% graphviz.tex
% originally written by Derek Rayside, November 2003
% following an idea that Daniel Jackson implemented in his Tagger program
%
% Nov 19, 2007: reuse write channel (Erik Pitzer)
%
% parameters to \digraph:
% 1 - parameters for \includegraphics (optional; default value is "scale=1")
% 2 - name of the digraph
% 3 - body of the digraph

\newwrite\dotfile

\newcommand{\digraph}[3][scale=1]{
    \immediate\openout\dotfile=#2.dot
    \immediate\write\dotfile{digraph #2 {\string#3}}
    \immediate\closeout\dotfile
    \IfFileExists{#2.ps}
        % the postscript exists: include it
        { \includegraphics[#1]{#2} }
        % the postscript doesn't exist: tell the user how to create it
        { \fbox{ \begin{tabular}{l}
            The file \texttt{#2.ps} hasn't been created from
            \texttt{#2.dot} yet. \\
            Run texttt{dot -Tps -o #2.ps #2.dot}' to create it. \\
            Here is a \textsf{bash} loop to process all \textsf{dot} files
            in the current directory: \\
            \texttt{
            for f in *.dot do ;
            dot -Tps -o \$\{f\%dot\}ps \$f ;
            done
            }
            \end{tabular}}
        }
}