Source code for httk.core.datastream.textstream_filename_view

from typing import Any, Self

from ..views import unwrap
from .textstream_backend import TextstreamBackend
from .textstream_like import TextstreamLike
from .textstream_view import TextstreamView




class TextstreamFilenameView(TextstreamView, str):
    r"""
    A view presenting an underlying data streaming backend via a filename.
    This view is probably mostly useful for providing filenames to functions that will open them.
    Note: this view is not lazy (this is impossible for views inherting str, since str is immutable)

    Raises TypeError if created with a streaming data source that does not have a name.

    :param obj: Text-stream source whose filename should be presented.
    :param \**hints: Backend-selection, encoding, and compression hints.
    :raises TypeError: If the source has no filename.
    """

    _backend: TextstreamBackend

    def __new__(cls, obj: TextstreamLike, **hints: Any) -> Self:
        if isinstance(obj, cls):
            return obj
        backend = cls._prepare_backend(obj, hints)
        if backend.name is None:
            raise TypeError("This backend cannot be represented as a filename (no underlying filename)")
        instance = super().__new__(cls, backend.name)
        instance._backend = backend
        return instance

    def __init__(self, obj: TextstreamLike, **hints: Any) -> None:
        super().__init__()



    def unwrap(self) -> Any:
        """Return the raw representation of the wrapped backend.

        :return: The backend's most raw available representation.
        """
        return unwrap(self._backend)




    def unview(self) -> str:
        """Return the presented filename as a plain string.

        :return: The filename represented by this view.
        """
        # Shed to a plain str of the presented filename.
        return str(self)