// GenericsNote: Converted.
/*
 *  Copyright 2003-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package php.runtime.common.collections.map;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
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.
 *
 * @author java util HashMap
 * @author Matt Hall, John Watkinson, Stephen Colebourne
 * @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:32 $
 * @since Commons Collections 3.0
 */
public class IdentityMap <K,V> extends AbstractHashedMap<K, V> implements Serializable, Cloneable {

    /**
     * Serialisation version
     */
    private static final long serialVersionUID = 2028493495224302329L;

    /**
     * Constructs a new empty map with default size and load factor.
     */
    public IdentityMap() {
        super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD);
    }

    /**
     * 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 zero
     */
    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<? extends K, ? extends V> 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<K, V> createEntry(HashEntry<K, V> next, int hashCode, K key, V value) {
        return new IdentityEntry<K, V>(next, hashCode, key, value);
    }
    
    //-----------------------------------------------------------------------
    /**
     * HashEntry
     */
    protected static class IdentityEntry <K,V> extends HashEntry<K, V> {

        protected IdentityEntry(HashEntry<K, V> next, int hashCode, K key, V value) {
            super(next, hashCode, key, value);
        }

        public boolean equals(Object obj) {
            if (obj == this) {
                return true;
            }
            if (!(obj instanceof Entry)) {
                return false;
            }
            Entry other = (Entry) obj;
            return (getKey() == other.getKey()) && (getValue() == other.getValue());
        }

        public int hashCode() {
            return System.identityHashCode(getKey()) ^ System.identityHashCode(getValue());
        }
    }
    
    //-----------------------------------------------------------------------
    /**
     * Clones the map without cloning the keys or values.
     *
     * @return a shallow clone
     */
    public Object clone() {
        return super.clone();
    }

    /**
     * Write the map out using a custom routine.
     */
    private void writeObject(ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
        doWriteObject(out);
    }

    /**
     * Read the map in using a custom routine.
     */
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        doReadObject(in);
    }

}