%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]
%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 This is a temporary module, some of this code will move to
%D the other math modules. Much is copied from Plain \TEX.

% \points should become \bodyfontsize

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

\unprotect

\ifx\displ@y\undefined \let\displ@y\relax\fi

\def\oalign#1%
  {\leavevmode
   \vtop
     {\baselineskip\zeroskip \lineskip.25ex%
      \ialign{##\crcr#1\crcr}}}

\def\o@lign
  {\lineskiplimit\zeropoint \oalign}

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

\def\sh@ft#1% kern by #1 times the current slant
  {\dimen@#1%
   \kern\expandafter\withoutpt\the\slantperpoint
   \dimen@}

\def\dots
  {\relax\ifmmode\ldots\else$\mathsurround\zeropoint\ldots\,$\fi}

\def\hrulefill
  {\leaders\hrule\hfill}

\def\dotfill
  {\cleaders\hbox{$\mathsurround\zeropoint \mkern1.5mu.\mkern1.5mu$}\hfill}

\def\rightarrowfill
  {$\mathsurround\zeropoint\smash-\mkern-7mu%
   \cleaders\hbox{$\mkern-2mu\smash-\mkern-2mu$}\hfill
   \mkern-7mu\mathord\rightarrow$}

\def\leftarrowfill
  {$\mathsurround\zeropoint\mathord\leftarrow\mkern-7mu%
   \cleaders\hbox{$\mkern-2mu\smash-\mkern-2mu$}\hfill
   \mkern-7mu\smash-$}

\let\sp=^ % will become obsolete
\let\sb=_ % will become obsolete

\ifx\,\undefined \def\,{\mskip \thinmuskip } \fi
\ifx\>\undefined \def\>{\mskip \medmuskip  } \fi
\ifx\;\undefined \def\;{\mskip \thickmuskip} \fi
\ifx\!\undefined \def\!{\mskip-\thinmuskip } \fi
\ifx\*\undefined \def\*{\discretionary{\thinspace\the\textfont2\char2}{}{}} \fi

% {\catcode`\'=\active \gdef'{^\bgroup\prim@s}}

\def\activemathquote{^\bgroup\prim@s}

\def\prim@s
 {\prime\futurelet\next\pr@m@s}

\def\pr@m@s
  {\ifx'\next
     \@EA\pr@@@s
   \else\ifx^\next
     \@EAEAEA\pr@@@t
   \else
     \@EAEAEA\egroup
   \fi\fi}

\def\pr@@@s#1%
  {\prim@s}

\def\pr@@@t#1#2%
  {#2\egroup}

% {\catcode`\_=\active \global\let_=\_} % _ in math is either subscript or \_

\let\activemathunderscore\_

\def\relbar            {\mathrel{\smash-}} % - has the same height as +
\def\Relbar            {\mathrel=}

\def\Longrightarrow    {\Relbar\joinrel\Rightarrow}       % beware, this overloades cambria native
\def\longrightarrow    {\relbar\joinrel\rightarrow}
\def\longleftarrow     {\leftarrow\joinrel\relbar}
\def\Longleftarrow     {\Leftarrow\joinrel\Relbar}
\def\longmapsto        {\mapstochar\longrightarrow}
\def\longleftrightarrow{\leftarrow\joinrel\rightarrow}
\def\Longleftrightarrow{\Leftarrow\joinrel\Rightarrow}

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

\def\mathpalette#1#2%
  {\mathchoice
     {#1\displaystyle     {#2}}%
     {#1\textstyle        {#2}}%
     {#1\scriptstyle      {#2}}%
     {#1\scriptscriptstyle{#2}}}

\def\cong
  {\mathrel{\mathpalette\@vereq\sim}} % congruence sign

\def\@vereq#1#2%
  {\lower.5\points\vbox{\lineskiplimit\maxdimen\lineskip-.5\points
   \ialign{$\mathsurround\zeropoint#1\hfil##\hfil$\crcr#2\crcr=\crcr}}}

\def\notin
  {\mathrel{\mathpalette\c@ncel\in}}

\def\c@ncel#1#2%
  {\mathsurround\zeropoint\ooalign{$\hfil#1\mkern1mu/\hfil$\crcr$#1#2$}}

\def\rightleftharpoons
  {\mathrel{\mathpalette\rlh@{}}}

\def\rlh@#1%
  {\vcenter
     {\mathsurround\zeropoint
      \hbox
        {\ooalign
           {\raise2pt\hbox{$#1\rightharpoonup$}\crcr
            $#1\leftharpoondown$}}}}

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

\def\doteq
  {\buildrel\textstyle.\over=}

\ifx\mfunction\undefined \def\mfunction#1{\mathbin{\rm#1}} \fi

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

\def\pmod#1%
  {\allowbreak
   \mkern18mu
   (\mfunction{mod}\,\,#1)}

\def\cases#1%
  {\left\{%
   \,%
   \vcenter
     {\normalbaselines
      \mathsurround\zeropoint
      \ialign{$##\hfil$&\quad##\hfil\crcr#1\crcr}}%
   \right.}

\def\matrix#1%
  {\null
   \,%
   \vcenter
     {\normalbaselines\mathsurround\zeropoint
      \ialign{\hfil$##$\hfil&&\quad\hfil$##$\hfil\crcr
      \mathstrut\crcr\noalign{\kern-\baselineskip}
      #1\crcr\mathstrut\crcr\noalign{\kern-\baselineskip}}}%
   \,}

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

\newdimen\mathparentwd

% \setbox0=\hbox{\tenex B} \mathparentwd=\wd0 % width of the big left (

\def\bordermatrix#1%
  {\begingroup
   \mathsurround\zeropoint
   \setbox\zerocount\vbox
     {\def\cr{\crcr\noalign{\kern2\points\global\let\cr\endline}}%
      \ialign{$##$\hfil\kern2\points\kern\mathparentwd&\thinspace\hfil$##$\hfil
        &&\quad\hfil$##$\hfil\crcr
        \omit\strut\hfil\crcr\noalign{\kern-\baselineskip}%
        #1\crcr\omit\strut\cr}}%
   \setbox\plustwo\vbox
     {\unvcopy\zerocount\global\setbox\plusone\lastbox}%
   \setbox\plustwo\hbox
     {\unhbox\plusone\unskip\global\setbox\plusone\lastbox}%
   \setbox\plustwo\hbox
     {$\kern\wd\plusone\kern-\mathparentwd\left(\kern-\wd\plusone
      \global\setbox\plusone\vbox{\box\plusone\kern2\points}%
      \vcenter{\kern-\ht\plusone\unvbox\zerocount\kern-\baselineskip}\,\right)$}%
   \null
   \;%
   \vbox{\kern\ht\plusone\box\plustwo}%
   \endgroup}

% \def\openup{\afterassignment\@penup\dimen@=}
%
% \def\@penup{\advance\lineskip\dimen@
%   \advance\baselineskip\dimen@
%   \advance\lineskiplimit\dimen@}

\def\openup
  {\afterassignment\doopenup\scratchdimen=}

\def\doopenup
  {\advance\lineskip     \scratchdimen
   \advance\baselineskip \scratchdimen
   \advance\lineskiplimit\scratchdimen}

% \def\jot{.25\bodyfontsize} % plain tex: 3 pt (todo: better name and configurable)

\def\displayopenupvalue{.25\bodyfontsize}

\def\eqalign#1%
  {\null
   \,%
   \vcenter
     {\openup\displayopenupvalue % was \openup\jot
      \mathsurround\zeropoint
      \ialign
        {\strut\hfil$\displaystyle{##}$&$\displaystyle{{}##}$\hfil\crcr
         #1\crcr}}%
   \,}

\def\@lign % restore inside \displ@y
  {\tabskip\zeroskip
   \everycr{}}

\def\displaylines#1%
  {\displ@y
   \tabskip\zeroskip
   \halign
     {\hbox to \displaywidth{$\@lign\hfil\displaystyle##\hfil$}\crcr
      #1\crcr}}

\def\eqalignno#1%
  {\displ@y
   \tabskip\centering
   \halign to \displaywidth
     {\hfil$\@lign\displaystyle{##}$\tabskip\zeroskip
      &$\@lign\displaystyle{{}##}$\hfil\tabskip\centering
      &\llap{$\@lign##$}\tabskip\zeroskip\crcr
      #1\crcr}}

\def\leqalignno#1%
  {\displ@y
   \tabskip\centering
   \halign to \displaywidth
     {\hfil$\@lign\displaystyle{##}$\tabskip\zeroskip
      &$\@lign\displaystyle{{}##}$\hfil\tabskip\centering
      &\kern-\displaywidth\rlap{$\@lign##$}\tabskip\displaywidth\crcr
      #1\crcr}}

% temporary here (weird code)

% \startcatcodetable \mthcatcodes
%     \setcatcodetable\ctxcatcodes
%     \catcode`\_ = 13
%     \catcode`\' = 13
% \stopcatcodetable
%
% \letcatcodecommand \mthcatcodes `\_ \activemathunderscore
% \letcatcodecommand \mthcatcodes `\' \activemathquote

% \appendtoks \setcatcodetable\mthcatcodes \to \everymath : spoils xml

% tricky, but some day we will reimplement math

\bgroup
    \catcode`\_ = 13
    \catcode`\' = 13
    \doglobal\appendtoks
        \let_\activemathunderscore
        \let'\activemathquote
    \to \everymathematics
\egroup

% so far

\protect \endinput