[XeTeX] VIQR pre-processor wrotten in (Xe)TeX ?

[Bruno Le Floch]

> Bruno Le Floch wrote:
>> Is it simply a matter of going through the string and replace various
>> characters by TeX accents (and take care of character order), or does
>> the result have to be Unicode?
>>
>> E.g., does it have to be a(a^ → ăâ, or can it be a(a^ → \u{a}\^{a} ?
>> If the second one is ok, then it shouldn't be too hard to write the
>> conversion in TeX macros. Please provide a list of the necessary
>> conversion rules.
>
> Vietnamese is difficult for TeX, because over a single
> character there can be a requirement for both an
> accent (to indicate a pronunciation different from
> that for the unaccented letter) and a tone marker
> (which applies to the whole word, but which has
> a canonical placement that may well be on an
> already accented letter).  Hàn Thế Thành created
> a way of accomplishing this using standard TeX,
> but XeTeX can do it natively.  Incidentally,
> the "ế" at the end of Thành's middle name demonstrates
> exactly the problem : something that TeX cannot
> accomplish without special fonts, since it has
> no primitive for positioning two diacritics over
> a single character.

Thanks for the explanation. So we need to produce a Unicode string.

Firstly, I should have asked: is it possible to require the Vietnamese
VIQR input as an argument of a macro, rather than being typeset
directly? e.g., \viqr{a^o' e\.}. I'll assume that it is ok.

Then do you have a list of all Vietnamese characters and their VIQR
representation? Or some precise reference to what transformation you
want to apply? In particular, how many different characters do you
expect to get on output (that should be the size of the "alphabet")?

Regards,
Bruno