%D \module
%D   [       file=strc-lev,
%D        version=2010.09.23,
%D          title=\CONTEXT\ Structure Macros,
%D       subtitle=Automatic Levels,
%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.

\writestatus{loading}{ConTeXt Structure Macros / Automatic Levels}

%D This module is the result of a discussion between Alan Braslau and
%D me. I used to have a private (\MKII) module for this but the new
%D structure code in \MKIV\ is more suitable for this so now we have
%D it as core functionality. For the moment this an experiment that
%D Alan and I conduct so it might evolve.

\registerctxluafile{strc-lev}{}

\unprotect

\permanent\tolerant\protected\def\definesectionlevels[#category]#spacer[#list]%
  {\clf_definesectionlevels{#category}{#list}} % we could scan/use public at the lua end

\permanent\tolerant\protected\def\startsectionlevel[#category]%
  {\doifelseassignment{#category}%
     {\clf_startsectionlevel\plusone{\v!default}{\currentnamedsection}[#category]}%
     {\clf_startsectionlevel\plusone {#category}{\currentnamedsection}}}

\permanent\protected\def\stopsectionlevel
  {\clf_stopsectionlevel} % we could use public at the lua end

\permanent\tolerant\protected\def\startsubjectlevel[#category]%
  {\doifelseassignment{#category}%
     {\clf_startsectionlevel\plustwo{\v!default}{\currentnamedsection}[#category]}%
     {\clf_startsectionlevel\plustwo {#category}{\currentnamedsection}}}

\permanent\protected\def\stopsubjectlevel
  {\clf_stopsectionlevel} % we could use public at the lua end

\permanent\tolerant\protected\def\nostarthead[#category]#spacer[#S#settings]#spacer[#S#userdata]%
  {\blank
   \noindentation{\tttf[start missing section level #category]}
   \blank}

\permanent\tolerant\protected\def\nostophead[#category]%
  {\blank
   \noindentation{\tttf[stop missing section level #category]}
   \blank}

\definesectionlevels
  [\v!default]
  [{\v!chapter,\v!title},
   {\v!section,\v!subject},
   {\v!subsection,\v!subsubject},
   {\v!subsubsection,\v!subsubsubject},
   {\v!subsubsubsection,\v!subsubsubject},
   {\v!subsubsubsubsection,\v!subsubsubject}]

\aliased\let\definestructurelevels\definesectionlevels
\aliased\let\startstructurelevel  \startsectionlevel
\aliased\let\stopstructurelevel   \stopsectionlevel

\protect \endinput

% \starttext
%
% \definehead[xxxxxxsection][subsubsection]
% \setuphead [xxxxxxsection][color=red]
%
% \definesectionlevels[main][chapter,section,subsection,subsubsection]
% \definesectionlevels[next][chapter,section,subsection,xxxxxxsection]
%
% \startsectionlevel [main] [title=first top level]
%
%     \startsectionlevel [main] [title=first lower level]
%         \startsectionlevel [main] [title=second lower level]
%             \startsectionlevel [main] [title=third lower level]
%                 test
%             \stopsectionlevel
%         \stopsectionlevel
%     \stopsectionlevel
%
%     \startsectionlevel [main] [title=first lower level]
%         \startsectionlevel [main] [title=second lower level]
%             \startsectionlevel [next] [title=third lower level]
%                 test
%             \stopsectionlevel
%         \stopsectionlevel
%     \stopsectionlevel
%
% \stopsectionlevel
%
% \stoptext