1 /* 2 * This file is part of the LibreOffice project. 3 * 4 * This Source Code Form is subject to the terms of the Mozilla Public 5 * License, v. 2.0. If a copy of the MPL was not distributed with this 6 * file, You can obtain one at http://mozilla.org/MPL/2.0/. 7 * 8 * This file incorporates work covered by the following license notice: 9 * 10 * Licensed to the Apache Software Foundation (ASF) under one or more 11 * contributor license agreements. See the NOTICE file distributed 12 * with this work for additional information regarding copyright 13 * ownership. The ASF licenses this file to you under the Apache 14 * License, Version 2.0 (the "License"); you may not use this file 15 * except in compliance with the License. You may obtain a copy of 16 * the License at http://www.apache.org/licenses/LICENSE-2.0 . 17 */ 18 19 using System; 20 using unoidl.com.sun.star.lang; 21 22 namespace uno.util 23 { 24 25 /** This class can be used as a base class for UNO objects. 26 It implements the capability to be kept weakly 27 (unoidl.com.sun.star.uno.XWeak) and it implements 28 unoidl.com.sun.star.lang.XTypeProvider which is necessary for 29 using the object from StarBasic. 30 In addition, it implements the interface 31 unoidl.com.sun.star.lang.XComponent to be disposed explicitly. 32 */ 33 public class WeakComponentBase : WeakBase, XComponent 34 { t_disposing( EventObject evt )35 private delegate void t_disposing( EventObject evt ); 36 private t_disposing m_disposing = null; 37 private bool m_inDispose = false; 38 private bool m_disposed = false; 39 40 /** Indicates whether object is already disposed. 41 42 @return 43 true, if object has been disposed 44 */ isDisposed()45 protected bool isDisposed() 46 { 47 lock (this) 48 { 49 return m_disposed; 50 } 51 } 52 53 /** Checks whether this object is disposed and throws a DisposedException 54 if it is already disposed. 55 */ checkUnDisposed()56 protected void checkUnDisposed() 57 { 58 if (! isDisposed()) 59 { 60 throw new unoidl.com.sun.star.lang.DisposedException( 61 "object already disposed!", this ); 62 } 63 } 64 ~WeakComponentBase()65 ~WeakComponentBase() 66 { 67 bool doDispose; 68 lock (this) 69 { 70 doDispose = (!m_inDispose && !m_disposed); 71 } 72 if (doDispose) 73 { 74 dispose(); 75 } 76 } 77 78 /** Override to perform extra clean-up work. Provided for subclasses. 79 It is called during dispose() 80 */ preDisposing()81 protected void preDisposing() 82 { 83 } 84 85 /** Override to become notified right before the disposing action is 86 performed. 87 */ postDisposing()88 protected void postDisposing() 89 { 90 } 91 92 // XComponent impl 93 /** This method is called by the owner of this object to explicitly 94 dispose it. This implementation of dispose() first notifies this object 95 via preDisposing(), then all registered event listeners and 96 finally this object again calling postDisposing(). 97 */ dispose()98 public void dispose() 99 { 100 // Determine in a thread-safe way if this is the first call to this 101 // method. Only then we proceed with the notification of event 102 // listeners. It is an error to call this method more than once. 103 bool doDispose = false; 104 t_disposing call = null; 105 lock (this) 106 { 107 if (! m_inDispose && !m_disposed) 108 { 109 call = m_disposing; 110 m_disposing = null; 111 m_inDispose = true; 112 doDispose = true; 113 } 114 } 115 // The notification occurs in an unsynchronized block in order to avoid 116 // deadlocks if one of the listeners calls back in a different thread on 117 // a synchronized method which uses the same object. 118 if (doDispose) 119 { 120 try 121 { 122 // call sub class 123 preDisposing(); 124 // send disposing notifications to listeners 125 if (null != call) 126 { 127 EventObject evt = new EventObject( this ); 128 call( evt ); 129 } 130 // call sub class 131 postDisposing(); 132 } 133 finally 134 { 135 // finally makes sure that the flags are set ensuring 136 // that this function is only called once. 137 m_disposed = true; 138 m_inDispose = false; 139 } 140 } 141 else 142 { 143 // in a multithreaded environment, it can't be avoided, 144 // that dispose is called twice. 145 // However this condition is traced, because it MAY indicate an 146 // error. 147 #if DEBUG 148 Console.WriteLine( 149 "WeakComponentBase.dispose() - dispose called twice" ); 150 #endif 151 // Debug.Fail( "WeakComponentBase.dispose() - dispose called twice" ); 152 } 153 } 154 /** Registers an event listener being notified when this object is disposed. 155 156 @param xListener event listener 157 */ addEventListener( XEventListener xListener )158 public void addEventListener( XEventListener xListener ) 159 { 160 bool add; 161 lock (this) 162 { 163 add = (! m_inDispose && !m_disposed); 164 if (add) 165 m_disposing += new t_disposing( xListener.disposing ); 166 } 167 if (! add) 168 xListener.disposing( new EventObject( this ) ); 169 } 170 /** Revokes an event listener from being notified when this object 171 is disposed. 172 173 @param xListener event listener 174 */ removeEventListener( XEventListener xListener )175 public void removeEventListener( XEventListener xListener ) 176 { 177 lock (this) 178 { 179 if (! m_inDispose && !m_disposed) 180 m_disposing -= new t_disposing( xListener.disposing ); 181 } 182 } 183 } 184 185 } 186