--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/go/trove/util/Utils.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,379 @@
+/* ====================================================================
+ * 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;
+import java.io.ObjectStreamException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
+
+/******************************************************************************
+ * Some generic utilities.
+ *
+ * @author Brian S O'Neill
+ * @version
+ * <!--$$Revision:--> 28 <!-- $-->, <!--$$JustDate:--> 00/12/18 <!-- $-->
+ * @see java.util.Collections
+ */
+public class Utils {
+    // The choice of determining whether these constants are public or
+    // private is based on the design of the java.util.Collections class.
+    // For consistency, the "empty" fields are public, and the comparators are
+    // accessed from static methods.
+
+    public static final Enumeration EMPTY_ENUMERATION = new EmptyEnum();
+
+    /** This Map is already provided in JDK1.3. */
+    public static final Map EMPTY_MAP = new EmptyMap();
+
+    /**
+     * Similar to EMPTY_MAP, except the put operation is supported, but the
+     * values are immediately forgotten.
+     */
+    public static final Map VOID_MAP = new VoidMap();
+
+    private static final Comparator NULL_LOW_ORDER = new NullLowOrder();
+
+    private static final Comparator NULL_HIGH_ORDER = new NullHighOrder();
+
+    private static final Comparator NULL_EQUAL_ORDER = new NullEqualOrder();
+
+    private static FlyweightSet cFlyweightSet;
+    
+    /**
+     * Returns a Comparator that uses a Comparable object's natural ordering,
+     * except null values are always considered low order. This Comparator
+     * allows naturally ordered TreeMaps to support null values.
+     */
+    public static Comparator nullLowOrder() {
+        return NULL_LOW_ORDER;
+    }
+
+    /**
+     * Returns a Comparator that wraps the given Comparator except null values
+     * are always considered low order. This fixes Comparators that don't
+     * support comparisons against null and allows them to be used in TreeMaps.
+     */
+    public static Comparator nullLowOrder(Comparator c) {
+        return new NullLowOrderC(c);
+    }
+
+    /**
+     * Returns a Comparator that uses a Comparable object's natural ordering,
+     * except null values are always considered high order. This Comparator
+     * allows naturally ordered TreeMaps to support null values.
+     */
+    public static Comparator nullHighOrder() {
+        return NULL_HIGH_ORDER;
+    }
+
+    /**
+     * Returns a Comparator that wraps the given Comparator except null values
+     * are always considered high order. This fixes Comparators that don't
+     * support comparisons against null and allows them to be used in TreeMaps.
+     */
+    public static Comparator nullHighOrder(Comparator c) {
+        return new NullHighOrderC(c);
+    }
+
+    /**
+     * Returns a Comparator that uses a Comparable object's natural ordering,
+     * except null values are always considered equal order. This Comparator
+     * should not be used in a TreeMap, but can be used in a sorter.
+     */
+    public static Comparator nullEqualOrder() {
+        return NULL_EQUAL_ORDER;
+    }
+    
+    /**
+     * Returns a Comparator that wraps the given Comparator except null values
+     * are always considered equal order. This Comparator should not be used in
+     * a TreeMap, but can be used in a sorter.
+     */
+    public static Comparator nullEqualOrder(Comparator c) {
+        return new NullEqualOrderC(c);
+    }
+
+    /**
+     * Returns a Comparator that wraps the given Comparator, but orders in
+     * reverse.
+     */
+    public static Comparator reverseOrder(Comparator c) {
+        return new ReverseOrderC(c);
+    }
+
+    /**
+     * Just like {@link String#intern() String.intern}, except it generates
+     * flyweights for any kind of object, and it does not prevent them from
+     * being garbage collected. Calling intern on a String does not use the
+     * same String pool used by String.intern because those Strings are not
+     * always garbage collected. Some virtual machines free up Strings from the
+     * interned String pool, others do not.
+     * <p>
+     * For objects that do not customize the hashCode and equals methods,
+     * calling intern is not very useful because the object returned will
+     * always be the same as the one passed in.
+     * <p>
+     * The object type returned from intern is guaranteed to be exactly the
+     * same type as the one passed in. Calling intern on null returns null.
+     *
+     * @param obj Object to intern
+     * @return Interned object.
+     * @see FlyweightSet
+     */
+    public static Object intern(Object obj) {
+        FlyweightSet set;
+        if ((set = cFlyweightSet) == null) {
+            synchronized (Utils.class) {
+                if ((set = cFlyweightSet) == null) {
+                    set = new FlyweightSet();
+                }
+            }
+            cFlyweightSet = set;
+        }
+        return set.put(obj);
+    }
+
+    protected Utils() {
+    }
+
+    private static class EmptyEnum implements Enumeration, Serializable {
+        public boolean hasMoreElements() {
+            return false;
+        }
+        
+        public Object nextElement() throws NoSuchElementException {
+            throw new NoSuchElementException();
+        }
+
+        // Serializable singleton classes should always do this.
+        private Object readResolve() throws ObjectStreamException {
+            return EMPTY_ENUMERATION;
+        }
+    };
+
+    private static class EmptyMap implements Map, Serializable {
+        public int size() {
+            return 0;
+        }
+
+        public boolean isEmpty() {
+            return true;
+        }
+
+        public boolean containsKey(Object key) {
+            return false;
+        }
+
+        public boolean containsValue(Object value) {
+            return false;
+        }
+        
+        public Object get(Object key) {
+            return null;
+        }
+
+        public Object put(Object key, Object value) {
+            throw new UnsupportedOperationException
+                ("Cannot put into immutable empty map");
+        }
+
+        public Object remove(Object key) {
+            return null;
+        }
+
+        public void putAll(Map map) {
+            throw new UnsupportedOperationException
+                ("Cannot put into immutable empty map");
+        }
+
+        public void clear() {
+        }
+
+        public Set keySet() {
+            return Collections.EMPTY_SET;
+        }
+
+        public Collection values() {
+            return Collections.EMPTY_LIST;
+        }
+
+        public Set entrySet() {
+            return Collections.EMPTY_SET;
+        }
+
+        // Serializable singleton classes should always do this.
+        private Object readResolve() throws ObjectStreamException {
+            return EMPTY_MAP;
+        }
+    }
+
+    private static class VoidMap extends EmptyMap {
+        public Object put(Object key, Object value) {
+            return null;
+        }
+
+        public void putAll(Map map) {
+        }
+
+        // Serializable singleton classes should always do this.
+        private Object readResolve() throws ObjectStreamException {
+            return VOID_MAP;
+        }
+    }
+
+    private static class NullLowOrder implements Comparator, Serializable {
+        public int compare(Object obj1, Object obj2) {
+            if (obj1 != null) {
+                return (obj2 != null) ? ((Comparable)obj1).compareTo(obj2) : 1;
+            }
+            else {
+                return (obj2 != null) ? -1 : 0;
+            }
+        }
+
+        // Serializable singleton classes should always do this.
+        private Object readResolve() throws ObjectStreamException {
+            return NULL_LOW_ORDER;
+        }
+    }
+
+    private static class NullLowOrderC implements Comparator, Serializable {
+        private Comparator c;
+
+        public NullLowOrderC(Comparator c) {
+            this.c = c;
+        }
+
+        public int compare(Object obj1, Object obj2) {
+            if (obj1 != null) {
+                return (obj2 != null) ? c.compare(obj1, obj2) : 1;
+            }
+            else {
+                return (obj2 != null) ? -1 : 0;
+            }
+        }
+    }
+
+    private static class NullHighOrder implements Comparator, Serializable {
+        public int compare(Object obj1, Object obj2) {
+            if (obj1 != null) {
+                return (obj2 != null) ? ((Comparable)obj1).compareTo(obj2): -1;
+            }
+            else {
+                return (obj2 != null) ? 1 : 0;
+            }
+        }
+
+        // Serializable singleton classes should always do this.
+        private Object readResolve() throws ObjectStreamException {
+            return NULL_HIGH_ORDER;
+        }
+    }
+
+    private static class NullHighOrderC implements Comparator, Serializable {
+        private Comparator c;
+
+        public NullHighOrderC(Comparator c) {
+            this.c = c;
+        }
+
+        public int compare(Object obj1, Object obj2) {
+            if (obj1 != null) {
+                return (obj2 != null) ? c.compare(obj1, obj2) : -1;
+            }
+            else {
+                return (obj2 != null) ? 1 : 0;
+            }
+        }
+    }
+
+    private static class NullEqualOrder implements Comparator, Serializable {
+        public int compare(Object obj1, Object obj2) {
+            return (obj1 != null && obj2 != null) ?
+                ((Comparable)obj1).compareTo(obj2) : 0;
+        }
+
+        // Serializable singleton classes should always do this.
+        private Object readResolve() throws ObjectStreamException {
+            return NULL_EQUAL_ORDER;
+        }
+    }
+    
+    private static class NullEqualOrderC implements Comparator, Serializable {
+        private Comparator c;
+
+        public NullEqualOrderC(Comparator c) {
+            this.c = c;
+        }
+
+        public int compare(Object obj1, Object obj2) {
+            return (obj1 != null && obj2 != null) ? c.compare(obj1, obj2) : 0;
+        }
+    }
+
+    private static class ReverseOrderC implements Comparator, Serializable {
+        private Comparator c;
+
+        public ReverseOrderC(Comparator c) {
+            this.c = c;
+        }
+
+        public int compare(Object obj1, Object obj2) {
+            return c.compare(obj2, obj1);
+        }
+    }
+}