XML transformations 2

This topic is a continuation of XML Transformations. The previous topic showed a method of creating transformation rules then combining the rules to create a transformation that could be applied to an XML datastructure. This topic takes a different approach of
using a match statement an a recursive method to iterate through the tree.

1. scala> val xml = <library>
2.      | <videos>
3.      | <video type="dvd">Seven</video>
4.      | <video type="blue-ray">The fifth element</video>
5.      | <video type="hardcover">Gardens of the moon</video>
6.      | </videos>
7.      | <books>
8.      | <book type="softcover">Memories of Ice</book>
9.      | </books>
10.      | </library>
11. xml: scala.xml.Elem = 
12. <library>
13.        <videos>
14.        <video type="dvd">Seven</video>
15.        <video type="blue-ray">The fifth element</video>
16.        <video type="hardcover">Gardens of the moon</video>
17.        </videos>
18.        <books>
19.        <book type="softcover">Memories of Ice</book>
20.        </books>
21.        </library>
23. scala> import scala.xml._
24. import scala.xml._
26. scala> def moveElements (node:Node) : Node = node match {
27.      | case n:Elem if (n.label == "videos") => 
28.      |   n.copy( child = n.child diff mislabelledBooks)
29.      | case n:Elem if (n.label == "books") =>
30.      |   val newBooks = mislabelledBooks map { e => e.asInstanceOf[Elem].copy(label="book") }
31.      |   n.copy( child = n.child ++ newBooks)
32.      | case n:Elem => 
33.      |   val children = n.child map {moveElements _}
34.      |   n.copy(child = children)
35.      | case n => n
36.      | }
37. moveElements: (node: scala.xml.Node)scala.xml.Node
39. scala> moveElements(xml)
40. res1: scala.xml.Node = 
41. <library>
42.               <videos>
43.               <video type="dvd">Seven</video>
44.               <video type="blue-ray">The fifth element</video>
45.               
46.               </videos>
47.               <books>
48.               <book type="softcover">Memories of Ice</book>
49.               <book type="hardcover">Gardens of the moon</book></books>
50.               </library>