Does a (Lua) approach exist, to read XML data into a .tex file?

Question

I am having a lot of data in .xml files which look like this:

<DATA>
  <NAME="name" />
  <VERSION="1" />
  <VARIABLES>
    <TEST>
      <ELEMENT atr="0" atr2="1">123456.000000001</ELEMENT>
    </TEST>
  </VARIABLES>
</DATA>

I have to write a lot of templates reading this data for documentation and I would like to do this with LaTeX. Does any approach exist, to write this data into a .tex file? I want to write a file, where each {SOMETHING/SOMETHINGELSE} gets replaced by the XML value. A bonus would be, to get it rounded. As I am using LuaLaTeX, I guess there could be an approach in this language. But any other possibility would be interesting for me, too. Unluckily, I am not the scripting guy, but if you say, I should do this in python (which I would be willing to learn...), I will move this to an other SX-page.

The file would look something like this:

% arara: lualatex

\documentclass{article}
\usepackage{booktabs}
\usepackage{siunitx}

\begin{document}
\section{VolumeFlows}
A variable: $x=\SI{{VARIABLES/TEST/ELEMENT}}{\metre}$

\begin{table}%
\centering
\begin{tabular}{l S}
\toprule
Name & {Value}\\
\midrule
A variable & {VARIABLES/TEST/ELEMENT}\\
\bottomrule
\end{tabular}
\end{table}
\end{document}

Answer 1

Here is the general idea with the luaxml "package".

\documentclass{article}
\usepackage{luacode}
\begin{luacode*}
xml = require('luaxml-mod-xml')
handler = require('luaxml-mod-handler')
\end{luacode*}
\begin{document}
\begin{luacode*}
sample = [[
<DATA>
  <NAME="name" />
  <VERSION="1" />
  <VARIABLES>
    <TEST>
      <ELEMENT atr="0" atr2="1">123456.000000001</ELEMENT>
    </TEST>
  </VARIABLES>
</DATA>]]
treehandler = handler.simpleTreeHandler()
x = xml.xmlParser(treehandler)
x:parse(sample)
tex.sprint(treehandler.root["DATA"]["VARIABLES"]["TEST"]["ELEMENT"])
\end{luacode*}
\end{document}

EDIT

Probably a bit better but it's been a long time since I wrote some lua code...

% arara: lualatex

\documentclass{article}
\usepackage{siunitx}
\usepackage{booktabs}
\usepackage{luacode}
\begin{luacode*}
xml = require('luaxml-mod-xml')
handler = require('luaxml-mod-handler')
treehandler = handler.simpleTreeHandler()
xmlparser = xml.xmlParser(treehandler)

function readxmlfile(filename)
  local f = assert(io.open(filename, 'r'))
  local t = f:read('*all')
  f:close()
  return t
end

function parsexmlstring(string)
  xmlparser:parse(string)  
end
\end{luacode*}

\def\parsexmlfile#1{%
  \directlua{%
    parsexmlstring(readxmlfile('#1'))}}
\def\getxmlvalue#1#2#3#4{%
  \directlua{%
    tex.sprint(treehandler.root['#1']['#2']['#3']['#4'])}}    

\parsexmlfile{sample.xml}

\begin{document}
Variable: $x=\SI[round-mode=places,round-precision=1]{\getxmlvalue{DATA}{VARIABLES}{TEST}{ELEMENT}}{\metre}$

\begin{table}%
\centering
\begin{tabular}{l S[round-mode=places,round-precision=4]}
\toprule
Name & {Value}\\
\midrule
A variable & \getxmlvalue{DATA}{VARIABLES}{TEST}{ELEMENT}\\
\bottomrule
\end{tabular}
\end{table}
\end{document}

with sample.xml

<DATA>
  <NAME="name" />
  <VERSION="1" />
  <VARIABLES>
    <TEST>
      <ELEMENT atr="0" atr2="1">123456.000000001</ELEMENT>
    </TEST>
  </VARIABLES>
</DATA>