% \iffalse meta-comment
%
% Copyright (C) 2001, 2006 by Heiko Oberdiek <oberdiek@uni-freiburg.de>
%
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either
% version 1.3 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 1.3 or later is part of all distributions of
% LaTeX version 2005/12/01 or later.
%
% This work has the LPPL maintenance status "maintained".
%
% This Current Maintainer of this work is Heiko Oberdiek.
%
% This work consists of the main source file chemarr.dtx
% and the derived files
%    chemarr.sty, chemarr.pdf, chemarr.ins, chemarr.drv,
%    chemarr-example.tex.
%
% Distribution:
%    CTAN:macros/latex/contrib/oberdiek/chemarr.dtx
%    CTAN:macros/latex/contrib/oberdiek/chemarr.pdf
%
% Unpacking:
%    (a) If chemarr.ins is present:
%           tex chemarr.ins
%    (b) Without chemarr.ins:
%           tex chemarr.dtx
%    (c) If you insist on using LaTeX
%           latex \let\install=y\input{chemarr.dtx}
%        (quote the arguments according to the demands of your shell)
%
% Documentation:
%    (a) If chemarr.drv is present:
%           latex chemarr.drv
%    (b) Without chemarr.drv:
%           latex chemarr.dtx; ...
%    The class ltxdoc loads the configuration file ltxdoc.cfg
%    if available. Here you can specify further options, e.g.
%    use A4 as paper format:
%       \PassOptionsToClass{a4paper}{article}
%
%    Programm calls to get the documentation (example):
%       pdflatex chemarr.dtx
%       makeindex -s gind.ist chemarr.idx
%       pdflatex chemarr.dtx
%       makeindex -s gind.ist chemarr.idx
%       pdflatex chemarr.dtx
%
% Installation:
%    TDS:tex/latex/oberdiek/chemarr.sty
%    TDS:doc/latex/oberdiek/chemarr.pdf
%    TDS:doc/latex/oberdiek/chemarr-example.tex
%    TDS:source/latex/oberdiek/chemarr.dtx
%
%<*ignore>
\begingroup
  \def\x{LaTeX2e}
\expandafter\endgroup
\ifcase 0\ifx\install y1\fi\expandafter
         \ifx\csname processbatchFile\endcsname\relax\else1\fi
         \ifx\fmtname\x\else 1\fi\relax
\else\csname fi\endcsname
%</ignore>
%<*install>
\input docstrip.tex
\Msg{************************************************************************}
\Msg{* Installation}
\Msg{* Package: chemarr 2006/02/20 v1.2 Chemical reaction arrows (HO)}
\Msg{************************************************************************}

\keepsilent
\askforoverwritefalse

\preamble

This is a generated file.

Copyright (C) 2001, 2006 by Heiko Oberdiek <oberdiek@uni-freiburg.de>

This work may be distributed and/or modified under the
conditions of the LaTeX Project Public License, either
version 1.3 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 1.3 or later is part of all distributions of
LaTeX version 2005/12/01 or later.

This work has the LPPL maintenance status "maintained".

This Current Maintainer of this work is Heiko Oberdiek.

This work consists of the main source file chemarr.dtx
and the derived files
   chemarr.sty, chemarr.pdf, chemarr.ins, chemarr.drv,
   chemarr-example.tex.

\endpreamble

\generate{%
  \file{chemarr.ins}{\from{chemarr.dtx}{install}}%
  \file{chemarr.drv}{\from{chemarr.dtx}{driver}}%
  \usedir{tex/latex/oberdiek}%
  \file{chemarr.sty}{\from{chemarr.dtx}{package}}%
  \usedir{doc/latex/oberdiek}%
  \file{chemarr-example.tex}{\from{chemarr.dtx}{example}}%
}

\obeyspaces
\Msg{************************************************************************}
\Msg{*}
\Msg{* To finish the installation you have to move the following}
\Msg{* file into a directory searched by TeX:}
\Msg{*}
\Msg{*     chemarr.sty}
\Msg{*}
\Msg{* To produce the documentation run the file `chemarr.drv'}
\Msg{* through LaTeX.}
\Msg{*}
\Msg{* Happy TeXing!}
\Msg{*}
\Msg{************************************************************************}

\endbatchfile
%</install>
%<*ignore>
\fi
%</ignore>
%<*driver>
\NeedsTeXFormat{LaTeX2e}
\ProvidesFile{chemarr.drv}%
  [2006/02/20 v1.2 Chemical reaction arrows (HO)]
\documentclass{ltxdoc}
\usepackage{holtxdoc}
\usepackage{chemarr}
\begin{document}
  \DocInput{chemarr.dtx}
\end{document}
%</driver>
% \fi
%
% \CheckSum{48}
%
% \CharacterTable
%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%   Digits        \0\1\2\3\4\5\6\7\8\9
%   Exclamation   \!     Double quote  \"     Hash (number) \#
%   Dollar        \$     Percent       \%     Ampersand     \&
%   Acute accent  \'     Left paren    \(     Right paren   \)
%   Asterisk      \*     Plus          \+     Comma         \,
%   Minus         \-     Point         \.     Solidus       \/
%   Colon         \:     Semicolon     \;     Less than     \<
%   Equals        \=     Greater than  \>     Question mark \?
%   Commercial at \@     Left bracket  \[     Backslash     \\
%   Right bracket \]     Circumflex    \^     Underscore    \_
%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%   Right brace   \}     Tilde         \~}
%
% \GetFileInfo{chemarr.drv}
%
% \title{The \xpackage{chemarr} package}
% \date{2006/02/20 v1.2}
% \author{Heiko Oberdiek\\\xemail{oberdiek@uni-freiburg.de}}
%
% \maketitle
%
% \begin{abstract}
% Very often chemists need a longer version
% of reaction arrows (\cs{rightleftharpoons}) with
% the possibility to put text above and below.
% Analogous to \xpackage{amsmath}'s \cs{xrightarrow} and
% \cs{xleftarrow} this package provides the macro
% \cs{xrightleftharpoons}.
% \end{abstract}
%
% \tableofcontents
%
% \section{Usage}
%
% \DescribeMacro{\xrightleftharpoons}
% This \LaTeX\ package defines \cs{xrightleftharpoons}. It prints
% extensible arrows (harpoons), usually used in chemical reactions.
% It allows to put some text above and below the harpoons and can
% be used inside and outside of math mode.
%
% The package is based on \xpackage{amsmath}, thus it loads it,
% if necessary.
%
% \subsection{Example}
%
%    \begin{macrocode}
%<*example>
\documentclass{article}
\usepackage{chemarr}
\begin{document}
\begin{center}
  left
  \xrightleftharpoons[\text{below}]{\text{above}}
  right
\end{center}
\[
  A
  \xrightleftharpoons[T \geq 400\,\mathrm{K}]{p > 10\,\mathrm{hPa}}
  B
\]
\end{document}
%</example>
%    \end{macrocode}
%    The result:
%    \begin{center}
%      left
%      \xrightleftharpoons[\text{below}]{\text{above}}
%      right
%    \end{center}
%    \[
%      A
%      \xrightleftharpoons[T \geq 400\,\mathrm{K}]{p > 10\,\mathrm{hPa}}  
%      B
%    \]
%
% \StopEventually{
% }
%
% \section{Implementation}
%
%    \begin{macrocode}
%<*package>
%    \end{macrocode}
%    Package identification.
%    \begin{macrocode}
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{chemarr}%
  [2006/02/20 v1.2 Chemical reaction arrows (HO)]
%    \end{macrocode}
%
%    \begin{macrocode}
\RequirePackage{amsmath}
%    \end{macrocode}
%    The package \xpackage{amsmath} is needed for the following commands:
%    \begin{quote}
%      \cs{ext@arrow}, \cs{@ifnotempty}, \cs{arrowfill@}\\
%      \cs{relbar}, \cs{std@minus}\\
%      \cs{@ifempty}, \cs{@xifempty}, \cs{@xp}
%    \end{quote}
%
%    \begin{macro}{\xrightleftharpoons}
%    In \xfile{fontmath.ltx} \cs{rightleftharpoons} is defined with
%    a vertical space of 2pt.
%    \begin{macrocode}
\newcommand{\xrightleftharpoons}[2][]{%
  \ensuremath{%
    \mathrel{%
      \settoheight{\dimen@}{\raise 2pt\hbox{$\rightharpoonup$}}%
      \setlength{\dimen@}{-\dimen@}%
      \edef\CA@temp{\the\dimen@}%
      \settoheight\dimen@{$\rightleftharpoons$}%
      \addtolength{\dimen@}{\CA@temp}%
      \raisebox{\dimen@}{%
        \rlap{%
          \raisebox{2pt}{%
            $%
            \ext@arrow 0359\rightharpoonupfill@{\hphantom{#1}}{#2}%
            $%
          }%
        }%
        \hbox{%
          $%
          \ext@arrow 3095\leftharpoondownfill@{#1}{\hphantom{#2}}%
          $%
        }%
      }%
    }%
  }%
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\leftharpoondownfill@}
%    \begin{macrocode}
\newcommand*{\leftharpoondownfill@}{%
  \arrowfill@\leftharpoondown\relbar\relbar
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\rightharpoonupfill@}
%    \begin{macrocode}
\newcommand*{\rightharpoonupfill@}{%
  \arrowfill@\relbar\relbar\rightharpoonup
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macrocode}
%</package>
%    \end{macrocode}
% \section{Installation}
%
% \paragraph{CTAN.} This package is available on
% CTAN\footnote{\url{ftp://ftp.ctan.org/tex-archive/}}:
% \begin{description}
% \item[\CTAN{macros/latex/contrib/oberdiek/chemarr.dtx}] The source file.
% \item[\CTAN{macros/latex/contrib/oberdiek/chemarr.pdf}] Documentation.
% \end{description}
%
% \paragraph{Unpacking.} The \xfile{.dtx} file is a self-extracting
% \docstrip\ archive. The files are extracted by running the
% \xfile{.dtx} through \plainTeX:
% \begin{quote}
%   \verb|tex chemarr.dtx|
% \end{quote}
%
% \paragraph{TDS.} Now the different files must be moved into
% the different directories in your installation TDS tree
% (also known as \xfile{texmf} tree):
% \begin{quote}
% \sbox0{^^A
% \begin{tabular}{@{}>{\ttfamily}l@{$\quad\rightarrow\quad$}>{\ttfamily}l@{}}
%   chemarr.sty & tex/latex/oberdiek/chemarr.sty\\
%   chemarr.pdf & doc/latex/oberdiek/chemarr.pdf\\
%   chemarr-example.tex & doc/latex/oberdiek/chemarr-example.tex\\
%   chemarr.dtx & source/latex/oberdiek/chemarr.dtx\\
% \end{tabular}^^A
% }%
% \ifdim\wd0>\linewidth
%   \mbox{}\nobreak\hskip0pt minus\leftmargin
%   \usebox0
%   \nobreak\hskip0pt minus\rightmargin
% \else
%   \usebox0
% \fi
% \end{quote}
% If you have a \xfile{docstrip.cfg} that configures and enables \docstrip's
% TDS installing feature, then some files can already be in the right
% place, see the documentation of \docstrip.
%
% \paragraph{Refresh file databases.} If your \TeX~distribution
% (\teTeX, \mikTeX, \dots) rely on file databases, you must refresh
% these. For example, \teTeX\ users run \verb|texhash| or
% \verb|mktexlsr|.
%
% \subsection{Some details for the interested}
%
% \paragraph{Attached source.}
%
% The PDF documentation on CTAN also includes the
% \xfile{.dtx} source file. It can be extracted by
% AcrobatReader 6 or higher. Another option is \textsf{pdftk},
% e.g. unpack the file into the current directory:
% \begin{quote}
%   \verb|pdftk chemarr.pdf unpack_files output .|
% \end{quote}
%
% \paragraph{Unpacking with \LaTeX.}
% The \xfile{.dtx} chooses its action depending on the format:
% \begin{description}
% \item[\plainTeX:] Run \docstrip\ and extract the files.
% \item[\LaTeX:] Generate the documentation.
% \end{description}
% If you insist on using \LaTeX\ for \docstrip\ (really,
% \docstrip\ does not need \LaTeX), then inform the autodetect routine
% about your intention:
% \begin{quote}
%   \verb|latex \let\install=y\input{chemarr.dtx}|
% \end{quote}
% Do not forget to quote the argument according to the demands
% of your shell.
%
% \paragraph{Generating the documentation.}
% You can use both the \xfile{.dtx} or the \xfile{.drv} to generate
% the documentation. The process can be configured by the
% configuration file \xfile{ltxdoc.cfg}. For instance, put this
% line into this file, if you want to have A4 as paper format:
% \begin{quote}
%   \verb|\PassOptionsToClass{a4paper}{article}|
% \end{quote}
% An example follows how to generate the
% documentation with pdf\LaTeX:
% \begin{quote}
%\begin{verbatim}
%pdflatex chemarr.dtx
%makeindex -s gind.ist chemarr.idx
%pdflatex chemarr.dtx
%makeindex -s gind.ist chemarr.idx
%pdflatex chemarr.dtx
%\end{verbatim}
% \end{quote}
%
% \begin{History}
%   \begin{Version}{2001/06/21 v1.0}
%   \item
%     First public version.
%   \end{Version}
%   \begin{Version}{2001/06/22 v1.1}
%   \item
%     Documentation fixes.
%   \end{Version}
%   \begin{Version}{2006/02/20 v1.2}
%   \item
%     DTX framework.
%   \item
%     Example added.
%   \end{Version}
% \end{History}
%
% \PrintIndex
%
% \Finale
\endinput
