Re: feature/icomplete-vertical

[Manuel Uberti]

On 05/10/20 09:52, Gregory Heytings via Emacs development discussions. wrote:
> 
> Hi Ergus and João,
> 
> As I explained in a separate thread, at the moment the best way to implement
> icomplete-vertical (and in general to display completion candidates in the
> minibuffer) is to convince Emacs to start displaying the minibuffer at its
> beginning.  This avoids all known problems.
> 
> With this solution, displaying completion candidates after point in a 
> minibuffer
> is a trivial task: it suffices to insert the completion candidates in the
> minibuffer, and Emacs will display as many of these candidates as possible,
> given the user preferences (max-mini-window-height, resize-mini-windows, ...),
> the size of the Emacs frame, the phase of the moon, ...  This works on Emacs 
> 24,
> 25, 26, 27 and 28, with fixed and variable width fonts.
> 
> Part 1 of the solution (which solves the "root" problem, and is not specific 
> to
> icomplete-vertical):
> 
> (defvar-local start-display-at-beginning-of-minibuffer nil)
> (defun start-display-at-beginning-of-minibuffer (&rest args)
>   (when (and start-display-at-beginning-of-minibuffer (minibufferp))
>     (set-window-start-at-begin (point-min) (point))))
> (defun set-window-start-at-begin (beg end)
>   (when (< (+ beg 2) end)
>     (set-window-start nil beg)
>     (unless (pos-visible-in-window-p end nil t)
>       (set-window-start-at-begin (+ beg (/ (- end beg) 2)) end))))
> (add-hook 'window-scroll-functions #'start-display-at-beginning-of-minibuffer)
> (add-hook 'post-command-hook #'start-display-at-beginning-of-minibuffer)
> 
> Part 2 of the solution (which implements icomplete-vertical):
> 
> (setq icomplete-separator "\n")
> (add-hook 'icomplete-minibuffer-setup-hook (lambda () (setq
> start-display-at-beginning-of-minibuffer t)))
> (defun icomplete-vertical-reformat-completions (completions)
>   (save-match-data
>     (if (string-match "^\\((.*)\\|\\[.+\\]\\)?{\\(\\(?:.\\|\n\\)+\\)}" 
> completions)
>         (format "%s \n%s" (or (match-string 1 completions) "") (match-string 2
> completions))
>       completions)))
> (advice-add 'icomplete-completions :filter-return
> #'icomplete-vertical-reformat-completions)
> 
> The only limit of this solution is that is is not possible to display an
> ellipsis ("...") at the end of the completion candidates list, to indicate 
> that
> some completion candidates are not displayed.  This is a minor limitation, and
> IMO using one screen line just to display "..." is a waste of resources.
> 
> Gregory

Hi Gregory,

FWIW, your code works absolutely fine for me and I was able to replace the
external icomplete-vertical package with your solution.

Thanks for working on this.

-- 
Manuel Uberti
www.manueluberti.eu