%D \module
%D   [       file=math-ext,
%D        version=2006.01.14,
%D          title=\CONTEXT\ Math Macros,
%D       subtitle=Extra Macros,
%D         author={Hans Hagen \& Taco Hoekwater \& Adity Mahajan},
%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.

\unprotect

%D These will be generalized!

\def\exmthfont#1{\symbolicsizedfont#1\plusone{MathExtension}}

\def\domthfrac#1#2#3#4%
  {\begingroup
   \mathsurround\zeropoint
   \setbox0\hbox{$#1 #3$}%
   \setbox2\hbox{$#1 #4$}%
   \dimen0\wd0
   \ifdim\wd2>\dimen0 \dimen0\wd2 \fi
   \setbox4\hbox to \dimen0{\exmthfont#2\char"77\leaders\hbox{\char"75}\hss\char"76}%
   \mathord{\vcenter{{\offinterlineskip
     \hbox to \dimen0{\hss\box0\hss}%
     \kern \ht4%
     \hbox to \dimen0{\hss\copy4\hss}%
     \kern \ht4%
     \hbox to \dimen0{\hss\box2\hss}}}}%
   \endgroup}

\def\domthsqrt#1#2#3%
  {\begingroup
   \mathsurround\zeropoint
   \setbox0\hbox{$#1 #3$}%
   \dimen0\wd0
   \setbox4\hbox to \dimen0{\exmthfont#2\leaders\hbox{\char"75}\hfill\char"76}%
   \setbox2\hbox{\exmthfont#2\char"70}%
   \ifdim\dimexpr\dp0+\ht0+\ht2\relax>\dp2 \setbox2\hbox{\exmthfont#2\char"71}\fi
   \ifdim\dimexpr\dp0+\ht0+\ht2\relax>\dp2 \setbox2\hbox{\exmthfont#2\char"72}\fi
   \ifdim\dimexpr\dp0+\ht0+\ht2\relax>\dp2 \setbox2\hbox{\exmthfont#2\char"73}\fi
   \ifdim\dimexpr\dp0+\ht0+\ht2\relax>\dp2 \setbox2\hbox{\exmthfont#2\char"74}\fi
   \mathord{\vcenter{\hbox{%
     \raise\dimexpr\dp2-.5\ht2\relax\hbox{\copy2\rlap{\copy4}}%
     \raise\dp0                     \copy0}}}%
   \endgroup}

\def\mthfrac#1#2{\mathchoice
  {\domthfrac\displaystyle     \textface        {#1}{#2}}
  {\domthfrac\textstyle        \textface        {#1}{#2}}
  {\domthfrac\scriptstyle      \scriptface      {#1}{#2}}
  {\domthfrac\scriptscriptstyle\scriptscriptface{#1}{#2}}}

\def\mthsqrt#1{\mathchoice
  {\domthsqrt\displaystyle     \textface        {#1}}
  {\domthsqrt\textstyle        \textface        {#1}}
  {\domthsqrt\scriptstyle      \scriptface      {#1}}
  {\domthsqrt\scriptscriptstyle\scriptscriptface{#1}}}

% temp here

\def\mtharrfactor{1}
\def\mtharrextra {0}

\def\domthxarr#1#2#3#4#5% hm, looks like we do a double mathrel
  {\begingroup
   \def\mtharrfactor{1}%
   \def\mtharrextra {0}%
   \processaction[#1] % will be sped up
     [  \v!none=>\def\mtharrfactor{0},
       \v!small=>\def\mtharrextra{10},
      \v!medium=>\def\mtharrextra{15},
         \v!big=>\def\mtharrextra{20},
      \v!normal=>,
     \v!default=>,
     \v!unknown=>\doifnumberelse{#1}{\def\mtharrextra{#1}}\donothing]%
   \mathsurround\zeropoint
   \muskip0=\thirdoffourarguments  #2mu
   \muskip2=\fourthoffourarguments #2mu
   \muskip4=\firstoffourarguments  #2mu
   \muskip6=\secondoffourarguments #2mu
   \muskip0=\mtharrfactor\muskip0 \advance\muskip0 \mtharrextra mu
   \muskip2=\mtharrfactor\muskip2 \advance\muskip2 \mtharrextra mu
   \setbox0\hbox{$\scriptstyle
                  \mkern\muskip4\relax
                  \mkern\muskip0\relax
                  #5\relax
                  \mkern\muskip2\relax
                  \mkern\muskip6\relax
                 $}%
   \setbox4\hbox{#3}%
   \dimen0\wd0
   \ifdim\wd4>\dimen0 \dimen0\wd4 \fi
   \setbox2\hbox{$\scriptstyle
                  \mkern\muskip4\relax
                  \mkern\muskip0\relax
                  #4\relax
                  \mkern\muskip2\relax
                  \mkern\muskip6\relax
                 $}%
   \ifdim\wd2>\dimen0 \dimen0\wd2 \fi
   \setbox4\hbox to \dimen0{#3}%
   \mathrel{\mathop{\hbox to \dimen0{\hss\copy4\hss}}\limits^{\box0}_{\box2}}
   \endgroup}

\let\domthxarrsingle\domthxarr

\def\domthxarrdouble#1#2#3#4#5#6#7% opt l r sp rs top bot
  {\mathrel
     {\scratchdimen.22ex\relax
      \setbox0\hbox{$\domthxarr{#1}{#2}{#4}{\phantom{#6}}{#7}$}%
      \setbox2\hbox{$\domthxarr{#1}{#3}{#5}{#6}{\phantom{#7}}$}%
      \raise\scratchdimen\box0
      \kern-\wd2
      \lower\scratchdimen\box2}}

\def\definematharrow
  {\doquadrupleargument\dodefinematharrow}

\def\dodefinematharrow[#1][#2][#3][#4]% name type[none|both] template command
  {\iffourthargument
      \executeifdefined{dodefine#2arrow}\gobblethreearguments{#1}{#3}{#4}%
   \else\ifthirdargument
      \dodefinebotharrow{#1}{#2}{#3}%
   \fi\fi}

\def\dodefinebotharrow#1#2#3%
  {\setvalue{#1}{\dotripleempty\xmtharrow[#2][#3]}}

\def\xmtharrow[#1][#2][#3]% #3 == optional arg
  {\def\doxmtharrow{\dodoxmtharrow[#1,\empty,\empty][#2,\empty,\empty][#3]}% {##1}{##2}
   \dodoublegroupempty\doxmtharrow}

\def\dodoxmtharrow[#1,#2,#3][#4,#5,#6][#7]#8#9% [3] is the optional arg
  {\ifx#2\empty
     \mathrel{\domthxarrsingle{#7}{#1}{#4}{#8}{#9}}%
   \else
     \mathrel{\domthxarrdouble{#7}{#1}{#2}{#4}{#5}{#8}{#9}}%
   \fi}

% Adapted from amsmath.

\def\mtharrowfill#1#2#3%
  {$\m@th\thickmuskip0mu\medmuskip\thickmuskip\thinmuskip\thickmuskip
   \relax#1\mkern-7mu%
   \cleaders\hbox{$\mkern-2mu#2\mkern-2mu$}\hfill
   \mkern-7mu#3$}

% Maybe redefine leftarrowfill and rightarrowfill using arrowfill

\def\rightarrowfill       {\mtharrowfill \relbar            \relbar \rightarrow       }
\def\leftarrowfill        {\mtharrowfill \leftarrow         \relbar \relbar           }
\def\equalfill            {\mtharrowfill \Relbar            \Relbar \Relbar           }
\def\Rightarrowfill       {\mtharrowfill \Relbar            \Relbar \Rightarrow       }
\def\Leftarrowfill        {\mtharrowfill \Leftarrow         \Relbar \Relbar           }
\def\Leftrightarrowfill   {\mtharrowfill \Leftarrow         \Relbar \Rightarrow       }
\def\leftrightarrowfill   {\mtharrowfill \leftarrow         \relbar \rightarrow       }
\def\mapstofill           {\mtharrowfill{\mapstochar\relbar}\relbar \rightarrow       }
\def\twoheadrightarrowfill{\mtharrowfill \relbar            \relbar \twoheadrightarrow}
\def\twoheadleftarrowfill {\mtharrowfill \twoheadleftarrow  \relbar \relbar           }
\def\rightharpoondownfill {\mtharrowfill \relbar            \relbar \rightharpoondown }
\def\rightharpoonupfill   {\mtharrowfill \relbar            \relbar \rightharpoonup   }
\def\leftharpoondownfill  {\mtharrowfill \leftharpoondown   \relbar \relbar           }
\def\leftharpoonupfill    {\mtharrowfill \leftharpoonup     \relbar \relbar           }

% From amsmath.sty, extarrows.sty, extpfel.sty and mathtools.sty(ams)

\definematharrow [xrightarrow]        [0359] [\rightarrowfill]
\definematharrow [xleftarrow]         [3095] [\leftarrowfill]
\definematharrow [xequal]             [0099] [\equalfill]
\definematharrow [xRightarrow]        [0359] [\Rightarrowfill]
\definematharrow [xLeftarrow]         [3095] [\Leftarrowfill]
\definematharrow [xLeftrightarrow]    [0099] [\Leftrightarrowfill]
\definematharrow [xleftrightarrow]    [0099] [\leftrightarrowfill]
\definematharrow [xmapsto]            [0599] [\mapstofill]
\definematharrow [xtwoheadrightarrow] [5009] [\twoheadrightarrowfill]
\definematharrow [xtwoheadleftarrow]  [0590] [\twoheadleftarrowfill]
\definematharrow [xrightharpoondown]  [0359] [\rightharpoondownfill]
\definematharrow [xrightharpoonup]    [0359] [\rightharpoonupfill]
\definematharrow [xleftharpoondown]   [3095] [\leftharpoondownfill]
\definematharrow [xleftharpoonup]     [3095] [\leftharpoonupfill]

\definematharrow [xleftrightharpoons] [3095,0359] [\leftharpoonupfill,\rightharpoondownfill]
\definematharrow [xrightleftharpoons] [3095,0359] [\rightharpoonupfill,\leftharpoondownfill]

% \startformula \xrightarrow{}{stuff on top}\stopformula
% \startformula \xrightarrow{stuff below}{}\stopformula
% \startformula \xrightarrow{stuff below}{stuff on top}\stopformula

% \startformula \xleftarrow [none]{stuff below}{stuff on top}\stopformula
% \startformula \xleftarrow [small]{stuff below}{stuff on top}\stopformula
% \startformula \xleftarrow [medium]{stuff below}{stuff on top}\stopformula
% \startformula \xleftarrow [big]{stuff below}{stuff on top}\stopformula

\protect \endinput