characters

早期freebsd实现

   Ideas for extending GNU Emacs to deal with arbitrary character sets.

I would like GNU Emacs to be extended to handle all the world's alphabets
and word signs.  I don't expect to have time to do such a thing in the next
few years, so here are my ideas on the best way to do it.

* Each graphic is represented by a sequence of ordinary 8-bit characters.

* All the characters that make up such a sequence have codes >= 0200.

* The first character of such a sequence is between 0200 and 0237.

* The remaining characters of such a sequence are all 0240 or higher.

* The first character of the sequence determines the number of characters
in the sequence.  Thus, 0200...0207 could start two-character sequences,
0210...0227 could start three-character sequences, and 0230 could start
four-character sequences.  (Codes 0231...0237 would be reserved.)

*  Several common  alphabets,  and  some mathematical   symbols,  would get
two-character sequences.  (Probably Greek,  Russian,  Hebrew(?), Arabic(?),
Korean, and Japanese kana).  The remaining alphabets, and  some versions of
Chinese,  would   get  three-character sequences.    Other  sets of Chinese
characters would get four-character sequences.

Each country that uses Chinese characters has its own standard character
set, and it is not easy to correlate them to avoid overlap.  So there may
need to be several sets of Chinese characters.  That is why they need so
much code space.

True support for Hebrew and Arabic requires dealing with the problem of
writing direction for mixed text; I don't know what to do for that.

* The functions that use syntax table would determine the
syntax of a sequence from its first character.

* Functions in indent.c for computing widths and columns would
determine the width of a sequence from its first character.
So would display routines.

* Only a few other editing routines would need any change.  In
particular, searching and regexp matching might not need any change.

* Most of the work required would be in redisplay.  The only case that
needs to be supported is with X windows, since ordinary terminals
can't display all these characters anyway.

* There might need to be code to translate files from this format
to whatever format is typically stored on disk.


I would be very unhappy with half-measures, such as support for
Japanese only.