--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/frame/FrameDescriptor.java	Tue Dec 18 15:33:55 2012 +0100
@@ -0,0 +1,201 @@
+/*
+ * Copyright (c) 2012, 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.frame;
+
+import java.util.*;
+
+/**
+ * Descriptor of the slots of frame objects. Multiple frame instances are associated with one such descriptor.
+ */
+public final class FrameDescriptor {
+
+    protected final TypeConversion typeConversion;
+    private final ArrayList<FrameSlotImpl> slots;
+    private FrameVersionImpl lastVersion;
+    private final HashMap<String, FrameSlotImpl> nameToSlotMap;
+
+    public FrameDescriptor() {
+        this(DefaultTypeConversion.getInstance());
+    }
+
+    public FrameDescriptor(TypeConversion typeConversion) {
+        this.typeConversion = typeConversion;
+        slots = new ArrayList<>();
+        nameToSlotMap = new HashMap<>();
+        lastVersion = new FrameVersionImpl();
+    }
+
+    public FrameSlot addFrameSlot(String name) {
+        return addFrameSlot(name, typeConversion.getTopType());
+    }
+
+    public FrameSlot addFrameSlot(String name, Class<?> type) {
+        assert !nameToSlotMap.containsKey(name);
+        FrameSlotImpl slot = new FrameSlotImpl(this, name, slots.size(), type);
+        slots.add(slot);
+        nameToSlotMap.put(name, slot);
+        return slot;
+    }
+
+    public FrameSlot findFrameSlot(String name) {
+        return nameToSlotMap.get(name);
+    }
+
+    public FrameSlot findOrAddFrameSlot(String name) {
+        FrameSlot result = findFrameSlot(name);
+        if (result != null) {
+            return result;
+        }
+        return addFrameSlot(name);
+    }
+
+    public FrameVersion getCurrentVersion() {
+        return lastVersion;
+    }
+
+    public int getSize() {
+        return slots.size();
+    }
+
+    public List< ? extends FrameSlot> getSlots() {
+        return Collections.unmodifiableList(slots);
+    }
+
+    protected void appendVersion(FrameVersionImpl newVersion) {
+        lastVersion.next = newVersion;
+        lastVersion = newVersion;
+    }
+}
+
+class FrameVersionImpl implements FrameVersion {
+
+    protected FrameVersionImpl next;
+
+    @Override
+    public final FrameVersion getNext() {
+        return next;
+    }
+}
+
+class TypeChangeFrameVersionImpl extends FrameVersionImpl implements FrameVersion.TypeChange {
+
+    private final FrameSlotImpl slot;
+    private final Class< ? > oldType;
+    private final Class< ? > newType;
+
+    protected TypeChangeFrameVersionImpl(FrameSlotImpl slot, Class< ? > oldType, Class< ? > newType) {
+        this.slot = slot;
+        this.oldType = oldType;
+        this.newType = newType;
+    }
+
+    @Override
+    public final void applyTransformation(Frame frame) {
+        Object value = slot.getValue(oldType, frame);
+        slot.setValue(newType, frame, value);
+    }
+}
+
+class FrameSlotImpl implements FrameSlot {
+
+    private final FrameDescriptor descriptor;
+    private final String name;
+    private final int index;
+    private Class< ? > type;
+    private ArrayList<FrameSlotTypeListener> listeners;
+
+    protected FrameSlotImpl(FrameDescriptor descriptor, String name, int index, Class< ? > type) {
+        this.descriptor = descriptor;
+        this.name = name;
+        this.index = index;
+        this.type = type;
+        assert type != null;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getIndex() {
+        return index;
+    }
+
+    public Class< ? > getType() {
+        return type;
+    }
+
+    protected Object getValue(Class< ? > accessType, Frame frame) {
+        if (accessType == Integer.class) {
+            return frame.getInt(this);
+        } else if (accessType == Long.class) {
+            return frame.getLong(this);
+        } else if (accessType == Float.class) {
+            return frame.getFloat(this);
+        } else if (accessType == Double.class) {
+            return frame.getDouble(this);
+        } else {
+            return frame.getObject(this);
+        }
+    }
+
+    protected void setValue(Class< ? > accessType, Frame frame, Object value) {
+        Object newValue = descriptor.typeConversion.convertTo(accessType, value);
+        if (accessType == Integer.class) {
+            frame.setInt(this, (Integer) newValue);
+        } else if (accessType == Long.class) {
+            frame.setLong(this, (Long) newValue);
+        } else if (accessType == Float.class) {
+            frame.setFloat(this, (Float) newValue);
+        } else if (accessType == Double.class) {
+            frame.setDouble(this, (Double) newValue);
+        } else {
+            frame.setObject(this, newValue);
+        }
+    }
+
+    public void setType(final Class< ? > type) {
+        final Class< ? > oldType = this.type;
+        this.type = type;
+        ArrayList<FrameSlotTypeListener> oldListeners = this.listeners;
+        this.listeners = null;
+        if (oldListeners != null) {
+            for (FrameSlotTypeListener listener : oldListeners) {
+                listener.typeChanged(this, oldType);
+            }
+        }
+        descriptor.appendVersion(new TypeChangeFrameVersionImpl(this, oldType, type));
+    }
+
+    @Override
+    public String toString() {
+        return "[" + index + "," + name + "]";
+    }
+
+    @Override
+    public void registerOneShotTypeListener(FrameSlotTypeListener listener) {
+        if (listeners == null) {
+            listeners = new ArrayList<>();
+        }
+        listeners.add(listener);
+    }
+}