Re: Navigating completions from minibuffer

[Spencer Baugh]

Juri Linkov <juri@linkov.net> writes:
>> Here's an update patch with this approach.
>
> Sorry, the patch can't be applied, there is no existing
> completions--get-posn to change:
>
>> +This makes `completions--deselect' effective.")
>> +
>>  (defun completions--get-posn (position)
>>    "Return the completion at POSITION as a string."
>> -  (save-excursion
>> -    (goto-char position)

Oops, here it is again rebased directly onto master.

>From 874b455870ffd6057fd63e353240a91a742b3c2d Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh@catern.com>
Date: Thu, 23 Nov 2023 13:37:29 +0000
Subject: [PATCH] Deselect the selected completion candidate when typing

minibuffer-choose-completion-or-exit submits the selected completion
candidate, if any, ignoring the contents of the minibuffer.  But a
user might select a completion candidate and then want to type
something else in the minibuffer and submit what they typed.

Now typing will automatically deselect the selected completion
candidate so that minibuffer-choose-completion-or-exit will not choose
it.

minibuffer-choose-completion has the same behavior as before, and is
not affected by the deselection.

* lisp/minibuffer.el (completions-auto-update, completions--deselect)
(completions--update-if-displayed, completions--after-change)
(minibuffer--old-point, completions--post-command): Add.
(minibuffer-completion-help): Add completions--after-change and
completions--post-command as hooks.
(minibuffer-next-completion): Bind completions-auto-update to nil to
avoid immediately deselecting the completion.
(minibuffer-choose-completion-or-exit): Bind
choose-completion-deselect-if-after so deselection takes effect.
* lisp/simple.el (choose-completion-deselect-if-after): Add.
(completions--get-posn): Check choose-completion-deselect-if-after.
---
 lisp/minibuffer.el | 57 ++++++++++++++++++++++++++++++++++++++++++++--
 lisp/simple.el     | 10 +++++++-
 2 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 5c12d9fc914..a6acd1e999b 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -2378,6 +2378,52 @@ completions--fit-window-to-buffer
         (resize-temp-buffer-window win))
     (fit-window-to-buffer win completions-max-height)))
 
+(defcustom completions-auto-update 'deselect
+  "If non-nil, change the *Completions* buffer as you type.
+
+If `deselect', if a completion candidate in *Completions* is
+selected (point is on it), it will be deselected (point will be
+moved just before it) when the minibuffer point or contents
+change.
+
+This only affects the *Completions* buffer if it is already
+displayed."
+  :type '(choice (const :tag "*Completions* doesn't change as you type" nil)
+                 (const :tag "Typing deselects any completion candidate in 
*Completions*" deselect))
+  :version "30.1")
+
+(defun completions--deselect ()
+  "If in a completion candidate, move to just after the end of it.
+
+The candidate will still be chosen by `choose-completion' unless
+`choose-completion-deselect-if-after' is non-nil."
+  (when (get-text-property (point) 'mouse-face)
+    (goto-char (or (next-single-property-change (point) 'mouse-face)
+                   (point-max)))))
+
+(defun completions--update-if-displayed ()
+  "Update a displayed *Completions* buffer based on `completions-auto-update'"
+  (when completions-auto-update
+    (when-let (window (get-buffer-window "*Completions*" 0))
+      (with-selected-window window
+        (when (eq completions-auto-update 'deselect)
+          (completions--deselect))))))
+
+(defun completions--after-change ()
+  "Update displayed *Completions* buffer after change in minibuffer contents."
+  (when (minibufferp)
+    (completions--update-if-displayed)))
+
+(defvar-local minibuffer--old-point nil)
+
+(defun completions--post-command ()
+  "Update displayed *Completions* buffer after change in minibuffer point."
+  (when (and (minibufferp) (not (eq minibuffer--old-point (point))))
+    (setq minibuffer--old-point (point))
+    (unless (and completions-auto-update
+                 (memq this-command '(minibuffer-next-completion 
minibuffer-previous-completion)))
+      (completions--update-if-displayed))))
+
 (defun minibuffer-completion-help (&optional start end)
   "Display a list of possible completions of the current minibuffer contents."
   (interactive)
@@ -2400,6 +2446,8 @@ minibuffer-completion-help
           ;; If there are no completions, or if the current input is already
           ;; the sole completion, then hide (previous&stale) completions.
           (minibuffer-hide-completions)
+          (remove-hook 'post-command-hook #'completions--post-command t)
+          (remove-hook 'after-change-hook #'completions--after-change t)
           (if completions
               (completion--message "Sole completion")
             (unless completion-fail-discreetly
@@ -2460,6 +2508,9 @@ minibuffer-completion-help
             (body-function
              . ,#'(lambda (_window)
                     (with-current-buffer mainbuf
+                      (when completions-auto-update
+                        (add-hook 'post-command-hook 
#'completions--post-command nil t)
+                        (add-hook 'after-change-hook 
#'completions--after-change t))
                       ;; Remove the base-size tail because `sort' requires a 
properly
                       ;; nil-terminated list.
                       (when last (setcdr last nil))
@@ -4673,7 +4724,8 @@ minibuffer-next-completion
           (next-line-completion (or n 1))
         (next-completion (or n 1)))
       (when auto-choose
-        (let ((completion-use-base-affixes t))
+        (let ((completion-use-base-affixes t)
+              (completions-auto-update nil))
           (choose-completion nil t t))))))
 
 (defun minibuffer-previous-completion (&optional n)
@@ -4721,7 +4773,8 @@ minibuffer-choose-completion-or-exit
 contents."
   (interactive "P")
   (condition-case nil
-      (minibuffer-choose-completion no-exit no-quit)
+      (let ((choose-completion-deselect-if-after t))
+        (minibuffer-choose-completion no-exit no-quit))
     (error (minibuffer-complete-and-exit))))
 
 (defun minibuffer-complete-history ()
diff --git a/lisp/simple.el b/lisp/simple.el
index 02c68912dba..791b7dddedc 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -10094,6 +10094,11 @@ next-line-completion
           (if pos (goto-char pos))))
       (setq n (1+ n)))))
 
+(defvar choose-completion-deselect-if-after nil
+  "If non-nil, don't choose a completion candidate if point is right after it.
+
+This makes `completions--deselect' effective.")
+
 (defun choose-completion (&optional event no-exit no-quit)
   "Choose the completion at point.
 If EVENT, use EVENT's position to determine the starting position.
@@ -10114,6 +10119,9 @@ choose-completion
           (insert-function completion-list-insert-choice-function)
           (completion-no-auto-exit (if no-exit t completion-no-auto-exit))
           (choice
+           (if choose-completion-deselect-if-after
+               (substring-no-properties
+                (get-text-property (posn-point (event-start event)) 
'completion--string))
            (save-excursion
              (goto-char (posn-point (event-start event)))
              (let (beg)
@@ -10129,7 +10137,7 @@ choose-completion
                               beg 'completion--string)
                              beg))
                (substring-no-properties
-                (get-text-property beg 'completion--string))))))
+                (get-text-property beg 'completion--string)))))))
 
       (unless (buffer-live-p buffer)
         (error "Destination buffer is dead"))
-- 
2.42.1