gh-97930: Apply changes from importlib_resources 5.12. (GH-102010)

3 files changed, 67 insertions, 42 deletions

diff --git a/Lib/importlib/resources/_adapters.py b/Lib/importlib/resources/_adapters.py
index f22f6bc..50688fb 100644
--- a/Lib/importlib/resources/_adapters.py
+++ b/Lib/importlib/resources/_adapters.py
@@ -34,9 +34,7 @@ def _io_wrapper(file, mode='r', *args, **kwargs):
         return TextIOWrapper(file, *args, **kwargs)
     elif mode == 'rb':
         return file
-    raise ValueError(
-        f"Invalid mode value '{mode}', only 'r' and 'rb' are supported"
-    )
+    raise ValueError(f"Invalid mode value '{mode}', only 'r' and 'rb' are supported")
 
 
 class CompatibilityFiles:
diff --git a/Lib/importlib/resources/_itertools.py b/Lib/importlib/resources/_itertools.py
index cce0558..7b775ef5a 100644
--- a/Lib/importlib/resources/_itertools.py
+++ b/Lib/importlib/resources/_itertools.py
@@ -1,35 +1,38 @@
-from itertools import filterfalse
+# from more_itertools 9.0
+def only(iterable, default=None, too_long=None):
+    """If *iterable* has only one item, return it.
+    If it has zero items, return *default*.
+    If it has more than one item, raise the exception given by *too_long*,
+    which is ``ValueError`` by default.
+    >>> only([], default='missing')
+    'missing'
+    >>> only([1])
+    1
+    >>> only([1, 2])  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+    ...
+    ValueError: Expected exactly one item in iterable, but got 1, 2,
+     and perhaps more.'
+    >>> only([1, 2], too_long=TypeError)  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+    ...
+    TypeError
+    Note that :func:`only` attempts to advance *iterable* twice to ensure there
+    is only one item.  See :func:`spy` or :func:`peekable` to check
+    iterable contents less destructively.
+    """
+    it = iter(iterable)
+    first_value = next(it, default)
 
-from typing import (
-    Callable,
-    Iterable,
-    Iterator,
-    Optional,
-    Set,
-    TypeVar,
-    Union,
-)
-
-# Type and type variable definitions
-_T = TypeVar('_T')
-_U = TypeVar('_U')
-
-
-def unique_everseen(
-    iterable: Iterable[_T], key: Optional[Callable[[_T], _U]] = None
-) -> Iterator[_T]:
-    "List unique elements, preserving order. Remember all elements ever seen."
-    # unique_everseen('AAAABBBCCDAABBB') --> A B C D
-    # unique_everseen('ABBCcAD', str.lower) --> A B C D
-    seen: Set[Union[_T, _U]] = set()
-    seen_add = seen.add
-    if key is None:
-        for element in filterfalse(seen.__contains__, iterable):
-            seen_add(element)
-            yield element
+    try:
+        second_value = next(it)
+    except StopIteration:
+        pass
     else:
-        for element in iterable:
-            k = key(element)
-            if k not in seen:
-                seen_add(k)
-                yield element
+        msg = (
+            'Expected exactly one item in iterable, but got {!r}, {!r}, '
+            'and perhaps more.'.format(first_value, second_value)
+        )
+        raise too_long or ValueError(msg)
+
+    return first_value
diff --git a/Lib/importlib/resources/readers.py b/Lib/importlib/resources/readers.py
index 80cb320..c3cdf76 100644
--- a/Lib/importlib/resources/readers.py
+++ b/Lib/importlib/resources/readers.py
@@ -1,11 +1,12 @@
 import collections
-import operator
+import itertools
 import pathlib
+import operator
 import zipfile
 
 from . import abc
 
-from ._itertools import unique_everseen
+from ._itertools import only
 
 
 def remove_duplicates(items):
@@ -41,8 +42,10 @@ class ZipReader(abc.TraversableResources):
             raise FileNotFoundError(exc.args[0])
 
     def is_resource(self, path):
-        # workaround for `zipfile.Path.is_file` returning true
-        # for non-existent paths.
+        """
+        Workaround for `zipfile.Path.is_file` returning true
+        for non-existent paths.
+        """
         target = self.files().joinpath(path)
         return target.is_file() and target.exists()
 
@@ -67,8 +70,10 @@ class MultiplexedPath(abc.Traversable):
             raise NotADirectoryError('MultiplexedPath only supports directories')
 
     def iterdir(self):
-        files = (file for path in self._paths for file in path.iterdir())
-        return unique_everseen(files, key=operator.attrgetter('name'))
+        children = (child for path in self._paths for child in path.iterdir())
+        by_name = operator.attrgetter('name')
+        groups = itertools.groupby(sorted(children, key=by_name), key=by_name)
+        return map(self._follow, (locs for name, locs in groups))
 
     def read_bytes(self):
         raise FileNotFoundError(f'{self} is not a file')
@@ -90,6 +95,25 @@ class MultiplexedPath(abc.Traversable):
             # Just return something that will not exist.
             return self._paths[0].joinpath(*descendants)
 
+    @classmethod
+    def _follow(cls, children):
+        """
+        Construct a MultiplexedPath if needed.
+
+        If children contains a sole element, return it.
+        Otherwise, return a MultiplexedPath of the items.
+        Unless one of the items is not a Directory, then return the first.
+        """
+        subdirs, one_dir, one_file = itertools.tee(children, 3)
+
+        try:
+            return only(one_dir)
+        except ValueError:
+            try:
+                return cls(*subdirs)
+            except NotADirectoryError:
+                return next(one_file)
+
     def open(self, *args, **kwargs):
         raise FileNotFoundError(f'{self} is not a file')