[PATCH] Unicode: update of combining code points

Unicode 6.3 defines the following code as combining or accents,
git_wcwidth() should return 0.

Earlier unicode standards had defined these code point as "reserved":

358 COMBINING DOT ABOVE RIGHT
359 COMBINING ASTERISK BELOW
35A COMBINING DOUBLE RING BELOW
35B COMBINING ZIGZAG ABOVE
35C COMBINING DOUBLE BREVE BELOW
487 COMBINING CYRILLIC POKRYTIE
5A2 HEBREW ACCENT ATNAH HAFUKH,
5BA HEBREW POINT HOLAM HASER FOR VAV
5C5 HEBREW MARK LOWER DOT
5C7 HEBREW POINT QAMATS QATAN
604 ARABIC SIGN SAMVAT
616 ARABIC SMALL HIGH LIGATURE ALEF WITH LAM WITH YEH
617 ARABIC SMALL HIGH ZAIN
618 ARABIC SMALL FATHA
619 ARABIC SMALL DAMMA
61A ARABIC SMALL KASRA
659 ARABIC ZWARAKAY
65A ARABIC VOWEL SIGN SMALL V ABOVE
65B ARABIC VOWEL SIGN INVERTED SMALL V ABOVE
65C ARABIC VOWEL SIGN DOT BELOW
65D ARABIC REVERSED DAMMA
65E ARABIC FATHA WITH TWO DOTS
65F ARABIC WAVY HAMZA BELOW

This commit touches only the range 300-6FF, there may be more to be updated.

Signed-off-by: Torsten Bögershausen <redacted>
---
 utf8.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/utf8.c b/utf8.c
index a831d50..77c28d4 100644
--- a/utf8.c
+++ b/utf8.c

@@ -84,11 +84,10 @@ static int git_wcwidth(ucs_char_t ch)
 	 *   "uniset +cat=Me +cat=Mn +cat=Cf -00AD +1160-11FF +200B c".
 	 */
 	static const struct interval combining[] = {
-		{ 0x0300, 0x0357 }, { 0x035D, 0x036F }, { 0x0483, 0x0486 },
-		{ 0x0488, 0x0489 }, { 0x0591, 0x05A1 }, { 0x05A3, 0x05B9 },
-		{ 0x05BB, 0x05BD }, { 0x05BF, 0x05BF }, { 0x05C1, 0x05C2 },
-		{ 0x05C4, 0x05C4 }, { 0x0600, 0x0603 }, { 0x0610, 0x0615 },
-		{ 0x064B, 0x0658 }, { 0x0670, 0x0670 }, { 0x06D6, 0x06E4 },
+		{ 0x0300, 0x036F }, { 0x0483, 0x0489 }, { 0x0591, 0x05BD },
+		{ 0x05BF, 0x05BF }, { 0x05C1, 0x05C2 }, { 0x05C4, 0x05C5 },
+		{ 0x05C7, 0x05C7 }, { 0x0600, 0x0604 }, { 0x0610, 0x061A },
+		{ 0x064B, 0x065F }, { 0x0670, 0x0670 }, { 0x06D6, 0x06E4 },
 		{ 0x06E7, 0x06E8 }, { 0x06EA, 0x06ED }, { 0x070F, 0x070F },
 		{ 0x0711, 0x0711 }, { 0x0730, 0x074A }, { 0x07A6, 0x07B0 },
 		{ 0x0901, 0x0902 }, { 0x093C, 0x093C }, { 0x0941, 0x0948 },

-- 
1.9.0

Torsten Bögershausen:

Is there a script that generates this code from the Unicode database 
files, or did you hand-update it?

-- 
\\// Peter - http://www.softwolves.pp.se/

On 15.04.14 21:10, Peter Krefting wrote:

Torsten Bögershausen:

quoted

diff --git a/utf8.c b/utf8.c
index a831d50..77c28d4 100644
--- a/utf8.c
+++ b/utf8.c

Is there a script that generates this code from the Unicode database files, or did you hand-update it?

Some of the code points which have "0 length on the display" are called
"combining", others are called "vowels" or "accents".
E.g. 5BF is not marked any of them, but if you look at the glyph, it should
be combining (please correct me if that is wrong).

If I could have found a file which indicates for each code point, what it
is, I could write a script.

So yes, it is updated by hand.

On 16/04/2014 07:48, Torsten Bögershausen wrote:

On 15.04.14 21:10, Peter Krefting wrote:

quoted

Torsten Bögershausen:

quoted

diff --git a/utf8.c b/utf8.c
index a831d50..77c28d4 100644
--- a/utf8.c
+++ b/utf8.c

Is there a script that generates this code from the Unicode database files, or did you hand-update it?

Some of the code points which have "0 length on the display" are called
"combining", others are called "vowels" or "accents".
E.g. 5BF is not marked any of them, but if you look at the glyph, it should
be combining (please correct me if that is wrong).

Indeed it is combining (more specifically it has General Category 
"Nonspacing_Mark" = "Mn").

If I could have found a file which indicates for each code point, what it
is, I could write a script.

The most complete and machine-readable data are in these files:

http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
http://www.unicode.org/Public/UCD/latest/ucd/EastAsianWidth.txt

The general categories can also be seen more legibly in:

http://www.unicode.org/Public/UCD/latest/ucd/extracted/DerivedGeneralCategory.txt

For docs, see:

http://www.unicode.org/reports/tr44/
http://www.unicode.org/reports/tr11/
http://www.unicode.org/ucd/

The existing utf8.c comments describe the attributes being selected from 
the tables (general categories "Cf","Mn","Me", East Asian Width "W", 
"F"). And they suggest that the combining character table was originally 
auto-generated from UnicodeData.txt with a "uniset" tool. Presumably this?

https://github.com/depp/uniset

The fullwidth-checking code looks like it was done by hand, although 
apparently uniset can process EastAsianWidth.txt.

Kevin

On 2014-04-16 12.51, Kevin Bracey wrote:

On 16/04/2014 07:48, Torsten Bögershausen wrote:

quoted

On 15.04.14 21:10, Peter Krefting wrote:

quoted

Torsten Bögershausen:

quoted

diff --git a/utf8.c b/utf8.c
index a831d50..77c28d4 100644
--- a/utf8.c
+++ b/utf8.c

Is there a script that generates this code from the Unicode database files, or did you hand-update it?

Some of the code points which have "0 length on the display" are called
"combining", others are called "vowels" or "accents".
E.g. 5BF is not marked any of them, but if you look at the glyph, it should
be combining (please correct me if that is wrong).

Indeed it is combining (more specifically it has General Category "Nonspacing_Mark" = "Mn").

quoted

If I could have found a file which indicates for each code point, what it
is, I could write a script.

The most complete and machine-readable data are in these files:

http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
http://www.unicode.org/Public/UCD/latest/ucd/EastAsianWidth.txt

The general categories can also be seen more legibly in:

http://www.unicode.org/Public/UCD/latest/ucd/extracted/DerivedGeneralCategory.txt

For docs, see:

http://www.unicode.org/reports/tr44/
http://www.unicode.org/reports/tr11/
http://www.unicode.org/ucd/

The existing utf8.c comments describe the attributes being selected from the tables (general categories "Cf","Mn","Me", East Asian Width "W", "F"). And they suggest that the combining character table was originally auto-generated from UnicodeData.txt with a "uniset" tool. Presumably this?

https://github.com/depp/uniset

The fullwidth-checking code looks like it was done by hand, although apparently uniset can process EastAsianWidth.txt.

Kevin

Excellent, thanks for the pointers.
Running the script below shows that 
"0X00AD SOFT HYPHEN" should have zero length (and some others too).
I wonder if that is really the case, and which one of the last 2 lines 
in the script is the right one.

What does this mean for us:
"Cf 	Format 	a format control character"


#!/bin/sh

if ! test -f UnicodeData.txt; then
  wget http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
fi &&
if ! test -f EastAsianWidth.txt; then
  wget http://www.unicode.org/Public/UCD/latest/ucd/EastAsianWidth.txt
fi
if ! test -f DerivedGeneralCategory.txt; then
  wget http://www.unicode.org/Public/UCD/latest/ucd/extracted/DerivedGeneralCategory.txt
fi &&
if ! test -d uniset; then
  git clone https://github.com/tboegi/uniset.git
fi &&
(
  cd uniset &&
  if ! test -x uniset; then 
    autoreconf -i &&
    ./configure --enable-warnings=-Werror CFLAGS='-O0 -ggdb'
  fi &&
  make
) &&
UNICODE_DIR=. ./uniset/uniset --32 cat:Me,Mn,Cf
#UNICODE_DIR=. ./uniset/uniset --32 cat:Me,Mn

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On 16/04/2014 22:58, Torsten Bögershausen wrote:

Excellent, thanks for the pointers.
Running the script below shows that
"0X00AD SOFT HYPHEN" should have zero length (and some others too).
I wonder if that is really the case, and which one of the last 2 lines
in the script is the right one.

What does this mean for us:
"Cf 	Format 	a format control character"

Maybe dig back through the Git logs to check the original logic, but the 
comments suggest that "Cf" characters have been viewed as zero-width. 
That makes sense - they're usually markers indicating things like 
bidirectional text flow, so won't be taking space. (Although they may be 
causing even more extreme layout effects...)

Soft-hyphen is noted as an explicit exception to the rule in the utf8.c 
comments. As of Unicode 4.0, it's supposed to be a character indicating 
a point where a hyphen could be placed if a line-wrap occurs, and if 
that wrap happens, then it can actually take up 1 space, otherwise not. 
So its width could be either 0 or 1, depending. Or, quite likely, the 
terminal doesn't treat it specially, and it always just looks like a 
hyphen... Thus we err on the safe side and give it width 1.

See http://en.wikipedia.org/wiki/Soft_hyphen for background.

The comments suggest adding "-00AD +1160-11FF" to the uniset command 
line for that tweak and for composing Hangul. (The +200B tweak isn't 
necessary any more - Zero-Width Space U+200B became Cf officially in 
Unicode 4.0.1:

http://en.wikipedia.org/wiki/Zero-width_space
http://www.unicode.org/review/resolved-pri.html#pri21
)

All of this is only really an approximation - a best-effort attempt to 
figure out the width of a string without any actual communication with 
the display device. So it'll never be perfect. The choice between double 
and single width in particular will often be unpredictable, unless you 
had deeper locale knowledge.

Actually, while doing this, I've realised that this was originally 
Markus Kuhn's implementation, and that is acknowledged at the top of the 
file:

http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c

Good, because he knows what he's doing.

Kevin

Torsten Bögershausen:

Some of the code points which have "0 length on the display" are called
"combining", others are called "vowels" or "accents".
E.g. 5BF is not marked any of them, but if you look at the glyph, it should
be combining (please correct me if that is wrong).

All combining characters has a non-zero combining class in 
http://www.unicode.org/Public/UNIDATA/UnicodeData.txt (fourth field, 
called Canonical_Combining_Class in 
http://www.unicode.org/reports/tr44/ ). For instance, the aforementioned 
U+05BF is defined as follows:

   05BF;HEBREW POINT RAFE;Mn;23;NSM;;;;;N;;;;;

The combining class is 23, so this is a combining character.

There is a difference between non-spacing combining marks ("Mn" in the 
third column (General_Category)) and others ("Mc" for spacing marks 
and "Me" for enclosing marks), so they might need specifial handling. 
Additionally, you have the "zero-width" characters, such as U+200B 
Zero Width Space. These have the "Cf" class, although it also contains 
visible characters IIRC.

-- 
\\// Peter - http://www.softwolves.pp.se/