Multi-directory tab completion for find-file?

Question

I am frequently diving through many layers of directory hierarchies (thanks, Java) to find files named like this…

java/test/com/company/thing/test/testy/testier/testier/Tester.java

The main issue that I have is that TAB-completion in find-file only completes one directory at a time, meaning that I may have to press TAB 5 times to get through the first few layers of the hierarchy, where each directory contains only one subdirectory and nothing more (e.g. com/ contains only company/, company/ contains only thing/), etc.

Is there any package that modifies TAB-completion with standard Emacs commands, including find-file, so that multiple directories will be "greedily" autocompleted when they contain only one subdirectory?

I'm aware of Projectile, and know that it has a similar feature, but I'm hoping to find something standalone and minimal that just solves this one issue.

Answer 1

I use ivy/counsel so I only have an ivy solution:

(defcustom dc4ever-cd-all-the-way t
  "Whether to enable cd-all-the-way feature." :type 'boolean)
(defvar dc4ever--cd-all-the-way-flag nil "Internal flag for cd-all-the-way.")

(defun dc4ever//ivy-magic-slash-advice (func &rest r)
  "Set `dc4ever--cd-all-the-way-flag' for `ivy--magic-file-slash'."
  (let ((dc4ever--cd-all-the-way-flag dc4ever-cd-all-the-way))
    (apply func r)))
(advice-add #'ivy--magic-file-slash :around #'dc4ever//ivy-magic-slash-advice)

(defun dc4ever//ivy--cd-advice (func &rest r)
  "Advice `ivy--cd' to do cd-all-the-way."
  (if (not dc4ever--cd-all-the-way-flag) (apply func r)
    (cl-labels ((get-only-dir
                 (dir)
                 (let* ((entries (f-entries dir))
                        (onlyent (when (= 1 (length entries))
                                   (concat (expand-file-name (car entries) dir)
                                           "/"))))
                   (cond
                    ((null onlyent) dir)
                    ((f-dir? onlyent) (get-only-dir onlyent))
                    (t dir)))))
      (funcall func (get-only-dir (car r))))))
(advice-add #'ivy--cd :around #'dc4ever//ivy--cd-advice)

NOTE:

This only works if you type / since I implemented that way, so that TAB would keep the original behavior.