%D \module
%D   [       file=strc-con,
%D        version=2008.10.20,
%D          title=\CONTEXT\ Structure Macros,
%D       subtitle=Constructions,
%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 / Constructions}

\registerctxluafile{strc-con}{}

% todo: check why \copy .. probably mkii leftover
%
% todo: check if commands similar to lists
% todo: \strc_constructions_setup_counter\strc_constructions_setup_counter{#1} in setup ... synchronization
%
% ? : \def\showdnlisttext{\constructionparameter\c!listtext}   % space in default
%
% maybe: pickup text and store in buffer ...
%
% \@@notemakeconstruction[##1]{}{##2}%
% \expandafter\endgroup\noteparameter\c!next}}
%
% todo: \currentconstructionattribute : can be a counter instead

%D Constructions are just descriptions but a bit more abstract so that we can
%D conveniently build upon them. They are not really meant for users but module
%D writers might find them useful. We mention a couple of parameters but these are
%D only mentioned because in the shared code we map all resolvers to constructions.
%D
%D On top of constructions we build descriptions, enumerations, notes, labels and
%D maybe some day more.

\unprotect

%D Todo:

\installcorenamespace{construction}

\installcommandhandler \??construction {construction} \??construction

\let\setupconstructions\setupconstruction

\setupconstructions[%
    %c!title=,
    %c!text=,
    %
    %c!style=,
    %c!color=,
    %c!command=,
    %c!align=,
    %
    %c!headstyle=,
    %c!headcolor=,
    %c!headalign=,
    %
    %c!titlestyle=,
    %c!titlecolor=,
    %c!titlecommand=,
    %c!titleleft=,
    %c!titleright=,
    %
    %c!closesymbol=,
    %c!closecommand=,
    %
    \c!alternative=\v!left,
    \c!display=\v!yes,
    \c!width=7\emwidth,
    \c!distance=\emwidth,
    \c!stretch=.50,
    \c!shrink=.25,
    \c!titledistance=.5\emwidth,
    %c!hang=,
    %c!sample=,
    \c!margin=\v!no,
    \c!before=\blank,
    \c!inbetween=\blank,
    \c!after=\blank,
    %c!indentnext=,
    %c!indenting=,
    %
    \c!expansion=\v!no,
    %c!xmlsetup=,
    %s!catcodes=,
]

%D Constructions and alike uses similar structures. In order to prevent issues
%D we freeze some states. There is some overhead in the intermediate define
%D step (as we could set them directly) but this is more flexible (and looks
%D nicer). Keep in mind that descriptions, enumeration and notations are all
%D independent and that we just remap the resolvers.

% \defineconstruction[test][handler=description,level=1]
% \defineconstruction[test][parent][handler=description,level=3]

\installcorenamespace{constructionmain}  % frozen after definition
\installcorenamespace{constructionlevel} % frozen after definition
\installcorenamespace{constructionclass} % frozen after definition

\let\currentconstructionmain   \empty
\let\currentconstructionlevel  \empty
\let\currentconstructionhandler\empty

\settrue\c_strc_constructions_define_commands % use with care, might become a proper key

\appendtoks
    \ifx\currentconstructionparent\empty
        \letvalue{\??constructionmain\currentconstruction}\currentconstruction
        \definelist[\currentconstruction]% goodie
    \else
        \letvalue{\??constructionmain\currentconstruction}\currentconstructionparent
        \definelist[\currentconstruction][\currentconstructionparent]% goodie
    \fi
    \setevalue{\??constructionlevel\currentconstruction}{\number\constructionparameter\c!level}%
    \setevalue{\??constructionclass\currentconstruction}{\constructionparameter\s!handler}%
\to \everydefineconstruction

\appendtoks
    \ifconditional\c_strc_constructions_define_commands
        \setuevalue{\e!start\currentconstruction}{\strc_constructions_start{\currentconstruction}}%
        \setuevalue{\e!stop \currentconstruction}{\strc_constructions_stop}%
    \fi
\to \everydefineconstruction

%D Just a basic environment (mostly for testing). We will provide a 'setup' based
%D plugin once the rest is sorted out.

\unexpanded\def\strc_constructions_start#1%
  {\begingroup
   \strc_constructions_initialize{#1}%
   \dodoubleempty\strc_constructions_start_regular}

\unexpanded\def\strc_constructions_start_regular[#1][#2]%
  {\strc_constructions_register[#2][\c!label={\constructionparameter\c!text},\c!reference=,\c!title=,\c!bookmark=,\c!list=,#1]%
   \csname\??constructionstarthandler\currentconstructionhandler\endcsname}

\unexpanded\def\strc_constructions_stop
  {\csname\??constructionstophandler\currentconstructionhandler\endcsname
   \endgroup}

%D As we will build on top of the generic construction mechanism we have handlers
%D as a sort of plug in mechanism. In order to have some consistency we share
%D some namespaces.

\installcorenamespace{constructioninitializer}
\installcorenamespace{constructionfinalizer}

\installcorenamespace{constructionmainhandler}
\installcorenamespace{constructioncommandhandler}
\installcorenamespace{constructionstarthandler}
\installcorenamespace{constructionstophandler}

\installcorenamespace{constructiontexthandler}
\installcorenamespace{constructionnotehandler}

\unexpanded\def\strc_constructions_initialize#1% class instance
  {\edef\currentconstruction{#1}%
   \let\currentconstructionhash\??construction
   \let\currentconstructionlistentry\!!zerocount
   \expandafter\let\expandafter\currentconstructionmain   \csname\??constructionmain \currentconstruction\endcsname
   \expandafter\let\expandafter\currentconstructionlevel  \csname\??constructionlevel\currentconstruction\endcsname
   \expandafter\let\expandafter\currentconstructionhandler\csname\??constructionclass\currentconstruction\endcsname
   \csname\??constructioninitializer\currentconstructionhandler\endcsname}

\unexpanded\def\strc_constructions_finalize
  {\csname\??constructionfinalizer\currentconstructionhandler\endcsname
   \strc_constructions_discard}

\newconditional\c_strc_constructions_number_state
\newconditional\c_strc_constructions_title_state

\unexpanded\setvalue{\??constructioninitializer\v!construction}%
  {\setfalse\c_strc_constructions_number_state
   \setfalse\c_strc_constructions_title_state}

\unexpanded\setvalue{\??constructionfinalizer\v!construction}%
  {}

%D We keep the command variant around but rather would move to the start-stop one.
%D Also, passing the title as argument has some history so we need to keep that as
%D well.

% \ifdefined\dotagsetconstruction \else \let\dotagsetconstruction\relax \fi

% \startuseMPgraphic{MyFrame}
%     picture p ; numeric o ; path a, b ; pair c ;
%     p := textext.rt("\FunnyFramed{\currentconstructiontext}") ;
%   % p := textext.rt("\wrappedconstruction{\FunnyFramed{\currentconstructiontext}}") ;
%   % p := textext.rt("\FunnyFramed{\wrappedconstruction{\currentconstructiontext}}") ;
%   % p := textext.rt("\FunnyFramed{\wrappedcurrentconstruction}") ;
%     ...
% \stopuseMPgraphic
%
% \defineoverlay[MyFrame][\useMPgraphic{MyFrame}]
%
% \defineframedtext
%   [MyText]
%   [frame=off,
%    background=MyFrame]
%
% \defineenumeration[Theorem]
%   [alternative=empty,
%    before=\startMyText,
%    after=\stopMyText]

\newtoks\everyconstruction

\unexpanded\def\currentconstructiontext
  {\begstrut
   \csname\??constructiontexthandler\currentconstructionhandler\endcsname
   \endstrut}

\unexpanded\def\currentconstructionsample
  {\begstrut
   \constructionparameter\c!text
   \p_strc_constructions_sample
   \endstrut}

\unexpanded\def\wrappedconstruction#1%
  {\begingroup
     \iftrialtypesetting \else
       \currentconstructionsynchronize
       \c_attr_destination\currentconstructionattribute\relax
     \fi
     #1%
   \endgroup}

\unexpanded\def\wrappedcurrentconstruction
  {\begingroup
     \iftrialtypesetting \else
       \currentconstructionsynchronize
       \c_attr_destination\currentconstructionattribute\relax
     \fi
     \currentconstructiontext
   \endgroup}

\unexpanded\setvalue{\??constructionmainhandler\v!construction}#1%
  {\iftrialtypesetting \else
     \begingroup
     \currentconstructionsynchronize % reinstated
     \c_attr_destination\currentconstructionattribute\relax % todo, whole text
     \signalcharacter
     \endgroup
   \fi#1}

\unexpanded\setvalue{\??constructiontexthandler\v!construction}%
  {\begingroup
   \useconstructionstyleandcolor\c!headstyle\c!headcolor % move to \currentconstructiontext
   \the\everyconstruction
   \constructionparameter\c!headcommand
     {\strut
      \constructionparameter\c!text
      \clf_savedlisttitle{\currentconstructionmain}\currentconstructionlistentry\relax}%
   \endgroup}

\unexpanded\def\strc_constructions_stored_start
  {\begingroup % brrr \endgroup elsewhere ... will be sorted out
   \csname\??constructionstarthandler\currentconstructionhandler\endcsname}

\unexpanded\def\strc_constructions_stored_stop
  {\csname\??constructionstophandler\currentconstructionhandler\endcsname}

\newconstant\c_strc_constructions_nested_state % to be redone

\def\resetconstructions % to be used in e.g. footnotes
  {\c_strc_constructions_nested_state\zerocount}

\unexpanded\setvalue{\??constructioncommandhandler\v!construction}%
  {\endgroup}

\let\p_strc_constructions_sample        \empty
\let\p_strc_constructions_align         \empty
\let\p_strc_constructions_indenting     \empty
\let\p_strc_constructions_width         \empty
\let\p_strc_constructions_aligntitle    \empty
\let\p_strc_constructions_renderingsetup\empty
\let\p_strc_constructions_headalign     \empty
\let\p_strc_constructions_hang          \empty
\let\p_strc_constructions_inbetween     \empty
\let\p_strc_constructions_closesymbol   \empty
\let\p_strc_constructions_distance      \empty

\newconditional\c_strc_constructions_distance_none

\def\strc_constructions_set_width_and_distance
  {\assignwidth
     \p_strc_constructions_width
     \constructionsheadwidth
     {\unhcopy\constructionheadbox}
     \constructionsheaddistance}

\def\strc_constructions_preroll_head#content%
  {\setbox\constructionheadbox\hbox
     {\forgetall
      \dontcomplain
      \settrialtypesetting
      \csname\??constructionmainhandler\currentconstructionhandler\endcsname#content}}

\def\strc_constructions_ignore_head
  {\constructionsheaddistance\zeropoint
   \constructionsheadwidth   \zeropoint
   % we also need to make sure that no stretch creeps in (new per 2015-02-02, for Alan)
   \settrue\c_strc_constructions_distance_none}

\let\currentconstructionhash\??construction

\unexpanded\setvalue{\??constructionstarthandler\v!construction}% this will be redone (reorganized) .. too much boxing
  {\dostarttaggedchained\t!construction\currentconstruction\currentconstructionhash
%    \dotagsetconstruction
   \constructionparameter\c!before
   \begingroup
   \edef\currentconstructionalternative{\constructionparameter\c!alternative}%
   \edef\p_strc_constructions_renderingsetup{\constructionalternativeparameter\c!renderingsetup}%
   % catch fuzzyness
   \ifx\p_strc_constructions_renderingsetup\empty
      \letconstructionparameter\c!alternative\v!left
      \let\currentconstructionalternative\v!left
      \edef\p_strc_constructions_renderingsetup{\constructionalternativeparameter\c!renderingsetup}%
   \else
     \doifnotsetups\p_strc_constructions_renderingsetup
       {\letconstructionparameter\c!alternative\v!left
        \let\currentconstructionalternative\v!left
        \edef\p_strc_constructions_renderingsetup{\constructionalternativeparameter\c!renderingsetup}}%
   \fi
   %
   \doadaptleftskip{\constructionparameter\c!margin}%
   \setlocalhsize % so we can use \localhsize in width assignments
   \edef\p_strc_constructions_distance{\constructionalternativeparameter\c!distance}%
   \edef\p_strc_constructions_width{\constructionalternativeparameter\c!width}%
   \ifx\p_strc_constructions_distance\v!none
     \settrue\c_strc_constructions_distance_none
     \constructionsheaddistance\zeropoint
   \else
     \setfalse\c_strc_constructions_distance_none
     \constructionsheaddistance\p_strc_constructions_distance\relax
     \ifdim\constructionsheaddistance=\zeropoint
       \ifx\p_strc_constructions_width\v!broad
         \constructionsheaddistance\emwidth
       \else\ifx\p_strc_constructions_width\v!line
         \constructionsheaddistance\emwidth
       \fi\fi
     \fi
   \fi
   % inefficient and not always needed, for instance not with margins so we will make checkers
   % per alternative some day (especially in labels this is unwanted overhead)
   %
   % maybe we should have an option as i cannot oversee the consequences now
   %
   % \edef\p_strc_constructions_sample{\constructionparameter\c!sample}%
   % \ifx\p_strc_constructions_sample\empty
   %   \strc_constructions_preroll_head\currentconstructiontext
   % \else
   %   \strc_constructions_preroll_head\currentconstructiontextsample
   % \fi
   % \strc_constructions_set_width_and_distance
   %
   \strc_constructions_preroll_head\currentconstructiontext
   \ifzeropt\wd\constructionheadbox
     \strc_constructions_ignore_head
   \else
     \edef\p_strc_constructions_sample{\constructionparameter\c!sample}%
     \ifx\p_strc_constructions_sample\empty
       \strc_constructions_set_width_and_distance
     \else
       \strc_constructions_preroll_head\currentconstructionsample
       \ifzeropt\wd\constructionheadbox
         \strc_constructions_ignore_head
       \else
         \strc_constructions_set_width_and_distance
       \fi
     \fi
   \fi
   %
   \dostarttagged\t!constructiontag\empty % todo
   \setbox\constructionheadbox\hbox
     {\forgetall
      \dontcomplain
      \ifx\currentconstructionalternative\v!serried % brrr, hack, will change
        \csname\??constructionmainhandler\currentconstructionhandler\endcsname\currentconstructiontext
      \else
        \csname\??constructionmainhandler\currentconstructionhandler\endcsname{\boxedconstructionhead\currentconstructiontext}%
      \fi}%
   \edef\p_strc_constructions_aligntitle{\constructionparameter\c!aligntitle}%
   \ifx\p_strc_constructions_aligntitle\v!no
     \leftconstructionskip \leftskip
     \rightconstructionskip\rightskip
   \else
     \ifcase\c_strc_constructions_nested_state
       \leftconstructionskip \leftskip
       \rightconstructionskip\rightskip
     \fi
   \fi
   \edef\p_strc_constructions_align{\constructionparameter\c!align}%
   \ifx\p_strc_constructions_align\empty \else
     \setupalign[\p_strc_constructions_align]% \use...
   \fi
   \ifcase\c_strc_constructions_nested_state
     \c_strc_constructions_nested_state\plusone
   \or
     \c_strc_constructions_nested_state\plustwo
   \fi
   \strc_constructions_close_symbol_reset
   %
   \edef\p_strc_constructions_headalign{\constructionparameter\c!headalign}%
   %
   \directsetup\p_strc_constructions_renderingsetup\relax
   % moved to here 2014-07-03
   \edef\p_strc_constructions_indenting{\constructionparameter\c!indenting}%
   \ifx\p_strc_constructions_indenting\empty \else
     \indenting[\p_strc_constructions_indenting]% \use...
   \fi
   %
   \dostoptagged % tag
   \dostarttagged\t!constructioncontent\empty
  %\freezeparagraphproperties
   \updateparagraphshapes
   \ignorespaces} % args not needed

\unexpanded\setvalue{\??constructionstophandler\v!construction}%
  {\strc_constructions_close_symbol_place
   \doifnot{\constructionparameter\c!display}\v!no\par
   \dostoptagged % content
   \dostoptagged % construction
   \endgroup
   \constructionparameter\c!after
   \useindentnextparameter\constructionparameter
   \strc_constructions_finalize
%   \endgroup
   \dorechecknextindentation}

\unexpanded\def\boxedconstructionhead#1%
  {\doifelse{\constructionalternativeparameter\c!alignbottom}{\v!yes}\vbox\vtop
     {\hsize\constructionsheadwidth
      \edef\p_strc_constructions_headalign{\constructionparameter\c!headalign}%
      \ifx\p_strc_constructions_headalign\empty \else
        \setupalign[\p_strc_constructions_headalign]% \use...
      \fi
      #1}}

\installcorenamespace{constructionalternative}
\installcorenamespace{constructionrenderings}

% see lists: alternativemethods ... todo
%
% there will be a proper interface to variables

\installcommandhandler \??constructionalternative {constructionalternative} \??constructionalternative

\setupconstructionalternative
  [%c!left=, % no inheritance
   %c!right=,% no inheritance
   \c!width=\constructionparameter\c!width,
   \c!distance=\constructionparameter\c!distance,
   \c!stretch=\constructionparameter\c!stretch,
   \c!shrink=\constructionparameter\c!shrink]

\defineconstructionalternative
  [\v!left]
  [%\c!width=7em,
   %\c!distance=1em,
   \c!renderingsetup=\??constructionrenderings:\v!left]

\defineconstructionalternative
  [\v!right]
  [%\c!width=7em,
   %\c!distance=1em,
   \c!renderingsetup=\??constructionrenderings:\v!right]

\defineconstructionalternative
  [\v!inmargin]
  [\c!renderingsetup=\??constructionrenderings:\v!inmargin]

\defineconstructionalternative
  [\v!inleft]
  [\c!renderingsetup=\??constructionrenderings:\v!inleft]

\defineconstructionalternative
  [\v!inright]
  [\c!renderingsetup=\??constructionrenderings:\v!inright]

\defineconstructionalternative
  [\v!margin]
  [\c!renderingsetup=\??constructionrenderings:\v!margin]

\defineconstructionalternative
  [\v!leftmargin]
  [\c!renderingsetup=\??constructionrenderings:\v!leftmargin]

\defineconstructionalternative
  [\v!rightmargin]
  [\c!renderingsetup=\??constructionrenderings:\v!rightmargin]

\defineconstructionalternative
  [\v!innermargin]
  [\c!renderingsetup=\??constructionrenderings:\v!innermargin]

\defineconstructionalternative
  [\v!outermargin]
  [\c!renderingsetup=\??constructionrenderings:\v!outermargin]

\defineconstructionalternative
  [\v!serried]
  [\c!renderingsetup=\??constructionrenderings:\v!serried]

\defineconstructionalternative
  [\v!hanging]
  [%\c!width=.75\emwidth
   \c!renderingsetup=\??constructionrenderings:\v!hanging]

\defineconstructionalternative
  [\v!top]
  [\c!renderingsetup=\??constructionrenderings:\v!top,
   \c!width=\localhsize]

\defineconstructionalternative
  [\v!command]
  [\c!renderingsetup=\??constructionrenderings:\v!command]

\defineconstructionalternative
  [\v!empty]
  [\c!renderingsetup=\??constructionrenderings:\v!empty]

\defineconstructionalternative
  [\v!label]
  [\c!renderingsetup=\??constructionrenderings:\v!label,
   \c!width=]

\newbox   \constructionheadbox
\newskip  \leftconstructionskip
\newskip  \rightconstructionskip
\newdimen \constructionsheadwidth    % replaces \!!widtha % TODO: proper namespace dimens
\newdimen \constructionsheaddistance % replaces \!!widthb % TODO: proper namespace dimens

\def\strc_constructions_set_hang_box#1% messy left/rightskip
  {\setbox\constructionheadbox\vtop   % \vbox gaat fout in hang
     {\forgetall
      \dontcomplain
      \hsize\constructionsheadwidth\relax
      \ifx\p_strc_constructions_headalign\empty
        \setupalign[#1]% use fast one
      \else
        \setupalign[\p_strc_constructions_headalign]% use fast one
      \fi
      \ifconditional\c_strc_constructions_distance_none \else
        \advance\ifx#1\v!flushleft\rightskip\else\leftskip\fi\constructionsheaddistance % only difference and wrong anyway
      \fi
      \flushconstructionheadbox}%
   \setbox\constructionheadbox\hpack{\box\constructionheadbox}% needed in case of e.g. a real big head font, see descriptions-006.tex
   \ht\constructionheadbox\strutht
   \dp\constructionheadbox\strutdp}

\def\strc_constructions_set_pure_box#1% default ... better set up differently
  {\setbox\constructionheadbox\vtop
     {\forgetall
      \dontcomplain
      \hsize\constructionsheadwidth\relax
      \ifx\p_strc_constructions_headalign\empty
        \setupalign[#1]% use fast one
      \else
        \setupalign[\p_strc_constructions_headalign]% use fast one
      \fi
      \flushconstructionheadbox}%
   \setbox\constructionheadbox\hpack{\box\constructionheadbox}% needed in case of e.g. a real big head font, see descriptions-006.tex
   \ht\constructionheadbox\strutht
   \dp\constructionheadbox\strutdp}

\def\strc_constructions_set_hang#1%
  {\ifx\p_strc_constructions_hang\empty
     % nothing
   \else\ifx\p_strc_constructions_hang\v!fit
     \scratchdimen\htdp\constructionheadbox
     \getnoflines\scratchdimen
     \hangafter-\noflines
   \else\ifx\p_strc_constructions_hang\v!broad
     \scratchdimen\dimexpr\htdp\constructionheadbox+.5\strutht\relax
     \getnoflines\scratchdimen
     \hangafter-\noflines
   \else
     \hangafter-\p_strc_constructions_hang
   \fi\fi\fi
   \relax
   \hangindent\ifx#1\v!right-\fi\constructionsheadwidth}

% \unexpanded\def\flushconstructionheadbox
%   {\ifhbox\constructionheadbox\unhcopy\else\copy\fi\constructionheadbox}

\unexpanded\def\flushconstructionheadbox
  {\ifhbox\constructionheadbox\unhbox\else\box\fi\constructionheadbox}

% The setups. These only deal with placement of the descriptor and initializing the
% environment. The wrapping happens elsewhere.

% todo: optimize the setups with
%
% \ifconditional\c_strc_constructions_distance_none : no need for skip
% \ifzeropt\wd\constructionheadbox : no need for box and skips

\startsetups[\??constructionrenderings:\v!left]
    \edef\p_strc_constructions_hang{\constructionparameter\c!hang}%
    \doifelsesetups{\??constructionrenderings:\v!left:\p_strc_constructions_hang} {
        \directsetup{\??constructionrenderings:\v!left:\p_strc_constructions_hang}
    } {
        \directsetup{\??constructionrenderings:\v!left:\v!hanging}
    }
\stopsetups

\startsetups[\??constructionrenderings:\v!right]
    \edef\p_strc_constructions_hang{\constructionparameter\c!hang}
    \doifelsesetups{\??constructionrenderings:\v!right:\p_strc_constructions_hang} {
        \directsetup{\??constructionrenderings:\v!right:\p_strc_constructions_hang}
    } {
        \directsetup{\??constructionrenderings:\v!right:\v!hanging}
    }
\stopsetups

\startsetups[\??constructionrenderings:\v!left:\v!none]
    \let\\\crlf
    \noindent
    \strc_constructions_set_pure_box\v!flushleft
    \leftskip\dimexpr\leftconstructionskip+\constructionsheadwidth+\constructionsheaddistance\relax
    \rightskip\rightconstructionskip\relax
    \llap {
        \hpack to \leftskip {
            \hskip\leftconstructionskip
            \box\constructionheadbox % was copy
            \hss
        }
    }
    \nobreak
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!left:0]
    \directsetup{\??constructionrenderings:\v!left:\v!none}
\stopsetups

\startsetups[\??constructionrenderings:\v!left:]
    \directsetup{\??constructionrenderings:\v!left:\v!none}
\stopsetups

\startsetups[\??constructionrenderings:\v!right:\v!none]
    \let\\\crlf
    \noindent
    \leftskip\leftconstructionskip
    \rightskip\dimexpr\rightconstructionskip+\constructionsheadwidth\relax
   %\strc_constructions_pure_hang_box\raggedleft
    \strc_constructions_set_pure_box\v!flushright
    \rlap {
        \hskip\dimexpr\hsize-\leftskip-\rightskip\relax
        \copy\constructionheadbox
        \hskip\rightconstructionskip
    }
    \nobreak
    \advance\rightskip \constructionsheaddistance
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!right:0]
    \directsetup{\??constructionrenderings:\v!right:\v!none}
\stopsetups

\startsetups[\??constructionrenderings:\v!right:]
    \directsetup{\??constructionrenderings:\v!right:\v!none}
\stopsetups

\startsetups[\??constructionrenderings:\v!left:\v!margin]%
    \let\\\crlf
    \noindent
    \strc_constructions_set_pure_box\v!flushleft
    \llap {
        \hpack to \constructionsheadwidth {
            \box\constructionheadbox % was copy
            \hss
        }
        \hskip\constructionsheaddistance
    }
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!right:\v!margin]%
    \let\\\crlf
    \noindent
    \strc_constructions_set_pure_box\v!flushright
    \rlap {
        \hskip\constructionsheaddistance
        \hpack to \constructionsheadwidth {
            \box\constructionheadbox % was copy
            \hss
        }
    }
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!left:\v!hanging]%
    \let\\\crlf
    \dontcomplain
    \advance\constructionsheadwidth \constructionsheaddistance
    \strc_constructions_set_hang_box\v!flushleft
    \strc_constructions_set_hang\v!left
    \noindent
    \llap {
        \tpack to \zeropoint {
            \box\constructionheadbox
        }
    }
    \nobreak
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!right:\v!hanging]%
    \let\\\crlf
    \dontcomplain
    \advance\constructionsheadwidth \constructionsheaddistance
    \strc_constructions_set_hang_box\v!flushright
    \strc_constructions_set_hang\v!right
    \noindent
    \rlap {
        \hpack to \dimexpr\hsize-\leftskip-\rightskip\relax {
            \hss
            \tpack to \zeropoint {
                \box\constructionheadbox
            }
        }
    }
    \nobreak
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!top]
  % \strc_sectioning_prevent_page_break % commented per 31/5/2019
    \let\\\space
    \noindent
    \copy\constructionheadbox % why copy ?
    \par
    \nobreak
    \edef\p_strc_constructions_inbetween{\constructionparameter\c!inbetween}%
    \ifx\p_strc_constructions_inbetween\empty \else
      \p_strc_constructions_inbetween
      % shouldn't this move to after the fi?
      \directcheckedvspacing\v!samepage
    \fi
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

% why copy? historic reason?

\startsetups[\??constructionrenderings:\v!margin]
    \let\\\crlf
    \noindent
    \inmargin[\c!scope=\v!local]{\flushconstructionheadbox}%
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!leftmargin]
    \let\\\crlf
    \noindent
    \inleft[\c!scope=\v!local]{\flushconstructionheadbox}%
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!rightmargin]
    \let\\\crlf
    \noindent
    \inright[\c!scope=\v!local]{\flushconstructionheadbox}%
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!innermargin]
    \let\\\crlf
    \noindent
    \ininner[\c!scope=\v!local]{\flushconstructionheadbox}%
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!outermargin]
    \let\\\crlf
    \noindent
    \inouter[\c!scope=\v!local]{\flushconstructionheadbox}%
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!inmargin]
    \directsetup{\??constructionrenderings:\v!margin}
\stopsetups

\startsetups[\??constructionrenderings:\v!inleft]
    \directsetup{\??constructionrenderings:\v!leftmargin}
\stopsetups

\startsetups[\??constructionrenderings:\v!inright]
    \directsetup{\??constructionrenderings:\v!rightmargin}
\stopsetups

\startsetups[\??constructionrenderings:\v!serried]
    % already set?
    \edef\p_strc_constructions_width{\constructionparameter\c!width}% CHECK ! ! ! wrong parameter namespace
    \doifelsesetups{\??constructionrenderings:\v!serried:\p_strc_constructions_width} {
        \directsetup{\??constructionrenderings:\v!serried:\p_strc_constructions_width}
    } {
        \directsetup{\??constructionrenderings:\v!serried:\v!wide}
    }
\stopsetups

\startsetups[\??constructionrenderings:\v!serried:\v!fit]
    \let\\\crlf
    \noindent
    \flushconstructionheadbox
    \nobreak
    \hskip\constructionsheaddistance\relax
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!serried:\v!broad]
    \let\\\crlf
    \noindent
    \flushconstructionheadbox
    \ifconditional\c_strc_constructions_distance_none \else
        \nobreak
        \hskip\constructionsheaddistance
          \s!plus \constructionalternativeparameter\c!stretch\constructionsheaddistance
          \s!minus\constructionalternativeparameter\c!shrink \constructionsheaddistance
        \relax
    \fi
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!serried:]
    \directsetup{\??constructionrenderings:\v!serried:\v!broad}
\stopsetups

\startsetups[\??constructionrenderings:\v!serried:\v!wide]
    \let\\\crlf
    \noindent
    \hbox to \constructionsheadwidth {
        \flushconstructionheadbox
        \hss
    }
    \nobreak
    \hskip\constructionsheaddistance\relax
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!hanging]
    % tricky: leftskipadaption is somewhat unpredictable
    \let\\\crlf
    \noindent
    \advance\leftskip-\leftskipadaption\relax
    \ifdim\leftskipadaption=\zeropoint
        \leftskipadaption1.5\emwidth\relax % just some default
        \ifnum\c_strc_constructions_nested_state=\plusone
            \ifdim\leftskip>\zeropoint \relax
                \leftskipadaption\leftskip
            \fi
        \fi
    \fi
    \ifnum\c_strc_constructions_nested_state>\zerocount % was \ifnum\c_strc_constructions_nested_state=\plusone
        \advance\leftskip\leftskipadaption % but we're already further on
    \fi
    \hskip-\leftskipadaption\relax
    \ifhbox\constructionheadbox \unhbox\else\box\fi\constructionheadbox
    \ifconditional\c_strc_constructions_distance_none \else
      % we used to have just a kern, but long lines look bad then
      \scratchdistance\ifdim\constructionsheaddistance=\zeropoint .75\emwidth\else\constructionsheaddistance\fi
      \hskip \scratchdistance
        \s!plus \constructionalternativeparameter\c!stretch\scratchdistance
        \s!minus\constructionalternativeparameter\c!shrink \scratchdistance
    \fi
    \ifhmode
        \ifx\p_strc_constructions_width\v!line
            \hfill\break
        \else
            \allowbreak
        \fi
    \fi
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

%D \starttyping
%D \setupfootnotation[location=command,headcommand=\llap]
%D \stoptyping

\startsetups[\??constructionrenderings:\v!command]
    \noindent
    \constructionparameter\c!headcommand{\flushconstructionheadbox}
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!empty]
    \noindent
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

\startsetups[\??constructionrenderings:\v!label]
    \dontleavehmode
    \begingroup
    \constructionparameter\c!headcommand{\flushconstructionheadbox}
    \endgroup
\stopsetups

\ifcase\contextlmtxmode \else
    % just an empty check so that we can grep for contextlmtxmode in mkiv files
\fi

% \definedescription[whatever][alternative=right:bottom]
%
% \startwhatever{just a small\\example}
%     \input ward
% \stopwhatever

\defineconstructionalternative
  [\v!right:\v!bottom]
  [%\c!width=7em,
   %\c!distance=1em,
   \c!alignbottom=\v!yes,
   \c!renderingsetup=\??constructionrenderings:\v!right:\v!bottom]

\startsetups[\??constructionrenderings:\v!right:\v!bottom]
    \let\\\crlf
    \noindent
    \leftskip\leftconstructionskip
    \rightskip\dimexpr\rightconstructionskip+\constructionsheadwidth+\constructionsheaddistance\relax
    \parfillskip\zeropoint
    \strc_constructions_set_pure_box\v!flushright
    \directparwrapper \relax {%
      \hfilll
      \rlap
        {\kern\constructionsheaddistance
         \copy\constructionheadbox}%
    }%
    \useconstructionstyleandcolor\c!style\c!color
    \ignorespaces
\stopsetups

%D This next feature will get an lmtx implementation (probably by using a new generic
%D close mechanism).

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

\installcorenamespace{constructionclosesymbol}

\let\placeclosesymbol\donothing
\let\qed             \donothing

\def\strc_constructions_close_symbol_reset % no need for global
  {\global\expandafter\settrue\csname\??constructionclosesymbol\currentconstruction\endcsname
   \let\placeclosesymbol\strc_constructions_close_symbol_place
   \let\qed             \strc_constructions_close_symbol_place}

\unexpanded\def\strc_constructions_close_symbol_place
  {\ifconditional\csname\??constructionclosesymbol\currentconstruction\endcsname
     \global\expandafter\setfalse\csname\??constructionclosesymbol\currentconstruction\endcsname
     \edef\p_strc_constructions_closesymbol{\constructionparameter\c!closesymbol}%
     \ifx\p_strc_constructions_closesymbol\empty \else
       \constructionparameter\c!closecommand{\p_strc_constructions_closesymbol}% hm why {} maybe because box expected
     \fi
   \fi}

\newif\ifnoconstructioncaption

%D The storage macros:

\let\currentconstructionlistentry\!!zerocount

\unexpanded\def\strc_constructions_register
  {\clf_doifelselisthasentry\numexpr\currentconstructionlistentry\relax
     \strc_constructions_register_nop
     \strc_constructions_register_yes}

% \def\strc_constructions_register{\strc_constructions_register_yes}

\def\strc_constructions_register_nop[#1][#2]% #1=optional user data #2=interfaced-settings
 %{\writestatus{constructions}{reusing \currentconstruction: \number\currentconstructionlistentry}}
  {}

\def\strc_constructions_discard
  {\iftrialtypesetting
   % \writestatus{constructions}{discarding \currentconstruction: \number\currentconstructionlistentry}%
     \clf_discardfromlist\currentconstructionlistentry\relax
   \fi}

\let\currentconstructionlistnumber \!!zerocount
\let\currentconstructionsynchronize\relax
\let\currentconstructionattribute  \attributeunsetvalue

\def\strc_constructions_register_yes[#1][#2]% #1=optional user data #2=interfaced-settings
  {\begingroup                              % similar to structure so we might generalize this
   \setupcurrentconstruction[#2]%           % xdef's will become edef's
   \xdef\currentconstructionexpansion      {\constructionparameter\c!expansion}%
   \xdef\currentconstructionxmlsetup       {\constructionparameter\c!xmlsetup}%
   \xdef\currentconstructioncatcodes       {\constructionparameter\s!catcodes}%
   \xdef\currentconstructionlabel          {\constructionparameter\c!label}%
   \xdef\currentconstructionreference      {\constructionparameter\c!reference}%
   \xdef\currentconstructionreferenceprefix{\constructionparameter\c!referenceprefix}%
   %xdef\currentconstructionshownumber     {\constructionparameter\c!number}%
   \xdef\currentconstructionincrementnumber{\constructionparameter\c!incrementnumber}%
   %
   \ifx\currentconstructionexpansion\empty
     \glet\currentconstructionexpansion\v!no
   \fi
   %
   \ifx\currentconstructionreferenceprefix\empty
     \glet\currentconstructionreferenceprefix\referenceprefix
   \fi
   \ifx\currentconstructionexpansion\s!xml
     \xmlstartraw
       \xdef\currentconstructiontitle   {\constructionparameter\c!title}%
       \xdef\currentconstructionbookmark{\constructionparameter\c!bookmark}%
       \xdef\currentconstructionmarking {\constructionparameter\c!marking}%
       \xdef\currentconstructionlist    {\constructionparameter\c!list}%
     \xmlstopraw
     \ifx\currentconstructionlist\empty
       \glet\currentconstructionlist\currentconstructiontitle
     \fi
     \glet\currentconstructioncoding\s!xml
   \else
     \ifx\currentconstructionexpansion\v!yes
       \xdef\currentconstructiontitle   {\constructionparameter\c!title}%
       \xdef\currentconstructionbookmark{\constructionparameter\c!bookmark}%
       \xdef\currentconstructionmarking {\constructionparameter\c!marking}%
       \xdef\currentconstructionlist    {\constructionparameter\c!list}%
     \else
       \xdef\currentconstructiontitle   {\detokenizedconstructionparameter\c!title}%
       \xdef\currentconstructionbookmark{\detokenizedconstructionparameter\c!bookmark}%
       \xdef\currentconstructionmarking {\detokenizedconstructionparameter\c!marking}%
       \xdef\currentconstructionlist    {\detokenizedconstructionparameter\c!list}%
       \iflocation \ifx\currentconstructionbookmark\empty
         \begingroup
         \simplifycommands
         \xdef\currentconstructionbookmark{\detokenize\expandafter{\normalexpanded{\constructionparameter\c!title}}}%
         \endgroup
       \fi \fi
     \fi
     \ifx\currentconstructionlist\empty
       \glet\currentconstructionlist\currentconstructiontitle
     \fi
     \glet\currentconstructioncoding\s!tex
   \fi
   %
   \ifx\currentconstructiontitle\v!none % will become obsolete
     \global\noconstructioncaptiontrue\global\noconstructionnumbertrue
   \fi
   %
   \ifnoconstructioncaption % then why analyze anyway?
     \endgroup
     \let\currentconstructionlistnumber \relax
     \let\currentconstructionsynchronize\relax
     \let\currentconstructionattribute  \relax
   \else
     \setnextinternalreferences{construction}\currentconstructionmain % plural
     \relax
     \scratchcounter\clf_addtolist
        metadata {
            kind     {construction}
            name     {\currentconstructionmain}
          % level    structures.sections.currentlevel()
            catcodes \catcodetable
        }
        references {
            internal  \locationcount
            order     \locationorder
            reference {\currentconstructionreference}
            prefix    {\currentconstructionreferenceprefix}
          % block     {\currentsectionblock}
          % section   structures.sections.currentid(),
        }
        titledata  {
            label    {\detokenize\expandafter{\currentconstructionlabel}}
            title    {\detokenize\expandafter{\currentconstructiontitle}}
        \ifx\currentconstructionbookmark\currentconstructiontitle \else
            bookmark {\detokenize\expandafter{\currentconstructionbookmark}}
        \fi
        \ifx\currentconstructionlist\currentconstructiontitle \else
            list     {\detokenize\expandafter{\currentconstructionlist}}
        \fi
        }
    \ifconditional\c_strc_constructions_number_state
        prefixdata {
            prefix        {\constructionparameter\c!prefix}
            separatorset  {\constructionparameter\c!prefixseparatorset}
            conversion    {\constructionparameter\c!prefixconversion}
            conversionset {\constructionparameter\c!prefixconversionset}
            set           {\constructionparameter\c!prefixset}
            segments      {\constructionparameter\c!prefixsegments}
            connector     {\constructionparameter\c!prefixconnector}
        }
        numberdata {
            numbers       {\currentconstructionnumber}
            separatorset  {\constructionparameter\c!numberseparatorset}
            conversion    {\constructionparameter\c!numberconversion}
            conversionset {\constructionparameter\c!numberconversionset}
            starter       {\constructionparameter\c!numberstarter}
            stopper       {\constructionparameter\c!numberstopper}
            segments      {\constructionparameter\c!numbersegments}
        }
    \or
       % symbol
    \fi
        userdata {\detokenize{#1}}
     \relax
   % \writestatus{constructions}{registering \currentconstruction: \number\scratchcounter}%
     \clf_setinternalreference
       prefix    {\currentconstructionreferenceprefix}%
       reference {\currentconstructionreference}%
       internal  \locationcount
       view      {\interactionparameter\c!focus}%
     \relax
     \normalexpanded{%
       \endgroup
       \edef\noexpand\currentconstructionlistentry  {\the\scratchcounter}%
       \edef\noexpand\currentconstructionattribute  {\the\lastdestinationattribute}%
       \edef\noexpand\currentconstructionsynchronize{\clf_deferredenhancelist\the\scratchcounter}%
     }%
   \fi}

% This is not so nice, some day I'll just store the number with the entry
% and deal with all at the Lua end, but first we need to be able to set
% macros.

\def\reinstateconstructionnumberentry#1% was xdef
  {\edef\currentconstructionattribute  {\clf_getinternallistreference#1}%
   \edef\currentconstructionsynchronize{\clf_deferredenhancelist\number#1}}

\def\reinstatecachedconstructionnumberentry#1% was xdef | #1 = cached index can be different from real
  {\edef\currentconstructionattribute  {\clf_getinternalcachedlistreference#1}% destination
   \edef\currentconstructionsynchronize{\clf_deferredenhancelist\number#1}}

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

% Helpers:

\def\currentconstructionnumber{\constructionparameter\s!counter}

\unexpanded\def\strc_constructions_next_indeed #get#tag#level{\strc_counters_increment_sub{#get{#tag}\s!counter}{#level}}
\unexpanded\def\strc_constructions_reset_indeed#get#tag#level{\strc_counters_reset_sub    {#get{#tag}\s!counter}{#level}}

\protect \endinput