Source code for

"""Contains generic base classes for file IO."""

from abc import ABCMeta
from typing import (
from typing_extensions import Literal
from types import TracebackType

import can
import can.typechecking

[docs]class BaseIOHandler(ContextManager, metaclass=ABCMeta): """A generic file handler that can be used for reading and writing. Can be used as a context manager. :attr file: the file-like object that is kept internally, or `None` if none was opened """ file: Optional[can.typechecking.FileLike] def __init__( self, file: Optional[can.typechecking.AcceptedIOType], mode: str = "rt", *args: Any, **kwargs: Any ) -> None: """ :param file: a path-like object to open a file, a file-like object to be used as a file or `None` to not use a file at all :param mode: the mode that should be used to open the file, see :func:`open`, ignored if *file* is `None` """ if file is None or (hasattr(file, "read") and hasattr(file, "write")): # file is None or some file-like object self.file = cast(Optional[can.typechecking.FileLike], file) else: # pylint: disable=consider-using-with # file is some path-like object self.file = cast( can.typechecking.FileLike, open(cast(can.typechecking.StringPathLike, file), mode), ) # for multiple inheritance super().__init__() def __enter__(self) -> "BaseIOHandler": return self def __exit__( self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> Literal[False]: self.stop() return False
[docs] def stop(self) -> None: """Closes the underlying file-like object and flushes it, if it was opened in write mode.""" if self.file is not None: # this also implies a flush() self.file.close()
# pylint: disable=abstract-method,too-few-public-methods
[docs]class MessageWriter(BaseIOHandler, can.Listener, metaclass=ABCMeta): """The base class for all writers.""" file: Optional[can.typechecking.FileLike]
# pylint: disable=abstract-method,too-few-public-methods
[docs]class FileIOMessageWriter(MessageWriter, metaclass=ABCMeta): """A specialized base class for all writers with file descriptors.""" file: can.typechecking.FileLike def __init__( self, file: can.typechecking.AcceptedIOType, mode: str = "wt", *args: Any, **kwargs: Any ) -> None: # Not possible with the type signature, but be verbose for user-friendliness if file is None: raise ValueError("The given file cannot be None") super().__init__(file, mode)
[docs] def file_size(self) -> int: """Return an estimate of the current file size in bytes.""" return self.file.tell()
# pylint: disable=too-few-public-methods
[docs]class MessageReader(BaseIOHandler, Iterable[can.Message], metaclass=ABCMeta): """The base class for all readers."""