Re: Next Gen JDEE

Paul Landes <[email protected]> writes:

> Again, my earlier plans were to create a brand new project and port
> over pieces from JDEE. Starting new I think is necessary to start the
> ball rolling where as a major refactoring of the existing code base
> would be an up hill battle against the mentioned inertia of a large
> project.

I recently did the same for Emacs Ada mode; the new code is much
cleaner and easier to maintain.

I prefer to program in Ada; I only use Java for Android projects and
FIRST robotics.

> - Replace beanshell with clojure

I gather clojure is better maintained, and will stay current with any
new Java features? In particular, generics?

> - Replace semantic with some Java based parser (maybe compiler like
> ASM)--however all fly compilation and syntax correction etc happens in
> Java. 

I wrote a new parser for Emacs Ada mode in elisp, and am now attempting
to re-implement that in Ada as an emacs dynamic module, for speed
reasons (some people have Ada files with over 1000 lines ...)..

I did this because the Ada language is more complex than other languages
Emacs support, and/or I'm more picky about getting the indentation right
for _all_ constructs :).

What parser to use depends heavily on how much you care about handling
incorrect syntax gracefully (to get parser-dependent stuff right while
editing). For Ada, I make no attempt to handle this gracefully
currently, but I hope to improve that in the new parser.

The parser is used for several things: indentation, navigation,
completion, and possibly highlighting. They all add different
requirements, but they all push towards implementing a complete parser.

The Semantic parser is LALR. The Emacs Ada mode parser (called 'wisi';
http://stephe-leake.org/emacs/wisi/wisi.html) is generalized LALR; it
can handle conflicts. The language that wisi parses is described in a
bison-like grammar file, so it could be used for Java. Using a
generalized LALR parser means it is much easier to write the grammar in
a way that is clear and understandable.

Interfacing an external parser to Emacs is currently not easy. Operating
as a separate process communicating thru pipes is slow, partly because
the Emacs pipe operations are not designed for large amounts of data, so
they have built-in delays. There is now an experimental dynamic module
interface, allowing external code to link to Emacs as a dynamic library,
but it's on a branch, and probably won't be in Emacs 25.

> - Entire project becomes an Emacs plugin 

There are at least three styles of Emacs plugin:

- Gnu ELPA package

- random elisp files (current status)

- dynamic library with elisp files (very experimental)

So I'm not clear what you mean here.

It should be fairly straight-forward to clean up the current code for
emacs master and package it as a Gnu ELPA package.

> - Move to a plugin approach so each add on is a separately maintained
> Emacs plugin. 

If you can identify clear candidates for plugins in the current code,
then moving to a plugin architecture for a rewrite makes sense.

Emacs Ada mode makes an attempt to support different backends for
indentation, compiling, and navigating (cross-reference). It's fairly
clean. It would be cleaner with eieio classes.

> If someone wants to resurrect jde-debug from JDEE into the new
> version, then that person creates a new Emacs plugin that fits in some
> next gen JDEE plugin architecture. 

If jde-debug is a Java/JVM backend for Emacs gud, then gud already has a
plugin architecture for its backends; it has very little to do with the
main jde mode. For example, there is no code related to gud in Emacs Ada
mode.

> This gets rid of some bloat ini the core next gen JDEE.

Perhaps it just needs to be split into separate Gnu ELPA projects.

> - Who has the time and initiative to help out (I can't do it all
> myself with current time constraints)

I'd like to work on getting the current code working with emacs master,
each depending on jde-core.

> - Should the project have a new name or carry the same name? My
> feeling was start a brand new project for the purpose of name space
> and maybe create more "buzz" as a "new" Emacs java development
> library.

Keep jdee, just do a major version bump.

-- 
-- Stephe

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