gh-90385: Add pathlib.Path.walk() method (GH-92517)

Automerge-Triggered-By: GH:brettcannon

Lib/pathlib.py

@@ -1321,6 +1321,49 @@ class Path(PurePath):
 
         return self
 
+    def walk(self, top_down=True, on_error=None, follow_symlinks=False):
+        """Walk the directory tree from this directory, similar to os.walk()."""
+        sys.audit("pathlib.Path.walk", self, on_error, follow_symlinks)
+        return self._walk(top_down, on_error, follow_symlinks)
+
+    def _walk(self, top_down, on_error, follow_symlinks):
+        # We may not have read permission for self, in which case we can't
+        # get a list of the files the directory contains. os.walk
+        # always suppressed the exception then, rather than blow up for a
+        # minor reason when (say) a thousand readable directories are still
+        # left to visit. That logic is copied here.
+        try:
+            scandir_it = self._scandir()
+        except OSError as error:
+            if on_error is not None:
+                on_error(error)
+            return
+
+        with scandir_it:
+            dirnames = []
+            filenames = []
+            for entry in scandir_it:
+                try:
+                    is_dir = entry.is_dir(follow_symlinks=follow_symlinks)
+                except OSError:
+                    # Carried over from os.path.isdir().
+                    is_dir = False
+
+                if is_dir:
+                    dirnames.append(entry.name)
+                else:
+                    filenames.append(entry.name)
+
+        if top_down:
+            yield self, dirnames, filenames
+
+        for dirname in dirnames:
+            dirpath = self._make_child_relpath(dirname)
+            yield from dirpath._walk(top_down, on_error, follow_symlinks)
+
+        if not top_down:
+            yield self, dirnames, filenames
+
 
 class PosixPath(Path, PurePosixPath):
     """Path subclass for non-Windows systems.