The examples do not show forward-looking combiners.
Not sure what's happening with the ZWJ - I dimly recall that Unicode
says it is a misnomer and explicitly does not join arbitrary graphemes
into characters, but I don't have the reference handy.
Aleks-Daniel is showing that x 2 does not detect the situation when
concatenation places a combining mark behind a base character, which
should be turned into a single grapheme.
And that ~ does detect the combination.
Am 26.07.2017 um 18:33 schrieb Brandon Allbery:
Combining chars look forward now? This breaks *my* expectations.
On Wed, Jul 26, 2017 at 6:36 AM, Aleks-Daniel Jakimenko-Aleksejev
<perl6-bugs-follo...@perl.org <mailto:perl6-bugs-follo...@perl.org>> wrote:
# New Ticket Created by Aleks-Daniel Jakimenko-Aleksejev
# Please include the string: [perl #131801]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org/Ticket/Display.html?id=131801
<https://rt.perl.org/Ticket/Display.html?id=131801> >
Code:
say (“\c[COMBINING OVERLINE]a” x 2).chars
Result:
4
Code:
say (“\c[COMBINING OVERLINE]a” ~ “\c[COMBINING OVERLINE]a”).chars
Result:
3
Both should produce the same result (3). What happens here is “a” on
one side is not being squished into one grapheme with a combiner on
another side.
Please note that combiners are not the only thing can cause this.
Here is the same thing with ZWJ:
Code:
my $x = “\x[2695]\x[FE0F]a\x[1F468]\x[200D]”;
say ($x ~ $x).chars;
say ($x x 2).chars
Result:
5
6
I have a feeling that this is a known issue, and that there might be
a ticket for this already. However, I couldn't find it.
--
brandon s allbery kf8nh sine nomine associates
allber...@gmail.com <mailto:allber...@gmail.com> ballb...@sinenomine.net
<mailto:ballb...@sinenomine.net>
unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net
