%D \module
%D   [       file=math-pln,
%D        version=2001.11.16,
%D          title=\CONTEXT\ Math Macros,
%D       subtitle=Plain Helpers,
%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.

%D Here we collect some Plain \TEX\ leftovers.

\writestatus{loading}{ConTeXt Math Macros / Plain Helpers}

\unprotect

% we need proper unicode:

\def\relbar{\mathrel{\smash-}} % - has the same height as + .. no clue what this refers to

% might change

\unexpanded\def\hrulefill{\leaders\hrule\hfill}
\unexpanded\def\dotfill  {\cleaders\hbox{\normalstartimath\mathsurround\zeropoint\mkern1.5mu.\mkern1.5mu\normalstopimath}\hfill}

% will move

\def\oalign#1%
  {\leavevmode % plain tex uses this
   \vtop
     {\baselineskip\zeroskip
      \lineskip.25\exheight
      \ialign{\alignmark\alignmark\crcr#1\crcr}}}

\def\ooalign % chars over each other
  {\lineskiplimit-\maxdimen
   \oalign}

% needs checking

\def\choose{\atopwithdelims()}
\def\brack {\atopwithdelims[]}
\def\brace {\atopwithdelims\{\}}

% needs checking

\unexpanded\def\buildrel#1\over#2%
  {\mathrel{\mathop{\kern\zeropoint#2}\limits^{#1}}}

\unexpanded\def\bmod
  {\nonscript
   \mskip-\medmuskip
   \mkern5mu
   \mfunction{mod}%
   \penalty900
   \mkern5mu
   \nonscript
   \mskip-\medmuskip}

\unexpanded\def\pmod#1%
  {\allowbreak
   \mkern18mu
   (\mfunction{mod}\mskip\medmuskip#1)}

\unexpanded\def\cases#1%
  {\left\{%
   \mskip\thinmuskip
   \vcenter
     {\normalbaselines
      \mathsurround\zeropoint
      \ialign{%
        \normalstartimath\alignmark\alignmark\hfil\normalstopimath
        \aligntab
        \quad\alignmark\alignmark\hfil
        \crcr
        #1%
        \crcr}}%
   \right.}

\unexpanded\def\matrix#1%
  {\emptyhbox
   \mskip\thinmuskip
   \vcenter
     {\normalbaselines
      \mathsurround\zeropoint
      \ialign{%
        \hfil\normalstartimath\alignmark\alignmark\normalstopimath\hfil
        \aligntab
        \aligntab
        \quad\hfil\normalstartimath\alignmark\alignmark\normalstopimath\hfil
        \crcr
        \mathstrut
        \crcr
        \noalign{\kern-\baselineskip}
        #1\crcr
        \mathstrut
        \crcr
        \noalign{\kern-\baselineskip}}}%
   \mskip\thinmuskip}

\unexpanded\def\pmatrix#1%
  {\left(\matrix{#1}\right)}

% \unexpanded\def\openup
%   {\afterassignment\math_openup\scratchdimen=}
%
% \def\math_openup
%   {\advance\lineskip     \scratchdimen
%    \advance\baselineskip \scratchdimen
%    \advance\lineskiplimit\scratchdimen}

\let\math_closeup\relax

\unexpanded\def\math_openup
  {\afterassignment\math_openup_indeed\scratchdimen}

\def\math_openup_indeed
  {\unexpanded\edef\math_closeup
     {\lineskip     \the\lineskip
      \baselineskip \the\baselineskip
      \lineskiplimit\the\lineskiplimit
      \relax}%
   \advance \lineskip      \scratchdimen
   \advance \baselineskip  \scratchdimen
   \advance \lineskiplimit \scratchdimen}

\let\openup  \math_openup
\def\closeup{\math_closeup} % dynamic

\unexpanded\def\displaylines#1%
  {\the\mathdisplayaligntweaks
   \tabskip\zeroskip
   \halign
     {\hbox to \displaywidth{%
        \normalstartimath\tabskip\zeroskip\everycr\emptytoks\hfil\displaystyle\alignmark\alignmark\hfil\normalstopimath}\crcr
        #1\crcr}}

%D This comes from plain but I gave it a \CONTEXT\ touch:

\def\math_border_NC_indeed
  {\gdef\math_border_NC{\aligntab}}

\let\math_border_NC\math_border_NC_indeed

\def\math_border_NR
  {\glet\math_border_NC\math_border_NC_indeed
   \cr}

\unexpanded\def\math_border_matrix#1#2#3% adapted plain
  {\begingroup
   %
   \pushmacro\cr
   %
   \setbox\scratchbox\hbox\bgroup
     \mr B%
   \egroup
   \scratchdimenone\wd\scratchbox
   %
   \scratchdimentwo.2\bodyfontsize
   %
   \mathsurround\zeropoint
   %
   \def\NC{\math_border_NC}%
   \def\NR{\math_border_NR}%
   %
   \setbox\scratchboxone\vbox\bgroup
     \def\cr{%
       \crcr
       \noalign\bgroup
         \kern\scratchdimentwo
         \glet\cr\endline
       \egroup
     }%
     \ialign{%
       \startimath\alignmark\alignmark\stopimath
       \hfil
       \kern\dimexpr\scratchdimentwo+\scratchdimenone\relax
       \aligntab
       \thinspace
       \hfil
       \startimath\alignmark\alignmark\stopimath
       \hfil
       \aligntab
       \aligntab
       \quad
       \hfil
       \startimath\alignmark\alignmark\stopimath
       \hfil
       \crcr
       \omit
       \strut
       \hfil
       \crcr
       \noalign{\kern-\baselineskip}%
       #3\crcr
       \omit
       \strut
       \cr
     }%
   \egroup
   \setbox\scratchboxtwo\vbox\bgroup
     \unvcopy\scratchboxone
     \global\setbox\globalscratchbox\lastbox
   \egroup
   \setbox\scratchboxtwo\hbox\bgroup
     \unhbox\globalscratchbox
     \unskip
     \global\setbox\globalscratchbox\lastbox
   \egroup
   \setbox\scratchboxtwo\hbox\bgroup
     \startimath
     \kern\dimexpr\wd\globalscratchbox-\scratchdimenone\relax
     \left#1\relax
     \kern-\wd\globalscratchbox
     \global\setbox\globalscratchbox\vbox\bgroup
       \box\globalscratchbox
       \kern\scratchdimentwo
     \egroup
     \vcenter\bgroup
       \kern-\ht\globalscratchbox
       \unvbox\scratchboxone
       \kern-\baselineskip
     \egroup
     \thinspace
     \right#2\relax
     \stopimath
   \egroup
   \null
   \thickspace
   \vbox\bgroup
     \kern\ht\globalscratchbox
     \box\scratchboxtwo
   \egroup
   %
   \popmacro\cr
   %
   \endgroup}

\unexpanded\def\bordermatrix {\math_border_matrix()}
\unexpanded\def\bbordermatrix{\math_border_matrix[]}

\unexpanded\def\startbordermatrix #1\stopbordermatrix {\math_border_matrix(){#1}}
\unexpanded\def\startbbordermatrix#1\stopbbordermatrix{\math_border_matrix[]{#1}}

\let\stopbordermatrix \relax
\let\stopbbordermatrix\relax

\protect \endinput