README.org

@@ -5,7 +5,6 @@
 * Contents :TOC:noexport:
 - [[#introduction][Introduction]]
 - [[#changelog][Changelog]]
-  - [[#aug-26-2024][Aug. 26 2024]]
   - [[#sep-11-2019][Sep. 11 2019]]
   - [[#nov-15-2018][Nov. 15 2018]]
   - [[#initial-release-whats-changed-since-window-numbering][Initial release: what's changed since window-numbering]]
@@ -20,18 +19,16 @@
 - [[#future-developments][Future developments]]
 
 * Introduction
+Window numbers for Emacs: Navigate your windows and frames using numbers !
 
-This package is a fork of the [[https://github.com/deb0ch/emacs-winum][winum]] package, which is itself a fork of the
-[[https://github.com/nschum/window-numbering.el][window-numbering]] package.
+This package is an extended and actively maintained version of the
+[[https://github.com/nschum/window-numbering.el][window-numbering]] package by Nikolaj Schumacher, with some ideas and code taken
+from [[https://github.com/abo-abo/ace-window][ace-window]].
 
-Compared to winum, this fork adds support for windows having arbitrary Lisp values
-as identifiers, as opposed to strictly increasing numbers. The public
-API is largely the same, however, and simple numbers are still the default.
+This version brings, among other things, support for number sets across multiple
+frames, giving the user a smoother experience of multi-screen Emacs.
 
 * Changelog
-** Aug. 26 2024
-- Added support for arbitrary Lisp objects (non-nil, compared with =equal=) as indices.
-- Added customize variable =winum-auto-assign-function= to control auto-assigning behavior.
 ** Sep. 11 2019
 - Added customize variable =winum-ignored-buffers-regexp= to ignored buffers
   based on regexps.
@@ -104,7 +101,7 @@ your Emacs configuration:
 | Key binding | Description                                                                                 |
 |-------------+---------------------------------------------------------------------------------------------|
 | ~C-x w <n>~ | select window <n>, where <n> ranges from 0 to 9. A negative argument deletes the window.    |
-| ~C-x w `~   | select window by index. Integer indices can be given as prefix arg, or the index will be read from minibuffer. |
+| ~C-x w `~   | select window by number. Number can be given as prefix arg or will be read from minibuffer. |
 
 - =select-window-0-or-10=
 
@@ -114,19 +111,23 @@ your Emacs configuration:
   You can rebind this to the more straightforward =select-window-0= if you
   prefer.
 
-- =select-window-by-index=
+- =select-window-by-number=
 
-  If you happen to have more than 10 windows, or if you want to select a window that
-  doesn't have an integer index, you can use the =select-window-by-index= function, bound
-  by default to ~C-x w `~.
+  If you happen to have more than 10 windows, you can use the
+ =select-window-by-number= function, bound by default to ~C-x w `~.
 
   This function allows several ways to input the window number:
 
   - Use a numbered prefix argument.\\
  *Ex:* ~C-1 C-2 C-x w `~ to select window 12.
+  - Use a negative prefix argument to delete the window.\\
+ *Ex:* ~C-- C-1 C-2 C-x w `~ to delete window 12.
+  - Use the negative prefix argument to delete window 0.\\
+ *Ex:* ~C-- C-x w `~ to delete window 0.
   - Use the default prefix argument to delete current window.\\
  *Ex:* ~C-u C-x w `~ to delete current window.
-  - If no prefix argument is given, an un-evaluated Lisp value is read from minibuffer.
+  - If no prefix argument ig given, a number is read from minibuffer. A negative
+    input will delete the window instead of selecting it.
 
 * Configuration
 ** Keybindings
@@ -151,8 +152,8 @@ override =winum-keymap= in the minor mode bindings table:
 #+BEGIN_SRC emacs-lisp
   (setq winum-keymap
       (let ((map (make-sparse-keymap)))
-        (define-key map (kbd "C-`") 'winum-select-window-by-index)
-        (define-key map (kbd "C-²") 'winum-select-window-by-index)
+        (define-key map (kbd "C-`") 'winum-select-window-by-number)
+        (define-key map (kbd "C-²") 'winum-select-window-by-number)
         (define-key map (kbd "M-0") 'winum-select-window-0-or-10)
         (define-key map (kbd "M-1") 'winum-select-window-1)
         (define-key map (kbd "M-2") 'winum-select-window-2)
@@ -174,7 +175,7 @@ Note that it is important to set =winum-keymap= /before/ the =require=.
 You can also use the more conventional =define-key= on =winum-keymap=:
 
 #+BEGIN_SRC emacs-lisp
-  (define-key winum-keymap (kbd "C-x y o l o") 'winum-select-window-by-index)
+  (define-key winum-keymap (kbd "C-x y o l o") 'winum-select-window-by-number)
 #+END_SRC
 
 *NB:* Both ~`~ and ~²~ are mapped to =winum-select-window-by-number= by default
@@ -200,11 +201,11 @@ Several options are available through Emacs' Customize interface under
 
   Default: =nil=
 
-- =winum-minibuffer-auto-assign=
+- =winum-auto-assign-0-to-minibuffer=
 
-  If non-nil, =winum-mode= automatically assigns this index to the minibuffer.
+  If non-nil, =winum-mode= assigns 0 to the minibuffer if active.
 
-  Default: =0=
+  Default: =t=
 
 - =winum-assign-functions=
 
@@ -243,18 +244,6 @@ Several options are available through Emacs' Customize interface under
 
   Default: =nil=
 
-- =winum-auto-assign-function=
-  
-  The function called to auto-assign indices to windows.
-
-  This function is called after =winum-assign-functions= to automatically assign
-  indices to the remaining windows. It must take in a list of windows and call
-  the function =winum--assign= to assign an index to each, while avoiding
-  assigning any indices already taken (stored in =winum--assigned-indices=).
-  Members of this list should be tested for using `equal'.
-
-  Default: =#'winum--auto-assign=
-
 - =winum-auto-setup-mode-line=
 
   When nil, =winum-mode= will not display window numbers in the mode-line. You
@@ -301,8 +290,8 @@ available winum options.
 #+BEGIN_SRC emacs-lisp
   (setq winum-keymap
       (let ((map (make-sparse-keymap)))
-        (define-key map (kbd "C-`") 'winum-select-window-by-index)
-        (define-key map (kbd "C-²") 'winum-select-window-by-index)
+        (define-key map (kbd "C-`") 'winum-select-window-by-number)
+        (define-key map (kbd "C-²") 'winum-select-window-by-number)
         (define-key map (kbd "M-0") 'winum-select-window-0-or-10)
         (define-key map (kbd "M-1") 'winum-select-window-1)
         (define-key map (kbd "M-2") 'winum-select-window-2)
@@ -331,7 +320,7 @@ available winum options.
 
   (setq window-numbering-scope            'global
         winum-reverse-frame-list          nil
-        winum-minibuffer-auto-assign      0
+        winum-auto-assign-0-to-minibuffer t
         winum-assign-func                 'my-winum-assign-func
         winum-auto-setup-mode-line        t
         winum-format                      " %s "

winum.el

@@ -1,8 +1,7 @@
 ;;; winum.el --- Navigate windows and frames using numbers.
 ;;
 ;; Copyright (c) 2006-2015 Nikolaj Schumacher
-;; Copyright (c) 2016-2019 Thomas Chauvot de Beauchêne
-;; Copyright (c) 2024 Kiana Sheibani
+;; Copyright (c) 2016 Thomas Chauvot de Beauchêne
 ;;
 ;; This program is free software: you can redistribute it and/or modify
 ;; it under the terms of the GNU General Public License as published by
@@ -17,8 +16,8 @@
 ;; You should have received a copy of the GNU General Public License
 ;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ;;
-;; Author: Kiana Sheibani <kiana.a.sheibani@gmail.com>
-;; Version: 3.0.0
+;; Author: Thomas de Beauchêne <thomas.de.beauchene@gmail.com>
+;; Version: 2.2.0
 ;; Keywords: convenience, frames, windows, multi-screen
 ;; URL: http://github.com/deb0ch/winum.el
 ;; Created: 2016
@@ -39,6 +38,9 @@
 ;; frames, giving the user a smoother experience of multi-screen Emacs.
 ;;
 ;;; Code:
+;;
+;; FIXME: The mode-line's window number is not always up to date in all frames.
+;;
 
 (eval-when-compile (require 'cl-lib))
 (require 'dash)
@@ -63,15 +65,18 @@ Has effect only when `winum-scope' is not 'frame-local."
   :group 'winum
   :type  'boolean)
 
-(defcustom winum-minibuffer-auto-assign 0
-  "If non-nil, `winum-mode' automatically assigns this index to the minibuffer."
+(defcustom winum-auto-assign-0-to-minibuffer t
+  "If non-nil, `winum-mode' assigns 0 to the minibuffer when active."
   :group 'winum
-  :type  'sexp)
+  :type  'boolean)
 
 (defcustom winum-assign-func nil
   "Function called for each window by `winum-mode'.
 This is called before automatic assignment begins.  The function should
-return an index to have it assigned to the current-window, nil otherwise.
+return a number to have it assigned to the current-window, nil otherwise.
+
+This function along with `winum-auto-assign-0-to-minibuffer' are the only
+ways to have 0 assigned to a window.
 
 Example: always assign *Calculator* the number 9 and *NeoTree* the number 0:
 
@@ -93,18 +98,21 @@ Example: always assign *Calculator* the number 9 and *NeoTree* the number 0:
 (defcustom winum-assign-functions nil
   "List of functions called for each window by `winum-mode'.
 
-These functions allow for deterministic assignment of indices to windows. Each
-function is called for every window. A function should return the index to be
-assigned to a window or nil. The *first* function to output a value for a
-given window will determine this window's number.
+These functions allow for deterministic assignment of numbers to windows. Each
+function is called for every window. A function should return the number to be
+assigned to a window or nil. The *first* function to output a number for
+a given window will determine this window's number.
 
 If the list is empty or if every functions returns nil for a given window winum
-will proceed to automatic assignment.
+will proceed to automatic number assignment.
 
 Since this list is meant to allow custom window assignment for *mutiple*
 packages at once it should never be directly set, only added to and removed
 from.
 
+These functions, along with `winum-auto-assign-0-to-minibuffer', are the only
+way to have 0 assigned to a window.
+
 Example: always assign *Calculator* the number 9, *Flycheck-errors* the number 8
 and *NeoTree* the number 0:
 
@@ -121,21 +129,7 @@ and *NeoTree* the number 0:
   (add-to-list
     'winum-assign-functions #'winum-assign-0-to-neotree)"
   :group 'winum
-  :type  '(repeat function))
-
-(defcustom winum-auto-assign-function #'winum--auto-assign
-  "The function called to auto-assign indices to windows.
-
-This function is called after `winum-assign-functions' to automatically assign
-indices to the remaining windows. It must take in a list of windows and call
-the function `winum--assign' to assign an index to each, while avoiding
-assigning any indices already taken (stored in `winum--assigned-indices').
-Members of this list should be tested for using `equal'.
-
-The default auto-assign function is `winum--auto-assign', which assigns strictly
-increasing integers to each window."
-  :group 'winum
-  :type 'function)
+  :type  'list)
 
 (defcustom winum-auto-setup-mode-line t
   "When nil, `winum-mode' will not display window numbers in the mode-line.
@@ -149,38 +143,33 @@ numbers in the mode-line."
   :group 'winum
   :type  'integer)
 
-(defcustom winum-mode-line-p #'integerp
-  "A predicate that determines when to display a window index on the mode-line.
-By default, only integers are displayed."
-  :group 'winum
-  :type 'function)
-
 (defcustom winum-format " %s "
   "Format string defining how the window number looks like in the mode-line.
-This string is passed to the `format' function along with the index."
+This string is passed to the `format' function along with the
+result of `winum-get-number-string'."
   :group 'winum
   :type  'string)
 
 (defcustom winum-ignored-buffers '(" *which-key*")
-  "List of buffers to ignore when assigning indices."
+  "List of buffers to ignore when assigning numbers."
   :group 'winum
   :type  '(repeat string))
 
 (defcustom winum-ignored-buffers-regexp '()
-  "List of regexps for buffer names to ignore when assigning indices.
+  "List of regexps for buffer names to ignore when assigning numbers.
 See Info node `(emacs) Regexps' or Info node `(elisp) Regular Expressions'"
   :group 'winum
   :type '(repeat string)
   :risky t)
 
 (defface winum-face '()
-  "Face used for the index in the mode-line."
+  "Face used for the number in the mode-line."
   :group 'winum)
 
 (defvar winum-base-map
   (let ((map (make-sparse-keymap)))
-    (define-key map (kbd "`") 'winum-select-window-by-index)
-    (define-key map (kbd "²") 'winum-select-window-by-index)
+    (define-key map (kbd "`") 'winum-select-window-by-number)
+    (define-key map (kbd "²") 'winum-select-window-by-number)
     (define-key map (kbd "0") 'winum-select-window-0-or-10)
     (define-key map (kbd "1") 'winum-select-window-1)
     (define-key map (kbd "2") 'winum-select-window-2)
@@ -194,7 +183,7 @@ See Info node `(emacs) Regexps' or Info node `(elisp) Regular Expressions'"
     map)
   "Keymap to be used under the prefix provided by `winum-keymap-prefix'.")
 
-(defvar winum-mode-map (let ((map (make-sparse-keymap)))
+(defvar winum-keymap (let ((map (make-sparse-keymap)))
                        (define-key map (kbd "C-x w") winum-base-map)
                        map)
   "Keymap used for `winum-mode'.")
@@ -204,36 +193,37 @@ See Info node `(emacs) Regexps' or Info node `(elisp) Regular Expressions'"
 (defvar winum--max-frames 16
   "Maximum number of frames that can be numbered.")
 
-(defvar winum--assigned-indices nil
-  "List of indices that have already been assigned by `winum-assign-functions'.")
+(defvar winum--window-count nil
+  "Current count of windows to be numbered.")
 
-(defvar winum--window-table nil
-  "Hash table with indices as keys and windows as values.
-Used internally by winum to get a window provided an index.")
+(defvar winum--remaining nil
+  "A list of window numbers to assign.")
 
-(defvar winum--index-table nil
-  "Hash table with windows as keys and indices as values.
-Used internally by winum to get an index provided a window.")
+(defvar winum--window-vector nil
+  "Vector of windows indexed by their number.
+Used internally by winum to get a window provided a number.")
+
+(defvar winum--numbers-table nil
+  "Hash table of numbers indexed by their window.
+Used internally by winum to get a number provided a window.")
 
 (defvar winum--frames-table nil
-  "Table linking windows to indices and indices to windows for each frame.
+  "Table linking windows to numbers and numbers to windows for each frame.
 
 Used only when `winum-scope' is 'frame-local to keep track of
-separate window index sets in every frame.
+separate window numbers sets in every frame.
 
 It is a hash table using Emacs frames as keys and cons of the form
-\(`winum--window-table' . `winum--index-table')
+\(`winum--window-vector' . `winum--numbers-table')
 as values.
 
-To get a window given an index, use the `car' of a value.
-To get an index given a window, use the `cdr' of a value.
+To get a window given a number, use the `car' of a value.
+To get a number given a window, use the `cdr' of a value.
 
 Such a structure allows for per-frame bidirectional fast access.")
 
 (defvar winum--mode-line-segment
-  '(:eval (let ((index (winum-get-index)))
-            (when (funcall winum-mode-line-p index)
-              (propertize (format winum-format index) 'face 'winum-face))))
+  '(:eval (format winum-format (winum-get-number-string)))
   "What is pushed into `mode-line-format' when setting it up automatically.")
 
 (defvar winum--last-used-scope winum-scope
@@ -245,7 +235,9 @@ Needed to detect scope changes at runtime.")
 ;;;###autoload
 (define-minor-mode winum-mode
   "A minor mode that allows for managing windows based on window numbers."
-  :lighter nil
+  nil
+  nil
+  winum-keymap
   :global t
   (if winum-mode
       (winum--init)
@@ -253,145 +245,115 @@ Needed to detect scope changes at runtime.")
 
 ;;;###autoload
 (defun winum-select-window-0-or-10 (&optional arg)
-  "Jump to window 0, or window 10 if 0 is not assigned.
+  "Jump to window 0 if assigned or 10 if exists.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (let ((n (if (winum-get-window-by-index 0) 0 10)))
-    (if arg
-        (winum-delete-window-by-index n)
-      (winum-select-window-by-index n))))
+  (let ((n (if (winum-get-window-by-number 0)
+               (if arg '- 0)
+             (if arg -10 10))))
+    (winum-select-window-by-number n)))
 
 ;;;###autoload
 (defun winum-select-window-0 (&optional arg)
   "Jump to window 0.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 0)
-    (winum-select-window-by-index 0)))
+  (winum-select-window-by-number (if arg '- 0)))
 
 ;;;###autoload
 (defun winum-select-window-1 (&optional arg)
   "Jump to window 1.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 1)
-    (winum-select-window-by-index 1)))
+  (winum-select-window-by-number (if arg -1 1)))
 
 ;;;###autoload
 (defun winum-select-window-2 (&optional arg)
   "Jump to window 2.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 2)
-    (winum-select-window-by-index 2)))
+  (winum-select-window-by-number (if arg -2 2)))
 
 ;;;###autoload
 (defun winum-select-window-3 (&optional arg)
   "Jump to window 3.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 3)
-    (winum-select-window-by-index 3)))
+  (winum-select-window-by-number (if arg -3 3)))
 
 ;;;###autoload
 (defun winum-select-window-4 (&optional arg)
   "Jump to window 4.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 4)
-    (winum-select-window-by-index 4)))
+  (winum-select-window-by-number (if arg -4 4)))
 
 ;;;###autoload
 (defun winum-select-window-5 (&optional arg)
   "Jump to window 5.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 5)
-    (winum-select-window-by-index 5)))
+  (winum-select-window-by-number (if arg -5 5)))
 
 ;;;###autoload
 (defun winum-select-window-6 (&optional arg)
   "Jump to window 6.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 6)
-    (winum-select-window-by-index 6)))
+  (winum-select-window-by-number (if arg -6 6)))
 
 ;;;###autoload
 (defun winum-select-window-7 (&optional arg)
   "Jump to window 7.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 7)
-    (winum-select-window-by-index 7)))
+  (winum-select-window-by-number (if arg -7 7)))
 
 ;;;###autoload
 (defun winum-select-window-8 (&optional arg)
   "Jump to window 8.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 8)
-    (winum-select-window-by-index 8)))
+  (winum-select-window-by-number (if arg -8 8)))
 
 ;;;###autoload
 (defun winum-select-window-9 (&optional arg)
   "Jump to window 9.
 If prefix ARG is given, delete the window instead of selecting it."
   (interactive "P")
-  (if arg
-      (winum-delete-window-by-index 9)
-    (winum-select-window-by-index 9)))
+  (winum-select-window-by-number (if arg -9 9)))
 
 ;;;###autoload
-(defun winum-select-window-by-index (&optional arg)
-  "Select window whose index is specified by ARG.
-There are several ways to provide the value:
+(defun winum-select-window-by-number (&optional arg)
+  "Select or delete window which number is specified by ARG.
+If the number is negative, delete the window instead of selecting it.
+There are several ways to provide the number:
 - if called from elisp with an argument, use it.
-- if called from elisp without an argument, use current window.
 - if called interactively with a numeric prefix argument, use it.
-- if called interactively with the default prefix argument, use current window.
-- if called interactively and no argument is provided, read from minibuffer."
+- if prefix argument is the negative argument, delete window 0.
+- if prefix argument is the default prefix argument, delete current window.
+- if called interactively and no valid argument is provided, read from
+  minibuffer."
   (interactive "P")
-  (let* ((i (if (called-interactively-p 'any)
-                (cond
+  (let* ((n (cond
              ((integerp arg) arg)
-                 (arg (winum-get-index))
-                 (t (read--expression "Window: ")))
-              (or arg (winum-get-index))))
-         (w (winum-get-window-by-index i)))
-    (if w
-        (winum--switch-to-window w)
-      (user-error "No window with index %S" i))))
-
-;;;###autoload
-(defun winum-delete-window-by-index (&optional arg)
-  "Delete window whose index is specified by ARG.
-There are several ways to provide the value:
-- if called from elisp with an argument, use it.
-- if called from elisp without an argument, use current window.
-- if called interactively with a numeric prefix argument, use it.
-- if called interactively with the default prefix argument, use current window.
-- if called interactively and no argument is provided, read from minibuffer."
-  (interactive "P")
-  (let* ((i (if (called-interactively-p 'any)
-                (cond
-                 ((integerp arg) arg)
-                 (arg (winum-get-index))
-                 (t (read--expression "Window: ")))
-              (or arg (winum-get-index))))
-         (w (winum-get-window-by-index i)))
+             ((eq arg '-) 0) ; the negative argument
+             (arg (winum-get-number))
+             ((called-interactively-p 'any)
+              (let ((user-input-str (read-from-minibuffer "Window: ")))
+                (if (not (string-match-p "[+-]?[0-9]+\.*" user-input-str))
+                    (winum-get-number)
+                  (string-to-number user-input-str))))
+             (t (winum-get-number))))
+         (w (winum-get-window-by-number (abs n)))
+         (delete (and arg
+                      (or (not (integerp arg))
+                          (> 0 n)))))
     (if w
+        (if delete
             (delete-window w)
-      (user-error "No window with index %S" i))))
+          (winum--switch-to-window w))
+      (error "No window numbered %d" n))))
 
 ;; Public API ------------------------------------------------------------------
 
@@ -409,38 +371,41 @@ PREFIX must be a key sequence, like the ones returned by `kbd'."
           winum-keymap))
 
 ;;;###autoload
-(defun winum-get-window-by-index (index)
-  "Return window INDEX if exists, nil otherwise."
-  (let ((window-table (winum--get-window-table)))
-    (gethash index window-table)))
+(defun winum-get-window-by-number (n)
+  "Return window numbered N if exists, nil otherwise."
+  (let ((window-vector (winum--get-window-vector)))
+    (when (and (>= n 0) (< n (length window-vector)))
+      (aref window-vector n))))
 
-;;;###autoload
-(defun winum-get-index (&optional window)
-  "Get the index of WINDOW or the current window."
-  (let ((w (or window (selected-window))))
-    (gethash w (winum--get-index-table))))
-
-;; For backwards compatibility
 ;;;###autoload
 (defun winum-get-number-string (&optional window)
   "Get the current or specified window's current number as a propertized string.
 WINDOW: if specified, the window of which we want to know the number.
         If not specified, the number of the currently selected window is
         returned."
-  (let* ((n (winum-get-index window))
-         (s (if (funcall winum-mode-line-p n)
-                (format "%s" n)
+  (let* ((n (winum-get-number window))
+         (s (if (numberp n)
+                (int-to-string n)
               "")))
     (propertize s 'face 'winum-face)))
 
+;;;###autoload
+(defun winum-get-number (&optional window)
+  "Get the current or specified window's current number.
+WINDOW: if specified, the window of which we want to know the number.
+        If not specified, the number of the currently selected window is
+        returned."
+  (let ((w (or window (selected-window))))
+    (gethash w (winum--get-numbers-table))))
+
 ;; Internal functions ----------------------------------------------------------
 
 (defun winum--init ()
   "Initialize winum-mode."
+  (setq winum--window-count (length (winum--window-list)))
   (if (eq winum-scope 'frame-local)
       (setq winum--frames-table (make-hash-table :size winum--max-frames))
-    (setq winum--window-table (make-hash-table :test 'equal)
-          winum--index-table (make-hash-table :test 'equal)))
+    (setq winum--numbers-table (make-hash-table :size winum--window-count)))
   (when winum-auto-setup-mode-line
     (winum--install-mode-line))
   (add-hook 'minibuffer-setup-hook 'winum--update)
@@ -458,7 +423,7 @@ WINDOW: if specified, the window of which we want to know the number.
   (setq winum--frames-table nil))
 
 (defun winum--install-mode-line (&optional position)
-  "Install the window index from `winum-mode' to the mode-line.
+  "Install the window number from `winum-mode' to the mode-line.
 POSITION: position in the mode-line."
   (let ((mode-line (default-value 'mode-line-format))
         res)
@@ -475,7 +440,7 @@ POSITION: position in the mode-line."
   (force-mode-line-update t))
 
 (defun winum--clear-mode-line ()
-  "Remove the window index of `winum-mode' from the mode-line."
+  "Remove the window number of `winum-mode' from the mode-line."
   (let ((mode-line (default-value 'mode-line-format))
         res)
     (while mode-line
@@ -488,63 +453,71 @@ POSITION: position in the mode-line."
   (force-mode-line-update t))
 
 (defun winum--update ()
-  "Update window indices."
+  "Update window numbers."
   (let ((windows (winum--window-list)))
-    (setq winum--assigned-indices nil)
-    (clrhash (winum--get-window-table))
-    (clrhash (winum--get-index-table))
+    (setq winum--window-count (length windows)
+          winum--remaining (winum--available-numbers))
+    (winum--set-window-vector (make-vector (1+ winum--window-count) nil))
+    (clrhash (winum--get-numbers-table))
     (when winum-assign-functions
-      (--each (-copy windows) (when (winum--try-to-find-custom-index it)
-                                (setq windows (delq it windows)))))
-    (when (and winum-minibuffer-auto-assign
+      (-each windows #'winum--try-to-find-custom-number))
+    (when (and winum-auto-assign-0-to-minibuffer
                (active-minibuffer-window)
-               (not (winum-get-window-by-index winum-minibuffer-auto-assign)))
-      (winum--assign (active-minibuffer-window) winum-minibuffer-auto-assign)
-      (push winum-minibuffer-auto-assign winum--assigned-indices))
-    ;; Auto-assign remaining windows
-    (when windows
-      (funcall winum-auto-assign-function windows))))
-
-(defun winum--auto-assign (windows)
-  "The default auto-assign function for assigning indices to windows.
-Takes in the list of windows WINDOWS and uses `winum--assign' to assign
-increasing integers to it."
-  (let ((index 1))
+               (not (winum-get-window-by-number 0)))
+      (winum--assign (active-minibuffer-window) 0))
     (dolist (w windows)
-      (while (member index winum--assigned-indices)
-        (setq index (1+ index)))
-      (winum--assign w index)
-      (setq index (1+ index)))))
+      (winum--assign w))))
 
-(defun winum--try-to-find-custom-index (window)
-  "Try to find and assign a custom index for WINDOW.
+(defun winum--try-to-find-custom-number (window)
+  "Try to find and assign a custom number for WINDOW.
 Do so by trying every function in `winum-assign-functions' and assign the
-*first* non nil value.
-When multiple functions assign an index to a window log a warning and use the
-first index anyway."
+*first* non nil integer.
+When multiple functions assign a number to a window log a warning and use the
+first number anyway."
   (with-selected-window window
     (with-current-buffer (window-buffer window)
-      (when-let* ((inds (->> winum-assign-functions
+      (let* ((nums (->> winum-assign-functions
                         (--map (cons it (funcall it)))
                         (--remove (null (cdr it)))))
-                  (ind (-> inds (cl-first) (cdr))))
-        (when (> (length inds) 1)
-          (message "Winum conflict - window %s was assigned an index by multiple custom assign functions: '%s'"
-                   window (--map (format "%s -> %S" (car it) (cdr it)) inds)))
-        (winum--assign window ind)
-        (push ind winum--assigned-indices)))))
+             (num (-> nums (cl-first) (cdr))))
+        (when (> (length nums) 1)
+          (message "Winum conflict - window %s was assigned a number by multiple custom assign functions: '%s'"
+                   window (--map (format "%s -> %s" (car it) (cdr it)) nums)))
+        (when (integerp num) (winum--assign window num))))))
 
-(defun winum--assign (window index)
-  "Assign to window WINDOW the index INDEX.
-Returns the assigned index, or nil on error."
-  (if (gethash index (winum--get-window-table))
+(defun winum--assign (window &optional number)
+  "Assign to window WINDOW the number NUMBER.
+If NUMBER is not specified, determine it first based on `winum--remaining'.
+Returns the assigned number, or nil on error."
+  (if number
       (progn
-        (message "Index %S already assigned to %s, can't assign to %s"
-                 index (gethash index (winum--get-window-table)) window)
+        (winum--maybe-expand-window-vector number)
+        (if (aref (winum--get-window-vector) number)
+            (progn
+              (message "Number %s already assigned to %s, can't assign to %s"
+                       number (aref (winum--get-window-vector) number) window)
               nil)
-    (puthash index window (winum--get-window-table))
-    (puthash window index (winum--get-index-table))
-    index))
+          (setf (aref (winum--get-window-vector) number) window)
+          (puthash window number (winum--get-numbers-table))
+          (setq winum--remaining (delq number winum--remaining))
+          number))
+    ;; else determine number and assign
+    (when winum--remaining
+      (unless (gethash window (winum--get-numbers-table))
+        (let ((number (car winum--remaining)))
+          (winum--assign window number))))))
+
+(defun winum--maybe-expand-window-vector (number)
+  "Expand `winum--window-vector' if NUMBER is bigger than its size.
+The size of `winum--window-vector' is normally based on the number of live
+windows, however a higher number can be reserved by the user-defined
+`winum-assign-func'."
+  (let* ((window-vector (winum--get-window-vector))
+         (window-vector-length (length window-vector)))
+    (when (> number window-vector-length)
+      (winum--set-window-vector
+       (vconcat window-vector
+                (make-vector (1+ (- number window-vector-length)) nil))))))
 
 (defun winum--window-list ()
   "Return a list of interesting windows."
@@ -564,10 +537,10 @@ Returns the assigned index, or nil on error."
      (frame-local
       (winum--list-windows-in-frame))
      (t
-      (user-error "Invalid `winum-scope': %S" winum-scope)))))
+      (error "Invalid `winum-scope': %S" winum-scope)))))
 
 (defun winum--ignore-window-p (window)
-  "Non-nil if WINDOW should be ignored for indexing."
+  "Non-nil if WINDOW should be ignored for numbering."
   (let ((f (window-frame window)))
     (or (not (and (frame-live-p f)
                   (frame-visible-p f)))
@@ -581,25 +554,33 @@ Returns the assigned index, or nil on error."
   "List windows in frame F using natural Emacs ordering."
   (window-list f 0 (frame-first-window f)))
 
-(defun winum--get-window-table ()
-  "Return the window table used to get a window given an index.
-This hashtable is not stored the same way depending on the value of
-`winum-scope'."
+(defun winum--set-window-vector (window-vector)
+  "Set WINDOW-VECTOR according to the current `winum-scope'."
+  (winum--check-for-scope-change)
+  (if (eq winum-scope 'frame-local)
+      (puthash (selected-frame)
+               (cons window-vector
+                     (make-hash-table :size winum--window-count))
+               winum--frames-table)
+    (setq winum--window-vector window-vector)))
+
+(defun winum--get-window-vector ()
+  "Return the window vector used to get a window given a number.
+This vector is not stored the same way depending on the value of `winum-scope'."
   (winum--check-for-scope-change)
-  (winum--check-frames-table)
   (if (eq winum-scope 'frame-local)
       (car (gethash (selected-frame) winum--frames-table))
-    winum--window-table))
+    winum--window-vector))
 
-(defun winum--get-index-table ()
-  "Return the index hashtable used to get an index given a window.
+(defun winum--get-numbers-table ()
+  "Return the numbers hashtable used to get a number given a window.
 This hashtable is not stored the same way depending on the value of
-`winum-scope'."
+`winum-scope'"
   (winum--check-for-scope-change)
   (winum--check-frames-table)
   (if (eq winum-scope 'frame-local)
       (cdr (gethash (selected-frame) winum--frames-table))
-    winum--index-table))
+    winum--numbers-table))
 
 (defun winum--check-frames-table ()
   "Make sure `winum--frames-table' exists and is correctly equipped.
@@ -612,12 +593,17 @@ Verifies 2 things (when `winum-scope' is frame local):
     (unless winum--frames-table
       (setq winum--frames-table (make-hash-table :size winum--max-frames)))
     (unless (gethash (selected-frame) winum--frames-table)
-      (puthash (selected-frame) (cons
-                                 (make-hash-table :test 'equal)
-                                 (make-hash-table :test 'equal))
-               winum--frames-table)
       (winum--update))))
 
+(defun winum--available-numbers ()
+  "Return a list of numbers from 1 to `winum--window-count'.
+0 is is not part of the list as its assignment is either manual
+using the `winum-assign-func', or using `winum-auto-assign-0-to-minibuffer'."
+  (let ((numbers))
+    (dotimes (i winum--window-count)
+      (push (1+ i) numbers))
+    (nreverse numbers)))
+
 (defun winum--switch-to-window (window)
   "Switch to the window WINDOW and switch input focus if on a different frame."
   (let ((frame (window-frame window)))
@@ -643,6 +629,10 @@ internal data structures according to the new scope."
 
 (add-hook 'delete-frame-functions #'winum--remove-deleted-frame-from-frames-table)
 
+(push "^No window numbered .$"     debug-ignored-errors)
+(push "^Got a dead window .$"      debug-ignored-errors)
+(push "^Invalid `winum-scope': .$" debug-ignored-errors)
+
 (provide 'winum)
 
 ;;; winum.el ends here