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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 | } | ||