scala.xml.transform.BasicTransformer.scala Maven / Gradle / Ivy
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
package xml
package transform
/**
* A class for XML transformations.
*
* @author Burak Emir
* @version 1.0
*/
abstract class BasicTransformer extends Function1[Node, Node] {
protected def unchanged(n: Node, ns: Seq[Node]) =
ns.length == 1 && (ns.head == n)
/**
* Call transform(Node) for each node in ns, append results
* to NodeBuffer.
*/
def transform(it: Iterator[Node], nb: NodeBuffer): Seq[Node] =
it.foldLeft(nb)(_ ++= transform(_)).toSeq
/**
* Call transform(Node) to each node in ns, yield ns if nothing changes,
* otherwise a new sequence of concatenated results.
*/
def transform(ns: Seq[Node]): Seq[Node] = {
val (xs1, xs2) = ns span (n => unchanged(n, transform(n)))
if (xs2.isEmpty) ns
else xs1 ++ transform(xs2.head) ++ transform(xs2.tail)
}
def transform(n: Node): Seq[Node] = {
if (n.doTransform) n match {
case Group(xs) => Group(transform(xs)) // un-group the hack Group tag
case _ =>
val ch = n.child
val nch = transform(ch)
if (ch eq nch) n
else Elem(n.prefix, n.label, n.attributes, n.scope, nch.isEmpty, nch: _*)
}
else n
}
def apply(n: Node): Node = {
val seq = transform(n)
if (seq.length > 1)
throw new UnsupportedOperationException("transform must return single node for root")
else seq.head
}
}