--- /dev/null	Fri Sep  9 14:16:49 2011
+++ new/agent/src/share/classes/sun/jvm/hotspot/runtime/InstanceConstructor.java	Fri Sep  9 14:17:11 2011
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2011, 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 sun.jvm.hotspot.runtime;
+
+import java.util.*;
+import sun.jvm.hotspot.debugger.*;
+import sun.jvm.hotspot.debugger.cdbg.CDebugger;
+import sun.jvm.hotspot.debugger.cdbg.ClosestSymbol;
+import sun.jvm.hotspot.debugger.cdbg.LoadObject;
+import sun.jvm.hotspot.types.*;
+import sun.jvm.hotspot.HotSpotTypeDataBase;
+
+/** Given a pointer to some memory return an appropriate wrapper.
+ Various subclasses provide different mechanisms for identifying the
+ appropriate wrapper. */
+
+abstract public class InstanceConstructor<T> {
+  /** Instantiate the most-precisely typed wrapper object available
+      for the type of the given Address. If no type in the mapping
+      matched the type of the Address, throws a WrongTypeException.
+      Returns null for a null address (similar behavior to
+      VMObjectFactory). */
+  abstract public T instantiateWrapperFor(Address addr) throws WrongTypeException;
+
+  protected WrongTypeException newWrongTypeException(Address addr) {
+    String message = "No suitable match for type of address " + addr;
+    CDebugger cdbg = VM.getVM().getDebugger().getCDebugger();
+    if (cdbg != null) {
+      // Most common case: V-table pointer is the first field
+      Address vtblPtr = addr.getAddressAt(0);
+      LoadObject lo = cdbg.loadObjectContainingPC(vtblPtr);
+      if (lo != null) {
+        ClosestSymbol symbol = lo.closestSymbolToPC(vtblPtr);
+        if (symbol != null) {
+          message += " (nearest symbol is " + symbol.getName() + ")";
+        }
+      }
+    }
+
+    return new WrongTypeException(message);
+  }
+}