[issue:250] Fwd: regexpatch: error on (u)pTeX with Japanese char

[Hironobu Yamashita]

もう一本転送します。 -- Hironobu Yamashita

---------- Forwarded message ---------
From: Enrico Gregorio <enrico.gregorio ＠ univr.it>
Date: 2019年1月16日(水) 4:14
Subject: Re: regexpatch: error on (u)pTeX with Japanese char
To: Hironobu Yamashita <h.y.acetaminophen ＠ gmail.com>


Now I know better about the issue. Of course, e-TeX is
required, but this you already were aware of.

The main problem is that `\tl_set_rescan:Nnn needs to
check whether the text to be rescanned starts with a
space and to do this it looks at the first token. If
the token is not a control sequence, the category code
is checked, but \catcode doesn’t work with kanji or kana
characters (section 10 in the pTeX manual, if I understand
it correctly with the help of Google).

The team command of Japanese is very scarce (big understatement).
Maybe \kcatcode could help in this case, but the details are
only in Japanese.

If there is a sane way to check whether a character token will
give a character code illegal with \catcode, then I guess a
further check can be added when the engine is epTeX.

Ciao
Enrico