The history of luaTEX 2006–2009 / v 0.50 - Pragma ADE

document.xml, "/one/(three|five)/some"
), ', ', ' and '))
\stopluacode
We get: ‘pdftex, luatex, xetex and metapost’.
There a several helper functions, like xml.count which in this case returns 4.
\startluacode
tex.sprint(xml.count(document.xml,"/one/(three|five)/some"))
\stopluacode
Functions like this gives the opportunity to loop over lists of elements by index.
manipulations
We can manipulate elements too. The next code will add some elements at specic locations.
\startluacode
xml.before(document.xml,"/one/three/some","okay")
xml.after (document.xml,"/one/three/some","okay")
tex.sprint("\\starttyping")
xml.serialize_path(document.xml,"/one/three",tex.sprint)
tex.sprint("\\stoptyping")
\stopluacode
And indeed, we suddenly have a couple of ‘okay’'s there:
okaypdftexokay
okayluatexokay
okayxetexokay
Of course wel can also delete elements:
\startluacode
xml.delete(document.xml,"/one/three/some")
xml.delete(document.xml,"/one/three/af")
tex.sprint("\\starttyping")
xml.serialize_path(document.xml,"/one/three",tex.sprint)
tex.sprint("\\stoptyping")
\stopluacode
XML revisioned 137