%
% lltjp-atbegshi.sty
%

\newif\ifltj@ltshipout@avail
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{lltjp-atbegshi}[2020-08-08 Patching \string\shipout\space hooks for LuaTeX-ja]
\@ifl@t@r\fmtversion{2020-10-01}{%
  \ifnum\patch@level<0\relax \ifnum\patch@level<-6 \ltj@ltshipout@availtrue\fi
  \else\ltj@ltshipout@availtrue\fi
}{}
\ifltj@ltshipout@avail\else\RequirePackage{atbegshi}\fi

% concept: execute all hooks inside yoko direction \vbox

\ifltj@ltshipout@avail
%<*ltshipout>-----------------------------------
%
\RequirePackage{expl3}
\ExplSyntaxOn\makeatletter
\box_new:N \l__platex_shipout_dummy_box
\pretocmd {\__shipout_execute_cont:}
  {\tex_setbox:D \l__platex_shipout_dummy_box \tex_vbox:D \c_group_begin_token \yoko } {} {}
\apptocmd {\__shipout_execute_cont:} {\c_group_end_token} {} {}
\ExplSyntaxOff
%</ltshipout>-----------------------------------

\else
\AtBeginShipoutInit
%<*atbegshi>-------------------------------------
% patching atbegshi.sty
%%%  following codes are almost copied from
%%%  pxatbegshi.sty 2019/09/07 v0.5 (in platex-tools bundle, by H. Yamashita).

%% internal macros are locally effective
\begingroup

% helpers
%% unique tokens
\def\pxabgs@mark{\pxabgs@mark@}
\def\pxabgs@fin{\pxabgs@fin@}

%% \pxabgs@patch@cmd\CMD{<orig>}{<new>}
\def\pxabgs@patch@cmd#1#2#3{%
  \ifx#1\relax\else
  \def\pxabgs@next##1#2##2\pxabgs@mark##3\pxabgs@fin{%
    \ifx\pxabgs@mark##3\pxabgs@mark\let#1\relax
    \else
      \def\pxabgs@fragment{##2}\def#1{##1#3##2}%
    \fi}%
  \expandafter\pxabgs@next#1\pxabgs@mark#2\pxabgs@mark\pxabgs@fin
  \fi
}

% prepare
\ifdefined\AtBegShi@Output
  \let\pxabgs@AtBegShi@Output\AtBegShi@Output
\else\let\pxabgs@AtBegShi@Output\relax\fi
% try first patch
\pxabgs@patch@cmd\pxabgs@AtBegShi@Output
  {\let\AtBegShi@OrgProtect\protect}%
  {\setbox8\vbox\bgroup\yoko\let\AtBegShi@OrgProtect\protect}
\pxabgs@patch@cmd\pxabgs@AtBegShi@Output
  {\AtBeginShipoutOriginalShipout\box\AtBeginShipoutBox}%
  {\AtBeginShipoutOriginalShipout\box\AtBeginShipoutBox\egroup}
\pxabgs@patch@cmd\pxabgs@AtBegShi@Output
  {%
    \begingroup
      \setbox\AtBeginShipoutBox\box\AtBeginShipoutBox
    \endgroup
    \let\protect\AtBegShi@OrgProtect
  }{%
    \begingroup
      \setbox\AtBeginShipoutBox\box\AtBeginShipoutBox
    \endgroup
    \let\protect\AtBegShi@OrgProtect
    \egroup
  }
% commit the change only when successful
\ifx\pxabgs@AtBegShi@Output\relax
  \@PackageWarningNoLine{lltjp-atbegshi}{%
    Failed in patching \string\AtBegShi@Output.\MessageBreak
    This may cause error in tate direction%
  }
\else
  \global\let\AtBegShi@Output\pxabgs@AtBegShi@Output
\fi

\endgroup
%% internal macros are no longer effective
%</atbegshi>-------------------------------------
\fi
\endinput
