GH-116380: Move pathlib-specific code from glob to pathlib._abc.

In `glob._Globber`, move pathlib-specific methods to `pathlib._abc.Globber` and replace them with abstract methods. Rename `glob._Globber` to `glob._GlobberBase`, and `glob._StringGlobber` to `glob._Globber`. As a result, the `glob` module is no longer befouled by code that can only ever apply to pathlib. No change of behaviour.
b74b06174fc0598273cbf536422278ec2d1693be
commit b74b06174fc0598273cbf536422278ec2d1693be
diff --git a/Lib/glob.py b/Lib/glob.py
@@ -328,8 +328,8 @@ def _compile_pattern(pat, sep, case_sensitive, recursive=True):
     return re.compile(regex, flags=flags).match
 
 
-class _Globber:
-    """Class providing shell-style pattern matching and globbing.
+class _GlobberBase:
+    """Abstract class providing shell-style pattern matching and globbing.
     """
 
     def __init__(self, sep, case_sensitive, case_pedantic=False, recursive=False):
@@ -338,29 +338,32 @@ def __init__(self, sep, case_sensitive, case_pedantic=False, recursive=False):
         self.case_pedantic = case_pedantic
         self.recursive = recursive
 
-    # Low-level methods
+    # Abstract methods
 
-    lexists = operator.methodcaller('exists', follow_symlinks=False)
-    add_slash = operator.methodcaller('joinpath', '')
+    def lexists(self, path):
+        """Implements os.path.lexists().
+        """
+        raise NotImplementedError
+
+    def scandir(self, path):
+        """Implements os.scandir().
+        """
+        raise NotImplementedError
 
-    @staticmethod
-    def scandir(path):
-        """Emulates os.scandir(), which returns an object that can be used as
-        a context manager. This method is called by walk() and glob().
+    def add_slash(self, path):
+        """Returns a path with a trailing slash added.
         """
-        return contextlib.nullcontext(path.iterdir())
+        raise NotImplementedError
 
-    @staticmethod
-    def concat_path(path, text):
-        """Appends text to the given path.
+    def concat_path(self, path, text):
+        """Implements path concatenation.
         """
-        return path.with_segments(path._raw_path + text)
+        raise NotImplementedError
 
-    @staticmethod
-    def parse_entry(entry):
+    def parse_entry(self, entry):
         """Returns the path of an entry yielded from scandir().
         """
-        return entry
+        raise NotImplementedError
 
     # High-level methods
 
@@ -520,22 +523,22 @@ def select_exists(self, path, exists=False):
             yield path
 
 
-class _StringGlobber(_Globber):
+class _Globber(_GlobberBase):
+    """Provides shell-style pattern matching and globbing for string paths.
+    """
     lexists = staticmethod(os.path.lexists)
     scandir = staticmethod(os.scandir)
     parse_entry = operator.attrgetter('path')
     concat_path = operator.add
 
     if os.name == 'nt':
-        @staticmethod
-        def add_slash(pathname):
+        def add_slash(self, pathname):
             tail = os.path.splitroot(pathname)[2]
             if not tail or tail[-1] in '\\/':
                 return pathname
             return f'{pathname}\\'
     else:
-        @staticmethod
-        def add_slash(pathname):
+        def add_slash(self, pathname):
             if not pathname or pathname[-1] == '/':
                 return pathname
             return f'{pathname}/'
@@ -12,7 +12,8 @@
 """
 
 import functools
-from glob import _Globber, _no_recurse_symlinks
+import operator
+from glob import _GlobberBase, _no_recurse_symlinks
 from errno import ENOTDIR, ELOOP
 from stat import S_ISDIR, S_ISLNK, S_ISREG, S_ISSOCK, S_ISBLK, S_ISCHR, S_ISFIFO
 
@@ -84,6 +85,32 @@ def isabs(self, path):
         raise UnsupportedOperation(self._unsupported_msg('isabs()'))
 
 
+class Globber(_GlobberBase):
+    """
+    Class providing shell-style globbing for path objects.
+    """
+
+    lexists = operator.methodcaller('exists', follow_symlinks=False)
+    add_slash = operator.methodcaller('joinpath', '')
+
+    def scandir(self, path):
+        """Emulates os.scandir(), which returns an object that can be used as
+        a context manager. This method is called by walk() and glob().
+        """
+        import contextlib
+        return contextlib.nullcontext(path.iterdir())
+
+    def concat_path(self, path, text):
+        """Appends text to the given path.
+        """
+        return path.with_segments(path._raw_path + text)
+
+    def parse_entry(self, entry):
+        """Returns the path of an entry yielded from scandir().
+        """
+        return entry
+
+
 class PurePathBase:
     """Base class for pure path objects.
 
@@ -104,7 +131,7 @@ class PurePathBase:
         '_resolving',
     )
     parser = ParserBase()
-    _globber = _Globber
+    _globber = Globber
 
     def __init__(self, path, *paths):
         self._raw_path = self.parser.join(path, *paths) if paths else path

diff --git a/Lib/pathlib/_local.py b/Lib/pathlib/_local.py
@@ -4,7 +4,7 @@
 import os
 import posixpath
 import sys
-from glob import _StringGlobber
+from glob import _Globber
 from itertools import chain
 from _collections_abc import Sequence
 
@@ -101,7 +101,7 @@ class PurePath(PurePathBase):
         '_hash',
     )
     parser = os.path
-    _globber = _StringGlobber
+    _globber = _Globber
 
     def __new__(cls, *args, **kwargs):
         """Construct a PurePath from one or several strings and or existing