/**
* OpenSpotLight - Open Source IT Governance Platform
*
* Copyright (c) 2009, CARAVELATECH CONSULTORIA E TECNOLOGIA EM INFORMATICA LTDA
* or third-party contributors as indicated by the @author tags or express
* copyright attribution statements applied by the authors. All third-party
* contributions are distributed under license by CARAVELATECH CONSULTORIA E
* TECNOLOGIA EM INFORMATICA LTDA.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*
***********************************************************************
* OpenSpotLight - Plataforma de Governança de TI de Código Aberto
*
* Direitos Autorais Reservados (c) 2009, CARAVELATECH CONSULTORIA E TECNOLOGIA
* EM INFORMATICA LTDA ou como contribuidores terceiros indicados pela etiqueta
* @author ou por expressa atribuição de direito autoral declarada e atribuída pelo autor.
* Todas as contribuições de terceiros estão distribuídas sob licença da
* CARAVELATECH CONSULTORIA E TECNOLOGIA EM INFORMATICA LTDA.
*
* Este programa é software livre; você pode redistribuí-lo e/ou modificá-lo sob os
* termos da Licença Pública Geral Menor do GNU conforme publicada pela Free Software
* Foundation.
*
* Este programa é distribuído na expectativa de que seja útil, porém, SEM NENHUMA
* GARANTIA; nem mesmo a garantia implícita de COMERCIABILIDADE OU ADEQUAÇÃO A UMA
* FINALIDADE ESPECÍFICA. Consulte a Licença Pública Geral Menor do GNU para mais detalhes.
*
* Você deve ter recebido uma cópia da Licença Pública Geral Menor do GNU junto com este
* programa; se não, escreva para:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.openspotlight.common.util;
import static java.lang.Double.doubleToLongBits;
import static java.lang.Float.floatToIntBits;
import static org.openspotlight.common.util.Exceptions.logAndThrow;
import java.util.Map;
/**
* Helper class to build hashCode methods in a secure and concise way. All the hash functions for primitive types was created
* based on Effective Java book. to be used like this...
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = hashOf(attribute1,attribute2,..);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* or like this...
*
* <pre>
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = hashOf(attribute1,attribute2,..);
* hashcode = result;
* }
* return result;
* }
* </pre>
*
* @author Luiz Fernando Teston - feu.teston@caravelatech.com
*/
public class HashCodes {
/**
* Should not be instantiated
*/
private HashCodes() {
logAndThrow(new IllegalStateException(Messages.getString("invalidConstructor"))); //$NON-NLS-1$
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param b
* @return the hash code
*/
public static int hashOf(final boolean b) {
return b ? 1 : 0;
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param b
* @return the hash code
*/
public static int hashOf(final byte b) {
return b;
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param c
* @return the hash code
*/
public static int hashOf(final char c) {
return c;
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param d
* @return the hash code
*/
public static int hashOf(final double d) {
return hashOf(doubleToLongBits(d));
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param f
* @return the hash code
*/
public static int hashOf(final float f) {
return floatToIntBits(f);
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param i
* @return the hash code
*/
public static int hashOf(final int i) {
return i;
}
/**
* Hash helper method to be used like this (based on Effective Java book). To be used like this:
*
* <pre>
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = hashOf(attribute1,attribute2,..);
* hashcode = result;
* }
* return result;
* }
* </pre>
*
* @param iterable
* @return the hash code
*/
public static int hashOf(final Iterable<?> iterable) {
int result = 17;
for (final Object attribute: iterable) {
result = 31 * result + hashOf(attribute);
}
return result;
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param l
* @return the hash code
*/
public static int hashOf(final long l) {
return (int) (l ^ (l >>> 32));
}
/**
* Hash helper method to be used like this (based on Effective Java book). To be used like this:
*
* <pre>
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = hashOf(attribute1,attribute2,..);
* hashcode = result;
* }
* return result;
* }
* </pre>
*
* @param map
* @return the hash code
*/
public static int hashOf(final Map<?, ?> map) {
int result = 17;
for (final Map.Entry<?, ?> entry: map.entrySet()) {
result = 31 * result + hashOf(entry.getKey());
result = 31 * result + hashOf(entry.getValue());
}
return result;
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param o
* @return the hash code
*/
public static int hashOf(final Object o) {
return o == null ? 0 : o.hashCode();
}
/**
* Hash helper method to be used like this (based on Effective Java book). To be used like this:
*
* <pre>
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = hashOf(attribute1,attribute2,..);
* hashcode = result;
* }
* return result;
* }
* </pre>
*
* @param attributes
* @return the hash code
*/
public static int hashOf(final Object... attributes) {
int result = 17;
for (final Object attribute: attributes) {
if (attribute instanceof Iterable<?>) {
result = 31 * result + hashOf((Iterable<?>) attribute);
} else if (attribute instanceof Map<?, ?>) {
result = 31 * result + hashOf((Map<?, ?>) attribute);
} else {
result = 31 * result + hashOf(attribute);
}
}
return result;
}
/**
* Hash helper method to be used like this (based on Effective Java book):
*
* <pre>
* private volatile hashcode;
*
* public int hashCode(){
* int result = hashcode;
* if(result = 0){
* result = 17;
* result = 31 * result + hashOf(attribute1);
* result = 31 * result + hashOf(attribute2);
* result = 31 * result + hashOf(attribute3);
* hashcode = result;
* }
* return result;
* }
*
* </pre>
*
* @param s
* @return the hash code
*/
public static int hashOf(final short s) {
return s;
}
}