear()
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return
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super().clear()
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def copy(self) -> Self:
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obj = self.__class__()
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for key, value in self.items():
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obj[key] = value
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if self._frozen:
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obj.freeze()
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return obj
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def dict(self) -> Self:
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if self._dict is not None:
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return cast("Self", self._dict)
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return self
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def get(self, key: _K, default: _V | None = None) -> _V | None: # type: ignore[override]
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if self._dict is not None:
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return self._dict.get(key, default)
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return super().get(key, default)
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def items(self) -> ItemsView[_K, _V]: # type: ignore[override]
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if self._dict is not None:
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return self._dict.items()
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return super().items()
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def keys(self) -> KeysView[_K]: # type: ignore[override]
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if self._dict is not None:
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return self._dict.keys()
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return super().keys()
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def pop(self, key: _K, *args: Any) -> _V:
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self._check_frozen()
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if self._dict is not None:
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return self._dict.pop(key, *args) # type: ignore[no-any-return]
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return super().pop(key, *args) # type: ignore[no-any-return]
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def setdefault(self, key: _K, default: _V | None = None) -> _V:
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self._check_frozen()
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default = self._get_dict_or_value(default)
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assert default is not None
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if self._dict is not None:
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return self._dict.setdefault(key, default)
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return super().setdefault(key, default)
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def update(self, other: Any) -> None:
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self._check_frozen()
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other = self._get_dict_or_value(other)
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if self._dict is not None:
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self._dict.update(other)
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return
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super().update(other)
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def values(self) -> ValuesView[_V]: # type: ignore[override]
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if self._dict is not None:
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return self._dict.values()
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return super().values()
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