hello

3 files changed, 151 insertions, 0 deletions

diff --git a/sources/scala/xml/transform/BasicTransformer.scala b/sources/scala/xml/transform/BasicTransformer.scala
new file mode 100644
index 0000000000..bf8f4b24f6
--- /dev/null
+++ b/sources/scala/xml/transform/BasicTransformer.scala
@@ -0,0 +1,124 @@
+package scala.xml.transform ;
+
+/** a trait for XML transformations */
+trait BasicTransformer with Function1[Node,Node] {
+
+  protected case class NeedsCopy(result:Seq[Node]) extends java.lang.Throwable;
+
+  /** returns a new node buffer with the first pos elements from ns */
+  protected def buffer(pos:Int, ns:Seq[Node]): NodeBuffer = {
+    val nb = new NodeBuffer();
+    var jt = ns.elements;
+    var j = 0; while( j < pos-1 ) {
+      nb.append(jt.next);
+      j = j + 1;
+    }
+    nb
+  }
+
+  /** turns a nodebuffer into a sequence, so hashcode works */
+  protected def freeze(nb:NodeBuffer):Seq[Node] = {
+    val arr = new Array[Node](nb.length);
+    var i = 0;
+    val it = nb.elements; while( it.hasNext ) {
+      arr(i) = it.next;
+      i = i + 1;
+    }
+    val seq: Seq[Node] = arr;
+    seq
+  }
+
+  protected def single(ns:Seq[Node]) = {
+    (1 == ns.length)
+  }
+  protected def unchanged(n:Node, ns:Seq[Node]) = {
+    single(ns) && (ns.elements.next.eq(n))
+  }
+
+  /** call transform(Node) for each node in ns, append results
+   * to NodeBuffer */
+  def transform(it: Iterator[Node], nb:NodeBuffer): Seq[Node] = {
+    while( it.hasNext )
+      nb ++ transform( it.next );
+    freeze(nb);
+  }
+
+  /**
+   * 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] = {
+    var i = 0;
+    val it = ns.elements;
+    try {
+      while( it.hasNext ) {
+	val n = it.next;
+	val n2 = transform(n);
+	if(!unchanged(n,n2)) {
+	  throw NeedsCopy(n2)
+	}
+	i = i + 1;
+      }
+      ns
+    } catch {
+      case NeedsCopy(n2) =>
+	val nb = buffer(i, ns);
+	nb ++ n2;
+	transform(it, nb);
+    }
+  }
+
+  def transform(n: Node): Seq[Node] = {
+    if (n.typeTag$ < 0)
+      n
+    else {
+      val ch = n.child;
+      val nch = transform(ch);
+      if(ch.eq(nch))
+	n
+      else
+	Elem(n.namespace, n.label, n.attributes, nch:_*)
+    }
+  }
+
+  def apply(n: Node): Node = {
+    val seq = transform(n);
+    if( !single(seq) )
+      error("transform must return single node for root");
+    else seq.elements.next;
+  }
+}
+
+/*
+class IdentityTransformer extends BasicTransformer {
+  override def transform(n: Node): Seq[Node] = n.match {
+    case <world/> => <xml-world/>
+    case _ => super.transform(n);
+  }
+}
+
+object Foo with Application {
+
+  val tr = new IdentityTransformer;
+  val n = tr( <hello><world/></hello> );
+  Console.println(n);
+
+  val tr2 = new RewriteRule {
+    final override val name = "A rule";
+    override def transform(n: Node) = n.match {
+      case <a/> => <b/><c/>
+      case _    => n
+    }
+  }
+  val tr3 = new RewriteRule {
+    final override val name = "E rule";
+    override def transform(n: Node) = n.match {
+      case <e/> => <f><f/></f>
+      case _    => n
+    }
+  }
+  val tr4 = new RuleTransformer(tr2, tr3);
+  val m = tr4( <hello><a/><e/></hello> );
+  Console.println(m);
+}
+*/
diff --git a/sources/scala/xml/transform/RewriteRule.scala b/sources/scala/xml/transform/RewriteRule.scala
new file mode 100644
index 0000000000..c00d33aa96
--- /dev/null
+++ b/sources/scala/xml/transform/RewriteRule.scala
@@ -0,0 +1,13 @@
+package scala.xml.transform ;
+
+/** a RewriteRule, when applied to a term, yields either
+ *  the resulting of rewriting or the term itself it the rule
+ *  is not applied
+ */
+abstract class RewriteRule extends BasicTransformer {
+  /** a name for this rewrite rule */
+  val name = this.toString();
+  override def transform(ns:Seq[Node]): Seq[Node] = super.transform(ns);
+  override def transform(n:Node): Seq[Node] = n;
+}
+
diff --git a/sources/scala/xml/transform/RuleTransformer.scala b/sources/scala/xml/transform/RuleTransformer.scala
new file mode 100644
index 0000000000..6a967105e7
--- /dev/null
+++ b/sources/scala/xml/transform/RuleTransformer.scala
@@ -0,0 +1,14 @@
+package scala.xml.transform;
+
+class RuleTransformer(rules:RewriteRule*) extends BasicTransformer {
+  override def transform(n:Node): Seq[Node] = {
+    var m: Seq[Node] = super.transform(n);
+    val it = rules.elements; while(it.hasNext) {
+      val rule = it.next;
+      val m2 = rule.transform(m);
+      //if(!m2.eq(m)) Console.println("applied rule \""+rule.name+"\"");
+      m = m2;
+    }
+    m
+  }
+}