New GNU ELPA package: cursor-undo - Undo Cursor Movement

[Sacha Chua]

    Summary: Undo Cursor Movement
    Website: https://elpa.gnu.org/packages/cursor-undo.html
   Keywords: undo cursor 
 Maintainer: Luke Lee <luke.yx.lee@gmail.com>
     Author: Luke Lee <luke.yx.lee@gmail.com>

Cursor-undo allows you to undo cursor movement commands using the Emacs
standard `undo' command.

For frequent cursor movements such as up/down/left/right, it combines
the movements of the same direction into a single undo entry.  This
prevents the undo command from reversing each individual character
movement separately.  For example, if you move the cursor 20 characters
to the right and then 10 lines up, the first undo will go down 10 lines
back, and the next undo move back 20 characters left.  On the other
hand, for search commands that often jump across multiple pages, each
search command has its own undo entry, allowing you to undo them one at
a time rather than as a combined operation.

This cursor-undo functionality has existed in my local Emacs init file
for over 11+ years, since version 0 on 2013-06-26.  It was originally
intended to support my Brief Editor Mode only, but I later found it
would be more useful if implemented in a more generalized way.  For
years I have hoped for an official implementation of this feature,
which is commonly seen among various editors.  Considering my
implementation using advice functions a bit inelegant so I have always
hesitated to release it till recently.

Until there is official support for the cursor undo feature, this
package serves most common daily needs.  The core design is to align
with Emacs's native `undo' function by recording cursor positions
and screen-relative position undo entries in the `buffer-undo-list'
in accordance with its documentation.

As this package primarily consists of advice functions to wrap cursor
movement commands, each cursor movement command needs to be manually
wrapped with `def-cursor-undo'.  For interactive functions that
heavily invoke advised cursor movement commands, you may even need to
advise them with `disable-cursor-tracking' to prevent generating
numerous distinct cursor undo entries from a single command.  For user
convenience, we have prepared ready `def-cursor-undo' advice sets for
standard Emacs cursor movement commands, Brief Editor mode, Viper
mode, and EVIL mode.

Usage:

  Once this package is installed, you only need to enable cursor-undo
  mode by adding the following line into your Emacs init file .emacs or
  init.el:

    (cursor-undo 1)

Notes for EVIL mode user:

  If you choose to use default Emacs `undo' system, you should be able
  to use `evil-undo' to undo cursor movements.  If your choice is
  tree-undo or another undo system, you might need to use Emacs default
  `undo' (C-_, C-/ or C-x u ...) to undo cursor movements.

Notes for Viper mode user:

  The default `viper-undo' is advised to allow cursor-undo.  If you
  find the advised function not working properly, consider comment out
  the following source code `(define-advice viper-undo ...' to restore
  the original `viper-undo' function and use Emacs default `undo'
  (C-_, C-/ or C-x u ...) to undo cursor movements.

Future TODO thoughts: a more desired implementation is to integrate it
into Emacs source by extending the `interactive' spec to add code
letters for various cursor undo information.

Luke Lee [2024-07-19 Fri.]