1 files changed, 90 insertions, 0 deletions
diff --git a/libjava/classpath/java/beans/PersistenceDelegate.java b/libjava/classpath/java/beans/PersistenceDelegate.java
new file mode 100644
index 000000000..d4e777844
--- /dev/null
+++ b/libjava/classpath/java/beans/PersistenceDelegate.java
@@ -0,0 +1,90 @@
+/* java.beans.PersistenceDelegate
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.beans;
+
+/** <p>A <code>PersistenceDelegate</code> describes how a another object
+ * has to constructed and transformed in order to create a complete
+ * replicate.</p>
+ *
+ * <p>For custom classes you will need to implement
+ * <code>PersistenceDelegate</code> in a way that is suitable for them.
+ * To make use of the implementation you have to register it with an
+ * {@link Encoder} using the {Encoder#setPersistenceDelegate} method.</p>
+ *
+ * @author Robert Schuster (robertschuster@fsfe.org)
+ * @since 1.4
+ */
+public abstract class PersistenceDelegate
+{
+
+  protected void initialize(Class<?> type, Object oldInstance,
+                            Object newInstance, Encoder out)
+  {
+    if (type != Object.class)
+      {
+        type = type.getSuperclass();
+
+        PersistenceDelegate pd = out.getPersistenceDelegate(type);
+
+        pd.initialize(type, oldInstance, newInstance, out);
+      }
+  }
+
+  public void writeObject(Object oldInstance, Encoder out)
+  {
+    Object streamCandidate = out.get(oldInstance);
+
+    if (mutatesTo(oldInstance, streamCandidate))
+      {
+        initialize(oldInstance.getClass(), oldInstance, streamCandidate, out);
+      }
+    else
+      {
+        out.remove(oldInstance);
+        out.writeExpression(instantiate(oldInstance, out));
+      }
+  }
+
+  protected boolean mutatesTo(Object oldInstance, Object newInstance)
+  {
+    return (newInstance != null)
+           && oldInstance.getClass() == newInstance.getClass();
+  }
+
+  protected abstract Expression instantiate(Object oldInstance, Encoder out);
+}