catc-act.mkii / last modification: 2020-01-30 14:15
%D \module
%D   [       file=catc-act,
%D        version=2006.09.18,
%D          title=\CONTEXT\ Catcode Macros,
%D       subtitle=Default Catcode Tables,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

%D This module deals with some active character handling. Use
%D with care.

%D \macros
%D   {installactivecharacter}

\def\installactivecharacter#1 %
  {\edef\temp{\detokenize{#1}}%
   \cctcounterc\expandafter`\temp\relax % relax needed
   \expandafter\startextendcatcodetable
      \expandafter\ctxcatcodes\expandafter\catcode\the\cctcounterc\activecatcode
   \stopextendcatcodetable
   \letcatcodecommand \ctxcatcodes \cctcounterc \temp \relax
   \ifnum\currentcatcodetable=\ctxcatcodes \setcatcodetable\ctxcatcodes \fi}

%D \macros
%D   {defineactivecharacter}
%D
%D Use this one with care, esp in combination with catcode
%D vectors. There are better ways now.

\chardef\activehackcode=`~

\def\defineactivecharacter #1#2 #3%
  {\cctcounterc\uccode\activehackcode
   \if#1"\uccode\activehackcode\expandafter\doifnumberelse\expandafter{\string#1#2}\empty #1#2\else
         \uccode\activehackcode\expandafter\doifnumberelse\expandafter{\string#1#2}\empty`#1#2\fi
   \catcode\uccode\activehackcode\activecatcode
   \uppercase{\def\next{~}}%
   \uccode\activehackcode\cctcounterc
   \expandafter\expandafter\expandafter\def\expandafter\next\expandafter
     {\expandafter\dohandleactivecharacter\next{#3}}}

\chardef\activecharactermode\plusone % overloading still backward compatible

\def\dodohandleactivecharacter#1#2{#2}
\def\donthandleactivecharacter#1#2{\noexpand#1}

\def\dohandleactivecharacter
  {\ifcase\activecharactermode
     \expandafter\donthandleactivecharacter
   \else
     \expandafter\dodohandleactivecharacter
   \fi}

\def\makecharacteractive #1 {\catcode`#1\active}

% \def\installanddefineactivecharacter #1 % #2%
%   {\normalexpanded{\noexpand\installactivecharacter \utfchar{#1} }% wrong
%    \defineactivecharacter #1 }% {#2}}

\endinput