Mercurial > hg > blitz_condensed
view src/com/go/trove/util/Utils.java @ 28:4b2f23b6feca
Add a schema compatibility check to indexer that parallels storage.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 12 Jun 2010 10:11:15 +0100 |
parents | 3dc0c5604566 |
children |
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/* ==================================================================== * 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); } } }