/*
* RHQ Management Platform
* Copyright (C) 2005-2008 Red Hat, Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation, and/or the GNU Lesser
* General Public License, version 2.1, also as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License and the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License
* and the GNU Lesser General Public License along with this program;
* if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
//copied from org.apache.commons.lang
//this class was not public in that package.
//see comment below about internal optimization.
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2002-2003 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/>.
*/
/*
* Note: originally released under the GNU LGPL v2.1, but rereleased by the original author under the ASF license
* (above).
*/
package org.rhq.core.util.collection;
/**
* <p>A hash map that uses primitive ints for the key rather than objects.</p>
*
* <p>Note that this class is for internal optimization purposes only, and may not be supported in future releases of
* Jakarta Commons Lang. Utilities of this sort may be included in future releases of Jakarta Commons Collections.</p>
*
* @author Justin Couch
* @author Alex Chaffee (alex@apache.org)
* @author Stephen Colebourne
* @see java.util.HashMap
* @since 2.0
*/
public class IntHashMap {
/**
* The hash table data.
*/
private transient Entry[] table;
/**
* The total number of entries in the hash table.
*/
private transient int count;
/**
* The table is rehashed when its size exceeds this threshold. (The value of this field is (int)(capacity *
* loadFactor).)
*
* @serial
*/
private int threshold;
/**
* The load factor for the hashtable.
*
* @serial
*/
private float loadFactor;
/**
* <p>Innerclass that acts as a datastructure to create a new entry in the table.</p>
*/
private static class Entry {
int hash;
int key;
Object value;
Entry next;
/**
* <p>Create a new entry with the given values.</p>
*
* @param hash The code used to hash the object with
* @param key The key used to enter this in the table
* @param value The value for this key
* @param next A reference to the next entry in the table
*/
protected Entry(int hash, int key, Object value, Entry next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
}
/**
* <p>Constructs a new, empty hashtable with a default capacity and load factor, which is <code>20</code> and <code>
* 0.75</code> respectively.</p>
*/
public IntHashMap() {
this(20, 0.75f);
}
/**
* <p>Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is <code>
* 0.75</code>.</p>
*
* @param initialCapacity the initial capacity of the hashtable.
*
* @throws IllegalArgumentException if the initial capacity is less than zero.
*/
public IntHashMap(int initialCapacity) {
this(initialCapacity, 0.75f);
}
/**
* <p>Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.</p>
*
* @param initialCapacity the initial capacity of the hashtable.
* @param loadFactor the load factor of the hashtable.
*
* @throws IllegalArgumentException if the initial capacity is less than zero, or if the load factor is nonpositive.
*/
public IntHashMap(int initialCapacity, float loadFactor) {
super();
if (initialCapacity < 0) {
throw new IllegalArgumentException("Illegal Capacity: " + initialCapacity);
}
if (loadFactor <= 0) {
throw new IllegalArgumentException("Illegal Load: " + loadFactor);
}
if (initialCapacity == 0) {
initialCapacity = 1;
}
this.loadFactor = loadFactor;
table = new Entry[initialCapacity];
threshold = (int) (initialCapacity * loadFactor);
}
/**
* <p>Returns the number of keys in this hashtable.</p>
*
* @return the number of keys in this hashtable.
*/
public int size() {
return count;
}
/**
* <p>Tests if this hashtable maps no keys to values.</p>
*
* @return <code>true</code> if this hashtable maps no keys to values; <code>false</code> otherwise.
*/
public boolean isEmpty() {
return count == 0;
}
/**
* <p>Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the
* <code>containsKey</code> method.</p>
*
* <p>Note that this method is identical in functionality to containsValue, (which is part of the Map interface in
* the collections framework).</p>
*
* @param value a value to search for.
*
* @return <code>true</code> if and only if some key maps to the <code>value</code> argument in this hashtable as
* determined by the <tt>equals</tt> method; <code>false</code> otherwise.
*
* @throws NullPointerException if the value is <code>null</code>.
*
* @see #containsKey(int)
* @see #containsValue(Object)
* @see java.util.Map
*/
public boolean contains(Object value) {
if (value == null) {
throw new NullPointerException();
}
Entry[] tab = table;
for (int i = tab.length; i-- > 0;) {
for (Entry e = tab[i]; e != null; e = e.next) {
if (e.value.equals(value)) {
return true;
}
}
}
return false;
}
/**
* <p>Returns <code>true</code> if this HashMap maps one or more keys to this value.</p>
*
* <p>Note that this method is identical in functionality to contains (which predates the Map interface).</p>
*
* @param value value whose presence in this HashMap is to be tested.
*
* @see java.util.Map
* @since JDK1.2
*/
public boolean containsValue(Object value) {
return contains(value);
}
/**
* <p>Tests if the specified object is a key in this hashtable.</p>
*
* @param key possible key.
*
* @return <code>true</code> if and only if the specified object is a key in this hashtable, as determined by the
* <tt>equals</tt> method; <code>false</code> otherwise.
*
* @see #contains(Object)
*/
public boolean containsKey(int key) {
Entry[] tab = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index]; e != null; e = e.next) {
if (e.hash == hash) {
return true;
}
}
return false;
}
/**
* <p>Returns the value to which the specified key is mapped in this map.</p>
*
* @param key a key in the hashtable.
*
* @return the value to which the key is mapped in this hashtable; <code>null</code> if the key is not mapped to any
* value in this hashtable.
*
* @see #put(int, Object)
*/
public Object get(int key) {
Entry[] tab = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index]; e != null; e = e.next) {
if (e.hash == hash) {
return e.value;
}
}
return null;
}
/**
* <p>Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its
* entries more efficiently.</p>
*
* <p>This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity
* and load factor.</p>
*/
protected void rehash() {
int oldCapacity = table.length;
Entry[] oldMap = table;
int newCapacity = (oldCapacity * 2) + 1;
Entry[] newMap = new Entry[newCapacity];
threshold = (int) (newCapacity * loadFactor);
table = newMap;
for (int i = oldCapacity; i-- > 0;) {
for (Entry old = oldMap[i]; old != null;) {
Entry e = old;
old = old.next;
int index = (e.hash & 0x7FFFFFFF) % newCapacity;
e.next = newMap[index];
newMap[index] = e;
}
}
}
/**
* <p>Maps the specified <code>key</code> to the specified <code>value</code> in this hashtable. The key cannot be
* <code>null</code>.</p>
*
* <p>The value can be retrieved by calling the <code>get</code> method with a key that is equal to the original
* key.</p>
*
* @param key the hashtable key.
* @param value the value.
*
* @return the previous value of the specified key in this hashtable, or <code>null</code> if it did not have one.
*
* @throws NullPointerException if the key is <code>null</code>.
*
* @see #get(int)
*/
public Object put(int key, Object value) {
// Makes sure the key is not already in the hashtable.
Entry[] tab = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index]; e != null; e = e.next) {
if (e.hash == hash) {
Object old = e.value;
e.value = value;
return old;
}
}
if (count >= threshold) {
// Rehash the table if the threshold is exceeded
rehash();
tab = table;
index = (hash & 0x7FFFFFFF) % tab.length;
}
// Creates the new entry.
Entry e = new Entry(hash, key, value, tab[index]);
tab[index] = e;
count++;
return null;
}
/**
* <p>Removes the key (and its corresponding value) from this hashtable.</p>
*
* <p>This method does nothing if the key is not present in the hashtable.</p>
*
* @param key the key that needs to be removed.
*
* @return the value to which the key had been mapped in this hashtable, or <code>null</code> if the key did not
* have a mapping.
*/
public Object remove(int key) {
Entry[] tab = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index], prev = null; e != null; prev = e, e = e.next) {
if (e.hash == hash) {
if (prev != null) {
prev.next = e.next;
} else {
tab[index] = e.next;
}
count--;
Object oldValue = e.value;
e.value = null;
return oldValue;
}
}
return null;
}
/**
* <p>Clears this hashtable so that it contains no keys.</p>
*/
public synchronized void clear() {
Entry[] tab = table;
for (int index = tab.length; --index >= 0;) {
tab[index] = null;
}
count = 0;
}
}