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JEmacs and the gnu.jemacs.buffer Package
Provides various building blocks for building an Emacs-like text editor.
It also provides a number of Scheme procedures that have the same name
and similar functionality as the Emacs Lisp functions.
Somewhat out of date.
Check the JEmacs home page
for more information.
It uses the Swing tool-kit.
Plan
The plan is to use
this together with the (unfinished) gnu.jemacs.lang
package to provide a fully-functional re-implementation of
Emacs Lisp which compiles to Java bytecodes.
I'm hoping volunteers will help me make "JEmacs" into something
useful. I have fairly clear ideas about much of what need to be
done. Contact me if you are interested.
Home page
There is now a JEmacs home page.
Also check out the
Kawa home page.
Screen snapshot
There is a now a
teaser screen snapshot.
Status
Very unfinished proof of concerpt.
It is a functional but very minimal editor.
Many of the core Emacs concepts (keymaps, windows, frames,
buffers, markers) are implemented, and generally in such a way as
to provide the standard Emacs semantics. There are Scheme functions
with the same name and similar behavior as the standard Emacs Lisp
functions. However, there is only a very limited set of core "editing"
commands, and no searching commands. And it is not
robust or reliable.
To-do
A couple of things volunteers might start with
(but let me know before you spend serious time on any of these):
- Implement more of the editing commands: Insert/delete/forward/backward
word/line.
- Display the modeline in inverse video, but extend it to the full
window width.
- Come up with a design for narrowing a buffer. One possibility
is to use some kind of invisible style for the text outside the narrowing.
But I think a more flexible design would use an "IndirectDocument" class
that refers to a sub-range of a buffer. This would help with "Indirect
Buffers", and might be flexible and elegant in general.
- Perhaps Buffer should inherit from Document (or rather
DefaultStyledDocument). However, that might lose some flexibility.
- Needs methods to control Window scrolling.
- Think about how to map extents and faces to Swing attributes
and styles.
- Decide how to implement Emacs strings.
Initially, we'll use kawa.lang.FString, but we do want to support strings
with extents and text properties.
Usage
These classes depend on Swing, so make sure you have Swing available.
Then make sure you have a version of the Kawa classes that contains
the gnu.jemacs.buffer classes. (In other words,
Kawa needs to have been configure --with-swing support.)
Then just start Kawa in the usual way:
java kawa.repl
Then evaluate:
(emacs)
That brings up a Emacs window.
You can do (split-window) to create new (sub-)windows
in an existing frame; type (make-frame) to create
a new frame (to-level window), or do (get-buffer-create NAME)
to create a new buffer.
Note also how ctrl/B and ctrl/F have been
bound to the correct functions. For other working key-bindings,
look for the calls to define-key in emacs.scm.
The call (scheme-swing-window) creates a new Scheme
interaction window.
License
Same as the package gnu.expr: Modified Gnu Public License.
See the file COPYING.
For now, the copyright holder is Per Bothner; in the future it may
make more sense to make the FSF the copyright owner, since the plan
is to use a lot of the existing ELisp packages once ELisp support
is complete.
Author
Per Bothner,
<bothner@gnu.org>
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