%%
%% This is file `pbalance.sty',
%% generated with the docstrip utility.
%%
%% The original source files were:
%%
%% pbalance.dtx  (with options: `package')
%% Copyright 2020-2022 Nelson Lago <lago@ime.usp.br>
%% 
%% This work may be distributed and/or modified under the conditions of the
%% LaTeX Project Public License, either version 1.3c of this license or (at
%% your option) any later version. The latest version of this license can be
%% found at 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 Nelson Lago <lago@ime.usp.br>.
%% 
\NeedsTeXFormat{LaTeX2e}[2015/01/01]
\ProvidesPackage{pbalance}[2022/07/28 v1.4.0 Poor man's balance]

\RequirePackage{etoolbox}
\RequirePackage{expl3}
\RequirePackage{atbegshi} % Manipulate the page output routine
\RequirePackage{atveryend} % Write to the aux file after processing ends
\RequirePackage{zref-abspage} % Figure out the current page
\RequirePackage{filehook} % Patch other packages that modify the output routine

\newtoggle{@PBpatchFailed}

\providetoggle{@PBstabilized}
\providetoggle{@PBimpossible}

\newtoggle{@PBnoBalancePackage}
\DeclareOption{safe}{\toggletrue{@PBnoBalancePackage}}

\newtoggle{@PBdraft}
\DeclareOption{draft}{\toggletrue{@PBdraft}}

\ProcessOptions\relax

\AtEndPreamble{\@ifpackageloaded{lineno}{\toggletrue{@PBnoBalancePackage}}{}}

\@ifpackageloaded{lineno}{\toggletrue{@PBnoBalancePackage}}{}

\AtEndOfPackage{
    \ifboolexpr{togl {@PBdraft} or togl {@PBnoBalancePackage}}
      {}
      {\RequirePackage{balance}}
}

\gdef \@reinserts{%
  \ifvbox\@kludgeins\insert\@kludgeins
                      {\unvbox\@kludgeins}\fi
  \ifvoid\footins\else\insert\footins{\unvbox\footins}\fi
}



\AtBeginDocument{
  \@PBifShouldBalanceNascentPage
    {\@PBStartBalancing}
    {}
}

\AtBeginShipout{
  \@PBifShouldBalanceNascentPage
    {\@PBStartBalancing}
    {}
}

\newcommand\@PBifShouldBalanceNascentPage[2]{
  \ifboolexpr
    {
      togl {@PBdraft}
      or not togl {@PBstabilized}
      or test {\ifdefvoid{\@PBprevLastPage}}
    }
    {#2}
    {
      % abspage refers to the finished page, not the nascent page
      \ifnumcomp{\@PBprevLastPage - 1}{=}{\value{abspage}}
        {#1}
        {#2}
    }
}

\newcommand\shrinkLastPage[1]{\dimgdef\@PBslack{#1}}
\newcommand\balancePageNum[1]{\gdef\@PBthepage{#1}}
\newcommand\nopbalance{\toggletrue{@PBdraft}}

\newcommand\@PBStartBalancing{
  \ifdefvoid{\@PBslack}
    {\@PBautomaticBalance}
    {
      \PackageInfo{pbalance}{Automatic mode disabled, doing manual adjustment}
      \@PBshrinkPage
    }
}

\newcommand\@PBautomaticBalance{
  \@PBifBalancePossible
    {
      \@PBifBalancePkgPossible
        {\balance} % easy peasy, use the balance package
        {
          \@PBifPoorBalancePossible
            {
              % use the poor man's balance algorithm
              \@PBcalculateShrinkage
              \@PBshrinkPage
            }
            {\PackageInfo{pbalance}{Page "naturally" balanced, doing nothing}}
        }
    }
    {\PackageInfo{pbalance}{Float-only column at last page, doing nothing}}
}

\newcommand\@PBcalculateShrinkage{

  % Let's use some shorter names, please
  \dimdef\@PBtmpH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}Height}}
  \dimdef\@PBtmpUL{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}UsedLeft}}
  \dimdef\@PBtmpUR{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}UsedRight}}

  \dimdef\@PBtmpLH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}LeftHeight}}
  \dimdef\@PBtmpLFH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}LeftFloatsHeight}}
  \dimdef\@PBtmpRH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}RightHeight}}
  \dimdef\@PBtmpRFH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}RightFloatsHeight}}

  % Figure out the amount of unused space on the last page (both
  % cols); we will reduce the first column height by half that amount
  \dimgdef\@PBslack{\@PBtmpH *2 - \@PBtmpUL - \@PBtmpUR}
  \dimgdef\@PBslack{\@PBslack /2}

  % Actually, I lied. While half, as said above, sometimes yields
  % perfectly balanced columns, that is often not the case (the page
  % may have an odd number of lines, or textheight may not be a
  % multiple of baselineskip, or there may be glues etc.). Sometimes
  % the difference is very small, less than a line, which does not
  % look good at all, and sometimes the right column is slightly
  % higher than the left, which is also not ideal. Here, we force
  % the left column to always be somewhat taller than the left; the
  % result is often ``better''.
  \dimgdef\@PBslack{\@PBslack - 1.5\baselineskip}

  % If necessary, reduce @PBslack to prevent LaTeX from adding a page
  \@PBsafetyCheck
}

\def\@PBshrinkPage{
  % Zero obviously means ``do nothing''. We could
  % ``enlarge'' by 0, but IDK, maybe that would
  % trigger another LaTeX pass or something.
  \ifdimcomp{\@PBslack}{=}{0pt}
    {}
    {
      % Shrink the first column
      \enlargethispage{-\@PBslack}

      % Modify the behavior of \@outputdblcol
      % to raise footnotes in the second column.
      \global\let\@PBbalanceSecondColumn\@PBrealBalanceSecondColumn
    }
}

\pretocmd{\@outputdblcol}{\@PBbalanceSecondColumn}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@outputdblcol)}
         }

\let\@PBbalanceSecondColumn\relax

\def\@PBrealBalanceSecondColumn{
    \if@firstcolumn
      % Affects the next column
      \global\let\@PBorigtextbottom\@textbottom
      \gdef\@textbottom{\vskip \@PBslack plus .0001fil minus 10000fill\relax \@PBorigtextbottom}
    \else
      % Back to normal before starting the next page
      \global\let\@textbottom\@PBorigtextbottom
      \global\let\@PBbalanceSecondColumn\relax
    \fi
}



\newcommand\@PBifmidfloat[2]{\ifx\@midlist\empty #2\else #1\fi}
\newcommand\@PBiftopfloat[2]{\ifx\@toplist\empty #2\else #1\fi}
\newcommand\@PBifbotfloat[2]{\ifx\@botlist\empty #2\else #1\fi}
\newcommand\@PBiffootnote[2]{\ifvoid\footins #2\else #1\fi}
\newcommand\@PBiffloatcol[2]{\if@fcolmade #1\else #2\fi}
\newcommand\@PBifdbltopfloat[2]{\ifx\@dbltoplist\empty #2\else #1\fi}
\newcommand\@PBifdblbotfloat[2]{%
  \ifdefvoid{\@dblbotlist}
    {#2}
    {\ifx\@dblbotlist\empty #2\else #1\fi}%
}

\newtoggle{@PBtmpHasFootnotes}
\newtoggle{@PBtmpHasFloats}
\newtoggle{@PBtmpHasMarginpars}

\def\@PBcollectPageInfo{
  \ifboolexpr
    {
      test {\@PBifmidfloat} or test {\@PBiftopfloat} or
      test {\@PBifbotfloat} or test {\@PBifdblbotfloat} or
      test {\@PBifdbltopfloat}
    }
    {\global\toggletrue{@PBtmpHasFloats}}
    {}

  \@PBiffootnote
    {\global\toggletrue{@PBtmpHasFootnotes}}
    {}
}

\pretocmd{\@makecol}{\@PBcollectPageInfo}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@makecol)}
         }

\pretocmd{\@addmarginpar}{\global\toggletrue{@PBtmpHasMarginpars}}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@addmarginpar)}
         }


\ExplSyntaxOn
\seq_gclear_new:N \@PBtmpLeftFloatHeights
\seq_gclear_new:N \@PBtmpLeftFloatSpacesBelow
\def\@PBcollectFloatHeights{
  \if@firstcolumn
    \dimdef\@PBfloatHeight{\@textfloatsheight - \@PBtmpHeightBefore}
    \ifdimcomp{\@PBfloatHeight}{>}{0pt}
      {
        \global\seq_put_right:NV \@PBtmpLeftFloatHeights \@PBfloatHeight

        \dimdef\@PBspaceBelow{\@colroom - \@pageht - \@PBfloatHeight}
        % within \@addtocurcol, \@pageht corresponds to all
        % currently used space in the column, including footnotes
        % (check \@specialoutput in the LaTeX kernel). Let's
        % exclude the footnotes, we only want the space below
        % the float.
        \ifvoid\footins\else
          \dimdef\@PBspaceBelow{\@PBspaceBelow + \ht\footins + \skip\footins + \dp\footins}
        \fi

        % No idea why, but this can happen; maybe because of the page depth?
        \ifdimcomp{\@PBspaceBelow}{<}{0pt}
          {\dimdef\@PBspaceBelow{0pt}}
          {}

        \global\seq_put_right:NV \@PBtmpLeftFloatSpacesBelow \@PBspaceBelow
      }
      {}
  \fi
}
\ExplSyntaxOff

\pretocmd{\@addtocurcol}{\dimgdef{\@PBtmpHeightBefore}{\@textfloatsheight}}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@addtocurcol)}
         }

\apptocmd{\@addtocurcol}{\@PBcollectFloatHeights}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@addtocurcol)}
         }


\newtoggle{@PBtmpHasFloatcol}
\newtoggle{@PBtmpFloatcolBoth}

\newcommand\@PBcollectColumnUsedHeight{
    \setbox\@tempboxa=\vbox{\unvcopy\@outputbox\unskip\unskip}
    \dimgdef\@PBtmpColumnUsedHeight{\ht\@tempboxa\relax}
}

\apptocmd{\@makecol}{\@PBcollectColumnUsedHeight}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@makecol)}
         }

 % Let's make sure our patched code actually runs. We only switch this
 % to true after we verify that the patches in @makecol and @outputdblcol
 % are actually executed when the page is built (therefore, after the
 % preamble has ended).
\newtoggle{@PBpatchStillActive}

\newcommand\@PBcollectColumnInfo{
  \iftoggle{@PBpatchFailed}
    {}
    {
      \ifdefvoid{\@PBtmpColumnUsedHeight}
        {} % the patch to @makecol is not active, so we do nothing here
        {
          % the patch to @makecol is active and so is ours, we're good to go!
          \global\toggletrue{@PBpatchStillActive}
          \@PBreallyCollectColumnInfo
        }
    }
}

\newcommand\@PBreallyCollectColumnInfo{
  \if@firstcolumn

    \@PBiffloatcol
      {\global\toggletrue{@PBtmpHasFloatcol}}
      {}

    % Available vertical space excluding
    % dblfloats; the same for both columns
    \dimgdef\@PBtmpHeight{\@colht}

    % Available vertical space excluding top/bottom floats
    \dimgdef\@PBtmpLeftHeight{\@colroom}

    % Space used by \texttt{here} floats
    \dimgdef\@PBtmpLeftFloatsHeight{\@textfloatsheight}
    \dimgdef\@PBtmpUsedLeft{\@PBtmpColumnUsedHeight}

  \else

    \@PBiffloatcol
      {
        \iftoggle{@PBtmpHasFloatcol}
          {\global\toggletrue{@PBtmpFloatcolBoth}}
          {\global\toggletrue{@PBtmpHasFloatcol}}
      }
      {}

    \dimgdef\@PBtmpRightHeight{\@colroom}
    \dimgdef\@PBtmpRightFloatsHeight{\@textfloatsheight}
    \dimgdef\@PBtmpUsedRight{\@PBtmpColumnUsedHeight}
  \fi
}

\pretocmd{\@outputdblcol}{\@PBcollectColumnInfo}
         {}
         {
           \toggletrue{@PBpatchFailed}
           \PackageWarningNoLine{pbalance}{Patch failed (@outputdblcol)}
         }

\ifboolexpr{togl {@PBdraft} or togl {@PBnoBalancePackage}}
  {}
  {
    \AtEndOfPackage{
      \pretocmd{\@BAdblcol}{\@PBcollectColumnInfo}
               {}
               {
                 \toggletrue{@PBpatchFailed}
                 \PackageWarningNoLine{pbalance}{Patch failed (@BAdblcol)}
               }
      % Revert \balance before next page if it exists (it might be a float page)
      \patchcmd{\@BAdblcol}{\endgroup}{\endgroup\nobalance}
               {}
               {
                 \toggletrue{@PBpatchFailed}
                 \PackageWarningNoLine{pbalance}{Patch failed (@BAdblcol)}
               }
    }
  }


\AtEndOfPackageFile{stfloats}
  {

    \pretocmd{\@addtocurcol}{\dimgdef{\@PBtmpHeightBefore}{\@textfloatsheight}}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (stfloats/@addtocurcol)}
             }

    \apptocmd{\@addtocurcol}{\@PBcollectFloatHeights}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (stfloats/@addtocurcol)}
             }
  }

\AtEndOfPackageFile*{stfloats}
  {
    \pretocmd{\fn@makecol}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (stfloats/fn@makecol)}
             }
    \pretocmd{\org@makecol}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (stfloats/org@makecol)}
             }
    \apptocmd{\fn@makecol}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (stfloats/fn@makecol)}
             }
    \apptocmd{\org@makecol}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (stfloats/org@makecol)}
             }
  }



\ifdefvoid{\mem@makecol}
  {}
  {
    \pretocmd{\mem@makecol}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (memoir/mem@makecol)}
             }
    \apptocmd{\mem@makecol}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (memoir/mem@makecol)}
             }
    \pretocmd{\mem@makecolbf}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (memoir/mem@makecolbf)}
             }
    \apptocmd{\mem@makecolbf}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (memoir/mem@makecolbf)}
             }
  }


\AtEndOfPackageFile{footmisc}
  {
    \pretocmd{\@makecol}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (footmisc/@makecol)}
             }
    \apptocmd{\@makecol}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (footmisc/@makecol)}
             }
  }



\AtEndOfPackageFile{ftnright}
  {
    \pretocmd{\@makecol}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (ftnright/@makecol)}
             }
    \apptocmd{\@makecol}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (ftnright/@makecol)}
             }

    \pretocmd{\@outputdblcol}{\@PBbalanceSecondColumn}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (ftnright/@outputdblcol)}
             }

    \pretocmd{\@outputdblcol}{\@PBcollectColumnInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (ftnright/@outputdblcol)}
             }
  }





\AtEndOfPackageFile{flafter}
  {

    \pretocmd{\@addtocurcol}{\dimgdef{\@PBtmpHeightBefore}{\@textfloatsheight}}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (flafter/@addtocurcol)}
             }

    \apptocmd{\@addtocurcol}{\@PBcollectFloatHeights}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (flafter/@addtocurcol)}
             }
  }



\AtEndOfPackageFile{fnpos}
  {
    \pretocmd{\@makecol}{\@PBcollectPageInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (fnpos/@makecol)}
             }
    \apptocmd{\@makecol}{\@PBcollectColumnUsedHeight}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (fnpos/@makecol)}
             }
  }



\AtEndOfPackageFile{cuted}
  {
    \pretocmd{\@outputdblcol}{\@PBbalanceSecondColumn}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (cuted/@outputdblcol)}
             }

    \pretocmd{\@outputdblcol}{\@PBcollectColumnInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (cuted/@outputdblcol)}
             }
  }

\AtEndOfPackageFile{midfloat}
  {
    \pretocmd{\@outputdblcol}{\@PBbalanceSecondColumn}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (midfloat/@outputdblcol)}
             }

    \pretocmd{\@outputdblcol}{\@PBcollectColumnInfo}
             {}
             {
               \toggletrue{@PBpatchFailed}
               \PackageWarningNoLine{pbalance}{Patch failed (midfloat/@outputdblcol)}
             }
  }


\ExplSyntaxOn
\AtBeginShipout{
  \iftoggle{@PBpatchFailed}
    {}
    {
      % It only makes sense to consider pages that actually have two columns.
      \if@twocolumn
        \iftoggle{@PBpatchStillActive}
          {\@PBfinalizePageData}
          {
            \global\toggletrue{@PBpatchFailed}
            \PackageWarningNoLine{pbalance}{Patch~disabled~by~another~package}
          }
      \fi

      % Reset before processing next page
      \global\togglefalse{@PBtmpHasFloats}
      \global\togglefalse{@PBtmpHasFloatcol}
      \global\togglefalse{@PBtmpHasFootnotes}
      \global\togglefalse{@PBtmpHasMarginpars}
      \global\togglefalse{@PBtmpFloatcolBoth}

      \seq_gclear_new:N \@PBtmpLeftFloatHeights
      \seq_gclear_new:N \@PBtmpLeftFloatSpacesBelow

      \gundef{\@PBtmpHeight}
      \gundef{\@PBtmpLeftHeight}
      \gundef{\@PBtmpLeftFloatsHeight}
      \gundef{\@PBtmpUsedLeft}
      \gundef{\@PBtmpRightHeight}
      \gundef{\@PBtmpRightFloatsHeight}
      \gundef{\@PBtmpUsedRight}
    }
}
\ExplSyntaxOff

\newcommand\@PBfinalizePageData{
  % LaTeX3 does not do short-circuit evaluation,
  % so we cannot use a single ifboolexpr here
  \ifdefvoid{\@PBtmpUsedRight}
    % This is probably a float page or the user disabled
    % the package somehow and recompiled. Either way,
    % this is not the last text page, ignore
    {}
    {
      \ifboolexpr
        {
          % If both cols are float cols, this is not the last text page, ignore
          togl {@PBtmpFloatcolBoth}
          or
          % A page with a float column on the left and an empty
          % column on the right is not the last text page, ignore
          (
            togl {@PBtmpHasFloatcol}
            and
            test {\ifdimcomp{\@PBtmpUsedRight}{=}{\topskip}}
          )
        }
        {}
        {
          \ifdefvoid{\@PBthepage}
            {
              % The user did not choose a page, so this page is
              % a candidate to be the last two-column text page
              \xdef\@PBlastPage{\the\value{abspage}}
              \@PBcopyPageData{tmp}{candidate}
            }
            {
              \ifnumcomp{\@PBthepage}{=}{\the\value{abspage}}
                {
                  % This is the page the user indicated
                  % as the last two-column text page
                  \xdef\@PBlastPage{\the\value{abspage}}
                  \@PBcopyPageData{tmp}{candidate}
                }
                {}
            }
        }
    }
}


\AfterLastShipout{
  % If there are no two-column pages in the
  % document, there is no candidate page.
  \ifcsdef{@PBlastPage}
    {\@PBcopyPageData{candidate}{pg\@Roman{\@PBlastPage}}}
    {\PackageInfo{pbalance}{No two-column pages, doing nothing}}
}


\AfterLastShipout{
  % Reset \@PBimpossible if we are in draft mode,
  % so the user can start over if they want to.
  \iftoggle{@PBdraft}{\togglefalse{@PBimpossible}}{}

  \ifboolexpr{togl {@PBdraft} or togl {@PBimpossible} or togl {@PBpatchFailed}}
    {
      \iftoggle{@PBimpossible}
        {\PackageWarningNoLine{pbalance}{Could not balance, doing nothing}}
        {
          \iftoggle{@PBpatchFailed}
            {
              \PackageWarningNoLine{pbalance}{Patching failed, cannot balance;
                                              try \MessageBreak loading
                                              pbalance earlier or later}
            }
            {\PackageInfo{pbalance}{Draft mode, doing nothing}}
        }
    }
    {
      \ifdefvoid{\@PBprevLastPage}
        {\@PBsaveUnbalancedInfo\@PBnotifyRerun} % First pass
        {
          \iftoggle{@PBstabilized}
            {\@PBmanageBalancingPasses}
            {
              \@PBifSomethingChanged[unbal]
                % Document still changing; discard data from previous pass
                {\@PBsaveUnbalancedInfo[update]\@PBnotifyRerun}
                % No changes, so let's balance from now on (once @PBstabilized
                % becomes true, it never reverts back to false, unless the aux
                % file is deleted).
                {\toggletrue{@PBstabilized}\@PBsaveUnbalancedInfo\@PBnotifyRerun}
            }
        }
      \@PBsaveToggle{@PBstabilized}
    }

  \@PBsaveToggle{@PBimpossible}
  \immediate\write\@mainaux{\gdef\string\@PBprevLastPhysPage{\the\value{abspage}}}
}

\newcommand\@PBmanageBalancingPasses{
  % This is the second pass or later after we started balancing

  \providetoggle{@PBpg\@Roman{\@PBlastPage}alreadyBalanced}

  \iftoggle{@PBpg\@Roman{\@PBlastPage}alreadyBalanced}
    {
      % Third pass or later; document was already
      % balanced, so there should be no more changes
      \@PBifSomethingChanged
        % The document has changed, so we need to measure
        % stuff again; clear aux file and start over.
        {\@PBnotifyRerun}
        {
          % Nothing changed, just write the same info down
          \@PBsaveUnbalancedInfo
          \@PBsaveBalancedInfo
          \PackageInfo{pbalance}{Done balancing page \@PBlastPage}
        }
    }
    % Second pass, which means something did change: we have just
    % balanced the columns for the first time.
    {
      \xdef\@tempa{\the\value{abspage}}
      \ifboolexpr
        {
          test {\ifdefstrequal{\@PBprevLastPage}{\@PBlastPage}}
          and
          test {\ifdefstrequal{\@PBprevLastPhysPage}{\@tempa}}
        }
        % All is well; save the new info
        {\@PBsaveUnbalancedInfo\@PBsaveBalancedInfo}
        % Oh, no! As we attempted to balance, we actually changed
        % the number of pages (maybe we added a float page, maybe
        % we turned the last float page into a text page etc.). If
        % we continue, the document might never converge (endless
        % ``please rerun LaTeX'' messages). Let's give up balancing.
        {\toggletrue{@PBimpossible}}
    }
}


\newcommand\@PBifBalancePossible[2]{
  \iftoggle{@PBunbalpg\@Roman{\@PBprevLastPage}HasFloatcol}
    {#2}
    {#1}
}

\newcommand\@PBifBalancePkgPossible[2]{
  \ifboolexpr
    {
      togl {@PBunbalpg\@Roman{\@PBprevLastPage}HasFloats}
      or
      togl {@PBunbalpg\@Roman{\@PBprevLastPage}HasFootnotes}
      or
      togl {@PBunbalpg\@Roman{\@PBprevLastPage}HasMarginpars}
      or
      togl {@PBnoBalancePackage}
    }
    {#2}
    {#1}
}


\newcommand\@PBifPoorBalancePossible[2]{

  % Let's use some shorter names, please
  \dimdef\@PBtmpH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}Height}}
  \dimdef\@PBtmpUL{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}UsedLeft}}
  \dimdef\@PBtmpUR{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}UsedRight}}

  \dimdef\@PBtmpLH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}LeftHeight}}
  \dimdef\@PBtmpLFH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}LeftFloatsHeight}}
  \dimdef\@PBtmpRH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}RightHeight}}
  \dimdef\@PBtmpRFH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}RightFloatsHeight}}

  \ifboolexpr{
    % Plenty of space on right column, difference is worth it
    test {\ifdimcomp{\@PBtmpUL}{>}{\@PBtmpUR + 6\baselineskip}}
    or
    (
      test {\ifdimcomp{\@PBtmpUL}{>}{4\baselineskip}}
      and
      test {\ifdimcomp{\@PBtmpUR}{=}{\topskip}} % column is empty
    )
  }{#1}{#2}
}



\ExplSyntaxOn
\def\@PBsafetyCheck{

  % Let's use some shorter names, please
  \dimdef\@PBtmpH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}Height}}
  \dimdef\@PBtmpUL{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}UsedLeft}}
  \dimdef\@PBtmpUR{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}UsedRight}}

  \dimdef\@PBtmpLH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}LeftHeight}}
  \dimdef\@PBtmpLFH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}LeftFloatsHeight}}
  \dimdef\@PBtmpRH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}RightHeight}}
  \dimdef\@PBtmpRFH{\csuse{@PBunbalpg\@Roman{\@PBprevLastPage}RightFloatsHeight}}

  % Make sure we do not push top/bottom floats out of the left col
  \dimdef\@PBmaxSlack{\@PBtmpLH}

  \dimdef\@PBtmpdim{0pt}

  % Start from the bottom
  \numdef{\@PBtmpcnt}{\seq_count:c {@PBunbalpg\@Roman{\@PBprevLastPage}LeftFloatHeights}}
  \int_while_do:nNnn {\@PBtmpcnt} > {0}
    {

      \dimdef\@PBcurrentFloatHeight
        {\seq_item:cn {@PBunbalpg\@Roman{\@PBprevLastPage}LeftFloatHeights} {\@PBtmpcnt}}

      \dimdef\@PBcurrentFloatSpaceBelow
        {\seq_item:cn {@PBunbalpg\@Roman{\@PBprevLastPage}LeftFloatSpacesBelow} {\@PBtmpcnt}}

      \dimdef{\@PBtmpdim}{\@PBtmpdim + \@PBcurrentFloatHeight}

      \ifboolexpr
        {
          % Does the float fit in the second column?
          test {\ifdimcomp{\@PBtmpdim}{<}{\@PBtmpRH - \@PBtmpRFH}}
          and
          % Is there something above this float, i.e., if we move
          % this float to the next column, will anything remain?
          test
            {
               \ifdimcomp
                 {\@PBcurrentFloatSpaceBelow + \@PBcurrentFloatHeight}
                 {<}
                 {\@PBtmpLH - 6\baselineskip}
            }
        }
        {\numdef{\@PBtmpcnt}{\@PBtmpcnt - 1}} % this one is ok; check next
        {
          % this one should not be moved, we found the limit
          \ifdimcomp{\@PBmaxSlack}{>}{\@PBcurrentFloatSpaceBelow}
            {\dimdef{\@PBmaxSlack}{\@PBcurrentFloatSpaceBelow}}
            {}
          \numdef{\@PBtmpcnt}{0} % exit the loop
        }
    }

  \ifdimcomp{\@PBmaxSlack}{<}{\@PBslack}
    {\dimgdef{\@PBslack}{\@PBmaxSlack}}
    {}
}
\ExplSyntaxOff

\newcommand\@PBifSomethingChanged[3][bal]{
  \ifdefstrequal{\@PBprevLastPage}{\@PBlastPage}
  {
    \@PBifPageDataMatches
      {pg\@Roman{\@PBlastPage}}
      {#1pg\@Roman{\@PBlastPage}}
      {#3}
      {#2}
  }
  {#2}
}

\newcommand\@PBifPageDataMatches[4]{
  \ifboolexpr{
        test {\@PBifTogglesMatch{@PB#1HasFloats}{@PB#2HasFloats}}
    and test {\@PBifTogglesMatch{@PB#1HasFloatcol}{@PB#2HasFloatcol}}
    and test {\@PBifTogglesMatch{@PB#1HasFootnotes}{@PB#2HasFootnotes}}
    and test {\@PBifTogglesMatch{@PB#1HasMarginpars}{@PB#2HasMarginpars}}
    and test {\@PBifDimensionsMatch{@PB#1Height}{@PB#2Height}}
    and test {\@PBifDimensionsMatch{@PB#1LeftHeight}{@PB#2LeftHeight}}
    and test {\@PBifDimensionsMatch{@PB#1RightHeight}{@PB#2RightHeight}}
    and test {\@PBifDimensionsMatch{@PB#1UsedLeft}{@PB#2UsedLeft}}
    and test {\@PBifDimensionsMatch{@PB#1UsedRight}{@PB#2UsedRight}}
  }
  {#3}
  {#4}
}

\newcommand\@PBifTogglesMatch[4]{
  \ifboolexpr{(togl{#1} or not togl{#2}) and (togl{#2} or not togl{#1})}
    {#3}
    {#4}
}

\newcommand\@PBifDimensionsMatch[4]{
  \ifdimcomp{\csuse{#1}}{=}{\csuse{#2}}
    {#3}
    {#4}
}

\newcommand\@PBsaveUnbalancedInfo[1][]{

  % If there are no two-column pages in the
  % document, there is nothing to save.
  \ifcsdef{@PBlastPage}
    {
      \immediate\write\@mainaux{\gdef\string\@PBprevLastPage{\@PBlastPage}}

      \ifboolexpr{test {\ifdefvoid{\@PBprevLastPage}} or test {\ifstrequal{#1}{update}}}
        % Columns are currently unbalanced, either because this is
        % the first pass (we do not have any previous information)
        % or because the document has not stabilized yet, so any
        % previous information is unreliable. Save the information
        % we just collected as ``unbalanced''.
        {\@PBsavePageDataAs{pg\@Roman{\@PBlastPage}}{unbalpg\@Roman{\@PBlastPage}}}
        % Not the first pass, so columns are possibly balanced;
        % to save the unbalanced information, repeat what was
        % gathered during the first pass.
        {\@PBsavePageData{unbalpg\@Roman{\@PBprevLastPage}}}
    }
    {}
}

\def\@PBsaveBalancedInfo{
  \global\toggletrue{@PBpg\@Roman{\@PBlastPage}alreadyBalanced}
  \@PBsaveToggle{@PBpg\@Roman{\@PBlastPage}alreadyBalanced}

  \@PBsavePageDataAs{pg\@Roman{\@PBlastPage}}{balpg\@Roman{\@PBlastPage}}
}

\def\@PBnotifyRerun{
  \AtVeryEndDocument{
    % If there are no two-column pages in the document,
    % it makes no sense to emit this warning.
    \ifcsdef{@PBlastPage}
      {
        \PackageWarningNoLine{pbalance}
        {Last two-column page cols not balanced. Rerun LaTeX}
      }
      {
        \PackageWarningNoLine{pbalance}
        {No two-column pages, doing nothing}
      }
  }
}

\ExplSyntaxOn
\newcommand\@PBcopyPageData[2]{

  \global\providetoggle{@PB#2HasFloats}
  \global\providetoggle{@PB#2HasFloatcol}
  \global\providetoggle{@PB#2HasFootnotes}
  \global\providetoggle{@PB#2HasMarginpars}

  \iftoggle{@PB#1HasFloats}
    {\global\toggletrue{@PB#2HasFloats}}
    {\global\togglefalse{@PB#2HasFloats}}

  \iftoggle{@PB#1HasFloatcol}
    {\global\toggletrue{@PB#2HasFloatcol}}
    {\global\togglefalse{@PB#2HasFloatcol}}

  \iftoggle{@PB#1HasFootnotes}
    {\global\toggletrue{@PB#2HasFootnotes}}
    {\global\togglefalse{@PB#2HasFootnotes}}

  \iftoggle{@PB#1HasMarginpars}
    {\global\toggletrue{@PB#2HasMarginpars}}
    {\global\togglefalse{@PB#2HasMarginpars}}

  \csdimgdef{@PB#2Height}{\csuse{@PB#1Height}}
  \csdimgdef{@PB#2LeftHeight}{\csuse{@PB#1LeftHeight}}
  \csdimgdef{@PB#2LeftFloatsHeight}{\csuse{@PB#1LeftFloatsHeight}}
  \csdimgdef{@PB#2RightHeight}{\csuse{@PB#1RightHeight}}
  \csdimgdef{@PB#2RightFloatsHeight}{\csuse{@PB#1RightFloatsHeight}}
  \csdimgdef{@PB#2UsedLeft}{\csuse{@PB#1UsedLeft}}
  \csdimgdef{@PB#2UsedRight}{\csuse{@PB#1UsedRight}}

  \seq_gclear_new:c {@PB#2LeftFloatHeights}
  \seq_gclear_new:c {@PB#2LeftFloatSpacesBelow}
  \seq_gset_eq:cc {@PB#2LeftFloatHeights} {@PB#1LeftFloatHeights}
  \seq_gset_eq:cc {@PB#2LeftFloatSpacesBelow} {@PB#1LeftFloatSpacesBelow}
}
\ExplSyntaxOff

\newcommand\@PBsavePageDataAs[2]{
  \@PBsaveDimAs{@PB#1Height}{@PB#2Height}
  \@PBsaveDimAs{@PB#1LeftHeight}{@PB#2LeftHeight}
  \@PBsaveDimAs{@PB#1LeftFloatsHeight}{@PB#2LeftFloatsHeight}
  \@PBsaveDimAs{@PB#1RightHeight}{@PB#2RightHeight}
  \@PBsaveDimAs{@PB#1RightFloatsHeight}{@PB#2RightFloatsHeight}
  \@PBsaveDimAs{@PB#1UsedLeft}{@PB#2UsedLeft}
  \@PBsaveDimAs{@PB#1UsedRight}{@PB#2UsedRight}

  \@PBsaveToggleAs{@PB#1HasFloats}{@PB#2HasFloats}
  \@PBsaveToggleAs{@PB#1HasFloatcol}{@PB#2HasFloatcol}
  \@PBsaveToggleAs{@PB#1HasFootnotes}{@PB#2HasFootnotes}
  \@PBsaveToggleAs{@PB#1HasMarginpars}{@PB#2HasMarginpars}

  \@PBsaveSeqAs{@PB#1LeftFloatHeights}{@PB#2LeftFloatHeights}
  \@PBsaveSeqAs{@PB#1LeftFloatSpacesBelow}{@PB#2LeftFloatSpacesBelow}
}

\newcommand\@PBsavePageData[1]{
  \@PBsavePageDataAs{#1}{#1}
}

\newcommand\@PBsaveToggleAs[2]{
  \immediate\write\@mainaux{\providetoggle{#2}}
  \iftoggle{#1}
    {\immediate\write\@mainaux{\global\toggletrue{#2}}}
    {\immediate\write\@mainaux{\global\togglefalse{#2}}}
}

\newcommand\@PBsaveToggle[1]{
  \@PBsaveToggleAs{#1}{#1}
}

\newcommand\@PBsaveDimAs[2]{
  \immediate\write\@mainaux{\csdimgdef{#2}{\csuse{#1}}}
}

\newcommand\@PBsaveDim[1]{
  \@PBsaveDimAs{#1}{#1}
}

\ExplSyntaxOn
\newcommand\@PBsaveSeqAs[2]{
  \immediate\write\@mainaux{\string\ExplSyntaxOn}
  \immediate\write\@mainaux{\string\seq_gclear_new:c {#2}}
  \seq_map_inline:cn {#1}
    {\immediate\write\@mainaux{\string\global\string\seq_put_right:cn {#2}{##1}}}
  \immediate\write\@mainaux{\string\ExplSyntaxOff}
}
\ExplSyntaxOff

\newcommand\@PBsaveSeq[1]{
  \@PBsaveSeqAs{#1}{#1}
}

\endinput
%%
%% End of file `pbalance.sty'.