Add IdentityMap implementation for reference comparisons

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131387 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/collections/map/IdentityMap.java

@@ -0,0 +1,198 @@
+/*
+ * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/java/org/apache/commons/collections/map/IdentityMap.java,v 1.1 2003/12/02 21:57:08 scolebourne Exp $
+ * ====================================================================
+ *
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2001-2003 The Apache Software Foundation.  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 acknowledgement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgement may appear in the software itself,
+ *    if and wherever such third-party acknowledgements normally appear.
+ *
+ * 4. The names "The Jakarta Project", "Commons", and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Software Foundation.
+ *
+ * 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 APACHE SOFTWARE FOUNDATION 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.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+package org.apache.commons.collections.map;
+
+import java.util.Map;
+
+/**
+ * A <code>Map</code> implementation that matches keys and values based
+ * on <code>==</code> not <code>equals()</code>.
+ * <p>
+ * This map will violate the detail of various Map and map view contracts.
+ * As a general rule, don't compare this map to other maps.
+ * 
+ * @since Commons Collections 3.0
+ * @version $Revision: 1.1 $ $Date: 2003/12/02 21:57:08 $
+ *
+ * @author java util HashMap
+ * @author Stephen Colebourne
+ */
+public class IdentityMap extends HashedMap {
+    
+    /** Serialisation version */
+
+    /**
+     * Constructs a new empty map with default size and load factor.
+     */
+    public IdentityMap() {
+        super();
+    }
+
+    /**
+     * Constructs a new, empty map with the specified initial capacity. 
+     *
+     * @param initialCapacity  the initial capacity
+     * @throws IllegalArgumentException if the initial capacity is less than one
+     */
+    public IdentityMap(int initialCapacity) {
+        super(initialCapacity);
+    }
+
+    /**
+     * Constructs a new, empty map with the specified initial capacity and
+     * load factor. 
+     *
+     * @param initialCapacity  the initial capacity
+     * @param loadFactor  the load factor
+     * @throws IllegalArgumentException if the initial capacity is less than one
+     * @throws IllegalArgumentException if the load factor is less than one
+     */
+    public IdentityMap(int initialCapacity, float loadFactor) {
+        super(initialCapacity, loadFactor);
+    }
+
+    /**
+     * Constructor copying elements from another map.
+     *
+     * @param map  the map to copy
+     * @throws NullPointerException if the map is null
+     */
+    public IdentityMap(Map map) {
+        super(map);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the hash code for the key specified.
+     * This implementation uses the identity hash code.
+     * 
+     * @param key  the key to get a hash code for
+     * @return the hash code
+     */
+    protected int hash(Object key) {
+        return System.identityHashCode(key);
+    }
+    
+    /**
+     * Compares two keys for equals.
+     * This implementation uses <code>==</code>.
+     * 
+     * @param key1  the first key to compare
+     * @param key2  the second key to compare
+     * @return true if equal by identity
+     */
+    protected boolean isEqualKey(Object key1, Object key2) {
+        return (key1 == key2);
+    }
+    
+    /**
+     * Compares two values for equals.
+     * This implementation uses <code>==</code>.
+     * 
+     * @param value1  the first value to compare
+     * @param value2  the second value to compare
+     * @return true if equal by identity
+     */
+    protected boolean isEqualValue(Object value1, Object value2) {
+        return (value1 == value2);
+    }
+    
+    /**
+     * Creates an entry to store the data.
+     * This implementation creates an IdentityEntry instance.
+     * 
+     * @param next  the next entry in sequence
+     * @param hashCode  the hash code to use
+     * @param key  the key to store
+     * @param value  the value to store
+     * @return the newly created entry
+     */
+    protected HashEntry createEntry(HashEntry next, int hashCode, Object key, Object value) {
+        return new IdentityEntry(next, hashCode, key, value);
+    }
+    
+    //-----------------------------------------------------------------------
+    /**
+     * HashEntry
+     */
+    protected static class IdentityEntry extends HashEntry {
+        
+        protected IdentityEntry(HashEntry next, int hashCode, Object key, Object value) {
+            super(next, hashCode, key, value);
+        }
+        
+        public boolean equals(Object obj) {
+            if (obj == this) {
+                return true;
+            }
+            if (obj instanceof Map.Entry == false) {
+                return false;
+            }
+            Map.Entry other = (Map.Entry) obj;
+            return
+                (getKey() == other.getKey()) &&
+                (getValue() == other.getValue());
+        }
+        
+        public int hashCode() {
+            return System.identityHashCode(getKey()) ^
+                   System.identityHashCode(getValue());
+        }
+    }
+    
+}

src/test/org/apache/commons/collections/map/TestAll.java

@@ -1,5 +1,5 @@
 /*
- * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/test/org/apache/commons/collections/map/TestAll.java,v 1.5 2003/12/02 00:44:13 scolebourne Exp $
+ * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/test/org/apache/commons/collections/map/TestAll.java,v 1.6 2003/12/02 21:57:08 scolebourne Exp $
  * ====================================================================
  *
  * The Apache Software License, Version 1.1
@@ -65,7 +65,7 @@ import junit.framework.TestSuite;
  * Entry point for tests.
  * 
  * @since Commons Collections 3.0
- * @version $Revision: 1.5 $ $Date: 2003/12/02 00:44:13 $
+ * @version $Revision: 1.6 $ $Date: 2003/12/02 21:57:08 $
  * 
  * @author Stephen Colebourne
  */
@@ -86,8 +86,8 @@ public class TestAll extends TestCase {
         suite.addTest(TestFixedSizeMap.suite());
         suite.addTest(TestFixedSizeSortedMap.suite());
         suite.addTest(TestFlat3Map.suite());
-//        suite.addTest(TestHashedMap.suite());
+        suite.addTest(TestHashedMap.suite());
-//        suite.addTest(TestIdentityMap.suite());
+        suite.addTest(TestIdentityMap.suite());
         suite.addTest(TestLazyMap.suite());
         suite.addTest(TestLazySortedMap.suite());
         suite.addTest(TestListOrderedMap.suite());

src/test/org/apache/commons/collections/map/TestIdentityMap.java

@@ -0,0 +1,155 @@
+/*
+ * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/test/org/apache/commons/collections/map/TestIdentityMap.java,v 1.1 2003/12/02 21:57:08 scolebourne Exp $
+ * ====================================================================
+ *
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2001-2003 The Apache Software Foundation.  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 acknowledgement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgement may appear in the software itself,
+ *    if and wherever such third-party acknowledgements normally appear.
+ *
+ * 4. The names "The Jakarta Project", "Commons", and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Software Foundation.
+ *
+ * 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 APACHE SOFTWARE FOUNDATION 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.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+package org.apache.commons.collections.map;
+
+import java.util.Iterator;
+import java.util.Map;
+
+import junit.framework.Test;
+import junit.framework.TestSuite;
+import junit.textui.TestRunner;
+
+import org.apache.commons.collections.AMap;
+import org.apache.commons.collections.AbstractTestObject;
+
+/**
+ * JUnit tests.
+ * 
+ * @version $Revision: 1.1 $ $Date: 2003/12/02 21:57:08 $
+ * 
+ * @author Stephen Colebourne
+ */
+public class TestIdentityMap extends AbstractTestObject {
+    
+    private static final Integer I1A = new Integer(1);
+    private static final Integer I1B = new Integer(1);
+    private static final Integer I2A = new Integer(2);
+    private static final Integer I2B = new Integer(2);
+
+    public TestIdentityMap(String testName) {
+        super(testName);
+    }
+
+    public static void main(String[] args) {
+        TestRunner.run(suite());
+    }
+    
+    public static Test suite() {
+        return new TestSuite(TestIdentityMap.class);
+//        return BulkTest.makeSuite(TestIdentityMap.class);  // causes race condition!
+    }
+    
+    public Object makeObject() {
+        return new IdentityMap();
+    }
+    
+    public String getCompatibilityVersion() {
+        return "3";
+    }
+    
+    //-----------------------------------------------------------------------
+    public void testBasics() {
+        AMap map = new IdentityMap();
+        assertEquals(0, map.size());
+        
+        map.put(I1A, I2A);
+        assertEquals(1, map.size());
+        assertSame(I2A, map.get(I1A));
+        assertSame(null, map.get(I1B));
+        assertEquals(true, map.containsKey(I1A));
+        assertEquals(false, map.containsKey(I1B));
+        assertEquals(true, map.containsValue(I2A));
+        assertEquals(false, map.containsValue(I2B));
+        
+        map.put(I1A, I2B);
+        assertEquals(1, map.size());
+        assertSame(I2B, map.get(I1A));
+        assertSame(null, map.get(I1B));
+        assertEquals(true, map.containsKey(I1A));
+        assertEquals(false, map.containsKey(I1B));
+        assertEquals(false, map.containsValue(I2A));
+        assertEquals(true, map.containsValue(I2B));
+        
+        map.put(I1B, I2B);
+        assertEquals(2, map.size());
+        assertSame(I2B, map.get(I1A));
+        assertSame(I2B, map.get(I1B));
+        assertEquals(true, map.containsKey(I1A));
+        assertEquals(true, map.containsKey(I1B));
+        assertEquals(false, map.containsValue(I2A));
+        assertEquals(true, map.containsValue(I2B));
+    }
+    
+    //-----------------------------------------------------------------------
+    public void testHashEntry() {
+        AMap map = new IdentityMap();
+        
+        map.put(I1A, I2A);
+        map.put(I1B, I2A);
+        
+        Map.Entry entry1 = (Map.Entry) map.entrySet().iterator().next();
+        Iterator it = map.entrySet().iterator();
+        Map.Entry entry2 = (Map.Entry) it.next();
+        Map.Entry entry3 = (Map.Entry) it.next();
+        
+        assertEquals(true, entry1.equals(entry2));
+        assertEquals(true, entry2.equals(entry1));
+        assertEquals(false, entry1.equals(entry3));
+    }
+    
+}