%D \module
%D   [       file=back-exp,
%D        version=2010.08.22,
%D          title=\CONTEXT\ Backend Macros,
%D       subtitle=XML export,
%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 Backend Macros / XML export}

\registerctxluafile{back-exp.lua}{1.001}

%D This is an experimental exporter and a logical follow up on tagging. The
%D exporter assumes a properly tagged document. Some elements get a couple
%D of attributes becaus eitherwise rendering information would get lost. In
%D general we assume that when the \XML\ is converted to \HTML\ some stylesheet
%D is applied anyway.

\unprotect

% we can replace this by a more generic attributeset mechanism where we bind
% to any element (needed anyway, see userdata thingies)

\definesystemattribute[taggedpar][public]

\def\setelementexporttag
  {\dotripleargument\dosetelementexporttag}

\def\dosetelementexporttag
  {\ifthirdargument
     \expandafter\dosetelementexporttaga
   \else\ifsecondargument
     \expandafter\expandafter\expandafter\dosetelementexporttagb
   \fi\fi}

\def\dosetelementexporttaga[#1][#2][#3]{\taggedctxcommand{settagproperty("#1","#2","#3")}}
\def\dosetelementexporttagb[#1][#2][#3]{\taggedctxcommand{settagproperty("#1","export","#2")}}

% todo: no need for calls when trialtypesetting

\def\taggedctxcommand
  {\iftrialtypesetting
     \expandafter\gobbleoneargument
   \else
     \expandafter\ctxcommand
   \fi}

\newcount\tagparcounter

\let\dotagsetparcounter\relax

\appendtoks
    \dotagsetparcounter
\to \everypar

\appendtoks
    \dotagsetparcounter
\to \neverypar

\appendtoks
    \dotagsetparcounter
\to \everytabulatepar % tricky, maybe this should be neverypar

\appendtoks
    \def\dotagTABLEcell  {\taggedctxcommand{settagtablecell(\number\tablecellrows,\number\tablecellcolumns,\number\raggedstatus)}}%
    \def\dotagTABLEsignal{\char\zerocount}% brrr, we need to tag empty cells (unless we start numbering)
\to \everyenableelements

\appendtoks
    \def\dotagtabulatecell  {\taggedctxcommand{settagtabulatecell(\number\tabulatealign)}}%
    \def\dotagtabulatesignal{\dontleavehmode\char\zerocount\ignorespaces}%
\to \everyenableelements

\appendtoks
    \def\dotagsynonym{\taggedctxcommand{settagsynonym("\currentsynonym","\currentsynonymtag")}}%
\to \everyenableelements

\appendtoks % frozen and assumed global per highlight class
    \def\dotaghighlight{\taggedctxcommand{settaghighlight("\currenthighlight","\highlightparameter\c!style",\number\attribute\colorattribute)}}%
\to \everyenableelements

\appendtoks % we can have differently scaled images
    \def\dotagfigure{\taggedctxcommand{settagfigure("\figurefileoriginal","\figurefilepage",\number\dimexpr\figurewidth,\number\dimexpr\figureheight)}}%
\to \everyenableelements

\appendtoks
   %\def\dotagcombination{\taggedctxcommand{settagcombination(\combinationparameter\c!nx,\combinationparameter\c!ny)}}%
    \def\dotagcombination{\taggedctxcommand{settagcombination(\number\horcombination,\number\totcombination)}}%
\to \everyenableelements

\appendtoks
    \def\dotagsorting{\taggedctxcommand{settagsorting("\currentsorting","\currentsortingtag")}}%
\to \everyenableelements

\appendtoks
    \def\dotagsetparcounter{\global\advance\tagparcounter\plusone\attribute\taggedparattribute\tagparcounter}%
\to \everyenableelements

\appendtoks
    \def\dotagsetitemgroup{\taggedctxcommand{settagitemgroup("\currentitemgroup",\ifconditional\packlistitem true\else false\fi,"\currentitemsymbol")}}%
\to \everyenableelements

\appendtoks
    \def\dotagsetdescription{\taggedctxcommand{settagdescription("\currentdescription",\currentdescriptionnumberentry)}}%
\to \everyenableelements

\appendtoks
    \def\dotagsetnotesymbol{\taggedctxcommand{settagdescriptionsymbol("\currentnote",\currentnotenumber)}}%
\to \everyenableelements

\appendtoks
    \unexpanded\def\doverbatimspace{\char32\relax}% will be done permanently
\to \everyenableelements

% The action: \setupbackend[export=yes] % or filename

\def\c!export  {export}   % maybe: option={css,xhtml}
\def\c!css     {css}
\def\c!xhtml   {xhtml}

\appendtoks
    \doifsomething{\backendparameter\c!xhtml}
      {\enabledirectives[backend.export.xhtml=\backendparameter\c!xhtml]}%
    \doifsomething{\backendparameter\c!css}
      {\enabledirectives[backend.export.css={\backendparameter\c!css}]}%
\to \everysetupbackend

\appendtoks
    \doifsomething{\backendparameter\c!export}
      {\setupstructure
         [\c!state=\v!start]%
       \enabledirectives
         [backend.export=\backendparameter\c!export]}%
\to \everysetupbackend

\protect \endinput