--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/go/trove/util/WrappedCache.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,176 @@
+/* ====================================================================
+ * Trove - Copyright (c) 1997-2001 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.*;
+
+/******************************************************************************
+ * A Map that implements a write-through cache to another map. Two maps are
+ * supplied: one for caching and one for main storage. WrappedCache is not
+ * thread-safe and must be wrapped with Collections.synchronizedMap to be made
+ * thread-safe.
+ *
+ * @author Brian S O'Neill
+ * @version
+ * <!--$$Revision:--> 2 <!-- $-->, <!--$$JustDate:--> 01/07/31 <!-- $-->
+ */
+public class WrappedCache extends AbstractMap implements Map {
+    private final Map mCacheMap;
+    private final Map mBackingMap;
+
+    /**
+     * @param cacheMap the cache map should offer fast access, but it should
+     * automatically limit its maximum size
+     * @param backingMap the backingMap will be read from only if the requested
+     * entry isn't in the cache
+     */
+    public WrappedCache(Map cacheMap, Map backingMap) {
+        mCacheMap = cacheMap;
+        mBackingMap = backingMap;
+    }
+
+    /**
+     * Returns the size of the backing map.
+     */
+    public int size() {
+        return mBackingMap.size();
+    }
+
+    /**
+     * Returns the empty status of the backing map.
+     */
+    public boolean isEmpty() {
+        return mBackingMap.isEmpty();
+    }
+
+    /**
+     * Returns true if the cache contains the key or else if the backing map
+     * contains the key.
+     */
+    public boolean containsKey(Object key) {
+        return mCacheMap.containsKey(key) || mBackingMap.containsKey(key);
+    }
+
+    /**
+     * Returns true if the cache contains the value or else if the backing map
+     * contains the value.
+     */
+    public boolean containsValue(Object value) {
+        return mCacheMap.containsValue(value) ||
+            mBackingMap.containsValue(value);
+    }
+
+    /**
+     * Returns the value from the cache, or if not found, the backing map.
+     * If the backing map is accessed, the value is saved in the cache for
+     * future gets.
+     */
+    public Object get(Object key) {
+        Object value = mCacheMap.get(key);
+        if (value != null || mCacheMap.containsKey(key)) {
+            return value;
+        }
+        value = mBackingMap.get(key);
+        if (value != null || mBackingMap.containsKey(key)) {
+            mCacheMap.put(key, value);
+        }
+        return value;
+    }
+
+    /**
+     * Puts the entry into both the cache and backing map. The old value in
+     * the backing map is returned.
+     */
+    public Object put(Object key, Object value) {
+        mCacheMap.put(key, value);
+        return mBackingMap.put(key, value);
+    }
+
+    /**
+     * Removes the key from both the cache and backing map. The old value in
+     * the backing map is returned.
+     */
+    public Object remove(Object key) {
+        mCacheMap.remove(key);
+        return mBackingMap.remove(key);
+    }
+
+    /**
+     * Clears both the cache and backing map.
+     */
+    public void clear() {
+        mCacheMap.clear();
+        mBackingMap.clear();
+    }
+
+    /**
+     * Returns the key set of the backing map.
+     */
+    public Set keySet() {
+        return mBackingMap.keySet();
+    }
+
+    /**
+     * Returns the values of the backing map.
+     */
+    public Collection values() {
+        return mBackingMap.values();
+    }
+
+    /**
+     * Returns the entry set of the backing map.
+     */
+    public Set entrySet() {
+        return mBackingMap.entrySet();
+    }
+}