%D \module
%D   [       file=xtag-exp,
%D        version=2006.01.19,
%D          title=\CONTEXT\ XML Support,
%D       subtitle=Stacking Data,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\beginTEX
  \writestatus{XML}{sorry, XML is only supported in (pdf)etex}
  \endinput
\endTEX

\writestatus{loading}{Context XML Macros (stacks)}

%D This module is experimental. Don't use it (yet). It needs a
%D clean-up. The stack handler is used in the third MathML renderer.

\unprotect

\ifx\XMLRtoks     \undefined \newtoks \XMLRtoks      \fi
\ifx\XMLstacklevel\undefined \newcount\XMLstacklevel \fi

\def\@@xmlstack{xmlstack}

\let\XMLstackid\empty

\def\resetXMLelements
  {\XMLstacklevel\zerocount}

\def\startsavingXMLelements % maybe something with \ignorespaces \\removeunwantedspaces
  {\XMLstacklevel\zerocount
   \let\normalexecuteXMLelement\executeXMLelement
   \def\executeXMLelement{\csname\@@XMLelement:\@@xmlstack\ifcase\kindofXMLelement\or\or\or/\fi\endcsname}}

\def\stopsavingXMLelements
  {\let\executeXMLelement\normalexecuteXMLelement}

\defineXMLnestedenvironmentsave
  [\@@xmlstack]
  {}
  {\pushXMLdataonstack}

\startXMLmapping[xmlstack:test]

    \defineXMLnestedenvironmentsave
      [\@@xmlstack]
      {}
      {\pushXMLnameonstack}

  % in mathml handler:
  %
  % \defineXMLnested
  %   [apply]
  %   {\startsavingXMLelements}
  %   {\stopsavingXMLelements}

\stopXMLmapping

\def\pushXMLdataonstack
  {\advance\XMLstacklevel\plusone
   \letvalue            {\@@xmlstack:n:\XMLstackid:\number\XMLstacklevel}\currentXMLelement
   \saveXMLdata         {\@@xmlstack:t:\XMLstackid:\number\XMLstacklevel}                  \@@xmlstack
   \saveXMLdatainelement{\@@xmlstack:d:\XMLstackid:\number\XMLstacklevel}\currentXMLelement\@@xmlstack}

\def\pushXMLnameonstack
  {\advance\XMLstacklevel\plusone
   \letvalue            {\@@xmlstack:n:\XMLstackid:\number\XMLstacklevel}\currentXMLelement}

\def\eraseXMLdataonstack#1%
  {\letvalue{\@@xmlstack:n:\XMLstackid:\number#1}\empty
   \XMLerase{\@@xmlstack:t:\XMLstackid:\number#1}%
   \XMLerase{\@@xmlstack:d:\XMLstackid:\number#1}}

\def\getXMLstackdata{\getXMLstackiddata\XMLstackid}
\def\getXMLstackname{\getXMLstackidname\XMLstackid}
\def\getXMLstacktext{\getXMLstackidtext\XMLstackid}

\def\getXMLstackiddata#1#2{\flushXMLelement{\@@xmlstack:d:#1:\ifnum#2>\XMLstacklevel\else\number#2\fi}}
\def\getXMLstackidname#1#2{\getvalue       {\@@xmlstack:n:#1:\ifnum#2>\XMLstacklevel\else\number#2\fi}}
\def\getXMLstackidtext#1#2{\flushXMLelement{\@@xmlstack:t:#1:\ifnum#2>\XMLstacklevel\else\number#2\fi}}

\def\rawXMLstackdata{\rawXMLstackiddata\XMLstackid}
\def\rawXMLstackname{\rawXMLstackidname\XMLstackid}
\def\rawXMLstacktext{\rawXMLstackidtext\XMLstackid}

\def\rawXMLstackiddata#1#2{\flushXMLelement{\@@xmlstack:d:#1:\number#2}}
\def\rawXMLstackidname#1#2{\getvalue       {\@@xmlstack:n:#1:\number#2}}
\def\rawXMLstackidtext#1#2{\flushXMLelement{\@@xmlstack:t:#1:\number#2}}

\def\defXMLstackiddata#1#2#3%
  {\defXMLelement#1{\@@xmlstack:d:#2:\ifnum#3>\XMLstacklevel\else\number#3\fi}}

\def\defXMLstackdata#1% #2
  {\defXMLstackiddata#1\XMLstackid}

\def\showXMLstacknames
  {\hbox{[\space\dorecurse\XMLstacklevel{\getXMLstackname\recurselevel\space}]}}

\def\flushXMLstackfrom#1%
  {\dostepwiserecurse{#1}\XMLstacklevel\plusone
     {\getXMLstackdata\recurselevel}}

\def\flushXMLstackwith#1#2%
  {\dostepwiserecurse{#1}\XMLstacklevel\plusone
     {\relax\ifnum\recurselevel>#1\relax#2\fi
      \getXMLstackdata\recurselevel}}

\def\flushXMLnamedstackwith#1#2#3%
  {\dostepwiserecurse{#1}\XMLstacklevel\plusone
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#2}}
        {\ifnum\recurselevel>#1\relax#3\fi
         \getXMLstackdata\recurselevel}}}

\def\countXMLnamedstack#1% todo: \nofXMLchildren ! ! ! ! !
  {\scratchcounter\zerocount
   \dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#1}}
        {\advance\scratchcounter\plusone}}}

\def\collectXMLstack#1%
  {\XMLRtoks\emptytoks
   \dorecurse\XMLstacklevel
     {\ifnum\recurselevel>\plusone\appendtoks#1\to\XMLRtoks\fi
      \expandafter\appendtoks\expandafter\getXMLstackdata\expandafter{\recurselevel}\to\XMLRtoks}}

\def\collectXMLstackrows#1#2%
  {\XMLRtoks\emptytoks
   \dostepwiserecurse{#1}\XMLstacklevel\plusone
     {\ifnum\recurselevel>#1\appendtoks#2\to\XMLRtoks\fi
      \expandafter\appendtoks\expandafter\getXMLstackdata\expandafter{\recurselevel}\to\XMLRtoks}}

\def\collectXMLnamedstack#1#2%
  {\XMLRtoks\emptytoks
   \dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#1}}
        {\ifnum\recurselevel>\plusone\appendtoks#2\to\XMLRtoks\fi
         \expandafter\appendtoks\expandafter\getXMLstackdata\expandafter{\recurselevel}\to\XMLRtoks}}}

\def\collectXMLnamedstacknamed#1#2#3% names, inbetween, nestednames (maddness, this macro)
  {\XMLRtoks\emptytoks
   \!!doneafalse
   \let\globalascii\empty
   \dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#1}}
        {\begingroup
         \startsavingXMLelements
         \rawXMLstacktext\recurselevel % still on stack, raw does not test
         \stopsavingXMLelements
         \let\globalascii\empty
         \dorecurse\XMLstacklevel
           {\expanded{\doifinset{\getXMLstackname\recurselevel}{#2}}
              {\xdef\globalascii{\getXMLstackdata\recurselevel}}}%
         \endgroup
         \ifx\globalascii\empty\else
             \if!!donea\appendtoks#3\to\XMLRtoks\fi
             \expandafter\appendtoks\globalascii\to\XMLRtoks
             \!!doneatrue
         \fi}}}

\def\XMLcopydata#1#2% to from
  {\@EA\let\csname\@@XMLdata:#1\@EA\endcsname\csname\@@XMLdata:#2\endcsname}
\def\XMLcopysave#1#2% to from
  {\@EA\let\csname\@@XMLsave:#1\@EA\endcsname\csname\@@XMLsave:#2\endcsname}

\def\removeXMLdatafromstack#1%
  {\dorecurse\XMLstacklevel
     {\doif{\getXMLstackname\recurselevel}{#1}
        {\dostepwiserecurse\recurselevel{\numexpr\XMLstacklevel+\minusone}\plusone
           {\scratchcounter\numexpr\recurselevel+\plusone\relax
            \@EA\let\csname\@@xmlstack:n:\XMLstackid:\recurselevel\@EA\endcsname\csname\@@xmlstack:n:\XMLstackid:\number\scratchcounter\endcsname
            \XMLcopysave{\@@xmlstack:t:\XMLstackid:\recurselevel}{\@@xmlstack:t:\XMLstackid:\number\scratchcounter}%
            \XMLcopysave{\@@xmlstack:d:\XMLstackid:\recurselevel}{\@@xmlstack:d:\XMLstackid:\number\scratchcounter}}%
         \advance\XMLstacklevel\minusone
         \exitloop}}}

%D BEWARE: these names may change (get stack in the name)

\def\XMLallnamed#1%
  {\dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#1}}
        {\getXMLstackdata\recurselevel}}}

\def\defXMLfirstnamed#1#2% \cs list
  {\dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#2}}
        {\defXMLstackdata#1\recurselevel\exitloop}}}

\def\defXMLfirstnamedtext#1#2% \cs list
  {\dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#2}}
        {\edef#1{\getXMLstacktext\recurselevel}\exitloop}}}

\def\XMLfirstnamed#1%
  {\dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#1}}
        {\getXMLstackdata\recurselevel\exitloop}}}

\def\XMLnotnamed#1%
  {\dorecurse\XMLstacklevel
     {\expanded{\doifnotinset{\getXMLstackname\recurselevel}{#1}}
        {\getXMLstackdata\recurselevel\exitloop}}}

\let\XMLstackposition\!!zerocount

\def\XMLdoifonstackelse#1% was \XMLdoifelsefound
  {\!!doneafalse
   \let\XMLstackposition\!!zerocount
   \dorecurse\XMLstacklevel
     {\expanded{\doifinset{\getXMLstackname\recurselevel}{#1}}
        {\let\XMLstackposition\recurselevel\!!doneatrue\exitloop}}%
   \if!!donea
     \expandafter\firstoftwoarguments
   \else
     \expandafter\secondoftwoarguments
   \fi}

%D Handy:

\def\pushXMLmeaning#1% or [#1]
  {\@EA\pushmacro\csname\@@XMLelement:#1/\endcsname
   \@EA\pushmacro\csname\@@XMLelement:#1\endcsname
   \@EA\pushmacro\csname\@@XMLelement:/#1\endcsname}

\def\popXMLmeaning#1% or [#1]
  {\@EA\popmacro\csname\@@XMLelement:#1/\endcsname
   \@EA\popmacro\csname\@@XMLelement:#1\endcsname
   \@EA\popmacro\csname\@@XMLelement:/#1\endcsname}

\protect \endinput
