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-*-mode: text; coding: utf-8;-*-
Copyright (C) 2002-2015 Free Software Foundation, Inc.
See the end of the file for license conditions.
Importing a new Unicode Standard version into Emacs
-------------------------------------------------------------
Emacs uses the following files from the Unicode Character Database
(a.k.a. "UCD):
. UnicodeData.txt
. BidiMirroring.txt
. IVD_Sequences.txt
First, these files need to be copied into admin/unidata/, and then
Emacs should be rebuilt for them to take effect. Rebuilding Emacs
updates several derived files elsewhere in the Emacs source tree,
mainly in lisp/international/.
When Emacs is rebuilt for the first time after importing the new
files, pay attention to any warning or error messages. In particular,
admin/unidata/unidata-gen.el will complain if UnicodeData.txt defines
new bidirectional attributes of characters, because unidata-gen.el,
bidi.c and dispextern.h need to be updated in that case; failure to do
so will cause aborts in redisplay.
Next, review the changes in UnicodeData.txt vs the previous version
used by Emacs. Any changes, be it introduction of new scripts or
addition of codepoints to existing scripts, need corresponding changes
in the data used for filling char-script-table, see characters.el
around line 1300. Other databases and settings in characters.el, such
as the data for char-width-table, might also need changes.
Any new scripts added by UnicodeData.txt will also need updates to
script-representative-chars defined in fontset.el. Other databases in
fontset.el might also need to be updated as needed.
Problems, fixmes and other unicode-related issues
-------------------------------------------------------------
Notes by fx to record various things of variable importance. handa
needs to check them -- don't take too seriously, especially with
regard to completeness.
* SINGLE_BYTE_CHAR_P returns true for Latin-1 characters, which has
undesirable effects. E.g.:
(multibyte-string-p (let ((s "x")) (aset s 0 ?£) s)) => nil
(multibyte-string-p (concat [?£])) => nil
(text-char-description ?£) => "M-#"
These examples are all fixed by the change of 2002-10-14, but
there still exist questionable SINGLE_BYTE_CHAR_P in the
code (keymap.c and print.c).
* Rationalize character syntax and its relationship to the Unicode
database. (Applies mainly to symbol an punctuation syntax.)
* Fontset handling and customization needs work. We want to relate
fonts to scripts, probably based on the Unicode blocks. The
presence of small-repertoire 10646-encoded fonts in XFree 4 is a
pain, not currently worked round.
With the change on 2002-07-26, multiple fonts can be
specified in a fontset for a specific range of characters.
Each range can also be specified by script. Before using
ISO10646 fonts, Emacs checks their repertories to avoid such
fonts that don't have a glyph for a specific character.
fx has worked on fontset customization, but was stymied by
basic problems with the way the default face is dealt with
(and something else, I think). This needs revisiting.
* Work is also needed on charset and coding system priorities.
* The relevant bits of latin1-disp.el need porting (and probably
re-naming/updating). See also cyril-util.el.
* Quail files need more work now the encoding is largely irrelevant.
* What to do with the old coding categories stuff?
* The preferred-coding-system property of charsets should probably be
junked unless it can be made more useful now.
* find-multibyte-characters needs looking at.
* Implement Korean cp949/UHC, BIG5-HKSCS and any other important missing
charsets.
* Lazy-load tables for unify-charset somehow?
Actually, Emacs clears out all charset maps and unify-map just
before dumping, and they are loaded again on demand by the
dumped emacs. But, those maps (char tables) generated while
temacs is running can't be removed from the dumped emacs.
* iso-2022 charsets get unified on i/o.
With the change on 2003-01-06, decoding routines put `charset'
property to decoded text, and iso-2022 encoder pay attention
to it. Thus, for instance, reading and writing by
iso-2022-7bit preserve the original designation sequences.
The property name `preferred-charset' may be better?
We may have to utilize this property to decide a font.
* Revisit locale processing: look at treating the language and
charset parts separately. (Language should affect things like
spelling and calendar, but that's not a Unicode issue.)
* Handle Unicode combining characters usefully, e.g. diacritics, and
handle more scripts specifically (à la Devanagari). There are
issues with canonicalization.
* We need tabular input methods, e.g. for maths symbols. (Not
specific to Unicode.)
* Need multibyte text in menus, e.g. for the above. (Not specific to
Unicode -- see Emacs etc/TODO, but now mostly works with gtk.)
* There's currently no support for Unicode normalization.
* Populate char-width-table correctly for Unicode characters and
worry about what happens when double-width charsets covering
non-CJK characters are unified.
* There are type errors lurking, e.g. in
Fcheck_coding_systems_region. Define ENABLE_CHECKING to find them.
* Old auto-save files, and similar files, such as Gnus drafts,
containing non-ASCII characters probably won't be re-read correctly.
Source file encoding
--------------------
Most Emacs source files are encoded in UTF-8 (or in ASCII, which is a
subset), but there are a few exceptions, listed below. Perhaps
someday many of these files will be converted to UTF-8, for
convenience when using tools like 'grep -r', but this might need
nontrivial changes to the build process.
* chinese-big5
These are verbatim copies of files taken from external sources.
They haven't been converted to UTF-8.
leim/CXTERM-DIC/4Corner.tit
leim/CXTERM-DIC/ARRAY30.tit
leim/CXTERM-DIC/ECDICT.tit
leim/CXTERM-DIC/ETZY.tit
leim/CXTERM-DIC/PY-b5.tit
leim/CXTERM-DIC/Punct-b5.tit
leim/CXTERM-DIC/QJ-b5.tit
leim/CXTERM-DIC/ZOZY.tit
leim/MISC-DIC/CTLau-b5.html
leim/MISC-DIC/cangjie-table.b5
* chinese-iso-8bit
These are verbatim copies of files taken from external sources.
They haven't been converted to UTF-8.
leim/CXTERM-DIC/CCDOSPY.tit
leim/CXTERM-DIC/Punct.tit
leim/CXTERM-DIC/QJ.tit
leim/CXTERM-DIC/SW.tit
leim/CXTERM-DIC/TONEPY.tit
leim/MISC-DIC/pinyin.map
leim/MISC-DIC/CTLau.html
leim/MISC-DIC/ziranma.cin
* cp850
This file contains non-ASCII characters in unibyte strings. When
editing a keyboard layout it's more convenient to see 'é' than
'\202', and the MS-DOS compiler requires the single byte if a
backslash escape is not being used.
src/msdos.c
* iso-2022-cn-ext
This file is externally generated from leim/MISC-DIC/cangjie-table.b5
by Big5->CNS converter. It hasn't been converted to UTF-8.
leim/MISC-DIC/cangjie-table.cns
* japanese-iso-8bit
SKK-JISYO.L is a verbatim copy of a file taken from an external source.
It hasn't been converted to UTF-8.
leim/SKK-DIC/SKK-JISYO.L
* japanese-shift-jis
This is a verbatim copy of a file taken from an external source.
It hasn't been converted to UTF-8.
admin/charsets/mapfiles/cns2ucsdkw.txt
* iso-2022-7bit
This file switches between CJK charsets, which is not encoded in UTF-8.
etc/HELLO
Each of these files contains just one CJK charset, but Emacs
currently has no easy way to specify set-charset-priority on a
per-file basis, so converting any of these files to UTF-8 might
change the file's appearance when viewed by an Emacs that is
operating in some other language environment.
etc/tutorials/TUTORIAL.ja
lisp/international/ja-dic-cnv.el
lisp/international/ja-dic-utl.el
lisp/international/kinsoku.el
lisp/international/kkc.el
lisp/international/titdic-cnv.el
lisp/language/japan-util.el
lisp/language/japanese.el
lisp/leim/quail/cyril-jis.el
lisp/leim/quail/hanja-jis.el
lisp/leim/quail/japanese.el
lisp/leim/quail/py-punct.el
lisp/leim/quail/pypunct-b5.el
lisp/term/x-win.el
This file contains just Chinese characters, and has same problem.
Also, it contains characters that cannot be encoded in UTF-8.
lisp/international/titdic-cnv.el
* utf-8-emacs
These files contain characters that cannot be encoded in UTF-8.
lisp/language/tibetan.el
lisp/language/tibet-util.el
lisp/language/ind-util.el
lisp/leim/quail/ethiopic.el
lisp/leim/quail/tibetan.el
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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