Issue #14605: Expose importlib.abc.FileLoader and

importlib.machinery.(FileFinder, SourceFileLoader,
_SourcelessFileLoader, ExtensionFileLoader).

This exposes all of importlib's mechanisms that will become public on
the sys module.

1 files changed, 28 insertions, 5 deletions

diff --git a/Lib/importlib/abc.py b/Lib/importlib/abc.py
index 43e4866ef6..baa09fd885 100644
--- a/Lib/importlib/abc.py
+++ b/Lib/importlib/abc.py
@@ -1,6 +1,12 @@
 """Abstract base classes related to import."""
 from . import _bootstrap
 from . import machinery
+try:
+    import _frozen_importlib
+except ImportError as exc:
+    if exc.name != '_frozen_importlib':
+        raise
+    _frozen_importlib = None
 import abc
 import imp
 import marshal
@@ -9,6 +15,14 @@ import tokenize
 import warnings
 
 
+def _register(abstract_cls, *classes):
+    for cls in classes:
+        abstract_cls.register(cls)
+        if _frozen_importlib is not None:
+            frozen_cls = getattr(_frozen_importlib, cls.__name__)
+            abstract_cls.register(frozen_cls)
+
+
 class Loader(metaclass=abc.ABCMeta):
 
     """Abstract base class for import loaders."""
@@ -32,9 +46,8 @@ class Finder(metaclass=abc.ABCMeta):
         """
         raise NotImplementedError
 
-Finder.register(machinery.BuiltinImporter)
-Finder.register(machinery.FrozenImporter)
-Finder.register(machinery.PathFinder)
+_register(Finder, machinery.BuiltinImporter, machinery.FrozenImporter,
+          machinery.PathFinder, machinery.FileFinder)
 
 
 class ResourceLoader(Loader):
@@ -80,8 +93,8 @@ class InspectLoader(Loader):
         module.  The fullname is a str.  Returns a str."""
         raise NotImplementedError
 
-InspectLoader.register(machinery.BuiltinImporter)
-InspectLoader.register(machinery.FrozenImporter)
+_register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter,
+            machinery.ExtensionFileLoader)
 
 
 class ExecutionLoader(InspectLoader):
@@ -100,6 +113,15 @@ class ExecutionLoader(InspectLoader):
         raise NotImplementedError
 
 
+class FileLoader(_bootstrap.FileLoader, ResourceLoader, ExecutionLoader):
+
+    """Abstract base class partially implementing the ResourceLoader and
+    ExecutionLoader ABCs."""
+
+_register(FileLoader, machinery.SourceFileLoader,
+            machinery._SourcelessFileLoader)
+
+
 class SourceLoader(_bootstrap.SourceLoader, ResourceLoader, ExecutionLoader):
 
     """Abstract base class for loading source code (and optionally any
@@ -146,6 +168,7 @@ class SourceLoader(_bootstrap.SourceLoader, ResourceLoader, ExecutionLoader):
         """
         raise NotImplementedError
 
+_register(SourceLoader, machinery.SourceFileLoader)
 
 class PyLoader(SourceLoader):