[luatex] BiDi implementation in lua

[Khaled Hosny]

I've been working on an implementation of Unicode Bidirectional
Algorithm[1] purely in lua for quite sometime now, the code started as
translation of an implementation written in C but have evolved since
then.

The algorithm part is more or less done, I've, informally,
verified that relevant rules are implemented correctly (some optional
rules make no sense in the ConTeXt of luatex). The interface with
luatex's node list is the trickiest part, but so far I think the result
is acceptable now, though I still encounter some mysterious results
occasionally that I've no explanation for.

The code is macro package neutral as far as it goes, and there is
currently packages for ConTeXt, plain and LaTeX though only ConTeXt was
tested with real world documents.

The code is located on github[2]. There are some sample documents (a
ConTeXt demo is at the end of the t-bidi.tex file, processing it with
context will run it).

There are some issue that I want to solve, including handling of math
mode a providing a real interface with more options for customisable
parts and writing some documentation.

The LaTeX package is called luabidi but there already a package with
that name and bidi is already taken, I'm still thinking of another name
(originally I named it luadirection as I had that ambitious goal of
supporting vertical text as well, but I'm now aiming at bidi in
horizontal contexts only).

[1] http://www.unicode.org/reports/tr9/
[2] https://github.com/khaledhosny/luadirections

Regards,
 Khaled

-- 
 Khaled Hosny
 Egyptian
 Arab