112 lines
3.3 KiB
Java
112 lines
3.3 KiB
Java
/*
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* Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.tools.jstat;
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import java.util.*;
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/**
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* A typesafe enumeration for describing mathematical operators.
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*
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* @author Brian Doherty
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* @since 1.5
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*/
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public abstract class Operator {
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private static int nextOrdinal = 0;
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private static HashMap<String, Operator> map = new HashMap<String, Operator>();
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private final String name;
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private final int ordinal = nextOrdinal++;
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private Operator(String name) {
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this.name = name;
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map.put(name, this);
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}
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protected abstract double eval(double x, double y);
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/* Operator '+' */
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public static final Operator PLUS = new Operator("+") {
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protected double eval(double x, double y) {
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return x + y;
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}
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};
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/* Operator '-' */
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public static final Operator MINUS = new Operator("-") {
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protected double eval(double x, double y) {
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return x - y;
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}
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};
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/* Operator '/' */
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public static final Operator DIVIDE = new Operator("/") {
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protected double eval(double x, double y) {
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if (y == 0) {
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return Double.NaN;
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}
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return x / y;
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}
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};
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/* Operator '*' */
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public static final Operator MULTIPLY = new Operator("*") {
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protected double eval(double x, double y) {
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return x * y;
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}
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};
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/**
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* Returns the string representation of this Operator object.
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*
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* @return the string representation of this Operator object
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*/
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public String toString() {
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return name;
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}
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/**
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* Maps a string to its corresponding Operator object.
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*
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* @param s an string to match against Operator objects.
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* @return The Operator object matching the given string.
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*/
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public static Operator toOperator(String s) {
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return map.get(s);
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}
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/**
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* Returns an enumeration of the keys for this enumerated type
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*
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* @param s an string to match against Operator objects.
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* @return The Operator object matching the given string.
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*/
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protected static Set keySet() {
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return map.keySet();
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}
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}
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