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| import abc | |
| import io | |
| import itertools | |
| import pathlib | |
| from typing import Any, BinaryIO, Iterable, Iterator, NoReturn, Text, Optional | |
| from typing import runtime_checkable, Protocol | |
| from .compat.py38 import StrPath | |
| __all__ = ["ResourceReader", "Traversable", "TraversableResources"] | |
| class ResourceReader(metaclass=abc.ABCMeta): | |
| """Abstract base class for loaders to provide resource reading support.""" | |
| def open_resource(self, resource: Text) -> BinaryIO: | |
| """Return an opened, file-like object for binary reading. | |
| The 'resource' argument is expected to represent only a file name. | |
| If the resource cannot be found, FileNotFoundError is raised. | |
| """ | |
| # This deliberately raises FileNotFoundError instead of | |
| # NotImplementedError so that if this method is accidentally called, | |
| # it'll still do the right thing. | |
| raise FileNotFoundError | |
| def resource_path(self, resource: Text) -> Text: | |
| """Return the file system path to the specified resource. | |
| The 'resource' argument is expected to represent only a file name. | |
| If the resource does not exist on the file system, raise | |
| FileNotFoundError. | |
| """ | |
| # This deliberately raises FileNotFoundError instead of | |
| # NotImplementedError so that if this method is accidentally called, | |
| # it'll still do the right thing. | |
| raise FileNotFoundError | |
| def is_resource(self, path: Text) -> bool: | |
| """Return True if the named 'path' is a resource. | |
| Files are resources, directories are not. | |
| """ | |
| raise FileNotFoundError | |
| def contents(self) -> Iterable[str]: | |
| """Return an iterable of entries in `package`.""" | |
| raise FileNotFoundError | |
| class TraversalError(Exception): | |
| pass | |
| class Traversable(Protocol): | |
| """ | |
| An object with a subset of pathlib.Path methods suitable for | |
| traversing directories and opening files. | |
| Any exceptions that occur when accessing the backing resource | |
| may propagate unaltered. | |
| """ | |
| def iterdir(self) -> Iterator["Traversable"]: | |
| """ | |
| Yield Traversable objects in self | |
| """ | |
| def read_bytes(self) -> bytes: | |
| """ | |
| Read contents of self as bytes | |
| """ | |
| with self.open('rb') as strm: | |
| return strm.read() | |
| def read_text(self, encoding: Optional[str] = None) -> str: | |
| """ | |
| Read contents of self as text | |
| """ | |
| with self.open(encoding=encoding) as strm: | |
| return strm.read() | |
| def is_dir(self) -> bool: | |
| """ | |
| Return True if self is a directory | |
| """ | |
| def is_file(self) -> bool: | |
| """ | |
| Return True if self is a file | |
| """ | |
| def joinpath(self, *descendants: StrPath) -> "Traversable": | |
| """ | |
| Return Traversable resolved with any descendants applied. | |
| Each descendant should be a path segment relative to self | |
| and each may contain multiple levels separated by | |
| ``posixpath.sep`` (``/``). | |
| """ | |
| if not descendants: | |
| return self | |
| names = itertools.chain.from_iterable( | |
| path.parts for path in map(pathlib.PurePosixPath, descendants) | |
| ) | |
| target = next(names) | |
| matches = ( | |
| traversable for traversable in self.iterdir() if traversable.name == target | |
| ) | |
| try: | |
| match = next(matches) | |
| except StopIteration: | |
| raise TraversalError( | |
| "Target not found during traversal.", target, list(names) | |
| ) | |
| return match.joinpath(*names) | |
| def __truediv__(self, child: StrPath) -> "Traversable": | |
| """ | |
| Return Traversable child in self | |
| """ | |
| return self.joinpath(child) | |
| def open(self, mode='r', *args, **kwargs): | |
| """ | |
| mode may be 'r' or 'rb' to open as text or binary. Return a handle | |
| suitable for reading (same as pathlib.Path.open). | |
| When opening as text, accepts encoding parameters such as those | |
| accepted by io.TextIOWrapper. | |
| """ | |
| def name(self) -> str: | |
| """ | |
| The base name of this object without any parent references. | |
| """ | |
| class TraversableResources(ResourceReader): | |
| """ | |
| The required interface for providing traversable | |
| resources. | |
| """ | |
| def files(self) -> "Traversable": | |
| """Return a Traversable object for the loaded package.""" | |
| def open_resource(self, resource: StrPath) -> io.BufferedReader: | |
| return self.files().joinpath(resource).open('rb') | |
| def resource_path(self, resource: Any) -> NoReturn: | |
| raise FileNotFoundError(resource) | |
| def is_resource(self, path: StrPath) -> bool: | |
| return self.files().joinpath(path).is_file() | |
| def contents(self) -> Iterator[str]: | |
| return (item.name for item in self.files().iterdir()) | |