%D \module
%D   [       file=strc-blk,
%D        version=2008.10.20,
%D          title=\CONTEXT\ Structure Macros,
%D       subtitle=Descriptions,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright=PRAGMA-ADE / Hans Hagen]
%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 / Descriptions}

\registerctxluafile{strc-des}{1.001}

%D In order to be more flexible with theorems Aditya Mahajan added
%D support for titles and endsymbols. At the same time we added more
%D flexible support for inheriting numbers.
%D
%D \startbuffer
%D \defineenumeration[one]
%D \defineenumeration[two]   [one]
%D \defineenumeration[three] [number=one,style=slanted]
%D \defineenumeration[four]  [three]
%D \defineenumeration[five]  [three] [number=five]
%D
%D \startone   test test 1 \stopone
%D \starttwo   test test 2 \stoptwo
%D \startthree test test 3 \stopthree
%D \startfour  test test 4 \stopfour
%D \startfive  test test 1 \stopfive
%D \stopbuffer
%D
%D \typebuffer \start \getbuffer \stop

% list and titles are experimental
%
% \definedescription[test] [location=left,hang=4,headalign={right},distance=1em,list=test]
% \defineenumeration[lemma][title=yes,right=:,textdistance=1em, location=top, titlestyle=\bs,list=lemma]
% \defineenumeration[ammel][title=yes,right=:,textdistance=.5em,location=left,titlestyle=\it,width=9em]
%
% \placelist[enumeration:lemma]
% \placelist[description:test][width=0pt]
%
% \starttest  {something something something}    \input zapf  \stoptest
% \startlemma {with a title of a certain length} \input tufte \stoplemma
% \startammel {with a title}                     \input zapf  \stopammel
%
% \defineenumeration[lemma][...]
% \defineenumeration[titledlemma][lemma][title=yes,right=:,text=lemma,list=lemma]

\unprotect

% description parameters

\def\descriptionparameter      #1{\csname\dodescriptionparameter{\??dd\currentdescription      }#1\endcsname}
\def\descriptionmainparameter  #1{\csname\dodescriptionparameter{\??dd\currentdescriptionmain  }#1\endcsname}
\def\descriptionnumberparameter#1{\csname\dodescriptionparameter{\??dd\currentdescriptionnumber}#1\endcsname}

\def\detokenizeddescriptionparameter#1{\detokenize\expandafter\expandafter\expandafter{\csname\??dd\currentdescription#1\endcsname}}

\def\dodescriptionparameter#1#2%
  {\ifcsname#1#2\endcsname#1#2\else\expandafter\dodescriptionparentparameter\csname#1\s!parent\endcsname#2\fi}

\def\dodescriptionparentparameter#1#2%
  {\ifx#1\relax\s!empty\else\dodescriptionparameter#1#2\fi}

% description hashes (needed for style/color)

\def\descriptionparameterhash    #1{\dodescriptionparameterhash{\??dd\currentdescription    }#1}
\def\descriptionmainparameterhash#1{\dodescriptionparameterhash{\??dd\currentdescriptionmain}#1}

\def\dodescriptionparameterhash#1#2%
  {\ifcsname#1#2\endcsname#1\else\expandafter\dodescriptionparentparameterhash\csname#1\s!parent\endcsname#2\fi}

\def\dodescriptionparentparameterhash#1#2%
  {\ifx#1\relax\else\dodescriptionparameterhash#1#2\fi}

\def\dosetdescriptionattributes#1#2% style color
  {\edef\fontattributehash {\descriptionparameterhash#1}%
   \edef\colorattributehash{\descriptionparameterhash#2}%
   \ifx\fontattributehash \empty\else\dosetfontattribute \fontattributehash #1\fi
   \ifx\colorattributehash\empty\else\dosetcolorattribute\colorattributehash#2\fi}

% typesetting code

\newbox   \descriptionheadbox
\newskip  \leftdescriptionskip
\newskip  \rightdescriptionskip
\newdimen \descriptionsheadwidth    % replaces \!!widtha
\newdimen \descriptionsheaddistance % replaces \!!widthb

\setvalue{@@description\v!left }{\@@descriptionhang\@@descriptionleftpure \@@descriptionlefthang \@@descriptionleftmargin }
\setvalue{@@description\v!right}{\@@descriptionhang\@@descriptionrightpure\@@descriptionrighthang\@@descriptionrightmargin}

\def\@@descriptionhang#1#2#3% \next still needed?
  {\processaction
     [\descriptionparameter\c!hang]
     [   \v!none=>\let\next#1,%
               0=>\let\next#1,%
       \v!margin=>\let\next#3,%
      \s!unknown=>\let\next#2,%
      \s!default=>\let\next#1]%
   \next}

\def\@@descriptionleftpure
  {\def\\{\crlf}%
   \noindent
   \leftskip\dimexpr\leftdescriptionskip+\descriptionsheadwidth\relax
   \rightskip\rightdescriptionskip
   \@@makedescriptionpurebox\raggedright
   \advance\leftskip\descriptionsheaddistance
   \llap
     {\hbox to \leftskip
        {\hskip\leftdescriptionskip
         \copy\descriptionheadbox\hss}}%
   \@@dodescription}

\def\@@descriptionrightpure
  {\def\\{\crlf}%
   \noindent
   \leftskip\leftdescriptionskip
   \rightskip\dimexpr\rightdescriptionskip+\descriptionsheadwidth\relax
   \@@makedescriptionpurebox\raggedleft
   \rlap
     {\hskip\dimexpr\hsize-\leftskip-\rightskip\relax
      \copy\descriptionheadbox
      \hskip\rightdescriptionskip}%
   \advance\rightskip \descriptionsheaddistance
   \@@dodescription}

\def\@@descriptionleftmargin
  {\def\\{\crlf}%
   \noindent
   \llap
     {\@@makedescriptionpurebox\raggedright
      \hbox to \descriptionparameter\c!width{\copy\descriptionheadbox\hss}%
      \hskip\descriptionparameter\c!distance}%
   \@@dodescription}

\def\@@descriptionrightmargin % whatever this means
  {\def\\{\crlf}%
   \noindent
   \rlap
     {\hskip\descriptionparameter\c!distance
      \@@makedescriptionpurebox\raggedright
      \hbox to \descriptionparameter\c!width{\copy\descriptionheadbox\hss}}%
   \@@dodescription}

\def\@@makedescriptionpurebox#1%
  {\setbox\descriptionheadbox\vtop
     {\dontcomplain
      \hsize\descriptionsheadwidth
      \leftskip\zeropoint
      \rightskip\zeropoint
      #1\setupalign[\descriptionparameter\c!align]%
      \ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox}%
   \ht\descriptionheadbox\strutht
   \dp\descriptionheadbox\strutdp}

\def\@@descriptionlefthang
  {\def\\{\crlf}%
   \dontcomplain
   \advance\descriptionsheadwidth \descriptionsheaddistance
   \hangindent\descriptionsheadwidth
   \@@makedescriptionhangbox\raggedright{\advance\rightskip \descriptionsheaddistance}%
   \noindent
   \llap
     {\dontshowcomposition
      \vtop to \zeropoint{\box\descriptionheadbox}}%
   \@@dodescription}

\def\@@descriptionrighthang
  {\def\\{\crlf}%
   \dontcomplain
   \advance\descriptionsheadwidth \descriptionsheaddistance
   \hangindent-\descriptionsheadwidth
   \@@makedescriptionhangbox\raggedleft{\advance\leftskip \descriptionsheaddistance}%
   \noindent
   \rlap
     {\dontcomplain
      \dontshowcomposition
      \hbox to \dimexpr\hsize-\leftskip-\rightskip\relax % can be a macro
        {\hss\vtop to \zeropoint{\box\descriptionheadbox}}}%
   \@@dodescription}

\def\@@makedescriptionhangbox#1#2%
  {\setbox\descriptionheadbox\vtop % \vbox gaat fout in hang
     {\forgetall
      \dontcomplain
      \hsize\descriptionsheadwidth
      #1\setupalign[\descriptionparameter\c!align]#2%
      \ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox}%
   \ht\descriptionheadbox\strutht
   \dp\descriptionheadbox\strutdp
   \doifsomething{\descriptionparameter\c!hang}
     {\doifinsetelse{\descriptionparameter\c!hang}{\v!fit,\v!broad}
        {\scratchdimen\htdp\descriptionheadbox
         \doif{\descriptionparameter\c!hang}\v!broad
           {\advance\scratchdimen .5\strutht}%
         \getnoflines\scratchdimen
         \hangafter-\noflines}
        {\hangafter-\descriptionparameter\c!hang}}}

\setvalue{@@description\v!top}%
  {%\page[\v!preference]%       % Weg ermee!
   %\dosomebreak{\goodbreak}%   % Dit is beter en nodig!
   \dohandlepagebreakX\plusone  % En dit moet het maar worden.
   \let\\=\space
   \noindent
   \copy\descriptionheadbox\par
   \nobreak
  %\descriptionparameter\c!inbetween % .. brrrr ... :
   \doifelsenothing{\descriptionparameter\c!inbetween}{\blank}{\descriptionparameter\c!inbetween}%
   \nobreak
   \@@dodescription}

\def\do@@description#1%
  {\def\\{\crlf}%
   \noindent
   #1{\ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox}%
   \@@dodescription}

\setvalue{@@description\v!inmargin    }{\do@@description\inmargin}
\setvalue{@@description\v!inleft      }{\do@@description\inleft  }
\setvalue{@@description\v!inright     }{\do@@description\inright }
\setvalue{@@description\v!margin      }{\do@@description\inmargin}
\setvalue{@@description\v!leftmargin  }{\do@@description\inleft  }
\setvalue{@@description\v!rightmargin }{\do@@description\inright }
\setvalue{@@description\v!innermargin }{\do@@description\ininner }
\setvalue{@@description\v!outermargin }{\do@@description\inouter }

\setvalue{@@description\v!serried\v!fit}%
  {\def\\{\crlf}%
   \noindent
   \ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox
   \hskip\descriptionsheaddistance % toegevoegd
   \@@dodescription}

\setvalue{@@description\v!serried\v!broad}%
  {\def\\{\crlf}%
   \noindent
   \ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox
   \hskip\descriptionsheaddistance \!!plus .5\descriptionsheaddistance \!!minus .25\descriptionsheaddistance
   \@@dodescription}

\setvalue{@@description\v!serried\v!wide}%
  {\def\\{\crlf}%
   \noindent
   \hbox to \descriptionsheadwidth
     {\ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox\hss}%
   \hskip\descriptionsheaddistance
   \@@dodescription}

\setvalue{@@description\v!serried}%
  {\processaction
      [\descriptionparameter\c!width]
      [     \v!fit=>\let\next\v!fit,
          \v!broad=>\let\next\v!broad,
        \s!unknown=>\let\next\v!wide,
        \s!default=>\let\next\v!broad]%
   \getvalue{@@description\v!serried\next}}

\setvalue{@@description\v!hanging}%
  {\def\\{\crlf}%
   \noindent
   \advance\leftskip -\leftskipadaption \relax
   \ifdim\leftskipadaption=\zeropoint
     \leftskipadaption1.5em\relax % just some default
     \ifnum\nesteddescriptionstate=\plusone
       \ifdim\leftskip>\zeropoint \relax
         \leftskipadaption\leftskip
       \fi
     \fi
   \fi
   \ifnum\nesteddescriptionstate>\zerocount % was \ifnum\nesteddescriptionstate=\plusone
     \advance\leftskip \leftskipadaption % but we're already further on
   \fi
   \hskip-\leftskipadaption
   \ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox
   \kern\ifdim\descriptionsheaddistance=\zeropoint .75em\else\descriptionsheaddistance\fi
   \@@dodescription}

%D A bonus definition
%D
%D \starttyping
%D \setupfootnotedefinition[location=command,headcommand=\llap]
%D \stoptyping

% \setvalue{@@description\v!command}%
%   {\do@@description{\executeifdefined{\descriptionparameterhash\c!headcommand}\framed}}

\setvalue{@@description\v!command}%
  {\noindent
   \descriptionparameter\c!headcommand{\ifhbox\descriptionheadbox\unhcopy\else\copy\fi\descriptionheadbox}%
   \@@dodescription}

%D A new key 'headalign' in definitions.

\def\resetdescriptions % to be used in e.g. footnotes
  {\chardef\nesteddescriptionstate\zerocount}

\resetdescriptions

\def\@@dostartdescription
  {\descriptionparameter\c!before
   \begingroup
   \doadaptleftskip{\descriptionparameter\c!margin}%
   \showcomposition
   \descriptionsheaddistance\descriptionparameter\c!distance\relax
   \ifdim\descriptionsheaddistance=\zeropoint\relax
     \doif{\descriptionparameter\c!width}\v!broad{\descriptionsheaddistance=1em}%
   \fi
   \setbox\descriptionheadbox\hbox
     {\forgetall\dontcomplain
      \trialtypesettingtrue
      \doifelsenothing{\descriptionparameter\c!sample}
        {\dodescriptionhandler
           {\begstrut\descriptionparameter\c!text\ignorespaces\currentdescriptiontext\endstrut}}%
        {\dodescriptionhandler
           {\begstrut\descriptionparameter\c!text\descriptionparameter\c!sample\endstrut}}}%
   \assignwidth
     \descriptionsheadwidth
     {\descriptionparameter\c!width}
     {\unhcopy\descriptionheadbox}
     \descriptionsheaddistance
   \setbox\descriptionheadbox\hbox
     {\forgetall\dontcomplain
      \doifelse{\descriptionparameter\c!location}\v!serried % brrr, hack
        {\dodescriptionhandler
           {\begstrut\descriptionparameter\c!text\currentdescriptiontext\endstrut}}
        {\dodescriptionhandler
           {\vtop
              {\hsize\dimexpr\descriptionsheadwidth-\descriptionsheaddistance\relax
               \begstrut\descriptionparameter\c!text\ignorespaces\currentdescriptiontext\endstrut}}}}%
   \doifelse{\descriptionparameter\c!aligntitle}\v!no
     {\leftdescriptionskip\leftskip\rightdescriptionskip\rightskip}
     {\ifcase\nesteddescriptionstate\leftdescriptionskip\leftskip\rightdescriptionskip\rightskip\fi}%
   \normalexpanded{\noexpand\indenting[\descriptionparameter\c!indenting]}%
   % better a system mode
   \ifcase\nesteddescriptionstate
     \chardef\nesteddescriptionstate\plusone
   \or
     \chardef\nesteddescriptionstate\plustwo
   \fi % now happens elsewhere : \noindent\ignorespaces
   \@@resetdescriptionclosesymbol}

\def\@@stopdescription
  {\@@placedescriptionclosesymbol
   \par % else we loose
   \endgroup
   \descriptionparameter\c!after % which currentdescription is taken here?
   \egroup % temporary hack
   \checknextindentation[\descriptionparameter\c!indentnext]
   \dorechecknextindentation}

\def\@@dodescription
  {\dosetdescriptionattributes\c!style\c!color
   \ignorespaces}

% starters:

\def\@@startdescription[#1]%
  {\doifelse{\descriptionparameter\c!title}\v!yes
     {\permitspacesbetweengroups
      \dodoublegroupempty{\dohandledescriptionstart[#1]}}
     {\dohandledescriptionstart[#1]{}}}

\def\@@description[#1]%
  {\doifelse{\descriptionparameter\c!title}\v!yes
     {\permitspacesbetweengroups
      \dodoublegroupempty{\dohandledescriptiondo[#1]}}
     {\dohandledescriptiondo[#1]{}}}

% these call:

\long\def\@@somedescription[#1]#2%
  {\dowithpar
     {\bgroup % temporary hack
      \@@makedescription[#1]{#2}}%
     {\@@stopdescription}}

\long\def\@@startsomedescription[#1]#2%
  {\bgroup % temporary hack
   \BeforePar{\@@makedescription[#1]{#2}}%
   \GotoPar}

\def\@@dostartdescriptionindeed
  {\edef\currentdescriptionlocation{\descriptionparameter\c!location}%
   \ifx\currentdescriptionlocation\empty
     \let\currentdescriptionlocation\v!left
   \fi
   \ifcsname @@description\currentdescriptionlocation\endcsname \else
     \let\currentdescriptionlocation\v!left
   \fi
   \@@dostartdescription
   \csname @@description\currentdescriptionlocation\endcsname} % args not needed

\def\@@makedescription[#1]#2%
  {\postponenotes % new, assumes grouping
   \doenumerationcheckconditions
   \dodescriptioncomponent[\c!reference=#1,\c!label={\descriptionparameter\c!text},\c!title={#2},\c!bookmark=,][]%
   \@@dostartdescriptionindeed}

\def\dostartstoreddescription
  {\@@dostartdescriptionindeed}

\def\dostopstoreddescription
  {\@@stopdescription}

% % % % % % % % % % % %

% helpers

% todo: \dosetfontattributewithhash \descriptionparameterhash\c!headstyle

% setup descriptions

\def\setupdescriptions
  {\dodoubleempty\dosetupdescriptions}

\def\dosetupdescriptions[#1][#2]% % beter: \iffirstargument
  {\ifsecondargument
     \dodoubleargumentwithset\dodosetupdescriptions[#1][#2]%
   \else
     \dodosetupdescriptions[][#1]%
   \fi}

\def\dodosetupdescriptions[#1]% [#2]%
  {\getparameters[\??dd#1]}   % [#2]}

% define descriptions

\def\definedescription
  {\dotripleemptywithset\dodefinedescription}

\def\dodefinedescription[#1][#2][#3]% to be simplified cf enumeration
  {\dodescriptioninit{#1}%
   \getparameters[\??dd#1][\c!text=,\s!handler=\v!description,\c!title=\v!yes]%
   \ifsecondargument\doifassignmentelse{#2}\donetrue\donefalse\else\donetrue\fi
   \ifdone
     \getparameters[\??dd#1][\s!parent=\??dd,\c!text=,\s!handler=\v!description,#2]%
     \dodefinedescriptioncommands{#1}{\??dd}%
   \else % clone
     \getparameters[\??dd#1][\s!parent=\??dd#2,\c!text=,\s!handler=\v!description,#3]% clone
     \dodefinedescriptioncommands{#1}{\??dd#2}%
   \fi}

\def\dodefinedescriptioncommands#1#2%
  {\unexpanded\setevalue        {#1}{\noexpand\dodescriptioncommand{#1}}%
   \unexpanded\setevalue{\e!start#1}{\noexpand\dodescriptionstart  {#1}}%
   \unexpanded\setevalue{\e!stop #1}{\noexpand\dodescriptionstop   {#1}}}

% handle descriptions

\def\dodescriptioninit#1%
  {\let\currentdescriptionmain  \empty
   \let\currentdescriptionlevel \empty
   \edef\currentdescriptionname {#1}%
   \edef\currentdescription     {#1}}

\def\dodescriptioncommand#1{\dodescriptioninit{#1}\dosingleempty\@@description}
\def\dodescriptionstart  #1{\dodescriptioninit{#1}\dosingleempty\@@startdescription}
\def\dodescriptionstop   #1{\dodescriptioninit{#1}\@@stopdescription}

\def\dodescriptionhandler    {\csname\??dd:\descriptionparameter\s!handler:\s!handler         \endcsname}
\def\dohandledescriptiondo   {\csname\??dd:\descriptionparameter\s!handler:\s!handler:\s!do   \endcsname}
\def\dohandledescriptionstart{\csname\??dd:\descriptionparameter\s!handler:\s!handler:\s!start\endcsname}

% implementation

% beware: with footnotes #2 can be something messy but then #1 is
% empty anyway, so we have an extra safeguard

\newtoks \everydescription

\setvalue{\??dd:\v!description:\s!handler         }{\@@dodescriptionhandler}
\setvalue{\??dd:\v!description:\s!handler:\s!do   }{\@@somedescription}
\setvalue{\??dd:\v!description:\s!handler:\s!start}{\@@startsomedescription}

\def\@@dodescriptionhandler#1%
  {\strut
   \dodescriptionheadtext{#1}%
   \iftrialtypesetting \else
     \currentdescriptionsynchronize
     \dosetattribute{destination}\currentdescriptionattribute % todo
   \fi}

\def\dodescriptionheadtext#1% title
  {\begingroup
   \dosetdescriptionattributes\c!headstyle\c!headcolor
   \the\everydescription
   \descriptionparameter\c!command{\strut#1}% probably incomplete
   \endgroup}

% setup enumerations

\def\setupenumerations
  {\dodoubleempty\dosetupenumerations}

\def\dodosetupenumerations[#1][#2]%
  {\doenumerationinit{#1}{1}\empty
   \getparameters[\??dd#1][#2]%
   \dosetupenumerationcounter{#1}}

\def\dosetupenumerations[#1][#2]%
  {\ifsecondargument
     \dodoubleargumentwithset\dodosetupenumerations[#1][#2]%
   \else
     \getparameters[\??dn][#1]%
   \fi}

% define enumerations

\def\defineenumeration
  {\dotripleemptywithset\dodefineenumeration}

\def\dodefineenumeration[#1][#2][#3]% #2 or #3 assignment
  {\doenumerationinit{#1}{1}\empty
   \getparameters[\??dd#1][\c!text=#1,\c!state=\v!start,\s!handler=\v!enumeration,\c!levels=4]%
   \ifsecondargument\doifassignmentelse{#2}\donetrue\donefalse\else\donetrue\fi
   \ifdone % independent
     \getparameters[\??dd#1][\s!counter=#1,#2]%
     \dodefineenumerationcommands{#1}{1}{}{\??dn}%
     \let\@@subslevel\empty
     \dostepwiserecurse{2}{\descriptionparameter\c!levels}{1}
       {\normalexpanded{\noexpand\dodefineenumerationcommands{#1}{\recurselevel}{\@@subslevel\v!sub}{\??dd\@@subslevel#1}}%
        \edef\@@subslevel{\@@subslevel\v!sub}}%
   \else % clone
     \getparameters[\??dd#1][\s!counter=#2,#3]%
     \let\@@subslevel\empty
     \dorecurse{\descriptionparameter\c!levels}
       {\normalexpanded{\noexpand\dodefineenumerationcommands{#1}{\recurselevel}{\@@subslevel}{\??dd\@@subslevel#2}}%
        \edef\@@subslevel{\@@subslevel\v!sub}}%
   \fi
   \edef\currentdescriptioncounter{\descriptionparameter\c!number}%
   \ifx\currentdescriptioncounter\empty
     \ifdone\dodefineenumerationcounter{#1}\fi
   \else\ifx\currentdescriptioncounter\v!yes
     \ifdone\dodefineenumerationcounter{#1}\fi
   \else\ifx\currentdescriptioncounter\v!no
     \ifdone\dodefineenumerationcounter{#1}\fi
   \else
     \letvalue{\??dd#1\s!counter}\currentdescriptioncounter % ?
     \doifstructurecounterelse{\currentdescriptioncounter}{}{\dodefineenumerationcounter\currentdescriptioncounter}%
   \fi\fi\fi}

\newtoks\everysetupenumerationcounter
\let\currentenumerationcountername\empty

\def\dosetupenumerationcounter#1%
  {\edef\currentenumerationcountername{#1}% only used in the token list
   \edef\currentdiscription{#1}%
   \the\everysetupenumerationcounter}

\appendtoks
    \dostructurecountersetup\currentenumerationcountername\descriptionparameter
\to \everysetupenumerationcounter

\def\dodefineenumerationcounter#1% todo: fast inheritance (was mainparameter
  {\definestructurecounter[#1]%
   \dosetupenumerationcounter{#1}}

\def\dodefineenumerationcommands#1#2#3#4% since we use \currentdescription, we need an edef
  {\setevalue{\??dd#3#1\s!parent}{#4}%
   \unexpanded\setevalue        {#3#1}{\noexpand\doenumerationcommand{#1}{#2}{#3}}%
   \unexpanded\setevalue{\e!start#3#1}{\noexpand\doenumerationstart  {#1}{#2}{#3}}%
   \unexpanded\setevalue{\e!stop #3#1}{\noexpand\doenumerationstop   {#1}{#2}{#3}}}

% handle enumeration

\def\currentdescriptionnumber   {\csname\??dd\currentdescriptionmain\s!counter\endcsname}% no edef (yet)
\def\specificdescriptionnumber#1{\csname\??dd#1\s!counter\endcsname}% no edef (yet)

\def\doenumerationinit#1#2#3%
  {\edef\currentdescriptionmain {#1}%
   \edef\currentdescriptionlevel{#2}%
   \edef\currentdescriptionname {#1}%
   \edef\currentdescription     {#3#1}}

\def\doenumerationcommand#1#2#3{\doenumerationinit{#1}{#2}{#3}\dosingleempty\@@description}
\def\doenumerationstart  #1#2#3{\doenumerationinit{#1}{#2}{#3}\dosingleempty\@@startdescription}
\def\doenumerationstop   #1#2#3{\doenumerationinit{#1}{#2}{#3}\@@stopdescription}

\def\doresetenumerationnumber#1#2#3{\doresetsubstructurecounter    [\specificdescriptionnumber{#1}][#2]}
\def\dosetenumerationnumber#1#2#3#4{\dosetsubstructurecounter      [\specificdescriptionnumber{#1}][#2]{#4}}
\def\donextenumerationnumber #1#2#3{\doincrementsubstructurecounter[\specificdescriptionnumber{#1}][#2]}

% implementation

\newtoks       \everyenumeration
\newconditional\enumerationnumberenabled
\chardef       \enumerationcouplingmode        \zerocount
\def           \enumerationdisablenumbersignal {-}

\appendtoks \disablepseudocaps \to \everyenumeration  % sorry, uppercase causes troubles

\letvalue{\??dd:\c!couplingway:\v!local }\plusone
\letvalue{\??dd:\c!couplingway:\v!global}\plustwo

\setvalue{\??dd:\v!enumeration:\s!handler         }{\@@doenumerationhandler}
\setvalue{\??dd:\v!enumeration:\s!handler:\s!do   }{\@@somedescription}
\setvalue{\??dd:\v!enumeration:\s!handler:\s!start}{\@@startsomedescription}

\def\@@doenumerationhandler#1%
  {\strut
   \ifconditional\enumerationnumberenabled
     \iftrialtypesetting
       \doenumerationfullnumber\showdntext{#1}%
       \doenumerationcouplingsymbol
     \else
       \doenumerationregistercoupling
       \doenumerationfullnumber\showdntext{#1}%
       \doenumerationcouplingsymbol
     \fi
   \else
     \doenumerationfullnumber\showdnpuretext{#1}%
   \fi
   \iftrialtypesetting \else
     \currentdescriptionsynchronize
     \dosetattribute{destination}\currentdescriptionattribute % todo
   \fi}

\def\doenumerationsavecounter     {\savestructurecounter[\currentdescriptionnumber]}
\def\doenumerationrestorecounter  {\restorestructurecounter[\currentdescriptionnumber]}
\def\doenumerationincrementcounter{\doincrementsubstructurecounter[\currentdescriptionnumber][\currentdescriptionlevel]}

\def\doenumerationcheckconditions
  {\doifelse{\descriptionparameter\c!number}\v!yes
     {\ifx\currentdescriptionreference\enumerationdisablenumbersignal
        \setfalse\enumerationnumberenabled \else \settrue\enumerationnumberenabled
      \fi}%
     {\setfalse\enumerationnumberenabled}%
   \chardef\enumerationcouplingmode \iflocation
     \executeifdefined{\??dd:\c!couplingway:\descriptionparameter\c!coupling}\zerocount
   \else
     \zerocount
   \fi}

\def\doenumerationregistercoupling
  {\iflocation
     \ifcase\enumerationcouplingmode
     \or
        % todo
     \or
        % todo
     \fi
   \fi}

\def\doenumerationcouplingsymbol
  {\iflocation\ifcase\enumerationcouplingmode \else
     % todo
   \fi\fi}

\def\currentdescriptiontext
  {\ctxlua{structure.lists.savedtitle("\currentdescriptionmain",\currentdescriptionnumberentry)}}

\def\currentenumerationfullnumber
  {\ctxlua{structure.lists.savednumber("\currentdescriptionmain",\currentdescriptionnumberentry)}}

\def\doenumerationfullnumber#1#2% text, title
  {\begingroup
   \dosetdescriptionattributes\c!headstyle\c!headcolor
   \the\everyenumeration
   \descriptionparameter\c!command
     {\strut
      #1%
      \descriptionparameter\c!left
      \currentenumerationfullnumber
      % save cq. treat expansion etc
      \doiftext{#2} % always true anyway
        {\doif{\descriptionparameter\c!title}\v!yes
           {\begingroup
            \dosetdescriptionattributes\c!titlestyle\c!titlecolor
            \hskip\descriptionparameter\c!titledistance
            \descriptionparameter\c!titlecommand
               {\descriptionparameter\c!titleleft
                \begstrut#2\endstrut
                \descriptionparameter\c!titleright}%
            \endgroup}}%
      %
      \descriptionparameter\c!stopper
      \descriptionparameter\c!right}%
   \endgroup}

\def\showdnpuretext{\strut\descriptionparameter\c!text} % geen spatie
\def\showdnlisttext{\descriptionparameter\c!listtext}   % space in default
\def\showdntext    {\doifsomething{\descriptionparameter\c!text}{\descriptionparameter\c!text\removeunwantedspaces\fixedspace}}

\unexpanded\def\structurecounterreference#1%
  {[enumref: #1]}

% you can use \placeclosesymbol or \qed to place a symbol at the end of a
% description

\def\@@resetdescriptionclosesymbol
  {\global\@EA\settrue\csname\??dd\currentdescription:mrk\endcsname
   \let\placeclosesymbol\@@placedescriptionclosesymbol
   \let\qed             \@@placedescriptionclosesymbol}

\def\@@placedescriptionclosesymbol
  {\ifconditional\csname\??dd\currentdescription:mrk\endcsname
     \global\@EA\setfalse\csname\??dd\currentdescription:mrk\endcsname
     \doifsomething{\descriptionparameter\c!closesymbol}{\descriptionparameter\c!closecommand{\descriptionparameter\c!closesymbol}}%
   \fi}

\newif\ifnodescriptioncaption

\def\doifelsedescriptioncomponent
  {\ctxlua{structure.lists.doifstoredelse(currentdescriptionnumberentry)}}

\def\dodescriptioncomponent
  {\doifelsedescriptioncomponent\nododescriptioncomponent\dododescriptioncomponent}

\def\nododescriptioncomponent[#1][#2]% #1=interfaced-settings, #2=optional user data
  {}

\def\dododescriptioncomponent[#1][#2]% #1=interfaced-settings, #2=optional user data
  {\begingroup               % similar to structure so we might generalize this
   \getparameters[\??dd\currentdescription][#1]%
   \edef\currentdescriptionexpansion{\descriptionparameter\c!expansion}%
   \ifx\currentdescriptionexpansion\s!xml
     \xdef\currentdescriptiontitle   {\detokenizeddescriptionparameter\c!title}%
     \xdef\currentdescriptionbookmark{\detokenizeddescriptionparameter\c!bookmark}%
     \xmlstartraw
       \xdef\currentdescriptionlisttitle   {\descriptionparameter\c!title}%
     \xmlstopraw
     \globallet\currentdescriptioncoding\s!xml
   \else
     \ifx\currentdescriptionexpansion\v!yes
       \xdef\currentdescriptiontitle   {\descriptionparameter\c!title}%
       \xdef\currentdescriptionbookmark{\descriptionparameter\c!bookmark}%
     \else
       \xdef\currentdescriptiontitle   {\detokenizeddescriptionparameter\c!title}%
       \xdef\currentdescriptionbookmark{\detokenizeddescriptionparameter\c!bookmark}%
     \fi
     \globallet\currentdescriptionlisttitle   \currentdescriptiontitle
     \globallet\currentdescriptioncoding\s!tex
   \fi
   \xdef\currentdescriptionlabel    {\descriptionparameter\c!label}%
   \xdef\currentdescriptionreference{\descriptionparameter\c!reference}%
   %
   \doif{\descriptionparameter\c!title}\v!none{\global\nodescriptioncaptiontrue\global\nodescriptionnumbertrue}% will become obsolete
   %
   \ifconditional\enumerationnumberenabled
     \doifelsedescriptioncomponent\donothing\doenumerationincrementcounter
   \fi
   %
   \ifnodescriptioncaption
     \glet\currentdescriptionlistnumber \relax
     \glet\currentdescriptionsynchronize\relax
     \glet\currentdescriptionattribute  \relax
   \else
     \setnextinternalreference
     \xdef\currentdescriptionnumberentry{\ctxlua{structure.lists.push{
        metadata = {
            kind     = "description",
            name     = "\currentdescriptionname",
            level    = structure.sections.currentlevel(),
            catcodes = \the\catcodetable,
        },
        references = {
            internal        = \nextinternalreference,
            reference       = "\currentdescriptionreference",
            referenceprefix = "\referenceprefix",
            block           = "\currentstructureblock",
            section         = structure.sections.currentid(),
        },
        titledata = {
            label    = \!!bs\detokenize\expandafter{\currentdescriptionlabel   }\!!es,
            title    = \!!bs\detokenize\expandafter{\currentdescriptiontitle   }\!!es,
        \ifx\currentdescriptionbookmark\currentdescriptiontitle \else
            bookmark = \!!bs\detokenize\expandafter{\currentdescriptionbookmark}\!!es,
        \fi
        \ifx\currentdescriptionlisttitle\currentdescriptiontitle \else % \ifx\currentdescriptionsaveinlist\v!no
            list     = \!!bs\detokenize\expandafter{\currentdescriptionlisttitle   }\!!es,
        \fi % \fi
        },
    \ifconditional\enumerationnumberenabled
        prefixdata = {
            prefix        = "\descriptionparameter\c!prefix",
            separatorset  = "\descriptionparameter\c!prefixseparatorset",
            conversion    = \!!bs\descriptionparameter\c!prefixconversion\!!es,
            conversionset = "\descriptionparameter\c!prefixconversionset",
            set           = "\descriptionparameter\c!prefixset",
            segments      = "\descriptionparameter\c!prefixsegments",
            connector     = \!!bs\descriptionparameter\c!prefixconnector\!!es,
        },
        numberdata = {
            numbers       = structure.counters.compact("\currentdescriptionname",nil,true),
            separatorset  = "\descriptionparameter\c!numberseparatorset",
            conversion    = "\descriptionparameter\c!numberconversion",
            conversionset = "\descriptionparameter\c!numberconversionset",
            stopper       = \!!bs\descriptionparameter\c!numberstopper\!!es,
            segments      = "\descriptionparameter\c!numbersegments",
        },
    \fi
        userdata = structure.helpers.touserdata(\!!bs\detokenize{#2}\!!es)
       }
     }}%
     \xdef\currentdescriptionattribute  {\ctxlua    {tex.write(jobreferences.setinternalreference("\referenceprefix","\currentdescriptionreference",\nextinternalreference,"\@@iafocus"))}}%
     \xdef\currentdescriptionsynchronize{\ctxlatelua{structure.lists.enhance(\currentdescriptionnumberentry)}}%
   \fi
   \endgroup}

\installstructurelistprocessor{description}{\usestructurelistprocessor{number+title}}

% labels, we could share with enumerations and forget about the text; anyhow, figure
% labels etc can use enumerations; we keep labels for compatibility reasons; we need
% the slightly different namespace; we can still define structure counters directly
% (multiple levels) and use an enumeration without following text

% unfinished

\def\setuplabels
  {\getparameters[\??db]}

\def\definelabel
  {\dotripleargumentwithset\dodefinelabel}

\def\dodefinelabel[#1][#2][#3]% #2 or #3 assignment
  {\doenumerationinit{#1}{1}\empty
   \getparameters[\??dd#1][\c!command=,\c!state=\v!start,\c!location=,\c!text=#1]%
   \ifsecondargument\doifassignmentelse{#2}\donetrue\donefalse\else\donetrue\fi
   \ifdone
     % an independent one
     \getparameters[\??dd#1][\s!counter=#1,\s!parent=\??db,#2]%
     \dodefinelabelcommands{#1}{\??db}%
     \dodefineenumerationcounter{#1}%
   \else
     \getparameters[\??dd#1][\s!counter=#1,\s!parent=\??dd#2,#3]%
     \dodefinelabelcommands{#1}{\??dd#2}%
   \fi}

\def\dodefinelabelcommands#1#2%
  {\unexpanded\setevalue            {#1}{\noexpand\dolabelnumbercommand  {#1}}%
   \unexpanded\setevalue{\c!reset    #1}{\noexpand\doresetlabelnumber    {#1}}%
  %\unexpanded\setevalue{\c!set      #1}{\noexpand\dosetlabelnumber      {#1}}% [#2] or {#2}  ?
   \unexpanded\setevalue{\e!next     #1}{\noexpand\donextlabelnumber     {#1}}%
   \unexpanded\setevalue{\e!increment#1}{\noexpand\doincrementlabelnumber{#1}}%
   \unexpanded\setevalue{\c!current  #1}{\noexpand\docurrentlabelnumber  {#1}}}

% this is just for downward compatibility, we might drop it

\setvalue{\??db:\c!location:\v!inmargin}{\inmargin}
\setvalue{\??db:\c!location:\v!inleft  }{\inleft}
\setvalue{\??db:\c!location:\v!inright }{\inright}
\setvalue{\??db:\c!location:\v!margin  }{\inmargin}

\def\dolabelinit#1%
  {\def\currentdescriptionmain{#1}%
   \def\currentdescription    {#1}%
   \def\currentdescriptionlevel{1}}

\def\docurrentlabelnumber   #1{\dolabelinit{#1}\dosingleempty\dodocurrentlabelnumber}
\def\donextlabelnumber      #1{\dolabelinit{#1}\dosingleempty\dodonextlabelnumber}
\def\dolabelnumbercommand   #1{\dolabelinit{#1}\dosingleempty\dodolabelnumbercommand}

\def\doresetlabelnumber     #1{\dolabelinit{#1}\doresetsubstructurecounter    [\currentdescriptionnumber][\currentdescriptionlevel]}
\def\dosetlabelnumber     #1#2{\dolabelinit{#1}\dosetsubstructurecounter      [\currentdescriptionnumber][\currentdescriptionlevel]{#2}}
\def\doincrementlabelnumber #1{\dolabelinit{#1}\doincrementsubstructurecounter[\currentdescriptionnumber][\currentdescriptionlevel]}

\def\dodocurrentlabelnumber[#1]%
  {\dontleavehmode
   \writestatus{!!!}{todo: reference of label}%
   \dotextprefix{\descriptionparameter\c!text}%
   \convertedsubstructurecounter[\currentdescriptionnumber][\currentdescriptionlevel]}

\def\dodonextlabelnumber[#1]% todo: ref
  {\doincrementsubstructurecounter[\currentdescriptionnumber][\currentdescriptionlevel]%
   \dodocurrentlabelnumber[\currentdescriptionnumber]}

\def\dodolabelnumbercommand[#1]% todo: ref
  {\dontleavehmode
   \descriptionparameter\c!before
   \begingroup
   \doincrementsubstructurecounter[\currentdescriptionnumber][\currentdescriptionlevel]%
   \dosetdescriptionattributes\c!headstyle\c!headcolor
   \executeifdefined{\??db:\c!location:\descriptionparameter\c!location}{\descriptionparameter\c!command}{\dodocurrentlabelnumber[#1]}%
   \endgroup
   \descriptionparameter\c!after}

% to be reimplmented

\def\setupindentations
  {\dodoubleempty\dosetupindentations}

\def\dosetupindentations[#1][#2]%
  {\ifsecondargument
     \dodoubleargumentwithset\dodosetupindentations[#1][#2]%
   \else
     \dodosetupindentations[][#1]%
   \fi}

\def\dodosetupindentations[#1][#2]%
  {\getparameters[\??ds#1][#2]}

\def\defineindenting
  {\dodoubleargumentwithset\dodefineindenting}

\def\dodefineindenting[#1][#2]%
  {\copyparameters[\??ds#1][\??ds]
      [\c!text,\c!separator,\c!width,\c!style,\c!color,
       \c!headstyle,\c!sample,\c!before,\c!after,\c!distance]%
   \getparameters[\??ds#1][#2]%
   \unexpanded\setvalue            {#1}{\dododefineindenting{#1}{0}{1}}%
   \unexpanded\setvalue      {\v!sub#1}{\dododefineindenting{#1}{1}{2}}%
   \unexpanded\setvalue{\v!sub\v!sub#1}{\dododefineindenting{#1}{2}{3}}}

\def\dododefineindenting#1#2#3%
  {\par
   \getvalue{\??ds#1\c!before}%
   \begingroup
   \doifvaluenothing{\??ds#1\c!sample}
     {\setvalue{\??ds#1\c!sample}{\getvalue{\??ds#1\c!text}}}%
   \assignwidth
     {\descriptionsheadwidth}
     {\getvalue{\??ds#1\c!width}}
     {\doattributes
        {\??ds#1}\c!headstyle\c!headcolor
        {\getvalue{\??ds#1\c!sample}%
         \spr{\getvalue{\??ds#1\c!separator}}}}
     {\getvalue{\??ds#1\c!distance}}%
   \advance\descriptionsheadwidth \getvalue{\??ds#1\c!distance}%
   \setbox\scratchbox\hbox to \descriptionsheadwidth
     {\doattributes
        {\??ds#1}\c!headstyle\c!headcolor
        {\strut
         \getvalue{\??ds#1\c!text}%
         \hss
         \spr{\getvalue{\??ds#1\c!separator}}%
         \hskip\getvalue{\??ds#1\c!distance}}}%
   \parindent\zeropoint
   \hskip#2\descriptionsheadwidth\indent\box\scratchbox
   \hangindent#3\descriptionsheadwidth
   \doattributes{\??ds#1}\c!style\c!color\empty
   \AfterPar{\endgroup\getvalue{\??ds#1\c!after}}% must be redone
   \GetPar}

\setupdescriptions
  [\c!location=\v!left,
   \c!headstyle=\v!bold,
   \c!titlestyle=\v!bold,
   \c!style=\v!normal,
   \c!color=,
   \c!headcolor=,
   \c!titlecolor=,
   \c!width=8em,
   \c!distance=0pt,
   \c!titledistance=0.5em,
   \c!hang=,
   \c!sample=,
   \c!align=,
   \c!margin=\v!no,
   \c!before=\blank,
   \c!inbetween=\blank,
   \c!after=\blank,
   \c!indentnext=\v!yes,
   \c!indenting=\v!never,
   \c!titleleft=(,
   \c!titleright=),
   \c!closesymbol=,
   \c!closecommand=\wordright,
   \c!command=,
   \c!titlecommand=]

\setupenumerations
  [\c!location=\v!top,
   \c!text=,
   \c!way=\v!by\v!text,
   \c!prefixconnector=.,
   \c!stopper=,
   \c!number=\v!yes, % else description
   \c!start=0,
   \s!parent=\??dd]

\setuplabels
  [\s!parent=\??dn]

\setupindentations
  [\c!style=\v!normal,
   \c!headstyle=\v!normal,
   \c!color=,
   \c!headcolor=,
   \c!width=\v!fit,
   \c!text=\unknown,
   \c!sample=,
   \c!before=\blank,
   \c!after=\blank,
   \c!distance=1em,
   \c!separator={ :}]

\protect \endinput