[luatex] Fribidi for LuaTeX

[Khaled Hosny]

On Tue, Jul 19, 2011 at 12:28:46PM -0600, Idris Samawi Hamid ادريس   سماوي حامد wrote:
> On Tue, 19 Jul 2011 12:06:00 -0600, Khaled Hosny
> <khaledhosny at eglug.org> wrote:
> 
> >>>The algorithm actually has a dedicated rule of this use case:
> >>>  http://www.unicode.org/reports/tr9/#Higher-Level_Protocols
> >>
> >>Sure. At the same time, these are exactly the kinds of rules we
> >>_don't_ want to deify.
> 
> >I'm not deifying anything, but it is unfair to criticise the algorithm
> >for not considering certain use cases while it is actually considering
> >them!
> 
> >>The people who write these things are not typographers. The bidi
> >>algorithm mixes text-editing needs with typesetting needs.
> 
> >I haven't seen any evidence of this, no I see how this would be a bad
> >thing. Unicode BiDi algorithm have been implemented and deployed by
> >millions of users world wide, and its behaviour is what most people
> >expect, drifting from it too much is not a wise idea IMO and I can see
> >it making more problems than it solves.
> 
> ===================
> A higher-level protocol may use an entirely different algorithm that
> heuristically auto-detects the paragraph embedding level based on
> the paragraph text and its context. For example, it could base it on
> whether there are more RTL characters in the text than LTR. As
> another example, when the paragraph contains no strong characters,
> its direction could be determined by the levels of the paragraphs
> before and after.
> ===================
> 
> Vague, speculative, and whoever wrote that clearly is not a
> typographer but someone apparently interested in text-editors. For
> someone writing, eg, a multilingual critical edition this would
> create havoc.

Those are mere hints; examples on what a higher protocol would do, not
part of the standard and you are in no way obliged to implement them.

> Anyway, the only point was that these rules need not be hard-coded
> in the core of luatex, that's all.

Agreed, though one can still write a core implementation that is
configurable, still, I don't see much benefit here over a pure lua
implementation.

Regards,
 Khaled

-- 
 Khaled Hosny
 Egyptian
 Arab