From e526edff1f4884090f58dfaf692bd9a4a6c177d1 Mon Sep 17 00:00:00 2001
From: Karl Berry <karl@freefriends.org>
Date: Thu, 1 Feb 2018 23:06:27 +0000
Subject: unicode-math (1feb18)

git-svn-id: svn://tug.org/texlive/trunk@46515 c570f23f-e606-0410-a88d-b1316a301751
---
 .../latex/unicode-math/um-code-sym-commands.dtx    | 89 ++--------------------
 1 file changed, 5 insertions(+), 84 deletions(-)

(limited to 'Master/texmf-dist/source/latex/unicode-math/um-code-sym-commands.dtx')

diff --git a/Master/texmf-dist/source/latex/unicode-math/um-code-sym-commands.dtx b/Master/texmf-dist/source/latex/unicode-math/um-code-sym-commands.dtx
index cd7263ecf9e..9b1d67a3061 100644
--- a/Master/texmf-dist/source/latex/unicode-math/um-code-sym-commands.dtx
+++ b/Master/texmf-dist/source/latex/unicode-math/um-code-sym-commands.dtx
@@ -8,83 +8,6 @@
 %<*package>
 %    \end{macrocode}
 %
-% Switching to a different style of alphabetic symbols was traditionally performed with
-% commands like \cmd\mathbf, which literally changes fonts to access alternate symbols.
-% This is not as simple with Unicode fonts.
-%
-% In traditional \TeX{} maths font setups, you simply switch between different `families' (\cmd\fam), which is analogous to changing from one font to another---a symbol such as `a' will be upright in one font, bold in another, and so on.
-% In pkg{unicode-math}, a different mechanism is used to switch between styles. For every letter (start with ascii a-zA-Z and numbers to keep things simple for now), they are assigned a `mathcode' with \cmd\Umathcode\ that maps from input letter to output font glyph slot. This is done with the equivalent of
-% \begin{Verbatim}
-% \Umathcode`\a = 7 1 "1D44E\relax
-% \Umathcode`\b = 7 1 "1D44F\relax
-% \Umathcode`\c = 7 1 "1D450\relax
-% ...
-% \end{Verbatim}
-% When switching from regular letters to, say, \cmd\mathrm, we now need to execute a new mapping:
-% \begin{Verbatim}
-% \Umathcode`\a = 7 1 `\a\relax
-% \Umathcode`\b = 7 1 `\b\relax
-% \Umathcode`\c = 7 1 `\c\relax
-% ...
-% \end{Verbatim}
-% This is fairly straightforward to perform when we're defining our own commands such as \cmd\symbf\ and so on. However, this means that `classical' \TeX\ font setups will break, because with the original mapping still in place, the engine will be attempting to insert unicode maths glyphs from a standard font.
-%
-% \subsection{Hooks into \LaTeXe}
-%
-% To overcome this, we patch \cs{use@mathgroup}.
-% (An alternative is to patch \cs{extract@alph@from@version}, which constructs the \cs{mathXYZ} commands, but this method fails if the command has been defined using \cs{DeclareSymbolFontAlphabet}.)
-% As far as I can tell, this is only used inside of commands such as \cs{mathXYZ}, so this shouldn't have any major side-effects.
-%
-%    \begin{macrocode}
-\cs_set:Npn \use@mathgroup #1 #2
-  {
-    \mode_if_math:T % <- not sure if this is really necessary since we've just checked for mmode and raised an error if not!
-      {
-        \math@bgroup
-          \cs_if_eq:cNF {M@\f@encoding} #1 {#1}
-          \@@_switchto_literal:
-          \mathgroup #2 \relax
-        \math@egroup
-      }
-  }
-%    \end{macrocode}
-%
-% In LaTeX maths, the command |\operator@font| is defined that switches to the |operator| mathgroup. The classic example is the |\sin| in |$\sin{x}$|; essentially we’re using |\mathrm| to typeset the upright symbols, but the syntax is |{\operator@font sin}|.
-% I thought that hooking into |\operator@font| would be hard because all other maths font selection in 2e uses |\mathrm{...}| style.
-% Then reading source2e a little more I stumbled upon \cs{@fontswitch}.
-% Reimplement that here to avoid \cs{bgroup}/\cs{egroup}.
-% \begin{macro}{\operator@font}
-%    \begin{macrocode}
-\cs_set:Npn \operator@font
-  {
-    \@@_switchto_literal:
-    \@@_fontswitch:n { \g_@@_operator_mathfont_tl }
-  }
-%    \end{macrocode}
-% \end{macro}
-%
-% \begin{macro}{\@@_fontswitch:n}
-%    \begin{macrocode}
-\cs_set:Nn \@@_fontswitch:n
-  {
-    \mode_if_math:T
-      {
-        \cs_set_eq:NN \math@bgroup     \scan_stop:
-        \cs_set_eq:NN \@@_group_begin: \scan_stop:
-        \cs_set:Npn \@@_group_end:
-          {
-            \cs_set_eq:NN \@@_group_begin: \@@_group_begin_frozen:
-            \cs_set_eq:NN \@@_group_end:   \@@_group_end_frozen:
-            \cs_set_eq:NN \math@bgroup \@@math@bgroup
-            \cs_set_eq:NN \math@egroup \@@math@egroup
-          }
-        \cs_set_eq:NN \math@egroup \@@_group_end:
-        #1 \scan_stop:
-      }
-  }
-%    \end{macrocode}
-% \end{macro}
-%
 %
 % \subsection{Setting styles}
 %
@@ -134,19 +57,17 @@
   {
     \seq_gput_right:Nn \g_@@_mathstyles_seq {#1}
     \@@_init_alphabet:n {#1}
-    \cs_set_protected:cpx {sym#1} ##1
+    \cs_set_protected:cpx {sym#1}
       {
         \@@_group_begin:
           \exp_not:n
             {
-              \mode_if_math:F
-                {
-                  \exp_args:Nc \non@alpherr {sym#1}
-                }
+              \mode_if_math:F { \exp_args:Nc \non@alpherr {sym#1} }
               \tl_set:Nn \l_@@_mathstyle_tl {#1}
             }
-          \exp_not:c {@@_switchto_#1:} ##1
-        \@@_group_end:
+          \exp_not:c {@@_switchto_#1:}
+          \@@_mathgroup_set:n {-1}
+        \@@_group_end:n
       }
   }
 %    \end{macrocode}
-- 
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