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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 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.applet; | ||
| 27 | |||
| 28 | import java.util.EventListener; | ||
| 29 | import java.io.Serializable; | ||
| 30 | import java.io.ObjectOutputStream; | ||
| 31 | import java.io.IOException; | ||
| 32 | |||
| 33 | /** | ||
| 34 | * AppletEventMulticaster class. This class manages an immutable | ||
| 35 | * structure consisting of a chain of AppletListeners and is | ||
| 36 | * responsible for dispatching events to them. | ||
| 37 | * | ||
| 38 | * @author Sunita Mani | ||
| 39 | */ | ||
| 40 | public class AppletEventMulticaster implements AppletListener { | ||
| 41 | |||
| 42 | private final AppletListener a, b; | ||
| 43 | |||
| 44 | public AppletEventMulticaster(AppletListener a, AppletListener b) { | ||
| 45 | this.a = a; this.b = b; | ||
| 46 | } | ||
| 47 | |||
| 48 | public void appletStateChanged(AppletEvent e) { | ||
| 49 | a.appletStateChanged(e); | ||
| 50 | b.appletStateChanged(e); | ||
| 51 | } | ||
| 52 | |||
| 53 | /** | ||
| 54 | * Adds Applet-listener-a with Applet-listener-b and | ||
| 55 | * returns the resulting multicast listener. | ||
| 56 | * @param a Applet-listener-a | ||
| 57 | * @param b Applet-listener-b | ||
| 58 | */ | ||
| 59 | public static AppletListener add(AppletListener a, AppletListener b) { | ||
| 60 | return addInternal(a, b); | ||
| 61 | } | ||
| 62 | |||
| 63 | /** | ||
| 64 | * Removes the old Applet-listener from Applet-listener-l and | ||
| 65 | * returns the resulting multicast listener. | ||
| 66 | * @param l Applet-listener-l | ||
| 67 | * @param oldl the Applet-listener being removed | ||
| 68 | */ | ||
| 69 | public static AppletListener remove(AppletListener l, AppletListener oldl) { | ||
| 70 | return removeInternal(l, oldl); | ||
| 71 | } | ||
| 72 | |||
| 73 | /** | ||
| 74 | * Returns the resulting multicast listener from adding listener-a | ||
| 75 | * and listener-b together. | ||
| 76 | * If listener-a is null, it returns listener-b; | ||
| 77 | * If listener-b is null, it returns listener-a | ||
| 78 | * If neither are null, then it creates and returns | ||
| 79 | * a new AppletEventMulticaster instance which chains a with b. | ||
| 80 | * @param a event listener-a | ||
| 81 | * @param b event listener-b | ||
| 82 | */ | ||
| 83 | private static AppletListener addInternal(AppletListener a, AppletListener b) { | ||
| 84 | if (a == null) return b; | ||
| 85 | if (b == null) return a; | ||
| 86 | return new AppletEventMulticaster(a, b); | ||
| 87 | } | ||
| 88 | |||
| 89 | |||
| 90 | /** | ||
| 91 | * Removes a listener from this multicaster and returns the | ||
| 92 | * resulting multicast listener. | ||
| 93 | * @param oldl the listener to be removed | ||
| 94 | */ | ||
| 95 | protected AppletListener remove(AppletListener oldl) { | ||
| 96 | if (oldl == a) return b; | ||
| 97 | if (oldl == b) return a; | ||
| 98 | AppletListener a2 = removeInternal(a, oldl); | ||
| 99 | AppletListener b2 = removeInternal(b, oldl); | ||
| 100 | if (a2 == a && b2 == b) { | ||
| 101 | return this; // it's not here | ||
| 102 | } | ||
| 103 | return addInternal(a2, b2); | ||
| 104 | } | ||
| 105 | |||
| 106 | |||
| 107 | /** | ||
| 108 | * Returns the resulting multicast listener after removing the | ||
| 109 | * old listener from listener-l. | ||
| 110 | * If listener-l equals the old listener OR listener-l is null, | ||
| 111 | * returns null. | ||
| 112 | * Else if listener-l is an instance of AppletEventMulticaster | ||
| 113 | * then it removes the old listener from it. | ||
| 114 | * Else, returns listener l. | ||
| 115 | * @param l the listener being removed from | ||
| 116 | * @param oldl the listener being removed | ||
| 117 | */ | ||
| 118 | private static AppletListener removeInternal(AppletListener l, AppletListener oldl) { | ||
| 119 | if (l == oldl || l == null) { | ||
| 120 | return null; | ||
| 121 | } else if (l instanceof AppletEventMulticaster) { | ||
| 122 | return ((AppletEventMulticaster)l).remove(oldl); | ||
| 123 | } else { | ||
| 124 | return l; // it's not here | ||
| 125 | } | ||
| 126 | } | ||
| 127 | } | ||