Re: A feature to go to last edit locations

[Jean Louis <bugs@gnu.support>]

* Dmitry Gutov <dgutov@yandex.ru> [2023-02-12 21:09]:
> On 12/02/2023 19:41, Daniel Martín wrote:
> > What do you think?  Third-party packages like goto-last-change.el [2] or
> > session.el [3] (see session-jump-to-last-change) implement this feature
> > in a per-buffer basis, but I wonder if we could do better and implement
> > something that works across buffers.
> 
> I agree this kind of feature should work across buffers (and that's my main
> criticism of the global/local marks feature already).

I was reading, thanks, it inspired me. 

But Eli said something important, why go somewhere back randomly, but
better going where user marked it to need it.

Now I get it with single click: S-C-<down> to record point and then
S-C-<left> and <right> to go to previous or next one.

It is using database, but it may serve for brainstorming. I also try
to use database tables to switch to them, instead of buffers with
files.

Emacs has SQLite built-in, this way of work could be used in future,
or package could easily be made.

It would persist over sessions without problems.

And I could make a switch that instead of moving over global points,
and buffers, to move only in single buffer.

(defvar rcd-db-emacs-point-id nil
  "Last Emacs point ID where user jumped to.")

(defun rcd-db-emacs-point-next ()
  "Go to next Emacs point."
  (interactive)
  (let ((next (rcd-db-emacs-point-to-go "next")))
    next))

(defun rcd-db-emacs-point-previous ()
  "Go to previous Emacs point."
  (interactive)
  (let ((previous (rcd-db-emacs-point-to-go "previous")))
    previous))

(defun rcd-db-emacs-point-go-to (id)
  "Go to Emacs point ID."
  (let ((point (rcd-db-table-id-hash "emacspoints" id cf-db)))
    (when (hash-table-keys point)
      (let ((buffer-name (gethash "emacspoints_buffername" point))
	    (file-name (gethash "emacspoints_bufferfilename" point))
	    (table (gethash "emacspoints_table" point))
	    (column (gethash "emacspoints_column" point))
	    (table-id (gethash "emacspoints_tableid" point))
	    (point (gethash "emacspoints_point" point)))
	(cond ((and buffer-name
		    (buffer-live-p (get-buffer buffer-name))
		    (not file-name)
		    (not table))
	       (switch-to-buffer buffer-name)
	       (goto-char point))
	      ((and buffer-name file-name
		    (buffer-live-p (get-buffer buffer-name))
		    (not table))
	       (switch-to-buffer buffer-name)
	       (goto-char point))
	      ((and buffer-name file-name
		    (not (buffer-live-p (get-buffer buffer-name)))
		    (not table))
	       (find-file file-name)
	       (goto-char point))
	      ((and buffer-name table column table-id
		    (buffer-live-p (get-buffer buffer-name)))
	       (switch-to-buffer buffer-name)
	       (goto-char point))
	      ((and buffer-name table column table-id
		    (not (buffer-live-p (get-buffer buffer-name))))
	       (hyperscope-edit-with-mode table-id column)
	       (switch-to-buffer buffer-name)
	       (goto-char point))
	      (t (rcd-message "Point ID %s not found" id)))))))

(keymap-global-set "M-s-<left>" #'rcd-db-emacs-point-previous)
(keymap-global-set "M-s-<right>" #'rcd-db-emacs-point-next)
(keymap-global-set "M-s-<down>" #'rcd-db-emacs-point-record)

(defun rcd-db-emacs-point-to-go (direction)
  "Return next Emacs point to go by using DIRECTION.

DIRECTION is string that may be \"previous\" or \"next\"."
  (when (string-match "^next$\\|^previous$" direction)
    (let ((last (rcd-sql-first "SELECT emacspoints_id FROM emacspoints ORDER BY emacspoints_id DESC LIMIT 1" cf-db))
	  (first (rcd-sql-first "SELECT emacspoints_id FROM emacspoints ORDER BY emacspoints_id ASC LIMIT 1" cf-db))
	  (message (format "No %s point found" direction))
	  (next (when (integerp rcd-db-emacs-point-id)
		  (rcd-sql-first 
		   "SELECT emacspoints_id FROM emacspoints WHERE emacspoints_id > $1 ORDER BY emacspoints_id ASC LIMIT 1" 
		   cf-db rcd-db-emacs-point-id)))
	  (previous (when (integerp rcd-db-emacs-point-id)
		      (rcd-sql-first 
		       "SELECT emacspoints_id FROM emacspoints WHERE emacspoints_id < $1 ORDER BY emacspoints_id DESC LIMIT 1" 
		       cf-db rcd-db-emacs-point-id))))
      (cond ((and (string= direction "previous") 
		  rcd-db-emacs-point-id
		  previous)
	     (rcd-db-emacs-point-go-to 
	      (setq rcd-db-emacs-point-id previous)))
	    ((and (string= direction "previous")
		  rcd-db-emacs-point-id
		  (null previous)
		  last)
	     (rcd-db-emacs-point-go-to 
	     (setq rcd-db-emacs-point-id last)))
	    ((and (string= direction "previous")
		  rcd-db-emacs-point-id
		  (null previous)
		  (null last))
	     (rcd-message message))
	    ((and (string= direction "next")
		  rcd-db-emacs-point-id
		  next)
	     (rcd-db-emacs-point-go-to 
	     (setq rcd-db-emacs-point-id next)))
	    ((and (string= direction "next")
		  rcd-db-emacs-point-id
		  (null next)
		  first)
	     (rcd-db-emacs-point-go-to 
	     (setq rcd-db-emacs-point-id first)))
	    (t (rcd-message message))))))

(defun rcd-db-emacs-point-record ()
  "Record Emacs point in the database."
  (interactive)
  (let* ((buffer-name (buffer-name))
	 (file-name (buffer-file-name))
	 (table rcd-db-current-table)
	 (column rcd-db-current-column)
	 (table-id rcd-db-current-table-id)
	 (db-handle rcd-db-current-database-handle)
	 (db-name (cond ((and db-handle (rcd-sql-first "SELECT current_database()" db-handle))
			(t nil))))
	 (point (point))
	 (name (cond (current-prefix-arg (rcd-ask-get "Point name: "))
		     (table (format "DB: %s, table: %s, column: %s, ID: %s"
				    db-name table column table-id))
		     ((not file-name) (format "Buffer: %s" buffer-name))
		     (t (format "File: %s" file-name))))
	 (description (cond (current-prefix-arg (sql-escape-string (rcd-ask "Point description: ")))
			    (t "NULL")))
	 (table-uuid (when (and table-id
				(rcd-db-uuid-by-id table table-id cf-db))
			    (rcd-db-uuid-by-id table table-id cf-db))))
    (rcd-sql-first 
     (format "INSERT INTO emacspoints 
              (emacspoints_name, emacspoints_description, emacspoints_buffername, emacspoints_bufferfilename, emacspoints_dbname,
               emacspoints_table, emacspoints_column, emacspoints_tableid, emacspoints_tableuuid, emacspoints_point)
              VALUES ($1, %s, $2, %s, %s, %s, %s, %s, %s, $3)
              ON CONFLICT DO NOTHING
              RETURNING emacspoints_id" description 
	      (sql-escape-string-or-null file-name) (sql-escape-string-or-null db-name)
	      (sql-escape-string-or-null table) (sql-escape-string-or-null column) (or table-id "NULL")
	      (sql-escape-string-or-null table-uuid))
     cf-db name buffer-name point)))

-- 
Jean

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