/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.lang.builder;

// adapted from org.apache.axis.utils.IDKey

Wrap an identity key (System.identityHashCode()) 
so that an object can only be equal() to itself.
This is necessary to disambiguate the occasional duplicate
identityHashCodes that can occur.
Author:
Apache Software Foundation/**
 * Wrap an identity key (System.identityHashCode()) 
 * so that an object can only be equal() to itself.
 * 
 * This is necessary to disambiguate the occasional duplicate
 * identityHashCodes that can occur.
 * 
 * @author Apache Software Foundation
 */ 
final class IDKey {
        private final Object value;
        private final int id;

        
Constructor for IDKey
Params:
_value – The value/**
         * Constructor for IDKey
         * @param _value The value
         */ 
        public IDKey(Object _value) {
            // This is the Object hashcode 
            id = System.identityHashCode(_value);  
            // There have been some cases (LANG-459) that return the 
            // same identity hash code for different objects.  So 
            // the value is also added to disambiguate these cases.
            value = _value;
        }

        
returns hashcode - i.e. the system identity hashcode.
Returns:
the hashcode/**
         * returns hashcode - i.e. the system identity hashcode.
         * @return the hashcode
         */ 
        public int hashCode() {
           return id;
        }

        
checks if instances are equal
Params:
other – The other object to compare to
Returns:
if the instances are for the same object/**
         * checks if instances are equal
         * @param other The other object to compare to
         * @return if the instances are for the same object
         */ 
        public boolean equals(Object other) {
            if (!(other instanceof IDKey)) {
                return false;
            }
            IDKey idKey = (IDKey) other;
            if (id != idKey.id) {
                return false;
            }
            // Note that identity equals is used.
            return value == idKey.value;
         }
}