Re: Composing Hebrew diacriticals

[Eli Zaretskii <eliz@gnu.org>]

> From: Kenichi Handa <handa@m17n.org>
> Cc: eliz@gnu.org, yair.f.lists@gmail.com, emacs-devel@gnu.org
> Date: Fri, 14 May 2010 17:10:33 +0900
> 
> I've just committed a fix.
> 
> Eli, please check the comments of set_iterator_to_next, and
> verify that I'm doing the right thing.

It looks okay at a first glance, thank you!

In the HELLO buffer, the RLM character is not composed with the
following parenthesis, though.  Is this a separate problem?

I will work on the issues you raised in the comments.  For now, I have
just one response: in this fragment from set_iterator_to_next:

		/* Update IT's char/byte positions to point the first
		   character of the next grapheme cluster, or to the
		   character visually after the current composition.  */
  #if 0
		/* Is it ok to do this directly? */
		IT_CHARPOS (*it) += it->cmp_it.nchars;
		IT_BYTEPOS (*it) += it->cmp_it.nbytes;
  #else
		/* Or do we have to call bidi_get_next_char_visually
		   repeatedly (perhaps not to confuse some internal
		   state of bidi_it)?  At least we must do this if we
		   have consumed all grapheme clusters in the current
		   composition because the next character will be in the
		   different bidi level.  */
		for (i = 0; i < it->cmp_it.nchars; i++)
		  bidi_get_next_char_visually (&it->bidi_it);

the "#else" part is doing TRT.  You cannot jump to a different place
in the buffer/string behind the back of bidi_get_next_char_visually,
because that would violate the integrity of its internal cache, which
must correspond to the buffer/string positions 1:1.

> I have not yet committed proper codes for Hebrew
> composition.  I'm now testing with this simple version.
> 
> (let ((pattern "[\u05D0-\u05F2][\u0591-\u05BF\u05C1-\u05C5\u05C7]+"))
>   (set-char-table-range
>    composition-function-table '(#x591 . #x5C7)
>    (list (vector pattern 1 'font-shape-gstring)
> 	 ["[\u0591-\u05C7]" 0 font-shape-gstring]))
>   (set-char-table-range
>    composition-function-table #x5C0 nil)
>   (set-char-table-range
>    composition-function-table #x5C6 nil))

Could you please look at the message I posted in
http://lists.gnu.org/archive/html/emacs-devel/2010-05/msg00251.html?
I still see the infloop, with the current trunk, even when
bidi-display-reordering is set to nil, after I type BET and DAGESH, as
described in that message.  What kind of problems in the information
that Uniscribe returns to Emacs could cause such a loop?

If I type a different diacritical after BET, like PATAH, there's no
infloop, but the display is incorrect: I see both the isolated PATAH
and the composed BAT+PATAH after it.

Jason, could you help me with this?  It looks like some
Uniscribe-specific issue.  TIA