bug#66970: 29.1; Overwrite-mode is not working with Korean characters

[Eli Zaretskii <eliz@gnu.org>]

> From: João Távora <joaotavora@gmail.com>
> Date: Thu, 9 Nov 2023 16:37:17 +0000
> 
> Eli brought up this bug in emacs-devel and I thought
> I would give it a shot.
> 
> I had never touched this code or anything like it, but I do
> use input methods a bit for portuguese.  Let me know what
> you think.

Thanks.

Sukbeom, could you please try the patch and see if it gives good
results, both with and without Overwrite mode?

> diff --git a/lisp/leim/quail/hangul.el b/lisp/leim/quail/hangul.el
> index 46a2e5a6ba2..7e6c7310179 100644
> --- a/lisp/leim/quail/hangul.el
> +++ b/lisp/leim/quail/hangul.el
> @@ -146,21 +146,34 @@ hangul-insert-character
>        (progn
>          (delete-region (region-beginning) (region-end))
>          (deactivate-mark)))
> -  (quail-delete-region)
> -  (let ((first (car queues)))
> -    (insert
> -     (hangul-character
> -      (+ (aref first 0) (hangul-djamo 'cho (aref first 0) (aref first 1)))
> -      (+ (aref first 2) (hangul-djamo 'jung (aref first 2) (aref first 3)))
> -      (+ (aref first 4) (hangul-djamo 'jong (aref first 4) (aref first 5))))))
> -  (move-overlay quail-overlay (overlay-start quail-overlay) (point))
> -  (dolist (queue (cdr queues))
> -    (insert
> -     (hangul-character
> -      (+ (aref queue 0) (hangul-djamo 'cho (aref queue 0) (aref queue 1)))
> -      (+ (aref queue 2) (hangul-djamo 'jung (aref queue 2) (aref queue 3)))
> -      (+ (aref queue 4) (hangul-djamo 'jong (aref queue 4) (aref queue 5)))))
> -    (move-overlay quail-overlay (1+ (overlay-start quail-overlay)) (point))))
> +  (let* ((chars-to-insert
> +          (with-temp-buffer
> +            (dolist (queue queues (mapcar #'identity (buffer-string)))
> +              (insert
> +               (hangul-character
> +                (+ (aref queue 0) (hangul-djamo 'cho (aref queue 0)
> (aref queue 1)))
> +                (+ (aref queue 2) (hangul-djamo 'jung (aref queue 2)
> (aref queue 3)))
> +                (+ (aref queue 4) (hangul-djamo 'jong (aref queue 4)
> (aref queue 5))))))))
> +         (may-have-to-overwrite-p
> +          (or
> +           ;; If the overlay isn't showing (i.e. it has 0 length) then
> +           ;; we may want to insert char overwriting (iff overwrite-mode is
> +           ;; non-nil, of course)
> +           (= (overlay-start quail-overlay) (overlay-end quail-overlay))
> +           ;; Likewise we want to do it if there is more then one
> +           ;; character that were combined.
> +           (cdr chars-to-insert))))
> +    (quail-delete-region) ; this kills the overlay
> +    (dolist (c chars-to-insert)
> +      (let ((last-command-event c)
> +            (overwrite-mode (and overwrite-mode
> +                                 may-have-to-overwrite-p
> +                                 overwrite-mode)))
> +        (self-insert-command 1)
> +        ;; TODO: maybe use cl-loop for an easier-to-read loop?
> +        (setq may-have-to-overwrite-p nil)))
> +    ; this revives it (TODO: do we really always revive?)
> +    (move-overlay quail-overlay (1- (point)) (point))))
> 
>  (defun hangul-djamo (jamo char1 char2)
>    "Return the double Jamo index calculated from the arguments.
> 
> 
> 
> -- 
> João Távora
>