How to sort a list of files/directories by hierarchical depth?

Question

I am working on implementing my own feature request -- http://debbugs.gnu.org/cgi/bugreport.cgi?bug=31601 -- to give wdired the ability to handle a dired- buffer that contains an arbitrary list of absolute paths to directories and files; e.g.,

(dired (directory-files-recursively "/path/to/directory" "" 'include-directories))

However, the files and directories may not necessarily be recursive -- i.e., dired-mode can handle creating a buffer containing an arbitrary list of files and directories.

I have added draft code to wdired that places read-only text properties on the file-name-directory. That way, a user cannot edit those portions of the path while in wdired-mode.

The next step is to process the renaming of files/directories, which requires they be done in a hierarchical order. For example, a user may have renamed a directory and a file:

OLD NAME:   /path/to/directory

NEW NAME:   /path/to/the_directory

OLD NAME:   /path/to/directory/file

NEW NAME:   /path/to/directory/the_file

OLD NAME:   /path/to/different_directory

NEW NAME:   /path/to/the_different_directory

OLD NAME:   /path/to/different_directory/different_file

NEW NAME:  /path/to/different_directory/the_different_file

If we first rename the directory from /path/to/directory to /path/to/the_directory, then rename-file will be unable to rename /path/to/directory/file because the directory no longer exists; i.e., the directory was changed to the_directory.

Therefore, it makes sense to sort all of the files and directories into a hierarchical order such that the deepest file or directory is processed fist in time when renaming the files/directories. For example, if we have a set of files that are 5 directories deep, then those should be processed before processing directories or files that are less than 5 deep.

Q: How to sort a list of files/directories by hierarchical depth?

WORKING LIST:

'("/path/to/different_directory/different_file"
  "/path/to/directory/file"
  "/X/Y"
  "/a/b/c/d/e/f"
  "/1/2/3/4"
  "/A/B/C/D/e"
  "/x/y/Z"
  "/Z"
  "/path/to/different_directory"
  "/path/to/directory")

RESULT DESIRED:

'("/a/b/c/d/e/f"
  "/A/B/C/D/e"
  "/path/to/different_directory/different_file"
  "/1/2/3/4"
  "/path/to/directory/file"
  "/x/y/Z"
  "/path/to/different_directory"
  "/path/to/directory"
  "/X/Y"
  "/Z")

Answer 1

Hm, I am not so sure why you decide to sort "/1/2/3/4" before "/path/to/directory/file" in your desired result.

If you can skip that specification the solution is rather simple:

(let ((paths
       '("/path/to/different_directory/different_file"
         "/path/to/directory/file"
         "/X/Y"
         "/a/b/c/d/e/f"
         "/1/2/3/4"
         "/A/B/C/D/e"
         "/x/y/Z"
         "/Z"
         "/path/to/different_directory"
         "/path/to/directory")))
  (cl-stable-sort paths
       (lambda (path1 path2)
         (> (cl-count ?/ path1)
            (cl-count ?/ path2)))))