Dynamic Table/Multirow with xstring macro

Question

I'm getting a little bit lost with the following. As I'm quite new to using TeX for more than just typesetting, I hope to get some help here.

I already searched this forum for some helpful posts and found many of them, but I didn't got all problems solved I ran into.

What I want to do is to automatically typeset a list of IP addresses and the corresponding FQDNs into a table. It should look like:

Source: IP1:FQDN1;IP2:FQDN2;...

       |  IP1   FQDN1
Hosts  |  IP2   FQDN2
       |  ...   ...

Here's what I tried to do (shortened down the code to the essential piece):

\documentclass{article}
\usepackage{xstring}
\usepackage{multirow}

\begin{document}
% test input
\newcommand{\myinput}{IP1:FQDN1;IP2:FQDN2}

\newcommand{\splitstring}[1]{
  % split input into table rows
  \ifx\@empty#1\else
  \saveexpandmode\expandarg
  % split column elements with leading & (after multirow)
  \StrSubstitute{\tmp}{;}{\empty\\&}[\tmp] % fails with: forbidden control sequence found while scanning use of \@xs@next
  % split row elements
  \StrSubstitute{#1}{:}{&}[\tmp]
  \restoreexpandmode\tmp
}

\begin{tabular}{l|ll}
  % StrCount fails (Missing number, treated as zero)
  \multirow{\StrCount{\myinput}{:}}{*}{Hosts} & \splitstring{\myinput}
\end{tabular}
\end{document}

Edit

Some additional information: Changing the line

 \StrSubstitute{\tmp}{;}{\empty\\&}[\tmp]

to

 \StrSubstitute{\tmp}{;}{\empty\\}[\tmp]

(and removing the &) makes this step build without errors. The output looks like this:

        |  IP1   FQDN1 
 Hosts  |
  IP2   |  FQDN2

As you can see the & is needed for correct alignement in the table. I'm wondering why the substitution of ":" by "&" works without error, but this one fails.

No further news on feeding the StrCount output into the multirow-environment.

Edit

I'm not sure if I can use the output from the xstring-functions for typesetting or if they can be converted to be used as parameters.

Any help is greatly appreciated.

Answer 1

I continue to believe that every table built with \multirow can be improved by removing it. This is one of the cases:

\documentclass{article}
\usepackage{xstring}

\begin{document}
% test input
\newcommand{\myinput}{IP1:FQDN1;IP2:FQDN2}

\newcommand{\splitstring}[1]{%
  \saveexpandmode\expandarg
  % split input into table rows
  \StrSubstitute{#1}{;}{\noexpand\\}[\tmp]%
  % split columns
  \StrSubstitute{\tmp}{:}{&}[\tmp]%
  \restoreexpandmode
  \begin{tabular}{@{}ll@{}}\tmp\end{tabular}
}

\begin{tabular}{l|l}
Hosts & \splitstring{\myinput}
\end{tabular}

\bigskip

\renewcommand{\myinput}{}

\begin{tabular}{l|l}
Hosts & \splitstring{\myinput}
\end{tabular}

\end{document}

The idea is to build an inner table with the addresses. I've also shown that it works also with empty input.