% pdfwebtofront.tex
% Code from knuth.drv in https://github.com/oberdiek/latex-tds
% 2020/05/21 v1.0 by Andreas Scherer.
%
% This file is part of project https://github.com/ascherer/cwebbin
% and may be distributed under the MIT License or the LaTeX Project
% Public License.
%
% Move table-of-contents page to the front in PDF output.
% Works with pdftex and xetex in connection with either 'webmac.tex'
% for Pascal/WEB programs or 'cwebmac.tex' for C/CWEB programs.
%
\ifx\detokenize\undefined\endinput\fi
\def\contentsfile{\jobname.toc} % file that gets table of contents info
\def\readcontents{\input \contentsfile}
\newread\testread
\openin\testread=\contentsfile\relax
\ifeof\testread % First run
\else % Second run
  \let\ORGcon\con \let\ORGtoc\topofcontents
  \ifx\undefined\grouptitle \mark{1} % WEB: let's start with section '1'.
  \else\def\topofcontents{\ORGtoc\gtitle={\the\grouptitle}}\fi % CWEB
  % Redefine '\con' to be invoked before the first '\N' (starred section).
  \def\con{%
    \def\:{\par\hangindent 2em} % Fix for 'bibtex.web'.
    % reduce size of PDF pages for more screen space
    \pdfpagewidth=\pagewidth  \advance\pdfpagewidth by 2cm
    \pdfpageheight=\pageheight \advance\pdfpageheight by 3cm
    \ifpdftex \pdfhorigin=1cm \pdfvorigin=1cm
    \else \advance\pdfpageheight by 1cm \global\pageshift=-1.54cm
      \global\hoffset=-1.54cm \global\voffset=-1.54cm \fi
    \begingroup
      \let\end\relax
      \ORGcon\eject
    \endgroup
    \let\con\end
  }%
  % Redefine '\N’ to invoke redefined '\con' before switching back
  % to original '\N'.
  \expandafter\let\csname ORGN\expandafter\endcsname
                  \csname N\endcsname
  \expandafter\outer\expandafter\def\csname N\endcsname{%
    \con
    \expandafter\let\csname N\expandafter\endcsname
                    \csname ORGN\endcsname
    \csname N\endcsname
  }%
  % Special variant of the above for 'mf.web' and 'tex.web'.  They put
  % their tables-of-contents on a sparce 'page 2' and start on page '3'.
  \begingroup
    \def\num{0}%
    \edef\x{\jobname}%
    \edef\y{\detokenize{tex}}%
    \ifx\x\y \def\num{1}\else
    \edef\y{\detokenize{mf}}%
    \ifx\x\y \def\num{1}\else
    \edef\y{\detokenize{pdftex}}%
    \ifx\x\y \def\num{1}\else
    \edef\y{\detokenize{xetex}}%
    \ifx\x\y \def\num{1}\fi\fi\fi\fi
  \expandafter\endgroup\ifnum\num=1 %
    \def\contentspagenumber{2}%
    \let\ORGpageno\pageno
    \def\pageno{%
      \let\pageno\ORGpageno
      \expandafter\let\csname ORGN\expandafter\endcsname
                      \csname N\endcsname
      \expandafter\outer\expandafter\def\csname N\endcsname{%
        \con
        \expandafter\let\csname N\expandafter\endcsname
                        \csname ORGN\endcsname
        \csname N\endcsname
      }%
      \pageno
    }%
  \fi
\fi
