Re: [emacs-bidi] Re: Callbacks?

[Martin Duerst]

At 22:13 05/11/30, Gregg Reynolds wrote:
>Have you taken a look at the source for nxml mode?  You might be able to 
hack it up do do something like this.  As I understand it, in Emacs you can 
set whatever properties you like on each character in a buffer.  See node 
32.19, "Text Properties", of the Elisp manual.

I haven't looked at the actual nxml source, but otherwise,
that's very much what I have thought about.

>Now the interesting possibility presents itself, which is to add 
Unicode-related "special" (ie. built-in) text properties.  In particular, 
directional class.

Exactly!

>Then allow the user to override the Unicode-defined class for any 
particular character or set of chars in a buffer.  So in your example 
above, the nxml parser identifies weakly directional chars in the XML 
syntax, and switches their "unicode-directionality" property to strong LTR. 
Voila!  The bidi reordering obeys the user-set directionality and does the 
right thing.

Sorry I wasn't able to express this as well as you did.
This is exactly the direction we are working on.
The problem is that in some cases, only e.g. making '<', '>',
and so on (the markup characters) strong LTR isn't enough.
(but it gets a long way). Sometimes embeddings or
overrides are needed, and they are a bit more difficult
to do with properties, in particular if they are nested.

Regards,    Martin.