1 files changed, 136 insertions, 0 deletions
diff --git a/Lib/importlib/resources/abc.py b/Lib/importlib/resources/abc.py
new file mode 100644
index 00000000000..e9efdab5ea8
--- /dev/null
+++ b/Lib/importlib/resources/abc.py
@@ -0,0 +1,136 @@
+import abc
+from typing import BinaryIO, Iterable, Text
+from typing import runtime_checkable, Protocol
+
+
+class ResourceReader(metaclass=abc.ABCMeta):
+    """Abstract base class for loaders to provide resource reading support."""
+
+    @abc.abstractmethod
+    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
+
+    @abc.abstractmethod
+    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
+
+    @abc.abstractmethod
+    def is_resource(self, path: Text) -> bool:
+        """Return True if the named 'path' is a resource.
+
+        Files are resources, directories are not.
+        """
+        raise FileNotFoundError
+
+    @abc.abstractmethod
+    def contents(self) -> Iterable[str]:
+        """Return an iterable of entries in `package`."""
+        raise FileNotFoundError
+
+
+@runtime_checkable
+class Traversable(Protocol):
+    """
+    An object with a subset of pathlib.Path methods suitable for
+    traversing directories and opening files.
+    """
+
+    @abc.abstractmethod
+    def iterdir(self):
+        """
+        Yield Traversable objects in self
+        """
+
+    def read_bytes(self):
+        """
+        Read contents of self as bytes
+        """
+        with self.open('rb') as strm:
+            return strm.read()
+
+    def read_text(self, encoding=None):
+        """
+        Read contents of self as text
+        """
+        with self.open(encoding=encoding) as strm:
+            return strm.read()
+
+    @abc.abstractmethod
+    def is_dir(self) -> bool:
+        """
+        Return True if self is a directory
+        """
+
+    @abc.abstractmethod
+    def is_file(self) -> bool:
+        """
+        Return True if self is a file
+        """
+
+    @abc.abstractmethod
+    def joinpath(self, child):
+        """
+        Return Traversable child in self
+        """
+
+    def __truediv__(self, child):
+        """
+        Return Traversable child in self
+        """
+        return self.joinpath(child)
+
+    @abc.abstractmethod
+    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.
+        """
+
+    @abc.abstractproperty
+    def name(self) -> str:
+        """
+        The base name of this object without any parent references.
+        """
+
+
+class TraversableResources(ResourceReader):
+    """
+    The required interface for providing traversable
+    resources.
+    """
+
+    @abc.abstractmethod
+    def files(self):
+        """Return a Traversable object for the loaded package."""
+
+    def open_resource(self, resource):
+        return self.files().joinpath(resource).open('rb')
+
+    def resource_path(self, resource):
+        raise FileNotFoundError(resource)
+
+    def is_resource(self, path):
+        return self.files().joinpath(path).is_file()
+
+    def contents(self):
+        return (item.name for item in self.files().iterdir())