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| 1 | +/* | |
| 2 | + * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package sun.tools.jstat; | |
| 27 | + | |
| 28 | +import java.util.*; | |
| 29 | + | |
| 30 | + | |
| 31 | +/** | |
| 32 | + * A typesafe enumeration for describing mathematical operators. | |
| 33 | + * | |
| 34 | + * @author Brian Doherty | |
| 35 | + * @since 1.5 | |
| 36 | + */ | |
| 37 | +public abstract class Operator { | |
| 38 | + | |
| 39 | + private static int nextOrdinal = 0; | |
| 40 | + private static HashMap<String, Operator> map = new HashMap<String, Operator>(); | |
| 41 | + | |
| 42 | + private final String name; | |
| 43 | + private final int ordinal = nextOrdinal++; | |
| 44 | + | |
| 45 | + private Operator(String name) { | |
| 46 | + this.name = name; | |
| 47 | + map.put(name, this); | |
| 48 | + } | |
| 49 | + | |
| 50 | + protected abstract double eval(double x, double y); | |
| 51 | + | |
| 52 | + /* Operator '+' */ | |
| 53 | + public static final Operator PLUS = new Operator("+") { | |
| 54 | + protected double eval(double x, double y) { | |
| 55 | + return x + y; | |
| 56 | + } | |
| 57 | + }; | |
| 58 | + | |
| 59 | + /* Operator '-' */ | |
| 60 | + public static final Operator MINUS = new Operator("-") { | |
| 61 | + protected double eval(double x, double y) { | |
| 62 | + return x - y; | |
| 63 | + } | |
| 64 | + }; | |
| 65 | + | |
| 66 | + /* Operator '/' */ | |
| 67 | + public static final Operator DIVIDE = new Operator("/") { | |
| 68 | + protected double eval(double x, double y) { | |
| 69 | + if (y == 0) { | |
| 70 | + return Double.NaN; | |
| 71 | + } | |
| 72 | + return x / y; | |
| 73 | + } | |
| 74 | + }; | |
| 75 | + | |
| 76 | + /* Operator '*' */ | |
| 77 | + public static final Operator MULTIPLY = new Operator("*") { | |
| 78 | + protected double eval(double x, double y) { | |
| 79 | + return x * y; | |
| 80 | + } | |
| 81 | + }; | |
| 82 | + | |
| 83 | + /** | |
| 84 | + * Returns the string representation of this Operator object. | |
| 85 | + * | |
| 86 | + * @return the string representation of this Operator object | |
| 87 | + */ | |
| 88 | + public String toString() { | |
| 89 | + return name; | |
| 90 | + } | |
| 91 | + | |
| 92 | + /** | |
| 93 | + * Maps a string to its corresponding Operator object. | |
| 94 | + * | |
| 95 | + * @param s an string to match against Operator objects. | |
| 96 | + * @return The Operator object matching the given string. | |
| 97 | + */ | |
| 98 | + public static Operator toOperator(String s) { | |
| 99 | + return map.get(s); | |
| 100 | + } | |
| 101 | + | |
| 102 | + /** | |
| 103 | + * Returns an enumeration of the keys for this enumerated type | |
| 104 | + * | |
| 105 | + * @param s an string to match against Operator objects. | |
| 106 | + * @return The Operator object matching the given string. | |
| 107 | + */ | |
| 108 | + protected static Set keySet() { | |
| 109 | + return map.keySet(); | |
| 110 | + } | |
| 111 | +} | |