% macros=mkvi

% makes sense (but rel vs op ...):

% \unexpanded\def\stackrel#1#2{\mathematics{\mathop{\let\limits\relax\mover{#2}{#1}}}}

% this can become a core helper

% bwe could do all of them in lua

\startluacode
local find = string.find
local lpegmatch = lpeg.match

local splitter = lpeg.Ct(lpeg.C(lpeg.patterns.nestedbraces + lpeg.patterns.utf8character)^1)

function commands.xmfenced(left,middle,right,content)
    local l = left   ~= "" and left   or "("
    local r = right  ~= "" and right  or ")"
    local m = middle ~= "" and middle and lpegmatch(splitter,middle) or { "," }
    local c = find(content,"{") and lpegmatch(splitter,content) or { content }
    local n = #c
    if n > 1 then
        context("\\left%s",l)
        for i=1,n do
            if i > 1 then
                context("%s %s",m[i] or m[#m],c[i])
            else
                context(c[i])
            end
        end
        context("\\right%s",r)
    else
        context("\\left%s %s \\right%s",l,content,r)
    end
end

\stopluacode

\unprotect

\unexpanded\def\mexecuteifdefined#1%
  {\ifx#1\empty
     \expandafter\secondoftwoarguments
   \else\ifcsname#1\endcsname
     \doubleexpandafter\firstoftwoarguments
   \else
     \doubleexpandafter\secondoftwoarguments
   \fi\fi
   {\csname#1\endcsname}}

% mrow

\let\mrow\mathematics

% msub msup  msubsup

\starttexdefinition msub #1#2
    \mathematics {
        #1_{#2}
    }
\stoptexdefinition

\starttexdefinition msup #1#2
    \mathematics {
        #1^{#2}
    }
\stoptexdefinition

\starttexdefinition msubsup #1#2#3
    \mathematics {
        #1_{#2}^{#3}
    }
\stoptexdefinition

% mn mo mi

\let\mn\mathematics
\let\mo\mathematics
\let\mi\mathematics

% ms  mtext

\starttexdefinition ms #1
    \text {
        "#1"
    }
\stoptexdefinition

\starttexdefinition mtext #1
    \text {
        #1
    }
\stoptexdefinition

% mover

\starttexdefinition unexpanded moverabove #1
    \edef\movercommand{\utfmathfiller\movertoken}
    \mexecuteifdefined\movercommand {#1} \relax
\stoptexdefinition
\starttexdefinition unexpanded moverbase #1
    \edef\mbasecommand{\utfmathfiller\mbasetoken}
    \mexecuteifdefined\mbasecommand {#1}
    \relax
\stoptexdefinition
\starttexdefinition unexpanded moverbasefiller #1#2
    \edef\mbasecommand{e\utfmathcommandfiller\mbasetoken}
    \mexecuteifdefined\mbasecommand \relax {#2} {}
\stoptexdefinition
\starttexdefinition unexpanded moveraccent #1#2
    \edef\movercommand{\utfmathcommandabove\movertoken}
    \mexecuteifdefined\movercommand \relax {#1}
\stoptexdefinition
\starttexdefinition unexpanded movertext #1#2
  % \mathtriplet {\mathstylehbox{#1}} {#2} {}
    \mathtriplet {\mathematics{#1}} {#2} {}
\stoptexdefinition
\starttexdefinition unexpanded moveraccentchecker #1#2
    \edef\movertoken{\tochar{#2}}
    \doifelseutfmathabove\movertoken \moveraccent \movertext {#1}{#2}
\stoptexdefinition

\starttexdefinition unexpanded mover #1#2
    \mathematics {
        \edef\mbasetoken{\tochar{#1}}
        \doifelseutfmathfiller\mbasetoken \moverbasefiller \moveraccentchecker {#1}{#2}
    }
\stoptexdefinition

% munder

\starttexdefinition unexpanded munderbelow #1
    \edef\mundercommand{\utfmathfiller\mundertoken}
    \mexecuteifdefined\mundercommand {#1} \relax
\stoptexdefinition
\starttexdefinition unexpanded munderbase #1
    \edef\mbasecommand{\utfmathfiller\mbasetoken}
    \mexecuteifdefined\mbasecommand {#1}
    \relax
\stoptexdefinition
\starttexdefinition unexpanded munderbasefiller #1#2
    \edef\mbasecommand{e\utfmathcommandfiller\mbasetoken}
    \mexecuteifdefined\mbasecommand \relax {#2} {}
\stoptexdefinition
\starttexdefinition unexpanded munderaccent #1#2
    \edef\mundercommand{\utfmathcommandbelow\mundertoken}
    \mexecuteifdefined\mundercommand \relax {#1}
\stoptexdefinition
\starttexdefinition unexpanded mundertext #1#2
  % \mathtriplet {\mathstylehbox{#1}} {} {#2}
    \mathtriplet {\mathematics{#1}} {} {#2}
\stoptexdefinition
\starttexdefinition unexpanded munderaccentchecker #1#2
    \edef\mundertoken{\tochar{#2}}
    \doifelseutfmathbelow\mundertoken \munderaccent \mundertext {#1}{#2}
\stoptexdefinition

\starttexdefinition unexpanded munder #1#2
    \mathematics {
        \edef\mbasetoken{\tochar{#1}}
        \doifelseutfmathfiller\mbasetoken \munderbasefiller \munderaccentchecker {#1}{#2}
    }
\stoptexdefinition

% munderover

% mfenced

% \mfenced{x,y}
% \mfenced{{x}{y}}
% \mfenced[separators]{{x}{y}}
% \mfenced[left][right]{{x}{y}}
% \mfenced[left][separators][right]{{x}{y}}

\starttexdefinition unexpanded mfenced
    \dotripleempty\do_mfenced
\stoptexdefinition

\starttexdefinition unexpanded do_mfenced [#1][#2][#3]#4
    \mathematics {
        \ctxcommand{xmfenced(
            \ifthirdargument  "#1","#2","#3"\else
            \ifsecondargument  "#1",",","#2"\else
            \iffirstargument    "(","#1",")"\else
                                 "(",",",")"\fi\fi\fi
        ,"#4")}
    }
\stoptexdefinition

% mfrac

\starttexdefinition unexpanded mfrac #1#2
    \mathematics {
        \frac{#1}{#2}
    }
\stoptexdefinition

% mroot msqrt

\starttexdefinition unexpanded mroot #1#2
    \mathematics {
        \sqrt[#1]{#2}
    }
\stoptexdefinition

\starttexdefinition unexpanded msqrt #1
    \mathematics {
        \sqrt{#1}
    }
\stoptexdefinition

% menclose

% merror

% mglyph

% mmultiscripts

% mpadded

% mphantom

% mspace

% mstyle

% mtable mtr mlabeledtr mtd

% maction

% semantics

\protect

\continueifinputfile{x-mathml-basics.mkiv}

\starttext

$\mfenced{1+a}$\par
$\mfenced[,]{1+a}$\par
$\mfenced[,]{{1+a}{1+b}}$\par

% $\mover{←}{test}$\par
% $\mover{\utfchar{"2190}}{test}$\par
% $\mover{e:leftarrow}{test}$\par
% $\mover{x:2190}{test}$\par

% $\mover{test}{⏞}$\par
% $\mover{test}{\utfchar{"23DE}}$\par
% $\mover{test}{e:overbrace}$\par
% $\mover{test}{x:23DE}$\par
% $\mover{test}{over}$\par

% \mover{test}{⏞}\par
% \mover{test}{\utfchar{"23DE}}\par
% \mover{test}{e:overbrace}\par
% \mover{test}{x:23DE}\par

% $\munder{←}{test}$\par
% $\munder{\utfchar{"2190}}{test}$\par
% $\munder{e:leftarrow}{test}$\par
% $\munder{x:2190}{test}$\par

% $\munder{test}{⏟}$\par
% $\munder{test}{\utfchar{"23DF}}$\par
% $\munder{test}{e:underbrace}$\par
% $\munder{test}{x:23DF}$\par
% $\munder{test}{under}$\par

% \math{{\msup{x}{2}\mo{+}\mn{2}\mi{x}\mo{+}\mi{b}}}

% \mrow{\msup{x}{2}\mo{+}\mn{2}\mi{x}\mo{+}\mi{b}}

\stoptext