%D \module
%D   [       file=tabl-ltb,
%D        version=2002.10.31,
%D          title=\CONTEXT\ Table Macros,
%D       subtitle=Line Tables,
%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.

% testfile: tfmetrics.tex

% todo: als nx>1, dan in geval van rek tussenruimte berekenen en optellen
% bij breedte, dus: nx nog niet gebruiken in combinatie met rek ! ! ! ! !

% This module is experimental, undocumented, and currently only set up
% eTeX. It provides a mechanism for typesetting very large tables,
% spanning many pages horizontally and vertically, with repeated
% header lines and (entry) columns, tab tracking, color, etc. In does
% two passes over a table, which is why the table goes into a
% buffer or file. As said, tables can be real huge.

% \BH \BC .. \EC \BC .. \EC \EH % append
% \BR \BC .. \EC \BC .. \EC \ER
%
% or
%
% \NC .. \NC .. \NC \NR (todo: optional last \NC)

% alternative:
%
% (1) direct run, save content in macro, but only if needed
%
% todo
%
% (2) buffered table content
%
% \startbuffer
%   \startlinetablehead
%   \stoplinetablehead
%   \startlinetablebody
%   \stoplinetablebody
% \stopbuffer
%
% \processlinetablebuffer[buffer]
%
% in buffer : head and body
%
% (3) unbuffered run, multipass
%
% - run with starting width zero / prev run
% - clip on prev run
% - flush real widths

\writestatus{loading}{ConTeXt Table Macros / Line Tables}

\unprotect

\chardef\linetablesplitstate\zerocount
\chardef\linetableheadstate \zerocount

\edef\??ler{\??le:r:}
\edef\??lec{\??le:c:}
\edef\??lew{\??le:w:}
\edef\??leh{\??le:h:}
\edef\??led{\??le:d:}

\newif\iflinetablepreroll
\newif\ifinlinetable

\newcount\linetablecolumn
\newcount\linetablesubcol
\newdimen\linetablewidth
\newdimen\linetableheight
\newbox  \linetablecell

\let\noflinetablecolumns\!!zerocount
\let\noflinetablerows   \!!zerocount
\let\noflinetablelines  \!!zerocount
\let\noflinetableparts  \!!zerocount
\let\linetablepart      \!!plusone
\let\linetablestep      \!!plusone
\let\linetableline      \!!zerocount
\let\linetablerow       \!!zerocount
\let\linetablerows      \!!zerocount

\initializetablebox     \zerocount % holds repeater

\chardef\linetablehmode \zerocount
\chardef\linetablepage  \zerocount
\chardef\linetablerepeat\zerocount

\def\setuplinetable
  {\dotripleempty\dosetuplinetable}

\def\dosetuplinetable[#1][#2][#3]%
  {\ifthirdargument
     \getparameters[\??le:#1:#2][#3]%
   \else\ifsecondargument
     \getparameters[\??lec#1][#2]%
   \else
     \getparameters[\??le][#1]%
   \fi\fi}

\setuplinetable
  [\c!n=\!!maxcard,
   \c!lines=\!!maxcard,
   \c!nx=\plusone,
   \c!nleft=0,
   \c!repeat=\v!yes, % when \c!nleft>0, repeat on both pages
   \c!before=,
   \c!after=,
   \c!inbetween=\page,
   \c!distance=\zeropoint,
   \c!stretch=\v!no,
   \c!align=\c!right,
   \c!leftoffset=.25ex,
   \c!rightoffset=\linetableparameter\c!leftoffset,
   \c!maxwidth=\zeropoint,
   \c!width=5em,
   \c!height=\v!fit, % \v!line = faster
   \c!background=,
   \c!backgroundcolor=]

\def\linetableparameter#1%
  {\csname\??le#1\endcsname}

\def\doifelselinetablecparameter#1%
  {\ifcsname\??lec\number\linetablecolumn#1\endcsname
     \expandafter\firstoftwoarguments
   \else
     \expandafter\secondoftwoarguments
   \fi}

\def\linetablecparameter#1%
  {\csname
     \ifcsname\??lec\number\linetablecolumn#1\endcsname
       \??lec\number\linetablecolumn
     \else
       \??le
     \fi
   #1\endcsname}

\def\linetablerparameter#1% faster, leaner and meaner
  {\csname
     \ifnum\linetablerow=\zerocount % geen ifcase
       \ifcsname\??ler\v!header#1\endcsname
         \??ler\v!header#1%
       \else\ifcsname\??ler0#1\endcsname
         \??ler0#1%
       \else
         \s!empty
       \fi\fi
     \else
       \ifcsname\??ler\number\linetablerow#1\endcsname
         \??ler\number\linetablerow#1%
       \else\ifcsname\??ler\v!oddeven\linetablerow#1\endcsname
         \??ler\v!oddeven\linetablerow#1%
       \else
         \s!empty
       \fi\fi
     \fi
   \endcsname}

\def\setnoftableslines
  {\doifelse{\linetableparameter\c!lines}\v!fit
     {% whitespace already added by vertical strut
      \ifdim\pagegoal<\maxdimen
        \scratchdimen\pagegoal
        \advance\scratchdimen -\pagetotal
      \else
        \scratchdimen\textheight
      \fi
      \getrawnoflines\scratchdimen
      \xdef\noflinetablelines{\the\noflines}
\iflinetablepreroll \else \ifnum\noflinetablelines<\plustwo
  \page \setnoftableslines
\fi \fi
}
     {\xdef\noflinetablelines{\linetableparameter\c!lines}}}

\def\startlinetablecell
  {\dosingleempty\dostartlinetablecell}

\def\dostartlinetablecell[#1]%
  {\global\setbox\linetablecell\hbox\bgroup
   \iffirstargument
     \getparameters[\??lec\number\linetablecolumn][#1]%
   \fi
   \xdef\linetablestep{\linetablecparameter\c!nx}%
   \ifcase\linetablestep\or
     \scratchdimen\linetablecparameter\c!width
     \scratchskip \linetablecparameter\c!distance
   \else
     \scratchdimen  \zeropoint
     \scratchskip   \zeropoint
     \scratchcounter\linetablecolumn
     \dorecurse\linetablestep
       {\advance\scratchdimen\linetablecparameter\c!width
       %\advance\scratchskip \linetablecparameter\c!distance
        \global\advance      \linetablecolumn\plusone
        \advance\scratchskip \linetablecparameter\c!distance
       }%
     \global\linetablecolumn\scratchcounter
   \fi
   \chardef\linetablemode
     \iflinetablepreroll
       \ifdim\scratchdimen>\zeropoint \zerocount \else \plustwo \fi
     \else
       \zerocount
     \fi
   \ifcase\linetablemode
     \ifcase\linetablehmode
       % nothing
     \or
       % fit, keep it simple
     \or
       \chardef\linetablemode\plusone % line
     \else
       % some already calculated height
     \fi
   \fi
   \setbox\scratchbox\hbox
     \bgroup
     \dontcomplain
     \hskip\linetablecparameter\c!leftoffset\relax
     % 0 = width, unknown height
     % 1 = width, fixed height
     % 2 = no width, auto hsize
     \ifnum\linetablemode<\plustwo
       \advance\scratchdimen-\linetablecparameter\c!leftoffset
       \advance\scratchdimen-\linetablecparameter\c!rightoffset
     \fi
     \ifcase\linetablemode
       \dosetraggedcommand{\linetablecparameter\c!align}%
       \vtop \ifdim\linetableheight>\zeropoint to\linetableheight \fi \bgroup
         \hsize\scratchdimen
         \raggedcommand
     \else
       \setalignmentswitch{\linetablecparameter\c!align}%
       \hbox \ifcase\linetablemode \or to\scratchdimen \fi \bgroup
         \ifcase\alignmentswitch\hss\or\hss\fi
     \fi
     \dostartattributes{\??lec\number\linetablecolumn}\c!style\c!color\empty
     \begstrut \ignorespaces}

% \def\stoplinetablecell
%   {\unskip \endstrut
%    \dostopattributes
%    \ifcase\linetablemode
%      \endgraf
%    \else
%      \ifcase\alignmentswitch\else\hss\fi
%    \fi
%    \egroup
%    \hskip\linetablecparameter\c!rightoffset
%    \egroup
%    \iflinetablepreroll
%      \box\scratchbox
%    \else
%      \doif{\linetablecparameter\c!background}\v!color
%        {\backgroundline[\linetablecparameter\c!backgroundcolor]}%
%        {\box\scratchbox}%
%    \fi
%    \egroup}

\newconditional\linetableautoheight  \settrue\linetableautoheight

\def\stoplinetablecell
  {\unskip \endstrut
   \dostopattributes
   \ifcase\linetablemode
     \endgraf
   \else
     \ifcase\alignmentswitch\else\hss\fi
   \fi
   \egroup
   \hskip\linetablecparameter\c!rightoffset
   \egroup
   \iflinetablepreroll
     \box\scratchbox
   \else
     \doifelse{\linetablecparameter\c!background}\v!color
       {\ifconditional\linetableautoheight
          \hbox{\blackrule
            [ \c!color=\linetablecparameter\c!backgroundcolor,
             \c!height=\linetablerparameter{x\c!height},
              \c!depth=\linetablerparameter{x\c!depth},
              \c!width=\wd\scratchbox]%
           \hskip-\wd\scratchbox\box\scratchbox}%
         \else
           \backgroundline[\linetablecparameter\c!backgroundcolor]{\box\scratchbox}%
         \fi}%
       {\box\scratchbox}%
   \fi
   \egroup}

% \def\stoplinetablecell
%   {\unskip \endstrut
%    \dostopattributes
%    \ifcase\linetablemode
%      \endgraf
%    \else
%      \ifcase\alignmentswitch\else\hss\fi
%    \fi
%    \egroup
%    \hskip\linetablecparameter\c!rightoffset
%    \egroup
%    \iflinetablepreroll
%      \box\scratchbox
%    \else
%      \doifelse{\linetablecparameter\c!background}\v!color
%        {\ifconditional\linetableautoheight
%         %           \hbox{\blackrule
%         %             [ \c!color=\linetablecparameter\c!backgroundcolor,
%         %              \c!height=\linetablerparameter{x\c!height},
%         %               \c!depth=\linetablerparameter{x\c!depth},
%         %               \c!width=\wd\scratchbox]%
%         %            \hskip-\wd\scratchbox\box\scratchbox}%
%           \dp\scratchbox\linetablerparameter{x\c!depth}%
%           \ht\scratchbox\linetablerparameter{x\c!height}%
%           \framed
%             [\c!offset=\v!overlay,
%              \c!frameoffset=.5\linewidth,
%              \c!leftframe=\v!off,\c!rightframe=\v!off,
%              \c!background=\v!color,
%              \c!backgroundcolor=\linetablecparameter\c!backgroundcolor%
%             ]{\box\scratchbox}%
%          \else
%            \backgroundline[\linetablecparameter\c!backgroundcolor]{\box\scratchbox}%
%          \fi}%
%        {\box\scratchbox}%
%    \fi
%    \egroup}

\def\savelinetablepart
  {\global\setbox\tablebox\linetablepart
   \ifnum\linetablepart=\zerocount
     \box\scratchbox % just storing
   \else
     \vbox
       {\ifvoid\tablebox\linetablepart\else\unvbox\tablebox\linetablepart\fi
        \doif{\linetablerparameter\c!background}\v!color
          {\backgroundline[\linetablerparameter\c!backgroundcolor]}%
          {\box\scratchbox}% is also arg to \backgroundline
        \endgraf
        \linetablerparameter\c!after}%
   \fi}

\def\flushlinetableparts
  {\doglobal\increment\linetableline
   \ifnum\linetableline<\noflinetablelines
     % keep collecting
   \else
     \iflinetablepreroll
       % forget about them
     \else
       \dorecurse\noflinetableparts
         {\let\linetablepart\recurselevel
          \dp\tablebox\linetablepart\strutdepth
          % noindent en endgraf needed else whitespace mess-up!
          \whitespace % here not after verticalstrut
          \ifdim\topskipgap=\zeropoint\else
            \verticalstrut\nobreak\kern-\struttotal\kern-\parskip\nobreak\nointerlineskip % fix topskip
          \fi
          \noindent\strut\hbox to \hsize{\box\tablebox\linetablepart\hss}\endgraf
          \ifnum\linetablepart<\noflinetableparts\relax
            \linetableparameter\c!inbetween
          \fi}%
       \ifnum\linetablerows<\noflinetablerows\relax
         \linetableparameter\c!inbetween
       \else
         % after, later
       \fi
       \chardef\linetableheadstate\plusthree
       \global\setbox\tablebox\zerocount\emptybox % here
     \fi
     % reset \linetablerow will be an option, currently
     % starts at zero after split
     \globallet\linetablerow\!!zerocount
     \globallet\linetableline\!!zerocount
     \global\chardef\linetablepage\zerocount
     \global\linetablewidth\zeropoint
     \setnoftableslines
   \fi}

\def\startlinetablepart
  {\global\linetablesubcol\zerocount
   \setbox\scratchbox\hbox\bgroup
   \doconvertfont{\linetablerparameter\c!style}%
   \startcolor[\linetablerparameter\c!color]%
   \ignorespaces}

\def\stoplinetablepart
  {\ifnum\linetablepart>\zerocount
     \unskip \unskip % remove last intercolumn skip (distance+fill)
   \fi
   \stopcolor
   \egroup
   \iflinetablepreroll \else
     \ifcase\linetablepart
       % we're collecting the repeater
     \else
       \scratchdimen\hsize \advance\scratchdimen-\wd\scratchbox\relax
       \ifdim\scratchdimen>\linetableparameter\c!stretch\else
         \setbox\scratchbox\hbox to \hsize{\unhbox\scratchbox}%
       \fi
     \fi
   \fi}

\def\checklinetablepart
  {\global\advance\linetablewidth\wd\linetablecell
   \global\advance\linetablecolumn\linetablestep
   \global\advance\linetablesubcol\linetablestep
   \relax
   %\message{\the\linetablecolumn,\the\linetablesubcol}\wait
   % from now on the column counter is already incremented
   \ifcase\linetablesplitstate
     \iflinetablepreroll \else
       \box\linetablecell
       % the columncounter is one ahead !
%      \hskip\linetablecparameter\c!afstand
       \hskip\scratchskip
     \fi
     %%%
     \donefalse
     \ifcase\linetablerepeat\else
       % van te voren berekenen
       \scratchcounter\linetablecolumn\advance\scratchcounter-\plustwo
       \ifnum\linetablerepeat=\scratchcounter
         \donetrue % collecting repeater
       \fi
     \fi
     %%%%
     \ifdone
       % collecting repeater
     \else
       \ifnum\linetablecolumn>\getvalue{\??le::\linetablepart}\relax
         \donetrue
       \fi
     \fi
     \ifdone
       \stoplinetablepart
       \iflinetablepreroll \else
         \savelinetablepart
       \fi
       \ifcase\linetablepage \or
         \global\chardef\linetablepage \plustwo
       \else
         \global\chardef\linetablepage \plusone
       \fi
       \doglobal\increment\linetablepart
       \global\linetablewidth\wd\tablebox\zerocount
       \startlinetablepart
     \fi
   \else
     \donefalse
     \!!doneafalse
     \ifcase\linetablerepeat\else
       % van te voren berekenen
       \scratchcounter\linetablecolumn \advance\scratchcounter-\plustwo
       \ifnum\linetablerepeat=\scratchcounter
         \donetrue % collecting repeater
       \fi
     \fi
     \ifdone
       \!!doneatrue
       % collecting repeater
     \else\ifdim\linetablewidth>\hsize
       \donetrue
     \else
%       \global\advance\linetablewidth\linetablecparameter\c!afstand\relax
       \global\advance\linetablewidth\scratchskip
       \ifdim\linetablewidth>\hsize % ?
         \donetrue
       \fi
     \fi\fi
     \ifdone
       \stoplinetablepart
       \savelinetablepart
       \ifcase\linetablepage \or
         \global\chardef\linetablepage \plustwo
       \else
         \global\chardef\linetablepage \plusone
       \fi
       \doglobal\increment\linetablepart
       \ifnum\linetablepart>\noflinetableparts
         \globallet\noflinetableparts\linetablepart
         \initializetablebox\linetablepart
       \fi
       \global\linetablewidth\wd\linetablecell
       \startlinetablepart
       \if!!doneb \else \ifcase\linetablerepeat \else
         % check for left/right page
         \ifcase\linetablepage\donetrue\or\donetrue\or\donefalse\fi\ifdone
           % insert repeater
           \global\advance\linetablewidth\wd\tablebox\zerocount
           \iflinetablepreroll\kern\wd\else\unhcopy\fi\tablebox\zerocount
         \fi
       \fi \fi
     \fi
     \iflinetablepreroll \else
       \box\linetablecell
       % the columncounter is one ahead !
%       \hskip\linetablecparameter\c!afstand
%       \hskip\scratchskip
\dorecurse\linetablestep{\strut\hfil}%
       \hskip\scratchskip
     \fi
   \fi}

% \linetableparameter\c!var -> \@@levar (when no classes)

\def\startlinetablerun % to do: quit when nested
  {\bgroup
   \inlinetabletrue
   % autowidth
   \doif{\linetableparameter\c!maxwidth}\v!fit
     {\setuplinetable[\c!maxwidth=\zeropoint]}%
   \processaction
     [\linetableparameter\c!stretch]
     [ \v!no=>{\setuplinetable[\c!stretch=\maxdimen]},% no stretch
      \v!yes=>{\setuplinetable[\c!stretch=\zeropoint]}]% max stretch
   \chardef\linetablerepeat\linetableparameter\c!nleft
   \chardef\linetablesplitstate % =
     \ifdim\linetableparameter\c!maxwidth>\zeropoint
       \zerocount \else \plusone
     \fi
   % optional prevdepth correction
   \iflinetablepreroll
     \globallet\noflinetablerows\!!zerocount
   \else
     \linetableparameter\c!before
   \fi
   \globallet\linetablerows\!!zerocount
   \globallet\noflinetablecolumns\!!zerocount
   \globallet\noflinetableparts\!!zerocount
   \!!counta\zerocount
   \def\docommand##1%
     {\doglobal\increment\noflinetableparts
      \advance\!!counta##1%
      \setxvalue{\??le::\noflinetableparts}{\the\!!counta}}%
   \processcommacommand[\linetableparameter\c!n]\docommand
   \initializetableboxes\noflinetableparts
   \ifcase\linetablerepeat
     \globallet\linetablepart\!!plusone
   \else
     \globallet\linetablepart\!!zerocount % repeater
   \fi
   \globallet\linetablestep\!!plusone
   \globallet\linetableline\!!zerocount
   \globallet\linetablerow \!!zerocount
   \global\linetablecolumn \zerocount
   \global\linetablesubcol \zerocount
   \global\linetablewidth  \zeropoint
\iflinetablepreroll \else \ifdim\pagetotal>\zeropoint
  \verticalstrut\kern-\struttotal
\fi \fi
   \setnoftableslines
   \checklinetablepage
   \let\BR\linetableBR
   \let\ER\linetableER
   \let\BH\linetableBR
   \let\EH\linetableER
   \let\BC\linetableBC
   \let\EC\linetableEC
   \let\NC\linetableNC
   \let\NR\linetableNR
   \flushlinetablehead}

\def\stoplinetablerun
  {\globallet\linetableline\!!maxcard
   \chardef\linetableheadstate\zerocount % blocked
   \flushlinetableparts
   \iflinetablepreroll \else
     \linetableparameter\c!after
   \fi
   \globallet\linetablepart    \!!zerocount
   \globallet\noflinetableparts\!!zerocount
   \egroup}

% \def\checklinecolumnwidth
%   {\ifundefined{\??lew\number\linetablecolumn}%
%      \donetrue
%    \else\ifdim\getvalue{\??lew\number\linetablecolumn}<\wd\linetablecell
%      \donetrue
%    \else
%      \donefalse
%    \fi\fi
%    \ifdone
%      \setxvalue{\??lew\number\linetablecolumn}{\the\wd\linetablecell}%
%    \fi}
%
% \def\checklinecolumnwidth
%   {\ifcsname\??lew\number\linetablecolumn\endcsname
%      \ifdim\csname\??lew\number\linetablecolumn\endcsname<\wd\linetablecell
%        \donetrue
%      \else
%        \donefalse
%      \fi
%    \else
%      \donetrue
%    \fi
%    \ifdone
%      \setxvalue{\??lew\number\linetablecolumn}{\the\wd\linetablecell}%
%    \fi}

% \def\checklinecolumnwidth
%   {\expandafter\xdef\csname\??lew\number\linetablecolumn\endcsname
%      {\expandafter\ifx\csname\??lew\number\linetablecolumn\endcsname\relax
%         \the\wd\linetablecell
%       \else\ifdim\csname\??lew\number\linetablecolumn\endcsname<\wd\linetablecell
%         \the\wd\linetablecell
%       \else
%         \csname\??lew\number\linetablecolumn\endcsname
%       \fi\fi}}

\def\checklinecolumndimension#1#2#3%
  {\expandafter\xdef\csname#1\number#3\endcsname
     {\expandafter\ifx\csname#1\number#3\endcsname\relax
        \the#2\linetablecell
      \else\ifdim\csname#1\number#3\endcsname<#2\linetablecell
        \the#2\linetablecell
      \else
        \csname#1\number#3\endcsname
      \fi\fi}}

\def\checklinecolumnwidth {\checklinecolumndimension\??lew\wd\linetablecolumn}
\def\checklinecolumnheight{\checklinecolumndimension\??leh\ht\linetablerow}
\def\checklinecolumndepth {\checklinecolumndimension\??led\dp\linetablerow}

\def\linetableBR
  {\dosingleempty\dolinetableBR}

\def\dolinetableBR[#1]% #1 not yet implemented
  {\ifnum\linetableheadstate=1\else
     \doglobal\increment\linetablerow
     \doglobal\increment\linetablerows
   \fi
   \global\linetablecolumn\plusone
   \global\linetablesubcol\plusone
%   \linetableheight\linetablerparameter\c!height
%
%   \ifx\linetableheight\empty
%     % nothing
%   \else\ifx\linetableheight\v!fit
%     % keep it simple
%   \else\ifx\linetableheight\v!line
%     \chardef\linetablemode\plusone
%   \else
%     \!!heighta\linetableheight
%     \advance\!!heighta-\strutdepth
%   \fi\fi\fi
%
   \linetableheight\zeropoint
   \edef\!!stringa{\linetablerparameter\c!height}%
   \ifx\!!stringa\empty
     \chardef\linetablehmode\zerocount
   \else\ifx\!!stringa\v!fit
     \chardef\linetablehmode\plusone
   \else\ifx\!!stringa\v!line
     \chardef\linetablehmode\plustwo
   \else
     \linetableheight\!!stringa
     \advance\linetableheight-\strutdepth
   \fi\fi\fi
%
   \startlinetablepart}

\def\linetableBC
  {\startlinetablecell}

\def\linetableEC
  {\stoplinetablecell
   \iflinetablepreroll
     \checklinecolumnwidth
     \checklinecolumnheight
     \checklinecolumndepth
   \fi
   \checklinetablepart}

\def\linetableER
  {% \stoplinetablecell
   % no \box\linetablecell, i.e. dummy columnn, last \NC \NR
   \stoplinetablepart
   \savelinetablepart
   \advance\linetablecolumn \minusone
   \ifnum\linetablecolumn>\noflinetablecolumns
     \xdef\noflinetablecolumns{\number\linetablecolumn}%
   \fi
   \flushlinetableparts
   \global\linetablecolumn\zerocount
   \global\linetablewidth \zeropoint
   \ifcase\linetablerepeat
     \globallet\linetablepart\!!plusone
   \else
     \globallet\linetablepart\!!zerocount % repeater
   \fi
   \checklinetablepage
   \flushlinetablehead}

\def\checklinetablepage
  {\global\chardef\linetablepage\zerocount
   \ifcase\linetablerepeat \else \ifcase\linetablepage
     \doif{\linetableparameter\c!repeat}\v!no
       {\global\chardef\linetablepage\doifoddpageelse\plusone\plustwo}%
   \fi \fi}

\def\flushlinetablehead
  {\ifcase\linetableheadstate
     % 0 blocked
   \or
     % 1 doing head
   \or
     % 2 head done
   \or
     % 3 trigger flush
     \chardef\linetableheadstate\plusone
     \the\@@linetablehead\relax
     \chardef\linetableheadstate\plustwo
   \fi}

\def\linetableNC % first time special treatment
  {\relax
   \ifcase\linetablecolumn
     \linetableBR
   \else
     \linetableEC
   \fi
   \linetableBC} % beware, this will result in BR BC EC BC NR

\def\linetableNR
  {\stoplinetablecell % dummy
   \linetableER}

\def\startlinetable
  {\startlinetablerun}

\def\stoplinetable
  {\stoplinetablerun}

\def\startlinetableanalysis
  {\bgroup
   \linetableprerolltrue
   \trialtypesettingtrue
   \startlinetablerun}

\def\stoplinetableanalysis
  {\stoplinetablerun
   \egroup
   \globallet\noflinetablerows\linetablerows
   \dorecurse\noflinetablerows % global, from last run {\linetableparameter\c!n}
     {%\writestatus{linetable}{\recurselevel->\getvalue{\??lew\recurselevel}}%
      \setevalue{\??ler\recurselevel x\c!height}{\getvalue{\??leh\recurselevel}}%
      \setevalue{\??ler\recurselevel x\c!depth }{\getvalue{\??led\recurselevel}}%
      \letgvalue{\??leh\recurselevel}\!!zeropoint
      \letgvalue{\??led\recurselevel}\!!zeropoint}
   \dorecurse\noflinetablecolumns % global, from last run {\linetableparameter\c!n}
     {%\writestatus{linetable}{\recurselevel->\getvalue{\??lew\recurselevel}}%
      \setevalue{\??lec\recurselevel\c!width}{\getvalue{\??lew\recurselevel}}%
      \letgvalue{\??lew\recurselevel}\!!zeropoint}} % init next table

% todo: store in box instead of macro

\newtoks \@@linetablehead

\long\def\startlinetablehead#1\stoplinetablehead
  {\ifinlinetable
     \@@linetablehead\emptytoks
   \fi
   \chardef\linetableheadstate3 % full
   \@@linetablehead{#1}%
   \ifinlinetable
     \flushlinetablehead
   \fi}

\def\linetableBH
  {\ifx\EC\relax
     % signal, grabbing lines
   \else
     \@@linetablehead\emptytoks
   \fi
   \pushmacro\BC
   \pushmacro\EC
   \def\BC##1\EC{\appendtoks##1\to\@@linetablehead}%
   \let\EC\relax} % signal

\def\linetableEH
  {\popmacro\EC
   \popmacro\BC
   \@EA\startlinetablehead\the\@@linetablehead\stoplinetablehead}

\let\startlinetablebody\donothing
\let\stoplinetablebody \donothing

\def\processlinetablebuffer
  {\dosingleempty\doprocesslinetablebuffer}

\def\doprocesslinetablebuffer[#1]%
  {\bgroup
   \let\startlinetable\donothing
   \let\stoplinetable \donothing
   \startlinetableanalysis\getbuffer[#1]\stoplinetableanalysis
   \startlinetablerun     \getbuffer[#1]\stoplinetablerun
   \egroup}

\def\processlinetablefile#1%
  {\bgroup
   \let\startlinetable\donothing
   \let\stoplinetable \donothing
   \startlinetableanalysis\readfile{#1}\donothing\donothing\stoplinetableanalysis
   \startlinetablerun     \readfile{#1}\donothing\donothing\stoplinetablerun
   \egroup}

% will go away:

\def\processlinetableXMLfile#1%
  {\bgroup
   \let\startlinetable\donothing
   \let\stoplinetable \donothing
   \startlinetableanalysis\processXMLfile{#1}\stoplinetableanalysis
   \startlinetablerun     \processXMLfile{#1}\stoplinetablerun
   \egroup}

\protect \endinput

\doifnotmode{demo}{\endinput}

\setuplinetable[n=6,m={2,2,2},lines=25] % m ?

\setuplinetable[c][1]   [width=2cm,background=color,backgroundcolor=red]
\setuplinetable[c][4]   [width=3cm,background=color,backgroundcolor=yellow]
\setuplinetable[c][6]   [width=3cm,background=color,backgroundcolor=magenta]
\setuplinetable[r][odd] [background=color,backgroundcolor=gray]
\setuplinetable[r][even][background=color,backgroundcolor=green]

\starttext

\showframe \showstruts

\setupcolors[state=start]

\setuppagenumbering[alternative=doublesided]\page[left]

\startlinetable
\NC aaa\crlf aaa \NC bb \NC c \NC ddddd \NC eeee \NC ff \NC \NR
\dorecurse{100}{\NC aaa \NC bb \NC c \NC ddddd \NC eeee \NC ff \NC \NR}
\stoplinetable

\startlinetable
\NC[style=slanted,color=green,background=color,backgroundcolor=darkred,nx=2,uitlijnen=middle] xxx
                 \NC yy \NC ddddd \NC eeee \NC ff \NC \NR
\dorecurse{100}{\NC aaa \NC bb \NC c \NC ddddd \NC eeee \NC ff \NC \NR}
\stoplinetable

% \startbuffer[lt]
% \NC aaa\crlf aaa \NC bb \NC c  \NC ddddd \NC ee   \NC ff \NC \NR
% \NC aaa\crlf aaa \NC b  \NC cc \NC ddd   \NC eeee \NC f  \NC \NR
% \stopbuffer
%
% \processlinetablebuffer[lt]

\stoptext