/* ===========================================================
* JFreeChart : a free chart library for the Java(tm) platform
* ===========================================================
*
* (C) Copyright 2000-2014, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jfreechart/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
* Other names may be trademarks of their respective owners.]
*
* ------------------
* HashUtils.java
* ------------------
* (C) Copyright 2006-2014, by Object Refinery Limited;
*
* Original Author: David Gilbert (for Object Refinery Limited);
* Contributor(s): -;
*
* Changes
* -------
* 03-Oct-2006 : Version 1 (DG);
* 06-Mar-2007 : Fix for hashCodeForDoubleArray() method (DG);
* 13-Nov-2007 : Added new utility methods (DG);
* 22-Nov-2007 : Added hashCode() method for 'int' (DG);
* 05-Dec-2007 : Added special methods to handle BooleanList, PaintList,
* and StrokeList (DG);
* 15-Jun-2012 : Removed JCommon dependency (DG);
*
*/
package org.jfree.chart.util;
import java.awt.GradientPaint;
import java.awt.Paint;
import java.awt.Stroke;
import org.jfree.chart.util.BooleanList;
import org.jfree.chart.util.StrokeList;
/**
* Some utility methods for calculating hash codes.
*
* @since 1.0.3
*/
public class HashUtils {
/**
* Returns a hash code for a <code>Paint</code> instance. If
* <code>p</code> is <code>null</code>, this method returns zero.
*
* @param p the paint (<code>null</code> permitted).
*
* @return The hash code.
*/
public static int hashCodeForPaint(Paint p) {
if (p == null) {
return 0;
}
int result = 0;
// handle GradientPaint as a special case
if (p instanceof GradientPaint) {
GradientPaint gp = (GradientPaint) p;
result = 193;
result = 37 * result + gp.getColor1().hashCode();
result = 37 * result + gp.getPoint1().hashCode();
result = 37 * result + gp.getColor2().hashCode();
result = 37 * result + gp.getPoint2().hashCode();
}
else {
// we assume that all other Paint instances implement equals() and
// hashCode()...of course that might not be true, but what can we
// do about it?
result = p.hashCode();
}
return result;
}
/**
* Returns a hash code for a <code>double[]</code> instance. If the array
* is <code>null</code>, this method returns zero.
*
* @param a the array (<code>null</code> permitted).
*
* @return The hash code.
*/
public static int hashCodeForDoubleArray(double[] a) {
if (a == null) {
return 0;
}
int result = 193;
long temp;
for (double anA : a) {
temp = Double.doubleToLongBits(anA);
result = 29 * result + (int) (temp ^ (temp >>> 32));
}
return result;
}
/**
* Returns a hash value based on a seed value and the value of a boolean
* primitive.
*
* @param pre the seed value.
* @param b the boolean value.
*
* @return A hash value.
*
* @since 1.0.7
*/
public static int hashCode(int pre, boolean b) {
return 37 * pre + (b ? 0 : 1);
}
/**
* Returns a hash value based on a seed value and the value of an int
* primitive.
*
* @param pre the seed value.
* @param i the int value.
*
* @return A hash value.
*
* @since 1.0.8
*/
public static int hashCode(int pre, int i) {
return 37 * pre + i;
}
/**
* Returns a hash value based on a seed value and the value of a double
* primitive.
*
* @param pre the seed value.
* @param d the double value.
*
* @return A hash value.
*
* @since 1.0.7
*/
public static int hashCode(int pre, double d) {
long l = Double.doubleToLongBits(d);
return 37 * pre + (int) (l ^ (l >>> 32));
}
/**
* Returns a hash value based on a seed value and a paint instance.
*
* @param pre the seed value.
* @param p the paint (<code>null</code> permitted).
*
* @return A hash value.
*
* @since 1.0.7
*/
public static int hashCode(int pre, Paint p) {
return 37 * pre + hashCodeForPaint(p);
}
/**
* Returns a hash value based on a seed value and a stroke instance.
*
* @param pre the seed value.
* @param s the stroke (<code>null</code> permitted).
*
* @return A hash value.
*
* @since 1.0.7
*/
public static int hashCode(int pre, Stroke s) {
int h = (s != null ? s.hashCode() : 0);
return 37 * pre + h;
}
/**
* Returns a hash value based on a seed value and a string instance.
*
* @param pre the seed value.
* @param s the string (<code>null</code> permitted).
*
* @return A hash value.
*
* @since 1.0.7
*/
public static int hashCode(int pre, String s) {
int h = (s != null ? s.hashCode() : 0);
return 37 * pre + h;
}
/**
* Returns a hash value based on a seed value and a <code>Comparable</code>
* instance.
*
* @param pre the seed value.
* @param c the comparable (<code>null</code> permitted).
*
* @return A hash value.
*
* @since 1.0.7
*/
public static int hashCode(int pre, Comparable c) {
int h = (c != null ? c.hashCode() : 0);
return 37 * pre + h;
}
/**
* Returns a hash value based on a seed value and an <code>Object</code>
* instance.
*
* @param pre the seed value.
* @param obj the object (<code>null</code> permitted).
*
* @return A hash value.
*
* @since 1.0.8
*/
public static int hashCode(int pre, Object obj) {
int h = (obj != null ? obj.hashCode() : 0);
return 37 * pre + h;
}
/**
* Computes a hash code for a {@link BooleanList}. In the latest version
* of JCommon, the {@link BooleanList} class should implement the hashCode()
* method correctly, but we compute it here anyway so that we can work with
* older versions of JCommon (back to 1.0.0).
*
* @param pre the seed value.
* @param list the list (<code>null</code> permitted).
*
* @return The hash code.
*
* @since 1.0.9
*/
public static int hashCode(int pre, BooleanList list) {
if (list == null) {
return pre;
}
int result = 127;
int size = list.size();
result = HashUtils.hashCode(result, size);
// for efficiency, we just use the first, last and middle items to
// compute a hashCode...
if (size > 0) {
result = HashUtils.hashCode(result, list.getBoolean(0));
if (size > 1) {
result = HashUtils.hashCode(result,
list.getBoolean(size - 1));
if (size > 2) {
result = HashUtils.hashCode(result,
list.getBoolean(size / 2));
}
}
}
return 37 * pre + result;
}
/**
* Computes a hash code for a {@link StrokeList}. In the latest version
* of JCommon, the {@link StrokeList} class should implement the hashCode()
* method correctly, but we compute it here anyway so that we can work with
* older versions of JCommon (back to 1.0.0).
*
* @param pre the seed value.
* @param list the list (<code>null</code> permitted).
*
* @return The hash code.
*
* @since 1.0.9
*/
public static int hashCode(int pre, StrokeList list) {
if (list == null) {
return pre;
}
int result = 127;
int size = list.size();
result = HashUtils.hashCode(result, size);
// for efficiency, we just use the first, last and middle items to
// compute a hashCode...
if (size > 0) {
result = HashUtils.hashCode(result, list.getStroke(0));
if (size > 1) {
result = HashUtils.hashCode(result,
list.getStroke(size - 1));
if (size > 2) {
result = HashUtils.hashCode(result,
list.getStroke(size / 2));
}
}
}
return 37 * pre + result;
}
}