From 8814de2aa0fc14df0785dfa9ee96d154c32e5646 Mon Sep 17 00:00:00 2001
From: Paul Phillips <paulp@improving.org>
Date: Fri, 28 Aug 2009 11:25:43 +0000
Subject: Fix and test case for #2276.

---
 .../scala/xml/transform/BasicTransformer.scala     | 16 ++++-----------
 test/files/run/bug2276.check                       |  8 ++++++++
 test/files/run/bug2276.scala                       | 24 ++++++++++++++++++++++
 3 files changed, 36 insertions(+), 12 deletions(-)
 create mode 100644 test/files/run/bug2276.check
 create mode 100644 test/files/run/bug2276.scala

diff --git a/src/library/scala/xml/transform/BasicTransformer.scala b/src/library/scala/xml/transform/BasicTransformer.scala
index 917884617c..a79c32a5f0 100644
--- a/src/library/scala/xml/transform/BasicTransformer.scala
+++ b/src/library/scala/xml/transform/BasicTransformer.scala
@@ -25,7 +25,7 @@ abstract class BasicTransformer extends Function1[Node,Node]
    *  @return   ...
    */
   protected def unchanged(n: Node, ns: Seq[Node]) =
-    ns.length == 1 && (ns.head eq n)
+    ns.length == 1 && (ns.head == n)
 
   /** Call transform(Node) for each node in ns, append results
    *  to NodeBuffer.
@@ -37,18 +37,10 @@ abstract class BasicTransformer extends Function1[Node,Node]
    *  otherwise a new sequence of concatenated results.
    */
   def transform(ns: Seq[Node]): Seq[Node] = {
-    def testForChange(n: Node): Option[Seq[Node]] = {
-      val n2 = transform(n)
-      if (unchanged(n, n2)) None
-      else Some(n2)
-    }
-    // if any node is changed by the transform, concatenate
-    // the unchanged nodes with a recursive call.
-    for ((n, i) <- ns.zipWithIndex ; n2 <- testForChange(n))
-      return (ns take i) ++ transform(n2)
+    val (xs1, xs2) = ns span (n => unchanged(n, transform(n)))
 
-    // no change, return original sequence
-    ns
+    if (xs2.isEmpty) ns
+    else xs1 ++ transform(xs2.head) ++ transform(xs2.tail)
   }
 
   def transform(n: Node): Seq[Node] = {
diff --git a/test/files/run/bug2276.check b/test/files/run/bug2276.check
new file mode 100644
index 0000000000..95f51c8e29
--- /dev/null
+++ b/test/files/run/bug2276.check
@@ -0,0 +1,8 @@
+<root>
+      <subnode>
+        <version>2</version>
+      </subnode>
+      <contents>
+        <version>2</version>
+      </contents>
+    </root>
diff --git a/test/files/run/bug2276.scala b/test/files/run/bug2276.scala
new file mode 100644
index 0000000000..815e88e429
--- /dev/null
+++ b/test/files/run/bug2276.scala
@@ -0,0 +1,24 @@
+import scala.xml._
+import scala.xml.transform._
+
+object Test extends Application {
+  val inputXml : Node =
+    <root>
+      <subnode>
+        <version>1</version>
+      </subnode>
+      <contents>
+        <version>1</version>
+      </contents>
+    </root>
+
+  object t1 extends RewriteRule {
+    override def transform(n: Node): Seq[Node] = n match {
+      case <version>{x}</version> if x.toString.toInt < 4 => <version>{x.toString.toInt+1}</version>
+      case other => other
+    }
+  }
+
+  val ruleTransformer = new RuleTransformer(t1)
+  println(ruleTransformer(inputXml))
+}
\ No newline at end of file
-- 
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