Re: locale-*independent* vi editor supporting UTF-8

From: Markus Kuhn (
Date: Thu Nov 26 1998 - 07:42:45 EST

Jungshik Shin wrote on 1998-11-26 11:33 UTC:
> > The changes necessary would not be too significant. The major change is
> > that in order to count the number of characters in a string, you have to
> > count the bytes with (x & 0xc0) != 0xc0 instead of all bytes. The only
> > other significant problem with UTF-8 is the [] operator in regular
> > expressions, which currently assumes 1 byte = 1 character.
> That's what I thought and Mark Leisher's ucdata would be sufficient
> for the job(well, for regular expression handling would be beyond the
> range covered by it, for sure), but the author of one of several vi
> clones for Korean EUC encoding(EUC-KR) and JOHAB(another 1byte-2byte
> popular encoding for Korean that encodes all modern complete *and*
> _incomplete/partial_ syllables) claimed differently. I'll try to
> figure out .....

This depends on how far your UTF-8 support goes.

Things stay very easy with UTF-8 as long as you use only a level 1
subset of ISO 10646-1 that can be implemented in a simple fixed-width
(monospaced) left-to-right font. An example of such a subset are the
2800 characters in the new 6x13 fixed font for X11
< ucs-fonts.html> (minus may be the Hebrew
characters in there). Significant structural modifications are however
necessary if you want to support bi-width fonts, bidi, combining characters,
Indian and Arabic presentation forms, etc. We should start with simple UTF-8
without these things first, and a level-1 fixed-width left-to-right UTF-8
editor can already easily handle a huge number of languages very adequately.


Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at,  WWW: <>

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