%D \module
%D   [       file=strc-mat,
%D        version=2008.10.20,
%D          title=\CONTEXT\ Structure Macros,
%D       subtitle=Math Numbering,
%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.

\writestatus{loading}{ConTeXt Structure Macros / Math Numbering}

\registerctxluafile{strc-mat}{1.001}

% -- we have potential for captions
% -- this module will use the commandhandler
% -- key/value pairs will be added (I have no time now)

\unprotect

\setupformulas
  [%\c!way=,
   %\c!blockway=,
   %\c!sectionnumber=,
   %\c!conversion=\v!numbers,
   %\c!numberstyle=,
   %\c!numbercolor=,
   %\c!numbercommand=,
   %\c!margin=,
   %\c!align=,
   %\c!separator=,
   %\c!grid=,
   \c!location=\v!right,
   \c!left=(,
   \c!right=),
   \c!expansion=\v!yes, % maybe automatically
   \c!spacebefore=\v!big,
   \c!spaceafter=\formulaparameter\c!spacebefore,
   \c!leftmargin=\!!zeropoint,
   \c!rightmargin=\!!zeropoint,
   \c!indentnext=\v!no,
   \c!alternative=\s!default,
   \c!strut=\v!no,
   \c!distance=1em]

\setupsubformulas % subformulas could be last in chain
  [\c!indentnext=\formulaparameter\c!indentnext]

\definecounter
  [\v!formula]

\defineconversionset
  [\v!formula]
  [numbers,characters]

\strc_counter_preset_using_parameter\setupformulas\sharedcounterparameter

\appendtoks
    \strc_counter_setup_using_parameter\v!formula\formulaparameter
    \strc_counters_check_setup\v!formula % yes or no
\to \everysetupformula

\setupformulas
  [\c!numberconversionset=\v!formula] % why forgotten

\appendtoks
    \normalexpanded{\definelist[\currentformula]}% is expansion needed?
    \setuevalue{\e!start\currentformula\v!formula}{\dostartformula{\currentformula}}%
    \setuevalue{\e!stop \currentformula\v!formula}{\dostopformula}%
\to \everydefineformula

\definelist[\v!formula]

\setuvalue{\e!start\v!formula}{\dostartformula{}}
\setuvalue{\e!stop \v!formula}{\dostopformula}

\let\dostartformula\relax % defined later
\let\dostopformula \relax % defined later

\unexpanded\def\defineformulaalternative         % this might change ... start and stop can become keys
  {\dotripleargument\dodefineformulaalternative} % to the general define .. s!startcommand

\def\dodefineformulaalternative[#1][#2][#3]%
  {\setvalue{\e!start#1\v!formula}{#2}%
   \setvalue{\e!stop #1\v!formula}{#3}}

% sp = single line paragraph  sd = single line display
% mp = multi  line paragraph  md = multy  line display

\defineformulaalternative[\s!default][\startdisplaymath][\stopdisplaymath]
\defineformulaalternative[\s!single] [\startdisplaymath][\stopdisplaymath]
\defineformulaalternative[\s!multi]  [\startdisplaymath][\stopdisplaymath]

\defineformula
  [sp]
  [\c!spacebefore=\v!none,
   \c!spaceafter=\v!none,
   \c!indentnext=\v!no,
   \c!alternative=\s!single]

\defineformula
  [sd]
  [\c!spacebefore=\v!none,
   \c!spaceafter=\v!none,
   \c!indentnext=\v!yes,
   \c!alternative=\s!single]

\defineformula
  [mp]
  [\c!indentnext=\v!no,
   \c!alternative=\s!multi]

\defineformula
  [md]
  [\c!indentnext=\v!yes,
   \c!alternative=\s!multi]

\newtoks\everyresetformulas

\appendtoks
    \let\currentformula\empty % to be checked:
\to \everyresetformulas

% implementation

\def\storecurrentformulanumber#1#2#3#4#5% ref, todo:str, \sync % todo: title etc (like float)
  {\settrue\handleformulanumber
   \strc_counters_register_component
     {formula}%
     \setupcurrentformula \formulaparameter \detokenizedformulaparameter
     \relax \relax \relax
     [\c!name=\v!formula,\s!counter=\v!formula,%
      \s!hascaption=\v!yes,\s!hastitle=\v!yes,\s!hasnumber=\v!yes,%\s!haslevel=#6,%
      \c!reference=#1,\c!title=\namedformulaentry,\c!bookmark=]%
     [#2]%
   \glet\namedformulaentry\empty % \relax
   \globallet#3\m_strc_counters_last_registered_index
   \globallet#4\m_strc_counters_last_registered_synchronize
   \globallet#5\m_strc_counters_last_registered_attribute}

% modes: 0=unset, 1=forced, 2=none, 3=reference

\newconstant\placeformulanumbermode
\newconstant\formulasnumbermode
\newconstant\subformulasnumbermode
\newconstant\nestedformulanumbermode

\appendtoks
    \placeformulanumbermode \zerocount
    \formulasnumbermode     \zerocount
    \subformulasnumbermode  \zerocount
    \nestedformulanumbermode\zerocount
\to \everyresetformulas

\newconditional\handleformulanumber
\newconditional\incrementformulanumber

\newconditional\insideplaceformula
\newconditional\insideplacesubformula
\newconditional\insideformulas
\newconditional\insidesubformulas

\appendtoks
    \global\setfalse\insideplaceformula
    \global\setfalse\insideplacesubformula
\to \everyresetformulas

\def\handleplaceformulanumbering % place formula
  {\settrue\handleformulanumber
   \docheckformulareference\placeformulanumbermode\currentplaceformulareference
   \glet\doplaceformulanumber \doplaceformulanumberindeed
   \glet\donestedformulanumber\donestedformulanumberindeed}

\def\handleformulasnumbering % formulas
  {\docheckformulareference\formulasnumbermode\currentformulareference}

\def\handlesubformulasnumbering % sub formulas
  {\docheckformulareference\subformulasnumbermode\currentsubformulasreference
   \strc_counters_increment\v!formula
   \storecurrentformulanumber
     \currentsubformulasreference
     \empty
     \currentsubformulasnumber
     \currentsubformulassynchronize
     \currentsubformulasattribute
  }

\let\dotraceformulareferencestate\relax
\let\doshowformulareferencestate \relax

% \def\dotraceformulareferencestate
%   {\rlap{\hbox{\quad\tt\txx[%
%       \number\placeformulanumbermode,%
%       \number\formulasnumbermode,%
%       \number\subformulasnumbermode,%
%       \number\nestedformulanumbermode
%    ]}}}

% \def\doshowformulareferencestate
%   {\writestatus{\v!formula}%
%      {place:      \number\placeformulanumbermode,\space
%       formula:    \number\formulasnumbermode,\space
%       subformula: \number\subformulasnumbermode,\space
%       nested:     \number\nestedformulanumbermode]}}

\unexpanded\def\placecurrentformulanumber
  {\rm % nodig ?
   \doif{\formulaparameter\c!location}\v!right{\hskip\formulaparameter\c!distance}%
   \formulaparameter\c!numbercommand
     {\useformulastyleandcolor\c!numberstyle\c!numbercolor
      \strut
      \formulaparameter\c!left
      \namedtaggedlabeltexts
        \t!formulalabel \v!formula
        \t!formulanumber\v!formula
        {\ignorespaces\doplacecurrentformulanumber\removeunwantedspaces}%
      \formulaparameter\c!right}%
   \doif{\formulaparameter\c!location}\v!left{\hskip\formulaparameter\c!distance}}

\def\doplacecurrentformulanumber
  {\dohandlecurrentformulareferences
   \labeltexts\currentformula{\convertedcounter[\v!formula][]}}

% \def\theboxdestinationattribute#1{\iflocation\ifx#1\relax\else\ifx#1\empty\else attr      \destinationattribute#1\fi\fi\fi}
% \def\thedestinationattribute   #1{\iflocation\ifx#1\relax\else\ifx#1\empty\else \attribute\destinationattribute#1\fi\fi\fi}

\def\theformuladestinationattribute#1%
  {\iflocation\ifx#1\relax\else\ifx#1\empty\else
     \attribute\destinationattribute#1%
     \glet#1\relax
   \fi\fi\fi}

\let\currentplaceformulaattribute\relax
\let\currentformulaattribute     \relax
\let\currentsubformulaattribute  \relax
\let\currentformulasattribute    \relax

\let\currentplaceformulanumber\relax
\let\currentformulanumber     \relax
\let\currentsubformulanumber  \relax
\let\currentformulasnumber    \relax

\let\currentformulasreference     \empty
\let\currentformulareference      \empty
\let\currentsubformulareference   \empty
\let\currentnestedformulareference\empty

\appendtoks
    \glet\currentformulasreference     \empty
    \glet\currentformulareference      \empty
    \glet\currentsubformulareference   \empty
    \glet\currentnestedformulareference\empty
\to \everyresetformulas

\let\currentformulassuffix     \empty
\let\currentformulasuffix      \empty
\let\currentsubformulasuffix   \empty
\let\currentnestedformulasuffix\empty

\appendtoks
    \glet\currentformulassuffix     \empty
    \glet\currentformulasuffix      \empty
    \glet\currentsubformulasuffix   \empty
    \glet\currentnestedformulasuffix\empty
\to \everyresetformulas

\let\currentplaceformulasynchronize\relax
\let\currentformulasynchronize     \relax
\let\currentsubformulasynchronize  \relax
\let\currentformulassynchronize    \relax

\appendtoks
    \glet\currentplaceformulasynchronize \relax
    \glet\currentformulassynchronize     \relax
    \glet\currentsubformulassynchronize  \relax
    \glet\currentnestedformulasynchronize\relax
\to \everyresetformulas

% currently we do the number, some day we will do the (sub) formula

\def\dohandlecurrentformulareferences
  {\doshowformulareferencestate
   \ifnum\placeformulanumbermode=\plusthree
     \storecurrentformulanumber
       \currentplaceformulareference
       \empty
       \currentplaceformulanumber
       \currentplaceformulasynchronize
       \currentplaceformulaattribute
     \currentplaceformulasynchronize
     \glet\currentplaceformulasynchronize\relax
     \theformuladestinationattribute\currentplaceformulaattribute
   \fi
   \ifnum\formulasnumbermode=\plusthree
     \storecurrentformulanumber
       \currentformulasreference
       \empty
       \currentformulasnumber
       \currentformulassynchronize
       \currentformulasattribute
     \currentformulassynchronize
     \glet\currentformulassynchronize\relax
     \theformuladestinationattribute\currentformulasattribute
   \fi
   \ifnum\subformulasnumbermode=\plusthree
     \currentsubformulassynchronize
     \glet\currentsubformulassynchronize\relax
   \fi
   \ifnum\nestedformulanumbermode=\plusthree
     \storecurrentformulanumber
       \currentnestedformulareference
       \empty
       \currentnestedformulanumber
       \currentnestedformulasynchronize
       \currentnestedformulaattribute
     \currentnestedformulasynchronize
     \glet\currentnestedformulasynchronize\relax
     \theformuladestinationattribute\currentnestedformulaattribute
   \fi}

% needs checking ... too many:

\def\dohandleformulanumbering
  {\strc_counters_increment\v!formula
   \doiftext\currentplaceformulasuffix{\strc_counters_setown_sub\v!formula\plustwo\currentplaceformulasuffix}%
   \placecurrentformulanumber}

\def\dohandlesubformulanumbering
  {\doiftextelse\currentsubformulasuffix
     {\strc_counters_setown_sub\v!formula\plustwo\currentsubformulasuffix}
     {\strc_counters_increment_sub\v!formula\plustwo}%
    \placecurrentformulanumber}

\def\dododoformulanumber
  {\ifconditional\handleformulanumber
     \hbox\bgroup
       % main counter
       \ifconditional\insidesubformulas
         % nothing
       \else
         \ifcase\formulasnumbermode
           \ifcase\placeformulanumbermode
             \dohandleformulanumbering
           \or
             \dohandleformulanumbering
           \or
             % nothing
           \or
             \dohandleformulanumbering
           \fi
         \or
           \dohandleformulanumbering
         \or
           % nothing
         \or
           \dohandleformulanumbering
         \fi
       \fi
       % subcounter
       \ifconditional\insidesubformulas
         \ifcase\subformulasnumbermode
           % nothing
         \or
           \dohandlesubformulanumbering
         \or
           % nothing
         \or
           \dohandlesubformulanumbering
         \fi
       \fi
      \dotraceformulareferencestate
     \egroup
   \fi}

\installstructurelistprocessor\v!formula % to be checked ...
  {\let\currentlistentrynumber    \structurelistgenericnumber
   \let\currentlistentrytitle     \structurelistgenerictitle
   \let\currentlistentrypagenumber\structurelistpagenumber
   \strc_lists_apply_renderingsetup}

\newif\ifinformula

%D We need a hook into the plain math alignment macros
%D
%D \starttyping
%D \displaylines
%D \eqalignno
%D \eqalignno
%D \stoptyping
%D
%D Otherwise we get a missing \type {$$} error reported.

\def\resetdisplaymatheq
  {\let\normalleqno\gobbleoneargument \let\leqno\gobbleoneargument
   \let\normalreqno\gobbleoneargument \let\eqno \gobbleoneargument
   \let\doplaceformulanumber\empty}

%D \macros
%D   {startsubformulas}

% \placeformula
% \startsubformulas[Maxwell]
%     \startformulas
%      \startformula \startalign
%        \NC \nabla\cdot\bf E  \NC = \frac{\rho}{\varepsilon_0} \NR[Maxwell 1]
%        \NC \nabla\times\bf E \NC = - \frac{\partial\bf B}{\partial t} \NR[Maxwell II]
%        \stopalign \stopformula
%        \startformula \startalign
%          \NC \nabla\cdot \bf B \NC = 0 \NR[Maxwell III]
%          \NC \nabla\times\bf B \NC = \mu_0{\bf j}+\varepsilon_0\mu_0\frac{\partial\bf E}{\partial t} \NR[Maxwell IV]
%        \stopalign \stopformula
%    \stopformulas
% \stopsubformulas
%
% Maxwell : \in [Maxwell] and II : \in [Maxwell II]

%D Tricky stuff:

\newdimen\lastlinewidth

\abovedisplayskip      \zeropoint
\abovedisplayshortskip \zeropoint % evt. 0pt minus 3pt
\belowdisplayskip      \zeropoint
\belowdisplayshortskip \zeropoint % evt. 0pt minus 3pt

\predisplaypenalty     \zerocount
\postdisplaypenalty    \zerocount % -5000 gaat mis, zie penalty bij \paragraaf

% we don't use the skip's

\def\forgetdisplayskips % to do
  {\abovedisplayskip     \zeropoint
   \belowdisplayskip     \zeropoint
   \abovedisplayshortskip\zeropoint
   \belowdisplayshortskip\zeropoint}

\def\predisplaysizethreshhold{2em} % was 3em

\def\leftdisplayskip    {\leftskip}
\def\rightdisplayskip   {\rightskip}
\def\leftdisplaymargin  {\formulaparameter\c!leftmargin}
\def\rightdisplaymargin {\formulaparameter\c!rightmargin}

\def\beforedisplayspace
  {\doifnot{\formulaparameter\c!spacebefore}\v!none{\blank[\formulaparameter\c!spacebefore]}}

\def\afterdisplayspace
  {\doifnot{\formulaparameter\c!spaceafter }\v!none{\blank[\formulaparameter\c!spaceafter ]}}

\def\setdisplaydimensions
  {\displayindent\leftdisplayskip
   \advance\displayindent\leftdisplaymargin
   \displaywidth\hsize
  %\setlocalhsize
  %\displaywidth\localhsize
   \ifdim\hangindent>\zeropoint
     \advance\displayindent\hangindent
   \else
     \advance\displaywidth\hangindent
   \fi
   \advance\displaywidth\dimexpr-\displayindent-\rightdisplayskip-\rightdisplaymargin\relax
   \hsize\displaywidth} % new, else overfull in itemize

\unexpanded\def\dostartformula#1%
  {\dodoubleempty\dodostartformula[#1]}

\newskip\formulaparskip
\newskip\formulastrutht
\newskip\formulastrutdp

%D \startbuffer
%D \startformula[9pt] x = 1 \stopformula
%D \startformula[7pt] x = 1 \stopformula
%D \stopbuffer
%D
%D \typebuffer \getbuffer

\def\dodostartformula[#1][#2]% setting leftskip adaption is slow !
  {\bgroup % HERE
   \def\currentformula{#1}%
   \dostarttagged\t!formula\currentformula
   \the\everybeforedisplayformula
   \formulaparskip\parskip
   \formulastrutdp\strutdepth
   \formulastrutht\strutheight
   \doifsomething{#2}{\switchtoformulabodyfont[#2]}%
   \parskip\formulaparskip
   % may look better in itemizations
   \doif{\formulaparameter\c!option}\v!middle
     {\def\leftdisplayskip{\zeropoint}%
      \def\rightdisplayskip{\zeropoint}}%
   % this was an experiment
   \doifsomething{\formulaparameter\c!margin}% so we test first
     {\dosetleftskipadaption{\formulaparameter\c!margin}%
      \edef\leftdisplaymargin{\the\leftskipadaption}}% overloaded
   \long\def\dostartformula##1{\bgroup\dostarttagged\t!subformula\def\dostopformula{\dostoptagged\egroup}}%
   \freezedimenmacro\leftdisplayskip
   \freezedimenmacro\rightdisplayskip
   \freezedimenmacro\leftdisplaymargin
   \freezedimenmacro\rightdisplaymargin
   \freezedimenmacro\predisplaysizethreshhold
   \forgetdisplayskips
   \getvalue{\e!start\formulaparameter\c!alternative\v!formula}}

% tagging of formulanumbers is not ok (we get two display maths blobs)

\unexpanded\def\dostopformula
  {\dostarttagged\t!formulacaption\empty
   \doplaceformulanumber
   \dostoptagged
   \dostarttagged\t!formulacontent\empty
   \getvalue{\e!stop\formulaparameter\c!alternative\v!formula}%
   \dostoptagged
   \dostoptagged
   \nonoindentation
   \useindentnextparameter\formulaparameter
   \egroup
   \hangafter\minusone   % added for side floats
   \hangindent\zeropoint % added for side floats
   \setfalse\handleformulanumber
   \the\everyresetformulas
   \dorechecknextindentation} % here ?

% experiment:

\appendtoks
   \edef\currentformulagrid{\formulaparameter\c!grid}%
   \ifx\currentformulagrid\empty \else
     \spac_grids_snap_value_auto\currentformulagrid
   \fi
\to \everybeforedisplayformula

\def\switchtoformulabodyfont{\switchtobodyfont}

\setuvalue{\v!formula}{\dosingleempty\doformula}

\def\doformula[#1]#2% todo: tagged
  {\begingroup
   \doifsomething{#1}{\switchtoformulabodyfont[#1]}%
   % not : \def\doformula[##1]##2{\mathematics{##2}}%
   \mathematics{#2}%
   \endgroup}

%D \starttyping
%D % test \par       % no preceding hlist
%D % $$x$$           % preceding hlist
%D % \noindent $$x$$ % no preceding hlist
%D \startformula x \stopformula % now has \noindent (in mkii we messed with baselineskip)
%D \stoptyping

\unexpanded\def\startdisplaymath
  {\bgroup
   \par
   \informulatrue
   \beforedisplayspace
   \par
   \ifvmode
      \prevdepth-\maxdimen % texbook pagina 79-80
   \fi
   \noindent % else funny hlist with funny baselineskip
   $$% \Ustartdisplaymath
   \setdisplaydimensions
  %\setpredisplaysize
   \startinnermath}

\unexpanded\def\stopdisplaymath
  {\stopinnermath
   $$% \Ustopdisplaymath
   \par
   \afterdisplayspace
   \par
   \egroup}

% already defined
%
% \let\startinnermath\empty
% \let\stopinnermath \empty

% \defineformulaalternative[multi][\begindmath][\enddmath]
%
% \fakewords{20}{40}\epar
% \placeformula {a} $$              \fakespacingformula $$
% \fakewords{20}{40}\epar
% \placeformula {b} \startformule   \fakespacingformula \stopformule
% \placeformula {b} \startformule   \fakespacingformula \stopformule
% \fakewords{20}{40}\epar
% \placeformula {c} \startmdformule \fakespacingformula \stopmdformule
% \placeformula {c} \startmdformule \fakespacingformula \stopmdformule
% \fakewords{20}{40}\epar
% \placeformula {d} \startmpformule \fakespacingformula \stopmpformule
% \placeformula {d} \startmpformule \fakespacingformula \stopmpformule
% \fakewords{20}{40}\epar
% \placeformula {e} \startsdformule \fakespacingformula \stopsdformule
% \placeformula {e} \startsdformule \fakespacingformula \stopsdformule
% \fakewords{20}{40}\epar
% \placeformula {f} \startspformule \fakespacingformula \stopspformule
% \placeformula {f} \startspformule \fakespacingformula \stopspformule
% \fakewords{20}{40}

\unexpanded\def\startsubformulas
  {\dosingleempty\dostartsubformulas}

\def\dostartsubformulas[#1]%
  {\edef\currentsubformulasreference{#1}%
   \global\settrue\insidesubformulas
   \handlesubformulasnumbering}

\unexpanded\def\stopsubformulas
  {\nonoindentation
   \useindentnextparameter\subformulaparameter
   \the\everyresetformulas % to be checked
   \global\setfalse\insidesubformulas
   \dorechecknextindentation} % here ?

%D Named subformulas (to be redone)

\unexpanded\def\startnamedsubformulas
  {\dosingleempty\dostartnamedsubformulas}

\def\dostartnamedsubformulas[#1]#2%
  {\setformulalistentry{#2}%
   \startsubformulas[#1]}

\unexpanded\def\stopnamedsubformulas
  {\stopsubformulas}

%D Experimental goodie:
%D
%D \startbuffer
%D \placelist[formula][criterium=text] \blank[2*big]
%D \placenamedformula[one]{first}  \startformula a = 1 \stopformula \endgraf
%D \placeformula                   \startformula a = 2 \stopformula \endgraf
%D \placenamedformula     {second} \startformula a = 3 \stopformula \endgraf
%D \stopbuffer
%D
%D \typebuffer \getbuffer

\unexpanded\def\startformulas
  {\dosingleempty\dostartformulas}

\def\dostartformulas[#1]#2\stopformulas % new / to be internationalized
  {\bgroup
   \dostarttagged\t!formulaset\empty
   \global\settrue\insideformulas
   \edef\currentformulasreference{#1}%
   \handleformulasnumbering
   \let\currentformula\empty
   \forgetdisplayskips
   \startdisplaymath
   \setlocalhsize
   \long\unexpanded\def\startformula##1\stopformula
     {\advance\scratchcounter\plusone}%
   \scratchcounter\zerocount
   #2% preroll
   \ifcase\scratchcounter\else
     \divide \hsize \scratchcounter
   \fi
   \hbox to \localhsize \bgroup
     \hss
     \def\normalstartformula{\vskip-\strutdepth\Ustartdisplaymath}% i hate this
     \def\normalstopformula {\Ustopdisplaymath}%
     \unexpanded\def\startformula      {\Ustartmath\vcenter\bgroup\normalstartformula}%
     \unexpanded\def\stopformula       {\normalstopformula\egroup\Ustopmath\hss}%
     #2%
     \egroup
   \stopdisplaymath
   \global\setfalse\insideformulas
   \dostoptagged
   \egroup
   \the\everyresetformulas
   \hangafter\minusone    % added for side floats
   \hangindent\zeropoint} % added for side floats

% place

\def\inhibitformulanumberflag{-}
\def\forceformulanumberflag  {+}

\def\docheckformulareference#1#2%
  {#1\unless\ifx\namedformulaentry\empty % \relax % new 29/8/2010
     \plusthree
   \else\ifx#2\empty
     \zerocount
   \else\ifx#2\forceformulanumberflag
     \plusone
   \else\ifx#2\inhibitformulanumberflag
     \plustwo
   \else
     \plusthree
   \fi\fi\fi\fi}

\unexpanded\def\formulanumber{\doformulanumber} % for the moment

\def\doformulanumber
  {\dosingleempty\dodoformulanumber}

\def\dodoformulanumber[#1]%
  {\def\currentformulareference{#1}%
   \dosinglegroupempty\dododoformulanumber}

\def\redoformulanumber#1%
  {\def\currentformulasuffix{#1}%
   \dododoformulanumber}

\unexpanded\def\placeformula
  {\global\settrue\insideplaceformula
   \settrue\incrementformulanumber
   \dosingleempty\doplaceformula}

\unexpanded\def\placesubformula
  {\global\settrue\insideplacesubformula
   \setfalse\incrementformulanumber
   \dosingleempty\doplaceformula}

\def\doplaceformula[#1]%
  {\def\currentplaceformulareference{#1}%
   \let\currentplaceformulasuffix\empty
   \doifnextbgroupelse\moreplaceformula\redoplaceformula} % [ref]{}

\def\moreplaceformula#1%
  {\def\currentplaceformulasuffix{#1}%
   \redoplaceformula}

\def\redoplaceformula
  {\doifnextcharelse$\dispplaceformula\dodoplaceformula} % [ref]$$ [ref]\start

\def\dodoplaceformula
  {\handleplaceformulanumbering}

\def\dispplaceformula$$#1$$%
  {\handleplaceformulanumbering
   \dostartformula{}#1\dostopformula}

\let\startplaceformula\placeformula
\let\stopplaceformula \relax

% to be checked

\let\doplaceformulanumber \relax
\let\donestedformulanumber\gobbletwoarguments

\def\donestedformulanumberindeed#1#2%
  {\def\currentnestedformulareference{#1}%
   \def\currentnestedformulasuffix{#2}%
   \glet\doplaceformulanumber\relax
   \docheckformulareference\nestedformulanumbermode\currentnestedformulareference
   \ifcase\nestedformulanumbermode
     % nothing
   \or
     \doformulanumber
   \or
     % nothing
   \or
     \doformulanumber
   \fi}

\def\doplaceformulanumberindeed
  {\glet\doplaceformulanumber\relax
   \doifelse{\formulaparameter\c!location}\v!left
     {\normalleqno{\dododoformulanumber}}
     {\normalreqno{\dododoformulanumber}}}

% todo

\unexpanded\def\placenamedformula
  {\dosingleempty\doplacenamedformula}

\def\doplacenamedformula[#1]#2%
  {\iffirstargument
     \def\next{\placeformula[#1]}%
   \else
     \let\next\placeformula
   \fi
   \setformulalistentry{#2}%
   \next}

\let\namedformulaentry\empty % \relax % this will become a key/value so that we can do bookmarks

\unexpanded\def\setformulalistentry#1%
  {\gdef\namedformulaentry{#1}}

\protect \endinput

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