Ok, just found time to continue the thread...
On Wed, 28 Mar 2001, Marco Cimarosti wrote:
> It depends. Enough for what?
>
> Storing the level with each character is enough for generating *one* valid
> Unicode logical order. This logical string should have the same logical
> order as the original string, and the embedding relationships (who embeds
> whom).
>
> But it is *not* enough to recreate *exactly* the same embedding controls
> that you had in the original text.
I know it will be enough for that. I'm just wondering about additional
bidi requirements (weak types, etc). We may need to have more info to make
life easier for the user, including outside the buffer information, like
"what is the user doing currently?", including 'inside a number', 'inside
a math-like expression', 'just finished an LTR embedding', etc. Also, we
may need to know which has been the character just inserted.
You know what I'm trying to do. I want to make it easier for the user at
all costs... I think we agree on the basic model (visual + emb. levels).
> For instance, imagine that the original text contained a stand-alone <PDF>.
> That control is just a terminator and, used alone is totally meaningless.
> So, once you remove it, you have lost it forever.
>
> If you ask me, this behavior is perfectly OK. But I was reasoning along your
> lines of being 100% prepared to future meanings of bidi controls.
It's OK. I'm almost sure that we should start working on a cannonical
equivalence thing for Bidi.
> Is this project online already? Where?
You should have received the announcement. For those who missed it, it's
at <http://fribidi.sourceforge.net/>. We're now working on stablizing it.
> > http://www.unicode.org/unicode/reports/tr20/#Bidi
>
> I read it, but I don't get a clear evidence that it is "illegal".
> [...]
> HTML 4.0 says: "If both methods are used, great care should be exercised to
> insure proper nesting of markup and directional embedding or override,
> otherwise, rendering results are undefined."
What I was refering to, was this:
This document goes beyond HTML and recommends that only the markup
should be used.
and this:
What to do if detected: In a browser context, ignore. [...]
I belive that these together mean that
<BDO dir="ltr">X&rlo;Y</BDO>Z&pdf; == <BDO dir="ltr">XY</BDO>Z
among man other things. (I think it also mean 'X&lro;Y&pdf;' == 'XY', but
perhaps we should ask the authors...)
--roozbeh
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