% see mathml, == \defineXMLdirective [mathml] \setupMMLappearance

\unprotect 

\def\setupCMLappearance[#1]{\dodoubleargument\getparameters[@@CML#1]}

\defineXMLdirective [chemml] \setupCMLappearance

\defineXMLargument [chem]  \doXMLchem
\defineXMLargument [ichem] \doXMLichem
\defineXMLargument [dchem] \doXMLdchem

\unexpanded\def\doXMLchem {\ifhmode\@EA\doXMLichem\else\@EA\doXMLdchem\fi}
\unexpanded\def\doXMLichem{\XMLremapdata[cml]{$\rm}{$}}
\unexpanded\def\doXMLdchem{\XMLremapdata[cml]{\dostartformula{}\rm}{\dostopformula}}

\startXMLmapping [cml]

\remapXMLsequence [molecule] [CPA] \doCMLmolecule
\remapXMLsequence [ion]      [CPA] \doCMLion
\remapXMLsequence [atom]     [CPA] \doCMLatom

\setupCMLappearance [ion] [\c!variant=\v!a]

\let\CMLtopcaption\empty
\let\CMLbotcaption\empty

\def\someCMLtext#1% 
  {\ifx\CMLtopcaption\empty
     \setbox0\null
   \else
     \setbox0\hbox{\txx\setstrut\strut\ignorespaces\CMLtopcaption\unskip}%
   \fi
   \setbox2\hbox{\ignorespaces\strut#1\unskip}%
   \ifx\CMLbotcaption\empty
     \setbox4\null
   \else
     \setbox4\hbox{\txx\setstrut\strut\ignorespaces\CMLbotcaption\unskip}%
   \fi
   \scratchdimen=\wd2\advance\scratchdimen-.5em 
   \ifdim\wd0>\scratchdimen
     \setbox0\hbox spread .5em{\hss\box0\hss}%
   \fi
   \ifdim\wd4>\scratchdimen
     \setbox4\hbox spread .5em{\hss\box4\hss}%
   \fi
   \setbox6=\vbox 
     {\offinterlineskip\halign{\hss##\hss\cr\copy0\cr\copy2\cr\copy4\cr}}%
   \hbox{\lower\ht4\hbox{\lower\dp2\box6}}}

\def\CMLscript#1%
  {$\scriptscriptstyle\ignorespaces#1\unskip$}

\def\doifnotXMLzero#1#2#3%
  {\ifcase\XMLpar{#1}{#2}{0}\else#3{\XMLpar{#1}{#2}{0}}\fi}

\newcounter\currentCMLatom
\newcounter\nofCMLatoms

\def\doCMLmolecule#1#2%
  {\resetCMLcaption
   \processXMLRchild{caption}{#2}%
   \someCMLtext
     {\bgroup
      \newcounter\currentCMLatom
      \newcounter\nofCMLatoms
      \getXMLarguments{cml-m}{n="0" #1}%
      \doifnotXMLzero{cml-m}{n}\firstofoneargument
      \ignorespaces\processXMLRchild{atom,ion,bond/,%
        singlebond/,doublebond/,triplebond/}{#2}\unskip
      \egroup}%
   \ignorespaces}

\def\doCMLion#1#2%
  {\resetCMLcaption
   \processXMLRchild{caption}{#2}%
   \someCMLtext
     {\bgroup
      \newcounter\currentCMLatom
      \newcounter\nofCMLatoms
      \getXMLarguments{cml-i}{n="0" charge="0" #1}%
      \doifnotXMLzero{cml-i}{n}\firstofoneargument
      \doifelse\@@CMLionvariant\v!b
        {[\ignorespaces\processXMLRchild{atom,bond/,%
            singlebond/,doublebond/,triplebond/}{#2}\unskip]%
         \high{\doifnotXMLzero{cml-i}{charge}\CMLscript}}
        {\countXMLRchild{atom}{\ignorespaces#2\unskip}%
         \let\nofCMLatoms\nofXMLRchildren   
         \ignorespaces\processXMLRchild{atom,bond/,%
           singlebond/,doublebond/,triplebond/}{#2}\unskip}%
      \egroup}%
   \ignorespaces}

\def\doCMLatom#1#2%
  {\getXMLarguments{cml-a}{n="0" weight="0" protons="0" charge="0" #1}%
   \increment\currentCMLatom
   \resetCMLcaption
  %\processXMLRchild{caption}{#2}% not here 
   \someCMLtext
     {\bgroup
      \lohi
        {\doifnotXMLzero{cml-a}{protons}\CMLscript}
        {\doifnotXMLzero{cml-a}{weight}\CMLscript}%
      \ignorespaces#2\unskip
      \lohi
        {\doifnotXMLzero{cml-a}{n}\CMLscript}
        {\ifnum\nofCMLatoms=\currentCMLatom\relax
           \doifnotXMLzero{cml-i}{charge}\CMLscript
         \else
           \doifnotXMLzero{cml-a}{charge}\CMLscript
         \fi}%
      \egroup}%
   \ignorespaces}

\remapXMLsequence [reaction] [CPA] \doCMLreaction

\let\someCMLsymbol\gobbleoneargument
\let\someCMLarrow \gobblethreearguments

\def\doCMLreaction#1#2%
  {\begingroup
   \let\someCMLsymbol\dosomeCMLsymbol
   \let\someCMLarrow \dosomeCMLarrow
   #2%
   \endgroup}

\remapXMLsequence [plus]  [CPA] \doCMLplus
\remapXMLsingular [plus]  [CPA] \doCMLplus
\remapXMLsequence [minus] [CPA] \doCMLminus
\remapXMLsingular [minus] [CPA] \doCMLminus
\remapXMLsequence [equal] [CPA] \doCMLequal
\remapXMLsingular [equal] [CPA] \doCMLequal

\def\doCMLplus #1#2{\someCMLsymbol{+}}
\def\doCMLminus#1#2{\someCMLsymbol{-}}
\def\doCMLequal#1#2{\someCMLsymbol{=}}

\def\dosomeCMLsymbol#1%
  {\quad\mathop{#1}\quad}

\remapXMLsequence [gives]       [CPA] \doCMLgives
\remapXMLsingular [gives]       [CPA] \doCMLgives
\remapXMLsequence [equilibrium] [CPA] \doCMLequilibrium
\remapXMLsingular [equilibrium] [CPA] \doCMLequilibrium
\remapXMLsequence [mesomeric]   [CPA] \doCMLmesomeric
\remapXMLsingular [mesomeric]   [CPA] \doCMLmesomeric

\def\doCMLgives      #1#2{\resetCMLcaption#2\someCMLgives      }
\def\doCMLequilibrium#1#2{\resetCMLcaption#2\someCMLequilibrium}
\def\doCMLmesomeric  #1#2{\resetCMLcaption#2\someCMLmesomeric  }

\def\dosomeCMLarrow#1% 
  {\quad
   \someCMLtext
     {$\vcenter{\offinterlineskip\halign{##\cr\hskip3em\cr#1\cr}}$}%
   \quad}

\def\someCMLgives      
  {\someCMLarrow{\rightarrowfill}}

\def\someCMLequilibrium
  {\someCMLarrow{\rightarrowfill\cr\noalign{\nointerlineskip}\leftarrowfill}}

\def\someCMLmesomeric  
  {\someCMLarrow{$\leftarrow\hskip-1em$\rightarrowfill}}

\remapXMLsequence [cml] [caption] [CPA] \doCMLcaption

\let\CMLtopcaption\empty
\let\CMLbotcaption\empty

\def\dodoCMLcaption#1#2%
  {\def\CMLbotcaption{#2}%
   \def\doCMLcaption##1##2%
     {\def\CMLtopcaption{##2}%
      \let\doCMLcaption\gobbletwoarguments}}

\def\resetCMLcaption%
  {\let\CMLtopcaption\empty
   \let\CMLbotcaption\empty
   \let\doCMLcaption\dodoCMLcaption}

\resetCMLcaption

\remapXMLsingular [bond]       [CPA] \doCMLbond 
\remapXMLsingular [singlebond] [CPA] \doCMLsinglebond
\remapXMLsingular [doublebond] [CPA] \doCMLdoublebond
\remapXMLsingular [triplebond] [CPA] \doCMLtriplebond

\def\doCMLbond#1#2%
  {\getXMLarguments{cml-b}{n="0" #1}%
   \ifcase\XMLpar{cml-b}{n}{0}\relax
     \doCMLsinglebond
   \or
     \doCMLdoublebond
   \or
     \doCMLtriplebond
   \fi}

\def\someCMLbond%
  {\hrule \!!width \hsize \!!height .1ex} % .4pt 

\def\dosomeCMLbond#1#2#3%
  {{\setbox\scratchbox=\hbox{$M$}%
    \vbox to \ht\scratchbox
      {\hsize\wd\scratchbox
       \vskip.1\wd\scratchbox
       #1\vfill#2\vfill#3%
       \vskip.1\wd\scratchbox}}}

\def\doCMLsinglebond%
  {\dosomeCMLbond\relax\someCMLbond\relax}

\def\doCMLdoublebond%
  {\dosomeCMLbond\someCMLbond\relax\someCMLbond}

\def\doCMLtriplebond%
  {\dosomeCMLbond\someCMLbond\someCMLbond\someCMLbond}

\stopXMLmapping 

\protect \endinput 
