186 lines
6.6 KiB
Python
186 lines
6.6 KiB
Python
from __future__ import annotations
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from collections.abc import Sequence
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from functools import partial
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from inspect import getmro, isclass
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from typing import Any, Callable, Generic, Tuple, Type, TypeVar, Union, cast
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T = TypeVar("T", bound="BaseExceptionGroup")
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EBase = TypeVar("EBase", bound=BaseException)
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E = TypeVar("E", bound=Exception)
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_SplitCondition = Union[
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Type[EBase],
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Tuple[Type[EBase], ...],
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Callable[[EBase], bool],
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]
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def check_direct_subclass(
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exc: BaseException, parents: tuple[type[BaseException]]
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) -> bool:
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for cls in getmro(exc.__class__)[:-1]:
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if cls in parents:
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return True
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return False
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def get_condition_filter(condition: _SplitCondition) -> Callable[[BaseException], bool]:
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if isclass(condition) and issubclass(
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cast(Type[BaseException], condition), BaseException
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):
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return partial(check_direct_subclass, parents=(condition,))
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elif isinstance(condition, tuple):
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if all(isclass(x) and issubclass(x, BaseException) for x in condition):
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return partial(check_direct_subclass, parents=condition)
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elif callable(condition):
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return cast(Callable[[BaseException], bool], condition)
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raise TypeError("expected a function, exception type or tuple of exception types")
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class BaseExceptionGroup(BaseException, Generic[EBase]):
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"""A combination of multiple unrelated exceptions."""
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def __new__(
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cls, __message: str, __exceptions: Sequence[EBase]
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) -> BaseExceptionGroup[EBase] | ExceptionGroup[E]:
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if not isinstance(__message, str):
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raise TypeError(f"argument 1 must be str, not {type(__message)}")
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if not isinstance(__exceptions, Sequence):
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raise TypeError("second argument (exceptions) must be a sequence")
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if not __exceptions:
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raise ValueError(
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"second argument (exceptions) must be a non-empty sequence"
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)
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for i, exc in enumerate(__exceptions):
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if not isinstance(exc, BaseException):
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raise ValueError(
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f"Item {i} of second argument (exceptions) is not an " f"exception"
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)
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if cls is BaseExceptionGroup:
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if all(isinstance(exc, Exception) for exc in __exceptions):
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cls = ExceptionGroup
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return super().__new__(cls, __message, __exceptions)
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def __init__(self, __message: str, __exceptions: Sequence[EBase], *args: Any):
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super().__init__(__message, __exceptions, *args)
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self._message = __message
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self._exceptions = __exceptions
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def add_note(self, note: str) -> None:
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if not isinstance(note, str):
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raise TypeError(
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f"Expected a string, got note={note!r} (type {type(note).__name__})"
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)
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if not hasattr(self, "__notes__"):
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self.__notes__: list[str] = []
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self.__notes__.append(note)
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@property
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def message(self) -> str:
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return self._message
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@property
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def exceptions(self) -> tuple[EBase, ...]:
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return tuple(self._exceptions)
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def subgroup(self: T, __condition: _SplitCondition[EBase]) -> T | None:
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condition = get_condition_filter(__condition)
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modified = False
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if condition(self):
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return self
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exceptions: list[BaseException] = []
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for exc in self.exceptions:
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if isinstance(exc, BaseExceptionGroup):
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subgroup = exc.subgroup(condition)
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if subgroup is not None:
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exceptions.append(subgroup)
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if subgroup is not exc:
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modified = True
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elif condition(exc):
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exceptions.append(exc)
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else:
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modified = True
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if not modified:
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return self
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elif exceptions:
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group = self.derive(exceptions)
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group.__cause__ = self.__cause__
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group.__context__ = self.__context__
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group.__traceback__ = self.__traceback__
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return group
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else:
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return None
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def split(
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self: T, __condition: _SplitCondition[EBase]
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) -> tuple[T | None, T | None]:
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condition = get_condition_filter(__condition)
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if condition(self):
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return self, None
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matching_exceptions: list[BaseException] = []
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nonmatching_exceptions: list[BaseException] = []
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for exc in self.exceptions:
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if isinstance(exc, BaseExceptionGroup):
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matching, nonmatching = exc.split(condition)
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if matching is not None:
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matching_exceptions.append(matching)
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if nonmatching is not None:
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nonmatching_exceptions.append(nonmatching)
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elif condition(exc):
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matching_exceptions.append(exc)
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else:
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nonmatching_exceptions.append(exc)
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matching_group: T | None = None
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if matching_exceptions:
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matching_group = self.derive(matching_exceptions)
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matching_group.__cause__ = self.__cause__
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matching_group.__context__ = self.__context__
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matching_group.__traceback__ = self.__traceback__
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nonmatching_group: T | None = None
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if nonmatching_exceptions:
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nonmatching_group = self.derive(nonmatching_exceptions)
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nonmatching_group.__cause__ = self.__cause__
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nonmatching_group.__context__ = self.__context__
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nonmatching_group.__traceback__ = self.__traceback__
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return matching_group, nonmatching_group
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def derive(self: T, __excs: Sequence[EBase]) -> T:
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eg = BaseExceptionGroup(self.message, __excs)
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if hasattr(self, "__notes__"):
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# Create a new list so that add_note() only affects one exceptiongroup
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eg.__notes__ = list(self.__notes__)
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return eg
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def __str__(self) -> str:
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suffix = "" if len(self._exceptions) == 1 else "s"
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return f"{self.message} ({len(self._exceptions)} sub-exception{suffix})"
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def __repr__(self) -> str:
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return f"{self.__class__.__name__}({self.message!r}, {self._exceptions!r})"
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class ExceptionGroup(BaseExceptionGroup[E], Exception, Generic[E]):
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def __new__(cls, __message: str, __exceptions: Sequence[E]) -> ExceptionGroup[E]:
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instance: ExceptionGroup[E] = super().__new__(cls, __message, __exceptions)
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if cls is ExceptionGroup:
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for exc in __exceptions:
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if not isinstance(exc, Exception):
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raise TypeError("Cannot nest BaseExceptions in an ExceptionGroup")
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return instance
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