% File:      ifvtex.sty
% Version:   2001/09/26 v1.0
% Author:    Heiko Oberdiek
% Email:     <oberdiek@uni-freiburg.de>
%
% Copyright: Copyright (C) 2001 Heiko Oberdiek.
%
%            This program may be distributed and/or modified under
%            the conditions of the LaTeX Project Public License,
%            either version 1.2 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 1.2 or later is part of all distributions
%            of LaTeX version 1999/12/01 or later.
%
% Function:  This package looks for VTeX and implements
%            and sets the switches \ifvtex, \ifvtex<mode>,
%            and \ifvtexgex.
%            It works with plain or LaTeX formats.
%
% Use:       LaTeX: \usepackage{ifvtex}
%            plain: \input ifvtex.sty
%            The package provides the switch \ifvtex:
%              \ifvtex
%                ... do things, if VTeX is running ...
%              \else
%                ... other TeX ...
%              \fi
%            The package can also be used to set global
%            documentclass options:
%              \RequirePackage{ifvtex}
%              \ifvtex
%                \documentclass[vtex,...]{...}
%              \else
%                \documentclass[...]{...}
%              \fi
%
%            For the different output modes the following switches
%            can be used:
%              \ifvtexdvi, \ifvtexpdf, \ifvtexps, \ifvtexhtml
%            And for GeX mode:
%              \ifvtexgex
%
%            For detecting VTeX \VTeXversion and \OpMode
%            has to be defined. The modes are detected by
%            \OpMode and GeX by \gexmode.
%
% History:   2001/09/26 v1.0:
%              * first public version,
%
% Prevent reloading more than one:
\begingroup
  \expandafter\let\expandafter\x\csname ver@ifvtex.sty\endcsname
  \ifcase 0%
    \ifx\x\relax % plain
    \else
      \ifx\x\empty % LaTeX
      \else
        1%
      \fi
    \fi
  \else
    \expandafter\ifx\csname PackageInfo\endcsname\relax
      \def\x#1#2{%
        \immediate\write-1{Package #1 Info: #2.}%
      }%
    \else
      \def\x#1#2{\PackageInfo{#1}{#2, stopped}}%
    \fi
    \x{ifvtex}{The package is already loaded}%
    \endgroup
    \expandafter\endinput
  \fi
\endgroup
%
% Package identification:
\begingroup
  \expandafter\ifx\csname ProvidesPackage\endcsname\relax
  \def\x#1#2#3[#4]{\endgroup
    \immediate\write-1{Package: #3 #4}%
    \xdef#1{#4}%
  }%
  \else
    \def\x#1#2[#3]{\endgroup
      #2[#3]%
      \ifx#1\relax
        \xdef#1{#3}%
      \fi
    }%
  \fi
\expandafter\x\csname ver@ifvtex.sty\endcsname
\ProvidesPackage{ifvtex}%
  [2001/06/14 v1.0 *TEST* Providing %
   \expandafter\string\csname ifvtex\endcsname\space switches (HO)]
%
% Check, whether \ifvtex is already defined:
\begingroup
  \expandafter\ifx\csname ifvtex\endcsname\relax
  \else
    \edef\i/{\expandafter\string\csname ifvtex\endcsname}%
    \expandafter\ifx\csname PackageError\endcsname\relax
      \def\x#1#2{%
        \edef\z{#2}%
        \expandafter\errhelp\expandafter{\z}%
        \errmessage{Package ifvtex Error: #1}%
      }%
      \def\y{^^J}%
      \newlinechar=10
    \else
      \def\x#1#2{%
        \PackageError{ifvtex}{#1}{#2}%
      }%
      \def\y{\MessageBreak}%
    \fi
    \x{Name clash, \i/ is already defined}{%
      Incompatible versions of \i/ can cause problems,\y
      therefore package loading is aborted.%
    }%
    \endgroup
    \expandafter\endinput
  \fi
\endgroup
%
% Implementing the switch \ifvtex:
\newif\ifvtex
\ifx\VTeXversion\undefined
\else
  \ifx\VTeXversion\relax
  \else
    \ifx\OpMode\undefined
    \else
      \ifx\OpMode\relax
      \else
        \vtextrue
      \fi
    \fi
  \fi
\fi
%
% Implementing the mode and GeX switches:
\newif\ifvtexdvi
\newif\ifvtexpdf
\newif\ifvtexps
\newif\ifvtexhtml
\newif\ifvtexgex
\ifvtex
  \ifcase\OpMode\relax
    \vtexdvitrue
  \or % 1
    \vtexpdftrue
  \or % 2
    \vtexpstrue
  \or % 3
    \vtexpstrue
  \or\or\or\or\or\or\or % 10
    \vtexhtmltrue
  \fi
  \ifx\gexmode\undefined
  \else
    \ifx\gexmode\relax
    \else
      \ifnum\gexmode>0 %
        \vtexgextrue
      \fi
    \fi
  \fi
\fi
%
% Log comment:
\begingroup
  \expandafter\ifx\csname PackageInfo\endcsname\relax
    \def\x#1#2{%
      \immediate\write-1{Package #1 Info: #2.}%
    }%
  \else
    \let\x\PackageInfo
    \expandafter\let\csname on@line\endcsname\empty
  \fi
  \x{ifvtex}{%
    VTeX %
    \ifvtex
      in \ifvtexdvi DVI\fi
         \ifvtexpdf PDF\fi
         \ifvtexps PS\fi
         \ifvtexhtml HTML\fi
      \space mode %
      with\ifvtexgex\else out\fi\space GeX %
    \else
      not %
    \fi
    detected%
  }%
\endgroup
\endinput