Count number of word occurrences in strings using XQuery - xquery

Question

We have a very similar XML file to this:
<?xml version="1.0" encoding="UTF-8"?>
<nodeOne>
<nodeTwo>
<nodeThree>
foo bar zoo
</nodeThree>
</nodeTwo>
</nodeOne>
<nodeOne>
<nodeTwo>
<nodeThree>
foo bar
</nodeThree>
</nodeTwo>
</nodeOne>
<nodeOne>
<nodeTwo>
<nodeThree>
zoo bar
</nodeThree>
</nodeTwo>
</nodeOne>
What I would like to achieve is to count the occurrences of every word (delimitered by a whitespace) inside nodeThree. Considering the above example, the output would be something like:
foo 2
bar 3
zoo 2
I've tried to fetch every text() of nodeThree, and tried to tokenize() it into sequences of strings. Then, I thought, I might be able to join them and group, count afterwards, but I was not able to do so. Tried a lot of things until now.

Answer 1

First note that your XML is ill-formed (i.e. it's not really XML) unless you create a single root node to wrap it.
If performance is a concern, this problem is much better suited to leverage a word index with frequency data, like in an XML database. Solving this in pure XQuery may be considerably slower for large XML but solves the problem:
let $xml :=
<root>
<nodeOne>
<nodeTwo>
<nodeThree>
foo bar zoo
</nodeThree>
</nodeTwo>
</nodeOne>
<nodeOne>
<nodeTwo>
<nodeThree>
foo bar
</nodeThree>
</nodeTwo>
</nodeOne>
<nodeOne>
<nodeTwo>
<nodeThree>
zoo bar
</nodeThree>
</nodeTwo>
</nodeOne>
</root>
let $toks := $xml//text()/fn:tokenize(fn:normalize-space(.),'\s')
for $t in distinct-values($toks)
let $count := count($toks[. = $t])
return element { $t } {
attribute count { $count }
}
=>
<foo count="2"/>
<bar count="3"/>
<zoo count="2"/>