/*
* Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package sun.tools.jstat;
import java.util.*;
/**
* A typesafe enumeration for describing mathematical operators.
*
* @author Brian Doherty
* @since 1.5
*/
public abstract class Operator {
private static int nextOrdinal = 0;
private static HashMap<String, Operator> map = new HashMap<String, Operator>();
private final String name;
private final int ordinal = nextOrdinal++;
private Operator(String name) {
this.name = name;
map.put(name, this);
}
protected abstract double eval(double x, double y);
/* Operator '+' */
public static final Operator PLUS = new Operator("+") {
protected double eval(double x, double y) {
return x + y;
}
};
/* Operator '-' */
public static final Operator MINUS = new Operator("-") {
protected double eval(double x, double y) {
return x - y;
}
};
/* Operator '/' */
public static final Operator DIVIDE = new Operator("/") {
protected double eval(double x, double y) {
if (y == 0) {
return Double.NaN;
}
return x / y;
}
};
/* Operator '*' */
public static final Operator MULTIPLY = new Operator("*") {
protected double eval(double x, double y) {
return x * y;
}
};
/**
* Returns the string representation of this Operator object.
*
* @return the string representation of this Operator object
*/
public String toString() {
return name;
}
/**
* Maps a string to its corresponding Operator object.
*
* @param s an string to match against Operator objects.
* @return The Operator object matching the given string.
*/
public static Operator toOperator(String s) {
return map.get(s);
}
/**
* Returns an enumeration of the keys for this enumerated type
*
* @param s an string to match against Operator objects.
* @return The Operator object matching the given string.
*/
protected static Set keySet() {
return map.keySet();
}
}