bpo-39791 native hooks for importlib.resources.files (GH-20576)

* Provide native .files support on SourceFileLoader.

* Add native importlib.resources.files() support to zipimporter. Remove fallback support.

* make regen-all

* 📜🤖 Added by blurb_it.

* Move 'files' into the ResourceReader so it can carry the relevant module name context.

* Create 'importlib.readers' module and add FileReader to it.

* Add zip reader and rely on it for a TraversableResources object on zipimporter.

* Remove TraversableAdapter, no longer needed.

* Update blurb.

* Replace backslashes with forward slashes.

* Incorporate changes from importlib_metadata 2.0, finalizing the interface for extension via get_resource_reader.

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

Lib/importlib/resources.py

@@ -1,15 +1,13 @@
 import os
 
-from . import abc as resources_abc
 from . import _common
-from ._common import as_file
+from ._common import as_file, files
 from contextlib import contextmanager, suppress
-from importlib import import_module
 from importlib.abc import ResourceLoader
 from io import BytesIO, TextIOWrapper
 from pathlib import Path
 from types import ModuleType
-from typing import ContextManager, Iterable, Optional, Union
+from typing import ContextManager, Iterable, Union
 from typing import cast
 from typing.io import BinaryIO, TextIO
 
@@ -33,60 +31,11 @@ Package = Union[str, ModuleType]
 Resource = Union[str, os.PathLike]
 
 
-def _resolve(name) -> ModuleType:
-    """If name is a string, resolve to a module."""
-    if hasattr(name, '__spec__'):
-        return name
-    return import_module(name)
-
-
-def _get_package(package) -> ModuleType:
-    """Take a package name or module object and return the module.
-
-    If a name, the module is imported.  If the resolved module
-    object is not a package, raise an exception.
-    """
-    module = _resolve(package)
-    if module.__spec__.submodule_search_locations is None:
-        raise TypeError('{!r} is not a package'.format(package))
-    return module
-
-
-def _normalize_path(path) -> str:
-    """Normalize a path by ensuring it is a string.
-
-    If the resulting string contains path separators, an exception is raised.
-    """
-    parent, file_name = os.path.split(path)
-    if parent:
-        raise ValueError('{!r} must be only a file name'.format(path))
-    return file_name
-
-
-def _get_resource_reader(
-        package: ModuleType) -> Optional[resources_abc.ResourceReader]:
-    # Return the package's loader if it's a ResourceReader.  We can't use
-    # a issubclass() check here because apparently abc.'s __subclasscheck__()
-    # hook wants to create a weak reference to the object, but
-    # zipimport.zipimporter does not support weak references, resulting in a
-    # TypeError.  That seems terrible.
-    spec = package.__spec__
-    if hasattr(spec.loader, 'get_resource_reader'):
-        return cast(resources_abc.ResourceReader,
-                    spec.loader.get_resource_reader(spec.name))
-    return None
-
-
-def _check_location(package):
-    if package.__spec__.origin is None or not package.__spec__.has_location:
-        raise FileNotFoundError(f'Package has no location {package!r}')
-
-
 def open_binary(package: Package, resource: Resource) -> BinaryIO:
     """Return a file-like object opened for binary reading of the resource."""
-    resource = _normalize_path(resource)
-    package = _get_package(package)
-    reader = _get_resource_reader(package)
+    resource = _common.normalize_path(resource)
+    package = _common.get_package(package)
+    reader = _common.get_resource_reader(package)
     if reader is not None:
         return reader.open_resource(resource)
     absolute_package_path = os.path.abspath(
@@ -140,13 +89,6 @@ def read_text(package: Package,
         return fp.read()
 
 
-def files(package: Package) -> resources_abc.Traversable:
-    """
-    Get a Traversable resource from a package
-    """
-    return _common.from_package(_get_package(package))
-
-
 def path(
         package: Package, resource: Resource,
         ) -> 'ContextManager[Path]':
@@ -158,17 +100,18 @@ def path(
     raised if the file was deleted prior to the context manager
     exiting).
     """
-    reader = _get_resource_reader(_get_package(package))
+    reader = _common.get_resource_reader(_common.get_package(package))
     return (
         _path_from_reader(reader, resource)
         if reader else
-        _common.as_file(files(package).joinpath(_normalize_path(resource)))
+        _common.as_file(
+            _common.files(package).joinpath(_common.normalize_path(resource)))
         )
 
 
 @contextmanager
 def _path_from_reader(reader, resource):
-    norm_resource = _normalize_path(resource)
+    norm_resource = _common.normalize_path(resource)
     with suppress(FileNotFoundError):
         yield Path(reader.resource_path(norm_resource))
         return
@@ -182,9 +125,9 @@ def is_resource(package: Package, name: str) -> bool:
 
     Directories are *not* resources.
     """
-    package = _get_package(package)
-    _normalize_path(name)
-    reader = _get_resource_reader(package)
+    package = _common.get_package(package)
+    _common.normalize_path(name)
+    reader = _common.get_resource_reader(package)
     if reader is not None:
         return reader.is_resource(name)
     package_contents = set(contents(package))
@@ -200,8 +143,8 @@ def contents(package: Package) -> Iterable[str]:
     not considered resources.  Use `is_resource()` on each entry returned here
     to check if it is a resource or not.
     """
-    package = _get_package(package)
-    reader = _get_resource_reader(package)
+    package = _common.get_package(package)
+    reader = _common.get_resource_reader(package)
     if reader is not None:
         return reader.contents()
     # Is the package a namespace package?  By definition, namespace packages