Re: [emacs-bidi] Re: Callbacks?

[Gregg Reynolds]

Martin Duerst wrote:
> Good to know. The following are potential problems:
> - Can the properties be set for each mode individually?
> - Can the properties change based on context? As a simple
>   example, attributes in XML can be quoted with single quotes
>   or with double quotes. In the attribute value, the 'other'
>   quote can then be used literally. So if we have something
>   like
>   <element attr1="What's up?" attr2='He cried "Help!" and ran away.' />
>                  1    2     1       1         2     2              1
>   then for the places marked 1, which are XML syntax, we want to
>   change the properties (e.g. to LTR), but for the cases marked
>   with 2, which are content, we do not want to change the properties.
>   Would such a thing be possible?
> - In our current approach, we not only change the properties of some
>   characters, but also introduce additional embedding (or occasionally
>   override) levels. Is this possible in your implementation?
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.

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

-g