[texhax] A macro programming question

[Vafa Khalighi]

I am trying to figure out how I can make longtable typeset RTL tabulars but
I started with something much simpler to understand what I should do. The
bigtabular package is defined as:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newskip\Tabularleftskip  \Tabularleftskip\@flushglue
\newskip\Tabularrightskip \Tabularrightskip\@flushglue
\newbox\Tabularbox
\newcount\Tabularcount
\newcount\Tabularcolumns
\def\@Tabclassz{\global\advance\Tabularcount\@ne\@tabclassz}
\let\@latexclassiii\@classiii
\def\@Tabclassiii{\global\advance\Tabularcount\@ne\@latexclassiii}
\def\@Tabularcr{{\ifnum0=`}\fi\@ifstar{\@xTabularcr}{\@xTabularcr}}
\def\@xTabularcr{\@ifnextchar[{\@argTabularcr}{\ifnum0=`{\fi}\cr
  \noalign{\pagebreak[1]}}}

\def\@argTabularcr[#1]{\ifnum0=`{\fi}\ifdim #1>\z@
   \unskip\@xargarraycr{#1}\else \@yargarraycr{#1}\fi
 \noalign{\pagebreak[1]}}
\let\@latexhline\hline
\let\@latextabarray\@tabarray
\def\@tabarray{\let\hline\@latexhline\@latextabarray}
\def\Tabularhline{\multispan{\Tabularcolumns}{\unskip\leaders\hrule
    height\arrayrulewidth\hfill}\cr
  \noalign{\vskip-\arrayrulewidth\pagebreak[2]}%
  \multispan{\Tabularcolumns}{\unskip\leaders\hrule
    height\arrayrulewidth\hfill}\cr}

\def\Tabular#1{\trivlist\item[]\noindent
  \setbox\Tabularbox\vbox\bgroup
    \let\@acol\@tabacol
    \let\@classz\@Tabclassz
    \let\@classiii\@Tabclassiii
    \let\@classiv\@tabclassiv
    \let\\\@Tabularcr
    \setbox\@arstrutbox=\hbox{\vrule
        height\arraystretch \ht\strutbox
        depth\arraystretch  \dp\strutbox
        width\z@}%
    \global\Tabularcount\z@
    \@mkpream{#1}%
    \Tabularcolumns\Tabularcount
    \let\hline\Tabularhline
    \let\@classiii\@latexclassiii
    \tabskip\Tabularleftskip
    \edef\@preamble{\halign to\linewidth\bgroup
      \tabskip\z@ \@arstrut \@preamble
      \tabskip\Tabularrightskip \cr}%
    \let\@starpbox\@@startpbox
    \let\@endpbox\@@endpbox
    \let\@sharp##\let\protect\relax
    \lineskip\z@\baselineskip\z@
    \@preamble}

\def\endTabular{\crcr\egroup\egroup\unvbox\Tabularbox\endtrivlist}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

To make it typeset tabular right to left, I thought of changing \Tabular and
\endTabular as follow:

\def\Tabular#1{\trivlist\item[]\noindent
  \setbox\Tabularbox\vbox\bgroup
    \let\@acol\@tabacol
    \let\@classz\@Tabclassz
    \let\@classiii\@Tabclassiii
    \let\@classiv\@tabclassiv
    \let\\\@Tabularcr
    \setbox\@arstrutbox=\hbox{\vrule
        height\arraystretch \ht\strutbox
        depth\arraystretch  \dp\strutbox
        width\z@}%
    \global\Tabularcount\z@
    \@mkpream{#1}%
    \Tabularcolumns\Tabularcount
    \let\hline\Tabularhline
    \let\@classiii\@latexclassiii
    \tabskip\Tabularleftskip
    \edef\@preamble{\halign to\linewidth\bgroup
      \tabskip\z@ \@arstrut \@preamble
      \tabskip\Tabularrightskip \cr}%
    \let\@starpbox\@@startpbox
    \let\@endpbox\@@endpbox
    \let\@sharp##\let\protect\relax
    \lineskip\z@\baselineskip\z@
   \hbox\bgroup\beginR\vbox\bgroup \@preamble}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% This is my first change

\def\endTabular{\crcr\egroup\egroup\endR\egroup\egroup\unvbox\Tabularbox\endtrivlist}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

but it no longer works (tabular appears on one page and no pagebreak
happens). What should I do to fix this?


Thanks
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