--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/go/trove/util/NullKeyMap.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,270 @@
+/* ====================================================================
+ * Trove - Copyright (c) 1997-2000 Walt Disney Internet Group
+ * ====================================================================
+ * The Tea Software License, Version 1.1
+ *
+ * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Walt Disney Internet Group (http://opensource.go.com/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must
+ *    not be used to endorse or promote products derived from this
+ *    software without prior written permission. For written
+ *    permission, please contact opensource@dig.com.
+ *
+ * 5. Products derived from this software may not be called "Tea",
+ *    "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet",
+ *    "Kettle", "Trove" or "BeanDoc" appear in their name, without prior
+ *    written permission of the Walt Disney Internet Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * For more information about Tea, please see http://opensource.go.com/.
+ */
+
+package com.go.trove.util;
+
+import java.util.*;
+import java.io.Serializable;
+
+/******************************************************************************
+ * A Map supporting null keys that wraps a Map that doesn't support null keys.
+ * NullKeyMap substitutes null keys with a special placeholder object. This
+ * technique does not work when the wrapped Map is a TreeMap because it cannot
+ * be compared against other objects. In order for TreeMaps to support null
+ * keys, use any of the null ordering comparators found in the {@link Utils}
+ * class.
+ *
+ * @author Brian S O'Neill
+ * @version
+ * <!--$$Revision: 1.1 $-->, <!--$$JustDate:-->  9/07/00 <!-- $-->
+ */
+public class NullKeyMap extends AbstractMap implements Serializable {
+    // Instead of using null as a key, use this placeholder.
+    private static final Object NULL = new Serializable() {};
+
+    private Map mMap;
+
+    private transient Set mKeySet;
+    private transient Set mEntrySet;
+
+    /**
+     * @param map The map to wrap.
+     */
+    public NullKeyMap(Map map) {
+        mMap = map;
+    }
+    
+    public int size() {
+        return mMap.size();
+    }
+
+    public boolean isEmpty() {
+        return mMap.isEmpty();
+    }
+
+    public boolean containsKey(Object key) {
+        return (key == null) ? mMap.containsKey(NULL) : mMap.containsKey(key);
+    }
+
+    public boolean containsValue(Object value) {
+        return mMap.containsValue(value);
+    }
+
+    public Object get(Object key) {
+        return (key == null) ? mMap.get(NULL) : mMap.get(key);
+    }
+
+    public Object put(Object key, Object value) {
+        return mMap.put((key == null) ? NULL : key, value);
+    }
+
+    public Object remove(Object key) {
+        return (key == null) ? mMap.remove(NULL) : mMap.remove(key);
+    }
+
+    public void putAll(Map map) {
+        Iterator it = map.entrySet().iterator();
+        while (it.hasNext()) {
+            Map.Entry entry = (Map.Entry)it.next();
+            put(entry.getKey(), entry.getValue());
+        }
+    }
+
+    public void clear() {
+        mMap.clear();
+    }
+
+    public Set keySet() {
+        if (mKeySet == null) {
+            mKeySet = new AbstractSet() {
+                public Iterator iterator() {
+                    final Iterator it = mMap.keySet().iterator();
+
+                    return new Iterator() {
+                        public boolean hasNext() {
+                            return it.hasNext();
+                        }
+
+                        public Object next() {
+                            Object key = it.next();
+                            return (key == NULL) ? null : key;
+                        }
+
+                        public void remove() {
+                            it.remove();
+                        }
+                    };
+                }
+                
+                public boolean contains(Object key) {
+                    return containsKey((key == null) ? NULL : key);
+                }
+
+                public boolean remove(Object key) {
+                    if (key == null) {
+                        key = NULL;
+                    }
+                    if (containsKey(key)) {
+                        NullKeyMap.this.remove(key);
+                        return true;
+                    }
+                    else {
+                        return false;
+                    }
+                }
+
+                public int size() {
+                    return NullKeyMap.this.size();
+                }
+                
+                public void clear() {
+                    NullKeyMap.this.clear();
+                }
+            };
+        }
+
+        return mKeySet;
+    }
+
+    public Collection values() {
+        return mMap.values();
+    }
+
+    public Set entrySet() {
+        if (mEntrySet == null) {
+            mEntrySet = new AbstractSet() {
+                public Iterator iterator() {
+                    final Iterator it = mMap.entrySet().iterator();
+
+                    return new Iterator() {
+                        public boolean hasNext() {
+                            return it.hasNext();
+                        }
+
+                        public Object next() {
+                            final Map.Entry entry = (Map.Entry)it.next();
+                            if (entry.getKey() == NULL) {
+                                return new AbstractMapEntry() {
+                                    public Object getKey() {
+                                        return null;
+                                    }
+
+                                    public Object getValue() {
+                                        return entry.getValue();
+                                    }
+
+                                    public Object setValue(Object value) {
+                                        return entry.setValue(value);
+                                    }
+                                };
+                            }
+                            else {
+                                return entry;
+                            }
+                        }
+
+                        public void remove() {
+                            it.remove();
+                        }
+                    };
+                }
+                
+                public boolean contains(Object obj) {
+                    if (!(obj instanceof Map.Entry)) {
+                        return false;
+                    }
+                    Map.Entry entry = (Map.Entry)obj;
+                    Object key = entry.getKey();
+                    Object value = entry.getValue();
+                    if (key == null) {
+                        key = NULL;
+                    }
+                    Object lookup = get(key);
+                    if (lookup == null) {
+                        return value == null;
+                    }
+                    else {
+                        return lookup.equals(value);
+                    }
+                }
+
+                public boolean remove(Object obj) {
+                    if (!(obj instanceof Map.Entry)) {
+                        return false;
+                    }
+                    Map.Entry entry = ((Map.Entry)obj);
+                    Object key = entry.getKey();
+                    if (key == null) {
+                        key = NULL;
+                    }
+                    if (containsKey(key)) {
+                        NullKeyMap.this.remove(key);
+                        return true;
+                    }
+                    else {
+                        return false;
+                    }
+                }
+
+                public int size() {
+                    return NullKeyMap.this.size();
+                }
+                
+                public void clear() {
+                    NullKeyMap.this.clear();
+                }
+            };
+        }
+
+        return mEntrySet;
+    }
+}