Text Formatting ⇒ Executing external code in Presentation

[turok]

I have posted similar question but it is without answer, so I try to workaround the problem.

I use beamer to create presentations with code listings. Sometimes I need to highlight some piece of text, for example one variable (counter in the code below). Now I do it using lstlisting and escapechar. Is it any way to execute external code, for example Java, Python, etc. I would modify (change counter to |\red{counter}|) source code externally and import modified source file.

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\documentclass{beamer}
\usepackage{ucs}
\usepackage[utf8x]{inputenc}
\usepackage{listings}

\lstset{
	language=Java,
	tabsize=4,
	breaklines=true,
	breakatwhitespace=true,
	escapechar=|,
	basicstyle=\footnotesize\ttfamily,
	numberstyle=\footnotesize\ttfamily,
	aboveskip=\baselineskip,
	captionpos=b,
	columns=fullflexible,
	showstringspaces=false,
	extendedchars=true,
	breaklines=true,
	showtabs=false,
	showspaces=false,
	showstringspaces=false,
	identifierstyle=\ttfamily,
	keywordstyle=\color[rgb]{0.498,0.0,0.333},
	stringstyle=\color[rgb]{0.165,0.0,0.999},
	commentstyle=\color[rgb]{0.247,0.498,0.372}
}

\newcommand\red[1]{\setlength\fboxsep{0pt}\colorbox{red}{\strut #1}}

\begin{document}

\begin{frame}[fragile]{Test}
\begin{lstlisting}
public class Main {
    int counter;
    public static void main(String[] args) {
        for (counter = 0; counter < 10; counter++)
            System.out.println('HelloWorld');
    }
}
\end{lstlisting}
\end{frame}

\begin{frame}[fragile]{Test}
\begin{lstlisting}
public class Main {
    int |\red{counter}|;
    public static void main(String[] args) {
        for (|\red{counter}| = 0; |\red{counter}| < 10; |\red{counter}|++)
            System.out.println('HelloWorld');
    }
}
\end{lstlisting}
\end{frame}

\begin{frame}[fragile]{Test}
\lstinputlisting{Main.java}
\end{frame}

\begin{frame}[fragile]{Test}
???
% extecute external code Java, Python, etc.
\lstinputlisting{ModifiedMain.java}
\end{frame}

\end{document}

[turok]

If there is no other way, I will solve this problem as follows. I will add mock instruction: \newcommand\modifyExternal[4]{}. For every file which should be modified I will add:
- invocation of the instruction, for example \modifyExternal{Main.java}{ModifiedMain.java}{"counter"}{"|\red{counter}|"},
- listing for modified fille (which will be generated later), for example \lstinputlisting{ModifiedMain.java}.
Before executing

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latex Main.tex

I will add

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java Modifier Main.tex

The Modifier will read file Main.java, change every counter to |\red{counter}| and write all to file ModifiedMain.java, so LaTeX will see modified file.