Hello,
I suggest allowing \Ucharcat to produce active characters. See
three-line patch attached. This would allow to produce active
characters expandably in all engines (pdfTeX, luaTeX, XeTeX, pTeX,
upTeX). My code makes
\Ucharcat `~ 13
\expandafter\show\Ucharcat `~ 13
\edef\foo{\expandafter\noexpand\Ucharcat `~ 13 }
run the code of the active ~ as if it had been typed directly, then show
its meaning, then do the equivalent of \def\foo{~}.
Bruno
>From ab3698191833315858cb5751af886230ffc2a82d Mon Sep 17 00:00:00 2001
From: Bruno Le Floch <br...@le-floch.fr>
Date: Wed, 18 Apr 2018 10:52:55 -0400
Subject: [PATCH] Allow Ucharcat to produce active characters
This is a bit more involved than changing the bounds check because
the "cur_tok" of active characters is like that of control sequences
rather than that of usual characters.
---
source/texk/web2c/xetexdir/xetex.web | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/source/texk/web2c/xetexdir/xetex.web b/source/texk/web2c/xetexdir/xetex.web
index f7b0bbe..2e5be00 100644
--- a/source/texk/web2c/xetexdir/xetex.web
+++ b/source/texk/web2c/xetexdir/xetex.web
@@ -10499,6 +10499,7 @@ while k<pool_ptr do
t := @"10000 + (t - @"D800) * @"400 + (so(str_pool[k]) - @"DC00);
end;
if cat=0 then t := other_token + t
+ else if cat=active_char then t := cs_token_flag + active_base + t
else t := max_char_val * cat + t;
end;
fast_store_new_token(t);
@@ -10658,7 +10659,7 @@ selector:=old_setting; link(garbage):=str_toks_cat(b,cat); ins_list(link(temp_he
end;
@ Not all catcode values are allowed by \.{\\Ucharcat}:
-@d illegal_Ucharcat_catcode(#)==(#<left_brace)or(#>other_char)or(#=out_param)or(#=ignore)
+@d illegal_Ucharcat_catcode(#)==(#<left_brace)or(#>active_char)or(#=out_param)or(#=ignore)
@<Scan the argument for command |c|@>=
case c of
@@ -10676,7 +10677,7 @@ XeTeX_Ucharcat_code:
if illegal_Ucharcat_catcode(cur_val) then
begin print_err("Invalid code ("); print_int(cur_val);
@.Invalid code@>
- print("), should be in the ranges 1..4, 6..8, 10..12");
+ print("), should be in the ranges 1..4, 6..8, 10..13");
help1("I'm going to use 12 instead of that illegal code value.");@/
error; cat:=12;
end else
--
1.9.1
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