2007-02-28 Kyle Galloway <kgallowa@redhat.com>

	* gnu/classpath/jdwp/id/NullObjectId.java: New class.
	* gnu/classpath/jdwp/util/NullObject.java: New class.
	* vm/reference/gnu/classpath/jdwp/VMIdManager.java
	(getObjectId): Handle null object.
	(get): Handle objectId of 0.

2 files changed, 129 insertions, 0 deletions

diff --git a/gnu/classpath/jdwp/id/NullObjectId.java b/gnu/classpath/jdwp/id/NullObjectId.java
new file mode 100644
index 000000000..0e7b5e39c
--- /dev/null
+++ b/gnu/classpath/jdwp/id/NullObjectId.java
@@ -0,0 +1,79 @@
+/* NullObjectId.java -- special objectId for null values
+   Copyright (C) 2007 Free Software Foundation
+
+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 gnu.classpath.jdwp.id;
+
+import gnu.classpath.jdwp.exception.InvalidObjectException;
+import gnu.classpath.jdwp.util.NullObject;
+
+import java.lang.ref.SoftReference;
+
+/**
+ * This is a special case of an ObjectId.  When a varaible slot contains
+ * null as its value, this is a valid value despite the fact that it does
+ * not reference an object.  To represent this, this will always be the id
+ * of the NullObject (0).
+ *
+ * @author Kyle Galloway  <kgallowa@redhat.com>
+ */
+public class NullObjectId
+  extends ObjectId
+{
+  /**
+   * The object class that this id represents
+   */
+  public static final Class typeClass = NullObject.class;
+  
+  /**
+   * Constructs a new <code>NullObjectId</code>
+   */
+  public NullObjectId()
+  {
+    super();
+    setId((long) 0);
+    _reference = new SoftReference<NullObject>(new NullObject());
+    try
+      {
+        disableCollection();
+      }
+    catch(InvalidObjectException ex)
+      {
+        //This will not happen
+      }
+  }
+
+}
diff --git a/gnu/classpath/jdwp/util/NullObject.java b/gnu/classpath/jdwp/util/NullObject.java
new file mode 100644
index 000000000..ec762fc2f
--- /dev/null
+++ b/gnu/classpath/jdwp/util/NullObject.java
@@ -0,0 +1,50 @@
+/* NullObject.java -- placeholder for null values
+   Copyright (C) 2007 Free Software Foundation
+
+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 gnu.classpath.jdwp.util;
+
+/**
+ * This is a placeholder for null.  There are several places in JDWP where null
+ * is a valid value (i.e. when geting the value of a variable slot that
+ * contains a null reference at that time).  This class distinguishes between
+ * these "meaningful" null values and invalid null pointers.
+ *
+ * @author Kyle Galloway  <kgallowa@redhat.com>
+ */
+public class NullObject
+{
+}