%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Copyright © 2022 Maximilian Keßler
% 
% This work may be distributed and/or modified
% 
% 1. under the LaTeX Project Public License and/or
% 2. under the GNU General Public License
% 
% Distribution under conditions of the LaTeX Project Public License,
% requires either version 1.3 of this license or (at your option)
% any later version.
% The latest version of this license is in
%    http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
% 
% This work has the LPPL maintenance status \`maintained'.
% 
% The Current Maintainer of this work is Maximilian Keßler.
% 
% 
% Distribution under the GNU General Public License requires either
% version 3 or (at your opinion) any later version.
% 
% This package has been generated by PyTeX, available at
%    https://github.com/kesslermaximilian/PyTeX
% and built from source file 'powerset.pysty3'.
% It is STRONGLY DISCOURAGED to edit this source file directly, since local
% changes will not be versioned by Git and overwritten by the next build. Always
% edit the source file and build the package again.
% 
% Build details:
%   PyTeX version: v1.2.0-28-ge661cee (commit e661cee)
%   Source code version: v2.8 (commit 1d48178)
% 
% This LaTeX package is free software and is dual-licensed
% under the LPPLv1.3c and the GPLv3 licenses.
% You may use it freely for your purposes.
% The latest version of the package sources can be obtained
% via GitLab under
%    https://gitlab.com/latexci/packages/LatexPackages
% The latest version of the built packages can be obtained via GitLab under
%    https://gitlab.com/latexci/packages/LatexPackagesBuild
% For further information see the urls above.
% Reportings of bugs, suggestions and improvements are welcome, see the README
% at the Git repository for further information.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\ProvidesExplPackage{mkessler-powerset}{2022/01/24}{2.8}{Iterate over powerset of clist}



\ExplSyntaxOn

%%% Iterate over powerset of claist

\clist_new:N  \l_powerset_copied_clist
\seq_new:N    \l_powerset_saved_seq



\cs_generate_variant:Nn \clist_remove_all:Nn { N V }

% Pseudocode of this macro
% remove left  -> push on stack
% call recursive
% add left to 'extra'
% call recursive
% remove left from 'extra'
% add from stack to left

\cs_new:Npn \__powerset_clist_foreach_aux:Nn #1 #2 
{
  \clist_if_empty:NTF \l_powerset_copied_clist
    {
      #2
    }
    {
      \clist_get:NN \l_powerset_copied_clist \l_tmpa_tl
      \seq_push:NV  \l_powerset_saved_seq \l_tmpa_tl
      \clist_pop:NN \l_powerset_copied_clist { \l_tmpa_tl }

      \__powerset_clist_foreach_aux:Nn #1 {#2}
      
      \seq_get:NN \l_powerset_saved_seq \l_tmpa_tl
      \clist_put_left:NV #1 \l_tmpa_tl

      \__powerset_clist_foreach_aux:Nn #1 {#2}

      \seq_get:NN \l_powerset_saved_seq \l_tmpa_tl
      \clist_remove_all:NV #1 \l_tmpa_tl
      \clist_push:NV \l_powerset_copied_clist \l_tmpa_tl
      \seq_pop:NN \l_powerset_saved_seq \l_tmpa_tl
    }
}


% Usage:
% \clist_use_powerset:Nn {clist variable name}{code for each subset}
% This will execute #2 for each subset of the listname given as #1
% In #2, the name given as #1 can be used for the current subset
% After execution, the value of #1 is restored
\cs_new:Npn \powerset_clist_foreach:Nn #1 #2
{
  \clist_set_eq:NN \l_powerset_copied_clist #1
  \clist_clear:N #1
  \clist_remove_duplicates:N \l_powerset_copied_clist

  \__powerset_clist_foreach_aux:Nn #1 {#2}

  \clist_set_eq:NN #1 \l_powerset_copied_clist
}