%D \module
%D   [       file=font-mat,
%D        version=2011.01.13, % (copied fron font-ini)
%D          title=\CONTEXT\ Font Macros,
%D       subtitle=Math,
%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.

% because we cannot mix we can just 'redefine' the relevant
% macro when \ifconditional\c_font_compact

\writestatus{loading}{ConTeXt Font Macros / Math}

\unprotect

%D The original (\MKIV) approach to bidi is that we have two extra families for
%D regular, bold and pseudobold:
%D
%D regular    normal=0 l2r=1 r2l=2
%D bold       normal=3 l2r=4 r2l=5
%D pseudobold normal=6 l2r=7 r2l=8
%D
%D where l2r is just an alias. Because we're now using the mirror lookup (like
%D we do a smaller lookup) in the engine we now just have:
%D
%D regular    normal=0
%D bold       normal=3
%D pseudobold normal=6
%D
%D And when one can wonder if pseudobold is needed (just bolden); we can then
%D actually go down to only two families. It is one of these cases when it hurts
%D to throw away a nice old mechanism that worked quite well so here we keep it
%D commented. For what it's worth: this variant switches a bit faster too and
%D produces less logging but I doubt if anyone will notice that.

%D We now have bidi handled via a tweak in the goodie file which means that we
%D could simplify the implementation and get rid of the (four) extra families
%D needed. For now we retain the zero/three designation for mr/mb but that might
%D go away. Actually we could drop the number of families in the engine to sixteen
%D again or even four if we need the space for more classes or something else.

%D Be nice:

\ifdefined\??fontinstanceready \else \installcorenamespace{fontinstanceready} \fi
\ifdefined\??fontinstancebasic \else \installcorenamespace{fontinstancebasic} \fi
\ifdefined\??fontinstanceclass \else \installcorenamespace{fontinstanceclass} \fi

%D The order 3 2 1 of size matters is historic and was needed for math-fbk relative
%D size storage! It is no longer relevant.

%D \macros
%D   {textonly}
%D
%D Traditionally math has a big impact on font definitions, mainly because we need
%D to define alphabet variants using families and fonts. This means that one can
%D easily get 10 fonts loaded per math size. In \MKIV\ we use a different approach:
%D one family which has either a virtual font made of traditional fonts, or an
%D \OPENTYPE\ font that has it all.
%D
%D We currently use only one math family but in the future we might consider using a
%D second one for bold math. For the moment we keep the \MKII\ method of using a
%D token register for definitions but we already dropped the text and symbols ones
%D since they now live in the same family. When we go always compact we can simplify
%D the code even more. For previous implementations see the \MKIV\ code and the
%D repository pre October 2022.

\newtoks       \t_font_math_strategies
\newconditional\c_font_synchronize_math_fonts \c_font_synchronize_math_fonts\conditionaltrue

\protected\def\font_helpers_synchronize_math % math stuff in mmode
  {\ifconditional\c_font_synchronize_math_fonts\expand\t_font_math_strategies\fi}

\permanent\protected\def\textonly{\c_font_synchronize_math_fonts\conditionalfalse} % document this

%D The main math font definer. We have removed some optimized code simply because we
%D now always have a fontclass. We could check for fontclass being default or empty
%D and save a few tests but it does not help us when no math is defined.
%D
%D Because we want to keep mr=.. and mb=... settings (read: not break downward
%D compatibility by enforcing mrlr etc) we need a bit more code that optimal.

\aliased\let\c_font_fam_mr\zerocount  % math regular
\aliased\let\c_font_fam_mb\plusthree  % math bold

\definesystemattribute[mathfamily][public]

% when we are always true we can as well remove this test:

\newconditional\c_font_complete_bold_mathstrategy  \c_font_complete_bold_mathstrategy\conditionaltrue

\permanent\cdef\mathtextsuffix        {-text}
\permanent\cdef\mathscriptsuffix      {-script}
\permanent\cdef\mathscriptscriptsuffix{-scriptscript}

%D Beware: truefontname also does a fallback on defaultfontclass so there can be
%D some interference here, which is why we use a different method for bold.

\def\font_helpers_set_math_family_a
  {\ifcsname\??fontinstanceready\fontclass       -\fontbody-\s!mm-\fontfamily-\fontsize\endcsname \c_font_auto_size\conditionalfalse
     \lastnamedcs \orelse
   \ifcsname\??fontinstanceready\fontclass       -\fontbody-\s!mm-\fontfamily          \endcsname \c_font_auto_size\conditionaltrue
     \lastnamedcs \else
     \font_helpers_set_math_family_b
   \fi}

\def\font_helpers_set_math_family_b
  {\ifcsname\??fontinstanceready\defaultfontclass-\fontbody-\s!mm-\fontfamily-\fontsize\endcsname \c_font_auto_size\conditionalfalse
     \lastnamedcs \orelse
   \ifcsname\??fontinstanceready\defaultfontclass-\fontbody-\s!mm-\fontfamily          \endcsname \c_font_auto_size\conditionaltrue
     \lastnamedcs \else
     \font_helpers_set_math_family_c
   \fi}

\def\font_helpers_set_math_family_c
  {\ifcsname\??fontinstanceready                  \fontbody-\s!mm-\fontfamily-\fontsize\endcsname \c_font_auto_size\conditionalfalse
     \lastnamedcs \orelse
   \ifcsname\??fontinstanceready                  \fontbody-\s!mm-\fontfamily          \endcsname \c_font_auto_size\conditionaltrue
     \lastnamedcs \else
                                                                                                  \c_font_auto_size\conditionaltrue
   \fi}

\mutable\lettonothing\mathsizesuffix

\mutable\let\fontfamily\relax % for now public but it is a helper

\newinteger\c_math_last_family_used

\lettonothing\font_math_last_font

\def\font_helpers_set_math_family_indeed_normal#mrtag#family% \fontface etc are also used later on
  {\let\savedfontbody\fontbody
   \let\savedfontstyle\fontstyle
   \let\fontstyle\s!mm
   \let\fontfamily#family%
   \c_math_last_family_used\zerocount
   % the order is important as we depend on known id's when completing fonts
   % enabling is needed when we have fallbacks which spoils the families; per
   % mid 2022 this is no longer true as we do fallbacks differently
   \let\mathsizesuffix\mathscriptscriptsuffix
   \let\fontface\!!plusthree
   \font_helpers_set_math_family_a\scriptscriptfont#mrtag\font % defines
   \font_helpers_set_math_family_a\scriptscriptfont#mrtag\font % enables / still needed ?
   \let\mathsizesuffix\mathscriptsuffix
   \let\fontface\!!plustwo
   \font_helpers_set_math_family_a\scriptfont      #mrtag\font % defines
   \font_helpers_set_math_family_a\scriptfont      #mrtag\font % enables / still needed ?
   \let\mathsizesuffix\mathtextsuffix
   \let\fontface\!!plusone
   \font_helpers_set_math_family_a\textfont        #mrtag\font % defines
   \font_helpers_set_math_family_a\textfont        #mrtag\font % enables / still needed ?
   \lettonothing\mathsizesuffix
   \let\fontface\!!zerocount
   \let\fontstyle\savedfontstyle
   \let\fontbody\savedfontbody
   \c_font_auto_size\conditionalfalse}

\def\font_helpers_set_math_family_set_scales_normal
  {\glyphtextscale        \plusthousand
   \glyphscriptscale      \plusthousand
   \glyphscriptscriptscale\plusthousand}

\def\font_helpers_set_math_family_set_scales_compact
  {\glyphtextscale        \plusthousand
   \glyphscriptscale      \plusthousand
   \glyphscriptscriptscale\plusthousand}

\installcorenamespace{compactmathrscale}

\def\font_helpers_set_math_scales_compact
  {\glyphtextscale        \the\floatexpr\v_font_size_relative*\plusthousand\relax
   \glyphscriptscale      \glyphtextscale
   \glyphscriptscriptscale\glyphtextscale
   \global\expandafter\integerdef\csname\??compactmathrscale\the\fontid\font\endcsname\glyphtextscale}

\def\font_helpers_get_math_scales_compact
  {\ifcsname\??compactmathrscale\the\fontid\font\endcsname
     \glyphtextscale        \lastnamedcs
     \glyphscriptscale      \glyphtextscale
     \glyphscriptscriptscale\glyphtextscale
   \fi}

\def\font_helpers_set_math_family_indeed_compact#mrfam#family% \fontface etc are also used later on
  {\let\savedfontbody\fontbody
   \let\savedfontstyle\fontstyle
   \let\fontstyle\s!mm
   \let\fontfamily#family%
   \c_math_last_family_used\zerocount
   % the order is important as we depend on known id's when completing fonts
   % enabling is needed when we have fallbacks which spoils the families
   \let\mathsizesuffix\mathtextsuffix
   \let\fontface\!!plusone
   % todo: set them al on one go
   \font_helpers_set_math_family_a\textfont        #mrfam\font % defines
   \font_helpers_set_math_family_a\textfont        #mrfam\font % enables / still needed ?
                                  \scriptfont      #mrfam\font % reuses
                                  \scriptscriptfont#mrfam\font % reuses
   \font_helpers_set_math_scales_compact
   \lettonothing\mathsizesuffix
   \let\fontface\!!zerocount
   \let\fontstyle\savedfontstyle
   \let\fontbody\savedfontbody
   \c_font_auto_size\conditionalfalse}

% why somewhat more save here than normal

\def\font_helpers_set_math_family_bold_indeed_normal#mbfam#family#mrfam% \c_font_fam_mb \s!mb \c_font_fam_mr
  {\let\savedfontclass\defaultfontclass
   \let\defaultfontclass\fontclass % else truefontname falls back on the wrong one
   \let\savedfontbody\fontbody
   \let\savedfontstyle\fontstyle
   \let\fontstyle\s!mm
   \let\fontfamily#family%
   \c_math_last_family_used\zerocount
   \font_helpers_set_math_family_set_scales_normal
   \let\mathsizesuffix\mathscriptscriptsuffix
   \let\fontface\!!plusthree
   \font_helpers_set_math_family_bold_a\scriptscriptfont#mbfam#mrfam% defines
   \font_helpers_set_math_family_bold_a\scriptscriptfont#mbfam#mrfam% enables / still needed ?
   \let\mathsizesuffix\mathscriptsuffix
   \let\fontface\!!plustwo
   \font_helpers_set_math_family_bold_a\scriptfont      #mbfam#mrfam% defines
   \font_helpers_set_math_family_bold_a\scriptfont      #mbfam#mrfam% enables / still needed ?
   \let\mathsizesuffix\mathtextsuffix
   \let\fontface\!!plusone
   \font_helpers_set_math_family_bold_a\textfont        #mbfam#mrfam% defines
   \font_helpers_set_math_family_bold_a\textfont        #mbfam#mrfam% enables / still needed ?
   \lettonothing\mathsizesuffix
   \let\fontface\!!zerocount
   \let\fontstyle\savedfontstyle
   \let\fontbody\savedfontbody
   \let\defaultfontclass\savedfontclass
   \c_font_auto_size\conditionalfalse}

\def\font_helpers_set_math_family_bold_indeed_compact#mbfam#family#mrfam% \c_font_fam_mb \s!mb \c_font_fam_mr
  {\let\savedfontclass\defaultfontclass
   \let\defaultfontclass\fontclass % else truefontname falls back on the wrong one
   \let\savedfontbody\fontbody
   \let\savedfontstyle\fontstyle
   \let\fontstyle\s!mm
   \let\fontfamily#family%
   \c_math_last_family_used\zerocount
   \let\mathsizesuffix\mathtextsuffix
   \let\fontface\!!plusone
   \font_helpers_set_math_family_bold_a\textfont        #mbfam#mrfam% defines
   \font_helpers_set_math_family_bold_a\textfont        #mbfam#mrfam% enables / still needed ?
                                       \scriptfont      #mbfam\textfont#mbfam% reuses
                                       \scriptscriptfont#mbfam\textfont#mbfam% reuses
   \lettonothing\mathsizesuffix
   \let\fontface\!!zerocount
   \let\fontstyle\savedfontstyle
   \let\fontbody\savedfontbody
   \let\defaultfontclass\savedfontclass
   \c_font_auto_size\conditionalfalse}

\def\font_helpers_set_math_family_bold_a#font#mbfam#mrfam%
  {\ifcsname\??fontinstanceready\fontclass-\fontbody-\s!mm-\fontfamily-\fontsize\endcsname \c_font_auto_size\conditionalfalse
     \lastnamedcs #font#mbfam\font \orelse
   \ifcsname\??fontinstanceready\fontclass-\fontbody-\s!mm-\fontfamily          \endcsname \c_font_auto_size\conditionaltrue
     \lastnamedcs #font#mbfam\font \else
     #font#mbfam#font#mrfam%
   \fi}

% optimized: math fonts are never changed (10K \bfa $x$: 3.2 => 2.5 (baseline 1.0))
%
% sort of tricky: we cannot reset in \everybeforedefinetypeface as we don't know
% all sizes so we postpone the optimization to the first starttext
%
% pitfall: we should reset them when a fontclass name is reused

\newconditional\optimizemathfontdefinitions \optimizemathfontdefinitions\conditionaltrue

\def\font_helpers_set_math_family_normal#mrfam#familytag%
  {\ifconditional\optimizemathfontdefinitions
     \ifcsname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize-1\endcsname
       % \writestatus{fonts}{math: reusing \fontclass\fontbody\s!mm#familytag\fontsize1}%
       \font_helpers_preset_math_family_indeed#mrfam#familytag%
     \else
       % \writestatus{fonts}{math: defining \fontclass\fontbody\s!mm#familytag\fontsize1}%
       \font_helpers_set_math_family_indeed_normal#mrfam#familytag%
     \fi
   \else
     \font_helpers_set_math_family_indeed_normal#mrfam#familytag%
   \fi}

\def\font_helpers_set_math_family_bold_normal#mbfam#familytag#mrfam%
  {\ifconditional\optimizemathfontdefinitions
     \ifcsname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize-1\endcsname
       \font_helpers_preset_math_family_indeed#mbfam#familytag%
     \else
       \font_helpers_set_math_family_bold_indeed_normal#mbfam#familytag#mrfam%
     \fi
   \else
     \font_helpers_set_math_family_bold_indeed_normal#mbfam#familytag#mrfam%
   \fi}

\def\font_helpers_set_math_family_compact#mrfam#familytag%
  {\ifconditional\optimizemathfontdefinitions
     \ifcsname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize\endcsname
       % \writestatus{fonts}{math: reusing \fontclass\fontbody\s!mm#familytag\fontsize1}%
       \font_helpers_preset_math_family_indeed#mrfam#familytag%
     \else
       % \writestatus{fonts}{math: defining \fontclass\fontbody\s!mm#familytag\fontsize1}%
       \font_helpers_set_math_family_indeed_compact#mrfam#familytag%
     \fi
   \else
     \font_helpers_set_math_family_indeed_compact#mrfam#familytag%
   \fi}

\def\font_helpers_set_math_family_bold_compact#mbfam#familytag#mrfam%
  {\ifconditional\optimizemathfontdefinitions
     \ifcsname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize\endcsname
       \font_helpers_preset_math_family_indeed#mbfam#familytag%
     \else
       \font_helpers_set_math_family_bold_indeed_compact#mbfam#familytag#mrfam%
     \fi
   \else
     \font_helpers_set_math_family_bold_indeed_compact#mbfam#familytag#mrfam%
   \fi}

\aliased\let\font_helpers_set_math_family     \font_helpers_set_math_family_normal
\aliased\let\font_helpers_set_math_family_bold\font_helpers_set_math_family_bold_normal

\appendtoks
    \aliased\let\font_helpers_set_math_family     \font_helpers_set_math_family_compact
    \aliased\let\font_helpers_set_math_family_bold\font_helpers_set_math_family_bold_compact
\to \everycompactfontmode

%D It can happen that we use a bodyfont with no math in which case we have a problem
%D with setting the global bodyfont size in the page builder. For instance in:
%D
%D \starttext
%D     \definetypeface[test][rm][serif][pagella][default]
%D     \setupbodyfont[test]
%D     test
%D \stoptext
%D
%D This is why we need the check. At the cost of some extra checking we gain a
%D little in restoring global states and, what's more important, we get rid of large
%D math parameter push/pop in tracingall when not needed.

\def\font_helpers_preset_math_family_indeed_normal#fam#familytag%
  {\expandafter\let\expandafter\font_math_last_font\csname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize-1\endcsname
   \font_math_last_font
   \ifnum\fontid\textfont#fam=\fontid\font\else
     \font_helpers_preset_math_family_indeed_changed_normal#fam#familytag%
   \fi}

\def\font_helpers_preset_math_family_indeed_changed_normal#fam#familytag%
  {\font_helpers_set_math_family_set_scales_normal
   \csname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize-3\endcsname\scriptscriptfont#fam\font
   \csname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize-2\endcsname\scriptfont      #fam\font
 % \csname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize-1\endcsname\textfont        #fam\font}
   \font_math_last_font                                                                  \textfont        #fam\font}

\def\font_helpers_preset_math_family_indeed_compact#fam#familytag%
  {\csname\??fontinstanceclass\fontclass-\fontbody-\s!mm-#familytag-\fontsize\endcsname
   \ifnum\fontid\textfont#fam=\fontid\font\else
     \font_helpers_preset_math_family_indeed_changed_compact#fam%
   \fi}

\def\font_helpers_preset_math_family_indeed_changed_compact#fam%
  {\scriptscriptfont#fam\font
   \scriptfont      #fam\font
   \textfont        #fam\font
   \font_helpers_get_math_scales_compact}

\aliased\let\font_helpers_preset_math_family_indeed\font_helpers_preset_math_family_indeed_normal

\appendtoks
    \enforced\let\font_helpers_preset_math_family_indeed\font_helpers_preset_math_family_indeed_compact
\to \everycompactfontmode

\let\font_helpers_reset_fontclass_math_families\gobbleoneargument

%D It would be nice if characters could be defined in a neutral way (say fam 255)
%D and be mapped to a real family during noad list construction. However, this
%D changes tex in critical places so for the moment we simulate this using
%D manipulation.
%D
%D For tracing purposes we use three families but in l2r mode 1 and 2 are copies of
%D 0 while in rl mode 0 is a copy of 1. There is no real overhead involved in this.
%D This also permits different font definitions for normal and mixed.

% moved to ini
%
% \lettonothing\m_font_class_direction
% \lettonothing\m_font_class_features
% \lettonothing\m_font_class_fallbacks
% \lettonothing\m_font_class_goodies
%
% \lettonothing\m_font_direction
% \lettonothing\m_font_features
% \lettonothing\m_font_fallbacks
% \lettonothing\m_font_goodies

\appendtoks
    \font_helpers_set_math_family\c_font_fam_mr\s!mr
\to \t_font_math_strategies

\def\font_helpers_complete_bold_mathstrategy_yes
  {\font_helpers_set_math_family_bold\c_font_fam_mb\s!mb\c_font_fam_mr\relax}

\def\font_helpers_complete_bold_mathstrategy_nop
  {\ifnum\fontid\textfont\c_font_fam_mb=\fontid\textfont\c_font_fam_mr\else
     \font_helpers_complete_bold_mathstrategy_nop_changed
   \fi}

\def\font_helpers_complete_bold_mathstrategy_nop_changed
  {\textfont        \c_font_fam_mb\textfont        \c_font_fam_mr
   \scriptfont      \c_font_fam_mb\scriptfont      \c_font_fam_mr
   \scriptscriptfont\c_font_fam_mb\scriptscriptfont\c_font_fam_mr}

\def\font_helpers_apply_complete_bold_mathstrategy
  {\ifconditional\c_font_complete_bold_mathstrategy
     \font_helpers_complete_bold_mathstrategy_yes
   \else
     \font_helpers_complete_bold_mathstrategy_nop
   \fi}

\appendtoks
    \font_helpers_apply_complete_bold_mathstrategy
\to \t_font_math_strategies

\ifdefined\defaultmathfamily \else
    \setnewconstant\defaultmathfamily\zerocount % no longer used, always zero
\fi

\appendtoks
    \fam\zerocount % all characters and symbols are in this family
\to \everymathematics

\protected\def\font_helpers_synchronize_math_family_mr
  {\c_attr_mathfamily\zerocount
  \font_helpers_synchronize_math_parameters_normal}

\protected\def\font_helpers_synchronize_math_family_mb
  {\c_attr_mathfamily\ifconditional\c_font_pseudo_bold_math_state\plussix\else\plusthree\fi
   \font_helpers_synchronize_math_parameters_bold}

\installcorenamespace{fontmathsynchronizer}
\installcorenamespace{fontmathstoredstrategy}

\letcsname\??fontmathsynchronizer\s!tf \endcsname\font_helpers_synchronize_math_family_mr
\letcsname\??fontmathsynchronizer\s!sl \endcsname\font_helpers_synchronize_math_family_mr
\letcsname\??fontmathsynchronizer\s!it \endcsname\font_helpers_synchronize_math_family_mr
\letcsname\??fontmathsynchronizer\s!bf \endcsname\font_helpers_synchronize_math_family_mb
\letcsname\??fontmathsynchronizer\s!bs \endcsname\font_helpers_synchronize_math_family_mb
\letcsname\??fontmathsynchronizer\s!bi \endcsname\font_helpers_synchronize_math_family_mb
\letcsname\??fontmathsynchronizer\empty\endcsname\font_helpers_synchronize_math_family_mr

\def\font_helpers_synchronize_math_family
  {\ifcsname\??fontmathsynchronizer\fontalternative\endcsname
     \lastnamedcs
   \else
     \font_helpers_synchronize_math_family_mr
   \fi}

\appendtoks
    \ifnum\fontid\textfont\zerocount=\fontid\textfont\plusthree
        \letcsname\??fontmathstoredstrategy\fontclass\endcsname\font_helpers_set_math_partial_bold_strategy
    \else
        \letcsname\??fontmathstoredstrategy\fontclass\endcsname\font_helpers_set_math_full_bold_strategy
    \fi
\to \t_font_math_strategies

\def\font_helpers_synchronize_math_bold_strategy{\begincsname\??fontmathstoredstrategy\fontclass\endcsname}

\newconditional\c_font_pseudo_bold_math_state

\def\font_helpers_set_math_partial_bold_strategy{\c_font_pseudo_bold_math_state\conditionaltrue}
\def\font_helpers_set_math_full_bold_strategy   {\c_font_pseudo_bold_math_state\conditionalfalse}

\appendtoks
    \font_helpers_synchronize_math_bold_strategy
\to \everymathematics

%D Bold is somewhat special as we might want both full-bold-math mixed regular-math,
%D as well as automatic adaption to outer bold (in titles and inline text bold) so
%D we will need explicit switches as well as an automatic one. (We will use lucida
%D as an example.)

\ifdefined\mathdefault \else \let\mathdefault\relax \fi

\newconditional\c_math_bold

\permanent\protected\def\mr % math regular
  {\ifmmode
     \font_helpers_synchronize_math_family_mr
   \else
     \font_helpers_set_current_font_alternative\s!mr
   \fi
   \mathdefault
   \c_math_bold\conditionalfalse}

\permanent\protected\def\mb % math bold
  {\ifmmode
     \font_helpers_synchronize_math_family_mb
   \else
     \font_helpers_set_current_font_alternative\s!mb
   \fi
   \mathdefault
   \c_math_bold\conditionaltrue}

\appendtoks
    \font_helpers_synchronize_math_family % auto bold
\to \everymathematics

\appendtoks
    \ifconditional\c_math_bold\mb\fi
\to \everymathematics

%D \macros
%D   {bigmath,nobigmath}
%D
%D We can inhibit this slow||downer with:

% these can best be combined

% 0=never 1=everymath 2=always

\setnewconstant\synchronizebigmathflag\plusone

\appendtoks
  \ifcase\synchronizebigmathflag
    % never
  \or
    \synchronizebigmath
  \or
    % always
  \fi
\to \everymathematics

\permanent\protected\def\nobigmath  {\synchronizebigmathflag\zerocount}
\permanent\protected\def\autobigmath{\synchronizebigmathflag\plusone\synchronizebigmath}
\permanent\protected\def\bigmath    {\synchronizebigmathflag\plustwo\synchronizebigmath}

\mutable\lettonothing\bigmathfontsize

\permanent\protected\def\synchronizebigmath
  {\ifx\bigmathfontsize\fontsize
     % already in sync
   \else
     \let\bigmathfontsize\fontsize
     \font_helpers_synchronize_math
   \fi}

\protected\def\font_helpers_check_big_math_synchronization
  {\ifcase\synchronizebigmathflag
     % never
   \or
     \ifmmode \synchronizebigmath \fi
   \or
     \synchronizebigmath
   \fi}

\appendtoks
    \enforced\lettonothing\synchronizebigmath
    \enforced\lettonothing\font_helpers_check_big_math_synchronization
\to \everycompactfontmode

%D This is an experiment!

% x$ x \beginmathgroup\scaledmathstyle600 x\endmathgroup x$x
% $ x{\setmscale{.5}x{\setmscale{.25}x}x}x$
% $ x{\setmscale{x}x{\setmscale{xx}x}x}x$
% $x \beginmathgroup\mxx x\endmathgroup x $
% $x \begingroup\mxx x\endgroup x $ % this one is like style, bleeds over group
% $x {\mxx x} x $

\installcorenamespace{mscaled}

\mutable\def\mathscalefactor{0.7} % 1/sqrt(2} = 0.70710678118655

\newinteger\c_math_m_scaled \c_math_m_scaled\plusthousand

\permanent\protected\def\setmscale#1%
  {\ifmmode
     \iftok{#1}{-}%
       \c_math_m_scaled{(\numericscale\mathscalefactor)*\c_math_m_scaled/\plusthousand}%
     \orelse\iftok{#1}{=}%
       \c_math_m_scaled\plusthousand
     \orelse\iftok{#1}{x}%
       \c_math_m_scaled{\plusthousand*\dimexpr\xtextface\relax/\dimexpr\textface\relax}%
     \orelse\iftok{#1}{xx}%
       \c_math_m_scaled{\plusthousand*\dimexpr\xxtextface\relax/\dimexpr\textface\relax}%
     \else
       \c_math_m_scaled\numericscale#1\relax
     \fi
     \scaledmathstyle
       \ifnum\glyphscale=\plusthousand
         \c_math_m_scaled
       \else
         {(\c_math_m_scaled*\glyphscale)/\plusthousand}%
       \fi
   \fi}

\permanent\protected\def\setmxscale {\ifmmode\scaledmathstyle{\glyphscale*\dimexpr\xtextface \relax/\dimexpr\textface\relax}\fi}
\permanent\protected\def\setmxxscale{\ifmmode\scaledmathstyle{\glyphscale*\dimexpr\xxtextface\relax/\dimexpr\textface\relax}\fi}

\permanent\protected\def\mx
  {\enforced\let\mx\mxx
   \setmxscale}

\permanent\protected\def\mxx
  {\enforced\let\mx\relax
   \enforced\let\mxx\relax
   \setmxxscale}

%D This is nasty, as the engine only stores the last set family parameters (per style) which
%D in our case can be bold.

\def\font_helpers_synchronize_math_parameters_normal
  {\c_math_last_family_used\mathstylefontid\textstyle\zerocount
   \textfont        \c_font_fam_mr\textfont        \c_font_fam_mr
   \scriptfont      \c_font_fam_mr\scriptfont      \c_font_fam_mr
   \scriptscriptfont\c_font_fam_mr\scriptscriptfont\c_font_fam_mr}

\def\font_helpers_synchronize_math_parameters_bold
  {\c_math_last_family_used\mathstylefontid\textstyle\zerocount
   \textfont        \c_attr_mathfamily\textfont        \c_attr_mathfamily
   \scriptfont      \c_attr_mathfamily\scriptfont      \c_attr_mathfamily
   \scriptscriptfont\c_attr_mathfamily\scriptscriptfont\c_attr_mathfamily}

\appendtoks
    \ifnum\c_math_last_family_used=\mathstylefontid\textstyle\zerocount\else
      \font_helpers_synchronize_math_parameters_normal
    \fi
\to\everybodyfont

%D Something new, see type {type-imp-antykwa} for an example:

% if we get more:

% \installcorenamespace {fractionbar}
% \installcorenamespace {radicalbar}

% \def\installfractionbar#1#2{\defcsname\??fractionbar#1\endcsname{#2}}
% \def\installradicalbar #1#2{\defcsname\??radicalbar #1\endcsname{#2}}

% \def\fractionbarunicode{\ifcsname\??fractionbar\fontclass\endcsname\lastnamedcs\else\zerocount\fi}
% \def\radicalbarunicode {\ifcsname\??radicalbar \fontclass\endcsname\lastnamedcs\else\zerocount\fi}

\mutable\lettonothing\currentmathfontclass

\def\math_synchronize_setup
  {\let\currentmathfontclass\fontclass
   \fastsetup{\s!math:\fontclass}}

\appendtoks
    \ifx\fontclass\currentmathfontclass\else
        \math_synchronize_setup
    \fi
\to \everymathematics

\protect \endinput