Hi, please could you add Zile? The following is the same as last year's entry:
<h2><a href="" href="http://www.gnu.org/software/zile/" target="_blank">http://www.gnu.org/software/zile/>Zile</h2>
<p>GNU Zile (short for "Zile Implements Lua Editors") is a toolkit
for building editors. Zile has all of Emacs's basic editing features:
it is 8-bit clean (though it currently lacks Unicode support), and the
number of editing buffers and windows is only limited by available
memory and screen space respectively. Syntax coloring, registers,
minibuffer completion and auto-fill are available. Function and variable
names are identical with Emacs's.</p>
<p>Zile currently currently comes with two editors: Zmacs,
which as the name suggests emulates Emacs, and Zz, which does not
support any form of Lisp, and is Emacs-inspired rather than a strict
clone.</p>
<p>In approximate order of increasing difficulty, here are some projects that would help improve Zile:</p>
<h3>Add Unicode support</h3>
<p>For Zile to be useful for building serious editors, it needs
Unicode support. Emacs's interface to encoding systems could be used as a
model. There are already a few unicode helper libraries for Lua, which
should serve as the basis for a unicode support module for
Zile.</p>
<h3>BDD/TDD</h3>
<p>Zile has a legacy test suite for Emacs lisp compatibility, and a
new infrastructure for a more comprehensive Behaviour Driven
Development suite. The legacy tests need to be moved to the new
infrastructure, and then the existing modules should be formally
specified with new BDD examples. This is a great opportunity to get
some practice working with TDD tools in a real project.</p>
<h3>Idiomatic Lua</h3>
<p>Lua Zile is still mostly a line-by-line translation of the
earlier C Zile implementation, and as such fails to make the most of
what the Lua language offers to simplify and shorten high level code,
while being too liberal with the global namespace and not keeping proper
cohesion and coupling between the potentially self-contained parts of
the code. Refactoring is already well underway, but there's a lot of
scope for re-engineering and refactoring the rest of the code base to
support easier reuse</p>
<h3>Syntax Highlighting</h3>
<p>An earlier fork of Lua Zile provides the proof of concept for a
barely-fast-enough restartable syntax parser and highlighting engine
based on regexps and a state-machine. The new combined multi-editor
tree needs to be refactored to allow merging the syntax highlighting
module. If time allows, the restartable regexp parser would benefit
hugely by being rewritten as using LPEG (Parsed _expression_ Grammars),
and parsers for languages other than Lua and C added.</p>
<h3>Nested Buffers</h3>
<p>The syntax highlighting proof of concept is engineered to allow
different parts of a buffer to be highlighted separately, for instance
an HTML file with embedded PHP, CSS and _javascript_. This concept should
be expanded to allow different keycaps to be active for certain parts
of a buffer, for instance a shell interaction buffer that recognizes
compiler error messages and in that part of the buffer treats an ENTER
keypress as jumping to the file and line of the error message. If time
allows, this feature could be improved to display of parts of other
buffers inside the current buffer, highlighted appropriately, in this
case injecting the text of the just the function surrounding the error
message directly into the current buffer, highlighting it correctly
according to the language it is written in, and then saving it back
correctly to the appropriate file and removing the injected text from
the current buffer.</p>
<h3>Splay Ropes Buffers</h3>
<p>Right now, Zile provides only a single buffer-gap based buffer
implementation - as used by GNU Emacs. A more comprehensive Editor
Building Toolkit really needs some alternative data-structures for
editor builders to select, such as a Splay Ropes data structure. Other
sensible data-structures as alternatives or additions to buffer-gap
would also be welcome.</p>
<h3>Zile Lisp</h3>
<p>The Lisp engine used to simulate a tiny subset of zmacs' elisp
emulation has seen dramatic improvements in recent months, and already
supports many features not available in the earlier C Zile project, such
as macros, eval/apply, a REPL; as well as better elisp compatibility to
provide minimal features for the BDD specs. There is a huge amount of
scope for improving the Lisp engine itself, adding a faster Cons/List
implementation and the like, and also for adding better elisp
compatibility to facilitate porting more of the zmacs implementation
itself to lisp.</p>
<h3>Zz</h3>
<p>Zz, the other editor currently shipped with Zile, aims to
leverage the already existing and well proven UNIX tools, as compared to
Zmacs which wants to be a Lisp shell and IDE in the vein of Emacs. The
current implementation has only gone so far in that direction as to
replace Lisp with Lua. Much more work is required to replace remaining
Emacs-like features with implementations that leverage the system
tools. Much inspiration can be gained from Sam and ACME on Plan 9; Wily
on Linux; and TextMate on Mac OS X... all of which integrate with the
operating system userspace rather than reimplement equivalent features
in the editor itself.</p>
<h3>Zi</h3>
<p>Zile currently provides a Lua implementation of a micro-emacs,
called Zmacs. To improve the flexibility of the new Lua Zile
frameworks, the components should be refactored and assembled into an
alternative modal vi like editor -- which we'll call Zi.</p>
<h3>Graphical Toolkit</h3>
<p>Some care was taken to maintain separation of concerns between
the user interface (keyboard input and buffer redisplay) and the
internals of Zile based editors, but with only a single curses user
interface it's hard to be sure that the abstractions are sufficiently
clean. Adding support for an alternative GUI using GTK+, Qt or even the
Mac or Windows native toolkits, along with whatever refactorings are
required to support that would make using Zile to implement future
editors with different io requirements much easier.</p>
<h3>More Editors</h3>
<p>In addition to Zmacs and Zz in the current Zile release, plus
Zi on the horizon, there is also a fork of the old single editor tree
called Zee, a much more minimal editor, which should be merged back in
as an alternative editor example in the new multi-editor tree. Further,
implementations of Nano, or WordStar, or some ancient DOS editor could
be added. Much of the work in adding an editor will be to refactor the
code on the boundaries between the Zile objects and files and the
existing editors to facilitate easily writing new editors, while keeping
the existing ones working correctly.</p>
<p>If you're interested in portable software engineering and
re-engineering, Emacs or other text editors, or traditional UNIX tools
and their future incarnations, you should find a project to interest
you.</p>