Unable to understand this xquery function

Question

I am new to xquery and unable to understand what does it means :

 declare function my:get-unique-lines($object)
 {
   let $lines := distinct-values (
      for $line in $object[contains(@name," ")]/@name
      return (string-join(tokenize($line," ")[position()< last()]," "))
   )
   return $lines
 };

Answer 1

Well firstly, the variable $lines is obviously redundant. We're left with

distinct-values (
      for $line in $object[contains(@name," ")]/@name
      return (string-join(tokenize($line," ")[position()< last()]," "))

What string-join(tokenize($line," ")[position()< last()] does is to split $line into tokens at space boundaries, take all tokens except the last, and then join them back together with space as a separator.

We do that for all the selected @name values, and then remove duplicates.

So if $object contains a list of element like

<e name="John Smith"/>
<e name="John Jones"/>
<e name="John Henry Jones"/>
<e name="John Henry Miller"/>

the result will be the two strings "John" and "John Henry".