bpo-25711: Move _ZipImportResourceReader from importlib to zipimport. (GH-9406)

Lib/importlib/resources.py

@@ -257,87 +257,3 @@ def contents(package: Package) -> Iterable[str]:
     else:
         package_directory = Path(package.__spec__.origin).parent
         return os.listdir(package_directory)
-
-
-# Private implementation of ResourceReader and get_resource_reader() called
-# from zipimport.c.  Don't use these directly!  We're implementing these in
-# Python because 1) it's easier, 2) zipimport may get rewritten in Python
-# itself at some point, so doing this all in C would difficult and a waste of
-# effort.
-
-class _ZipImportResourceReader(resources_abc.ResourceReader):
-    """Private class used to support ZipImport.get_resource_reader().
-
-    This class is allowed to reference all the innards and private parts of
-    the zipimporter.
-    """
-
-    def __init__(self, zipimporter, fullname):
-        self.zipimporter = zipimporter
-        self.fullname = fullname
-
-    def open_resource(self, resource):
-        fullname_as_path = self.fullname.replace('.', '/')
-        path = f'{fullname_as_path}/{resource}'
-        try:
-            return BytesIO(self.zipimporter.get_data(path))
-        except OSError:
-            raise FileNotFoundError(path)
-
-    def resource_path(self, resource):
-        # All resources are in the zip file, so there is no path to the file.
-        # Raising FileNotFoundError tells the higher level API to extract the
-        # binary data and create a temporary file.
-        raise FileNotFoundError
-
-    def is_resource(self, name):
-        # Maybe we could do better, but if we can get the data, it's a
-        # resource.  Otherwise it isn't.
-        fullname_as_path = self.fullname.replace('.', '/')
-        path = f'{fullname_as_path}/{name}'
-        try:
-            self.zipimporter.get_data(path)
-        except OSError:
-            return False
-        return True
-
-    def contents(self):
-        # This is a bit convoluted, because fullname will be a module path,
-        # but _files is a list of file names relative to the top of the
-        # archive's namespace.  We want to compare file paths to find all the
-        # names of things inside the module represented by fullname.  So we
-        # turn the module path of fullname into a file path relative to the
-        # top of the archive, and then we iterate through _files looking for
-        # names inside that "directory".
-        fullname_path = Path(self.zipimporter.get_filename(self.fullname))
-        relative_path = fullname_path.relative_to(self.zipimporter.archive)
-        # Don't forget that fullname names a package, so its path will include
-        # __init__.py, which we want to ignore.
-        assert relative_path.name == '__init__.py'
-        package_path = relative_path.parent
-        subdirs_seen = set()
-        for filename in self.zipimporter._files:
-            try:
-                relative = Path(filename).relative_to(package_path)
-            except ValueError:
-                continue
-            # If the path of the file (which is relative to the top of the zip
-            # namespace), relative to the package given when the resource
-            # reader was created, has a parent, then it's a name in a
-            # subdirectory and thus we skip it.
-            parent_name = relative.parent.name
-            if len(parent_name) == 0:
-                yield relative.name
-            elif parent_name not in subdirs_seen:
-                subdirs_seen.add(parent_name)
-                yield parent_name
-
-
-# Called from zipimport.c
-def _zipimport_get_resource_reader(zipimporter, fullname):
-    try:
-        if not zipimporter.is_package(fullname):
-            return None
-    except ZipImportError:
-        return None
-    return _ZipImportResourceReader(zipimporter, fullname)

Lib/zipimport.py

@@ -272,8 +272,16 @@ class zipimporter:
         If 'fullname' is a package within the zip file, return the
         'ResourceReader' object for the package.  Otherwise return None.
         """
-        from importlib import resources
-        return resources._zipimport_get_resource_reader(self, fullname)
+        try:
+            if not self.is_package(fullname):
+                return None
+        except ZipImportError:
+            return None
+        if not _ZipImportResourceReader._registered:
+            from importlib.abc import ResourceReader
+            ResourceReader.register(_ZipImportResourceReader)
+            _ZipImportResourceReader._registered = True
+        return _ZipImportResourceReader(self, fullname)
 
 
     def __repr__(self):
@@ -648,3 +656,74 @@ def _get_module_code(self, fullname):
             return code, ispackage, modpath
     else:
         raise ZipImportError(f"can't find module {fullname!r}", name=fullname)
+
+
+class _ZipImportResourceReader:
+    """Private class used to support ZipImport.get_resource_reader().
+
+    This class is allowed to reference all the innards and private parts of
+    the zipimporter.
+    """
+    _registered = False
+
+    def __init__(self, zipimporter, fullname):
+        self.zipimporter = zipimporter
+        self.fullname = fullname
+
+    def open_resource(self, resource):
+        fullname_as_path = self.fullname.replace('.', '/')
+        path = f'{fullname_as_path}/{resource}'
+        from io import BytesIO
+        try:
+            return BytesIO(self.zipimporter.get_data(path))
+        except OSError:
+            raise FileNotFoundError(path)
+
+    def resource_path(self, resource):
+        # All resources are in the zip file, so there is no path to the file.
+        # Raising FileNotFoundError tells the higher level API to extract the
+        # binary data and create a temporary file.
+        raise FileNotFoundError
+
+    def is_resource(self, name):
+        # Maybe we could do better, but if we can get the data, it's a
+        # resource.  Otherwise it isn't.
+        fullname_as_path = self.fullname.replace('.', '/')
+        path = f'{fullname_as_path}/{name}'
+        try:
+            self.zipimporter.get_data(path)
+        except OSError:
+            return False
+        return True
+
+    def contents(self):
+        # This is a bit convoluted, because fullname will be a module path,
+        # but _files is a list of file names relative to the top of the
+        # archive's namespace.  We want to compare file paths to find all the
+        # names of things inside the module represented by fullname.  So we
+        # turn the module path of fullname into a file path relative to the
+        # top of the archive, and then we iterate through _files looking for
+        # names inside that "directory".
+        from pathlib import Path
+        fullname_path = Path(self.zipimporter.get_filename(self.fullname))
+        relative_path = fullname_path.relative_to(self.zipimporter.archive)
+        # Don't forget that fullname names a package, so its path will include
+        # __init__.py, which we want to ignore.
+        assert relative_path.name == '__init__.py'
+        package_path = relative_path.parent
+        subdirs_seen = set()
+        for filename in self.zipimporter._files:
+            try:
+                relative = Path(filename).relative_to(package_path)
+            except ValueError:
+                continue
+            # If the path of the file (which is relative to the top of the zip
+            # namespace), relative to the package given when the resource
+            # reader was created, has a parent, then it's a name in a
+            # subdirectory and thus we skip it.
+            parent_name = relative.parent.name
+            if len(parent_name) == 0:
+                yield relative.name
+            elif parent_name not in subdirs_seen:
+                subdirs_seen.add(parent_name)
+                yield parent_name