--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/truffle/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/ReplaceTest.java	Wed Jun 17 10:58:08 2015 +0200
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.truffle.api.test;
+
+import static org.junit.Assert.*;
+
+import java.util.*;
+
+import org.junit.*;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.nodes.*;
+
+/**
+ * <h3>Replacing Nodes at Run Time</h3>
+ *
+ * <p>
+ * The structure of the Truffle tree can be changed at run time by replacing nodes using the
+ * {@link Node#replace(Node)} method. This method will automatically change the child pointer in the
+ * parent of the node and replace it with a pointer to the new node.
+ * </p>
+ *
+ * <p>
+ * Replacing nodes is a costly operation, so it should not happen too often. The convention is that
+ * the implementation of the Truffle nodes should ensure that there are maximal a small (and
+ * constant) number of node replacements per Truffle node.
+ * </p>
+ *
+ * <p>
+ * The next part of the Truffle API introduction is at {@link com.oracle.truffle.api.test.CallTest}.
+ * </p>
+ */
+public class ReplaceTest {
+
+    @Test
+    public void test() {
+        TruffleRuntime runtime = Truffle.getRuntime();
+        UnresolvedNode leftChild = new UnresolvedNode("20");
+        UnresolvedNode rightChild = new UnresolvedNode("22");
+        TestRootNode rootNode = new TestRootNode(new ValueNode[]{leftChild, rightChild});
+        CallTarget target = runtime.createCallTarget(rootNode);
+        assertEquals(rootNode, leftChild.getParent());
+        assertEquals(rootNode, rightChild.getParent());
+        Iterator<Node> iterator = rootNode.getChildren().iterator();
+        Assert.assertEquals(leftChild, iterator.next());
+        Assert.assertEquals(rightChild, iterator.next());
+        Assert.assertFalse(iterator.hasNext());
+        Object result = target.call();
+        assertEquals(42, result);
+        assertEquals(42, target.call());
+        iterator = rootNode.getChildren().iterator();
+        Assert.assertEquals(ResolvedNode.class, iterator.next().getClass());
+        Assert.assertEquals(ResolvedNode.class, iterator.next().getClass());
+        Assert.assertFalse(iterator.hasNext());
+        iterator = rootNode.getChildren().iterator();
+        Assert.assertEquals(rootNode, iterator.next().getParent());
+        Assert.assertEquals(rootNode, iterator.next().getParent());
+        Assert.assertFalse(iterator.hasNext());
+    }
+
+    class TestRootNode extends RootNode {
+
+        @Children private final ValueNode[] children;
+
+        public TestRootNode(ValueNode[] children) {
+            super(null);
+            this.children = children;
+        }
+
+        @Override
+        public Object execute(VirtualFrame frame) {
+            int sum = 0;
+            for (int i = 0; i < children.length; ++i) {
+                sum += children[i].execute();
+            }
+            return sum;
+        }
+    }
+
+    abstract class ValueNode extends Node {
+
+        public ValueNode() {
+            super(null);
+        }
+
+        abstract int execute();
+    }
+
+    class UnresolvedNode extends ValueNode {
+
+        private final String value;
+
+        public UnresolvedNode(String value) {
+            this.value = value;
+        }
+
+        @Override
+        int execute() {
+            int intValue = Integer.parseInt(value);
+            ResolvedNode newNode = this.replace(new ResolvedNode(intValue));
+            return newNode.execute();
+        }
+    }
+
+    class ResolvedNode extends ValueNode {
+
+        private final int value;
+
+        ResolvedNode(int value) {
+            this.value = value;
+        }
+
+        @Override
+        int execute() {
+            return value;
+        }
+    }
+}