%%^^A%%  fontspec-code-graphite.dtx -- part of FONTSPEC <latex3.github.io/fontspec>

% \section{Graphite/AAT code}
%
% \iffalse
%    \begin{macrocode}
%<*fontspec&XE>
%    \end{macrocode}
% \fi
%


% \begin{macro}{\@@_define_aat_feature_group:n}
%    \begin{macrocode}
\cs_new:Nn \@@_define_aat_feature_group:n
  {
    \keys_define:nn {fontspec-aat} { #1 .multichoice: }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_define_aat_feature:nnnn}
%    \begin{macrocode}
\cs_new:Nn \@@_define_aat_feature:nnnn
  {
    \keys_define:nn {fontspec-aat}
      {
        #1/#2 .code:n = { \@@_make_AAT_feature:nn {#3}{#4} }
      }
  }
%    \end{macrocode}
% \end{macro}

% \begin{macro}{\@@_make_AAT_feature:nn}
%    \begin{macrocode}
\cs_new:Nn \@@_make_AAT_feature:nn
  {
    \tl_if_empty:nTF {#1}
      { \@@_warning:n {aat-feature-not-exist} }
      {
        \exp_args:No \@@_make_AAT_feature_string:NnnTF \l_@@_fontface_cs_tl {#1} {#2}
          {
            \@@_update_featstr:n {\l_fontspec_feature_string_tl}
          }
          {
            \@@_warning:nx {aat-feature-not-exist-in-font} {#1,#2}
          }
      }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_make_AAT_feature_string:NnnTF}
%   This macro takes the numerical codes for a font feature and
%   creates a specified macro containing the string required in the
%   font definition to turn that feature on or off. Used primarily in
%   [...], but also used to check if small caps
%   exists in the requested font (see page~\pageref{mac:makesmallcaps}).
%
% For exclusive selectors, it's easy; just grab the string:
% For \emph{non}-exclusive selectors, it's a little more complex.
% If the selector is even, it corresponds to switching the feature on.
% If the selector is \emph{odd}, it corresponds to switching the feature off.
% But \XeTeX\ doesn't return a selector string for this number, since the
% feature is defined for the `switching on' value. So we need to check the
% selector of the previous number, and then prefix the feature string with |!|
% to denote the switch.
%
% Finally, save out the complete feature string in \cmd\l_fontspec_feature_string_tl.
%    \begin{macrocode}
\prg_new_conditional:Nnn \@@_make_AAT_feature_string:Nnn {TF,T,F}
  {
    \tl_set:Nx \l_@@_tmpa_tl { \XeTeXfeaturename #1 #2 }
    \tl_if_empty:NTF \l_@@_tmpa_tl
      { \prg_return_false: }
      {
        \int_compare:nTF { \XeTeXisexclusivefeature #1 #2 > 0 }
          {
            \tl_set:Nx \l_@@_tmpb_tl {\XeTeXselectorname #1 #2\space #3}
          }
          {
            \int_if_even:nTF {#3}
              {
                \tl_set:Nx \l_@@_tmpb_tl {\XeTeXselectorname #1 #2\space #3}
              }
              {
                \tl_set:Nx \l_@@_tmpb_tl
                  {
                    \XeTeXselectorname #1 #2\space \numexpr#3-1\relax
                  }
                \tl_if_empty:NF \l_@@_tmpb_tl { \tl_put_left:Nn \l_@@_tmpb_tl {!} }
              }
          }

        \tl_if_empty:NTF \l_@@_tmpb_tl
          { \prg_return_false: }
          {
            \tl_set:Nx \l_fontspec_feature_string_tl { \l_@@_tmpa_tl = \l_@@_tmpb_tl }
            \prg_return_true:
          }
     }
  }
%    \end{macrocode}
% \end{macro}
%
% \iffalse
%    \begin{macrocode}
%</fontspec&XE>
%    \end{macrocode}
% \fi


\endinput

% /©
% ------------------------------------------------
% The FONTSPEC package  <latex3.github.io/fontspec>
% ------------------------------------------------
% Copyright  2022-2024  The LaTeX project,  LPPL "maintainer"
% Copyright  2004-2022  Will Robertson
% Copyright  2009-2015  Khaled Hosny
% Copyright  2013       Philipp Gesang
% Copyright  2013-2016  Joseph Wright
% ------------------------------------------------
% This package is free software and may be redistributed and/or modified under
% the conditions of the LaTeX Project Public License, version 1.3c or higher
% (your choice): <http://www.latex-project.org/lppl/>.
% ------------------------------------------------
% ©/
