Re: [emacs-bidi] debugging visual-to-logical

[Behdad Esfahbod]

On Wed, 21 Nov 2001, Eli Zaretskii wrote:

> [Seems like my original reply didn't make it, so I'm resending.
> Sorry if you get this twice.]
> 
> > Date: Wed, 21 Nov 2001 14:51:57 +0330 (IRT)
> > From: Behdad Esfahbod <address@hidden>
> > 
> > > > Date: Tue, 20 Nov 2001 22:01:59 +0330 (IRT)
> > > > From: Behdad Esfahbod <address@hidden>
> > > > > > 
> > > > > > No, its ".3210-555-02 :SI REBMUN YM".
> > > > > 
> > > > > In what implementation of UAX#9 did you see this, and what type did
> > > > > that implementation assign to the upper-case letters and the digits?
> > > > > Especially the AN vs EN and AL vs R is important.
> > > > 
> > > > It was the Reference Implementations output, with A-F as AL and G-Z as 
> > > > R, also 0-5 as EN and 6-9 as AN
> > > 
> > > Didn't you (or someone else) just say that the reference
> > > implementation has incorrect definition of the type of `-'?
> > 
> > The definition is not incorrect, but just differenet from Unicode's 
> > types, this is the list of differences:
> > 
> > \x00-\x1f:
> > CapRTL:
> >   ON, ON, ON, ON,LTR,RTL, ON, ON, ON, ON, ON, ON, ON, BS,RLO,RLE, /* 00-0f 
> > */
> >  LRO,LRE,PDF, WS, ON, ON, ON, ON, ON, ON, ON, ON, ON, ON, ON, ON, /* 10-1f 
> > */
> >   WS, ON, ON, ON, ET, ON, ON, ON, ON, ON, ON, ET, CS, ON, ES, ES, /* 20-2f 
> > */
> > Unicode:
> >   BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,SS ,BS ,SS ,WS ,BS ,BN ,BN ,
> >   BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,BN ,BS ,BS ,BS ,SS ,
> >   WS ,ON ,ON ,ET ,ET ,ET ,ON ,ON ,ON ,ON ,ON ,ET ,CS ,ET ,CS ,ES ,
> 
> Now I'm _really_ confused: I thought we were talking about the
> differences between the Reference Implementation and the Unicode
> database, not between FriBidi and Unicode.  Or are you saying that
> FriBidi follows the Reference?

Eli, would you please have a look at the reference's code and 
fribidi's cmdline? (Let me know if you have not them around)

Reference has a char type set that is absolutely different and 
independent than Unicode, fribidi uses Unicode types, and supports 
some charsets, like utf-8, iso8859-6, .., and also an special charset 
named CapRTL, that is just for testing porpuses, and to make testing 
with Reference easy, it follows the Reference's char types in this 
special charset, everywhere (the default charset is utf-8) else it 
uses Unicode's types.

> > Char        CapRTL  Unicode
> > -----------------------
> > 6-9 AN      EN
> > @   RTL     ON
> > A-F AL      L
> > G-Z R       L
> > \   BS      ON
> > `   NSM     ON
> > |   SS      ON
> > ~   WS      ON
> > 
> > As you see it's much easier to test types like AN, AL, BS, NSM, SS,
> > RLE, LRE, RLO, LRO and PDF with CapRTL rather than Unicode, or your
> > variant, then we decided to use this for test porpuses in fribidi.
> 
> I agree that some codes must be allocated for character types that
> don't exist in the 7-bit ASCII area, but ON is not one of them.  So
> why was it a good idea to redefine `-' as ON?  `-' is a very
> frequently used character, and one that's involved in quite a few
> situations where the UAX#9 algorithm does not-so-wise things.
> Redefining the type of `-' is bound to produce lots of confusion, and
> complicates the task of judging the results from the user point of
> view.
> 
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> 

-- 
Behdad
30 Aban 1380, 2001 Nov 21

[Finger for Geek Code]