Coverage Report

Coverage Report - net.wotonomy.foundation.NSNotificationCenter

Classes in this File

2.955

 /*
 Wotonomy: OpenStep design patterns for pure Java applications.
 Copyright (C) 2000 Blacksmith, Inc.
 
 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.
 
 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 Lesser General Public License for more details.
 
 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, see http://www.gnu.org
 */
 
 package net.wotonomy.foundation;
 
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
 import java.util.Hashtable;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Vector;
 
 import net.wotonomy.foundation.internal.WotonomyException;
 
 /**
 * NSNotificationCenter broadcasts NSNotifications to
 * registered observers.  Observers can register for all
 * notifications of a specific type, or all notifications
 * about a specific object, or both.  Observers specify 
 * the method that will be called when they are notified.
 * A global notification center can be accessed with 
 * defaultCenter(), but other centers can be created and
 * used independently of the default center. <br><br>
 *
 * This implementation uses weak references for observers
 * and observables.  The advantage to this approach is
 * that you do not need to explicitly unregister observers
 * or observables; they will be unregistered when they are
 * garbage-collected.  Note that you will need to retain
 * a reference to any objects you register or they may
 * become unregistered if no other object references them.
 *
 * @author michael@mpowers.net
 * @author $Author: cgruber $
 * @version $Revision: 893 $
 */
 public class NSNotificationCenter
 {
     /** 
     * Null marker class simplifies equals() logic
     * for CompoundKey class below.  
     */
     public static final Object NullMarker = new Object();    
   
     private static NSNotificationCenter defaultCenter = null;
     
     /**
     * A Map of (name,object) pairs to a List 
     * of (observer,selector) pairs.
     */
     private Hashtable observers; // thread-safe
     
     /**
     * Default constructor creates a new notification center.
     */
     public NSNotificationCenter()
     {
         observers = new Hashtable();
     }
     
     /**
     * Returns the system default center, creating one
     * if it has not yet been created.
     */
     static public NSNotificationCenter defaultCenter()
     {
         if ( defaultCenter == null )
         {
             defaultCenter = new NSNotificationCenter();   
         }
         return defaultCenter;
     }
         
         /**
         * Addes the specified observer to the notification queue for
         * notifications with the specified name or the specified 
         * object or both.
         * @param anObserver The observer that wishes to be notified.
         * @param aSelector The selector that will be invoked.  
         * Must have exactly one argument, to which a notification
         * will be passed.
         * @param notificationName The name of the notifications for
         * which the observer will be notified.  If null, will notify
         * only based on matching anObject.
         * @param anObject The object of the notifications for which
         * the observer will be notified.  If null, will notify 
         * only based on matching notificationName.
         */
         public void addObserver(
                 Object anObserver, NSSelector aSelector,
                 String notificationName, Object anObject )
     {
         // remove freed objects
         processKeyQueue();
         
         Object name = notificationName;
         if ( name == null )
         {
             name = NullMarker;
         }
         if ( anObject == null )
         {
             anObject = NullMarker;
         }
         Object key = new CompoundKey( name, anObject );
         Object value = new CompoundValue( anObserver, aSelector );
         List list = (List) observers.get( key );
         if ( list == null )
         {
             // create new list with value and put it in map
             list = new Vector(); // thread-safe
             list.add( value );
             observers.put( new CompoundKey( 
                 name, anObject, keyQueue ), list );
         }
         else
         {
             // add only if not already in list
             if ( ! list.contains( value ) )
             {
                 list.add( value );   
             }
         }
     }
         
         /**
         * Posts the specified notification.  Notifies all registered
         * observers that match either the notification name or 
         * the notification object, or both.
         * @param aNotification The notification that will be passed
         * to the observers selector.
         */
         public void postNotification(
                 NSNotification aNotification )
     {
         List mergedList = new LinkedList();
         Object key, observerList;
         
         Object name = aNotification.name();
         Object object = aNotification.object();
         
         if ( name != null ) 
         {
             if ( object != null ) 
             { // both are specified
                 observerList = observers.get( new CompoundKey( name, object ) );
                 if ( observerList != null )
                 {
                     mergedList.addAll( (List) observerList );
                 }
                 observerList = observers.get( new CompoundKey( name, NullMarker ) );
                 if ( observerList != null )
                 {
                     mergedList.addAll( (List) observerList );
                 }
                 observerList = observers.get( new CompoundKey( NullMarker, object ) );
                 if ( observerList != null )
                 {
                     mergedList.addAll( (List) observerList );
                 }
             }
             else 
             { // object is null
                 observerList = observers.get( new CompoundKey( name, NullMarker ) );
                 if ( observerList != null )
                 {
                     mergedList.addAll( (List) observerList );
                 }
             }
         }
         else
         if ( object != null ) 
         { // name is null
             observerList = observers.get( new CompoundKey( NullMarker, object ) );
             if ( observerList != null )
             {
                 mergedList.addAll( (List) observerList );
             }
         }
 
         key = new CompoundKey(
             NullMarker, NullMarker );
         observerList = observers.get( key );
         if ( observerList != null )
         {
             mergedList.addAll( (List) observerList );
         }
 
         CompoundValue value;
         Iterator it = mergedList.iterator();
         while ( it.hasNext() )
         {
             value = (CompoundValue) it.next();
             if ( value.get() == null )
             {
                 it.remove();
             }
             else
             {
                 try
                 {
                     value.selector().invoke( 
                         value.get(), 
                         new Object[] { aNotification } );
                 }
                 catch ( Exception exc )
                 {
                     WotonomyException w = new WotonomyException(
                         "Error notifying object: " + value.get() + " : " + aNotification, exc );
 //                    throw w;
                     w.printStackTrace();
 postNotification( "Error notifying object", this, new NSDictionary( "exception", w ) );
                 }
             }
         }
         
     }
         
         /**
         * Posts a notification created from the specified name
         * and object.  Calls postNotification( NSNotification ).
         * @param notificationName a String key to distinguish
         * this notification.
         * @param anObject any object, by convention this is 
         * the originator of the notification.
         */
         public void postNotification(
                 String notificationName, Object anObject )
     {
         postNotification( new NSNotification( 
             notificationName, anObject ) );
     }
         
         /**
         * Posts a notification created from the specified name,
         * object, and info.  Calls postNotification( NSNotification ).
         * @param notificationName a String key to distinguish
         * this notification.
         * @param anObject any object, by convention this is 
         * the originator of the notification.
         * @param userInfo a Map containing information specific
         * to the originator of the notification and that may
         * be of interest to a knowledgable observer.
         */
         public void postNotification(
                 String notificationName, Object anObject, Map userInfo )
     {
         postNotification( new NSNotification( 
             notificationName, anObject, userInfo ) );
     }
         
         /**
         * Unregisters the specified observer from all notification
         * queues for which it is registered. 
         * @param anObserver The observer to be unregistered.
         */
         public void removeObserver(
                  Object anObserver )
     {
         // remove freed objects
         processKeyQueue();
         
         Iterator it = new LinkedList( observers.keySet() ).iterator();
         while ( it.hasNext() )
         {
             removeObserver( anObserver, it.next() );
         }
     }
         
         /**
         * Unregisters the specified observer from all notifications
         * queues associated with the specified name or object or both.
         * @param anObserver The observer to be unregistered, if null
         * will unregister all observers for the specified notification
         * name and object.
         * @param notificationName The name of the notification for which
         * the observer will be unregistered, if null will unregister
         * the specified observer for all notifications with the 
         * specified object.
         * @param anObject The object for the notification for which
         * the observer will be unregistered, if null will unregister 
         * the specified observer for all objects with the specified
         * notification.
         */
         public void removeObserver(
                 Object anObserver, String notificationName, Object anObject )
     {
         // remove freed objects
         processKeyQueue();
         
         // get key matches
         List keys = matchingKeys( notificationName, anObject );
         
         // remove specified observer from each matching key
         Iterator it = keys.iterator();
         while ( it.hasNext() )
         {
             removeObserver( anObserver, it.next() );               
         }
     }
     
     /**
     * Returns all keys that match the specified name and object,
     * but in this case null parameters are considered wildcards.
     * Pass NullMarkers if you want to explicitly match nulls.
     */
     private List matchingKeys( String name, Object object )
     {
         List result = new LinkedList();
 
         boolean willAdd;
         CompoundKey key;
         Iterator it = observers.keySet().iterator();
         while ( it.hasNext() )
         {
             key = (CompoundKey) it.next();
             willAdd = false;
             if ( ( name == null ) || ( name == key.name() ) )
             {
                 if ( ( object == null ) || ( object == key.get() ) )
                 {
                     willAdd = true;   
                 }
             }
             if ( willAdd )
             {
                 result.add( key );   
             }
         }
         return result;
     }
     
     /**
     * Removes the specified observer from the list referenced
     * by the specified key in the observer map.
     */
     private void removeObserver( 
         Object anObserver, Object key )
     {
         // if observer null, remove all observers for key
         if ( anObserver == null )
         {
             observers.remove( key );
             return;
         }
         
         List list = (List) observers.get( key );
         if ( list == null ) return;
 
         // remove specified observer from list
         Object observer;
         Iterator it = list.iterator();
         while ( it.hasNext() )
         {
             observer = ((CompoundValue)it.next()).get();
             if ( ( observer == null ) || ( anObserver == observer ) )
             {
                 // remove if match or freed object
                 it.remove();   
 
                 // do not return; process entire list
             }
         }
         if ( list.size() == 0 )
         {
             observers.remove( key );       
         }
     }
 
     /* Reference queues for cleared WeakKeys */
     private ReferenceQueue keyQueue = new ReferenceQueue();
        
     /**
     * Removes any keys whose object has been garbage collected.
     * (Garbage collected values are removed as they are encountered.)
     */       
     private void processKeyQueue() 
     {
         CompoundKey ck;
         while ((ck = (CompoundKey)keyQueue.poll()) != null) 
         {
             //System.out.println( "EOObserverCenter.processQueue: removing object" );
             observers.remove(ck);
         }
     }
    
     /**
     * Key combining a name with an object.
     * The object is weakly referenced, and keys
     * are deallocated by reference queue.
     * equals() compares by reference.
     */ 
     private static class CompoundKey extends WeakReference
     {
         private Object name;
         private int hashCode;
         
         /**
         * Creates compound key.  
         * Neither name nor object may be null.
         * Use NullMarker to represent null
         * in either name or object.
         */
         public CompoundKey ( 
             Object aName, Object anObject )
         {
             super( anObject );
             name = aName;
             hashCode = aName.hashCode() + anObject.hashCode();
         }
         
         /**
         * Creates compound key with queue.
         * Neither name nor object may be null.
         * Use NullMarker to represent null
         * in either name or object.
         */
         public CompoundKey ( 
             Object aName, Object anObject, ReferenceQueue aQueue )
         {
             super( anObject, aQueue );
             name = aName;
             hashCode = aName.hashCode() + anObject.hashCode();
         }
         
         public Object name()
         {
             return name;
         }
         
         public int hashCode()
         {
             return hashCode;
         }
         
         public boolean equals( Object anObject )
         {
             if ( this == anObject ) return true;
             // assumes only used with other compound keys
             CompoundKey key = (CompoundKey) anObject;
             if ( name == key.name || ( name != null && name.equals( key.name ) ) )
             {
                 Object object = get();
                 if ( object != null )
                 {
                     // compares by reference
                     if ( object == ( key.get() ) )
                     {
                         return true;   
                     }
                 }
             }
             return false;
         }
         
         public String toString()
         {
             return "[CompoundKey:"+name()+":"+get()+"]";   
         }
     }
         
     /**
     * Value combining an object with a selector.
     * The object is weakly referenced, and null
     * values are not allowed.
     */ 
     private static class CompoundValue extends WeakReference
     {
         private NSSelector selector;
         private int hashCode;
         
         public CompoundValue( Object anObject, NSSelector aSelector )
         {
             super( anObject );
             hashCode = anObject.hashCode();
             selector = aSelector;
         }
         
         public NSSelector selector()
         {
             return selector;
         }
         
         public int hashCode()
         {
             return hashCode;
         }
         
         public boolean equals( Object anObject )
         {
             if ( this == anObject ) return true;
             // assumes only used with other compound values
             CompoundValue value = (CompoundValue) anObject;
             if ( selector == value.selector || 
                ( selector != null && selector.equals( value.selector ) ) )
             {
                 Object object = get();
                 if ( object != null )
                 {
                     if ( object == value.get() )
                     {
                         return true;   
                     }
                 }
             }
             return false;
         }
 
         public String toString()
         {
             return "[CompoundValue:"+get()+":"+selector().name()+"]";   
         }
     }
 /*
     public static void main( String[] argv )
     {
         Object aSource = "aSource";
         Object bSource = "bSource";
         
         Object oneTest = new OneTest();
         Object twoTest = new TwoTest();
         NSSelector notifyMeOnce = 
             new NSSelector( "notifyMeOnce", 
             new Class[] { NSNotification.class } );
         NSSelector notifyMeTwice = 
             new NSSelector( "notifyMeTwice", 
             new Class[] { NSNotification.class } );
             
         NSNotificationCenter.defaultCenter().addObserver(
             oneTest, notifyMeOnce, "aMessage", null );
             
         NSNotificationCenter.defaultCenter().addObserver(
             oneTest, notifyMeOnce, null, aSource );
             
         NSNotificationCenter.defaultCenter().addObserver(
             twoTest, notifyMeOnce, "aMessage", aSource );
             
         NSNotificationCenter.defaultCenter().addObserver(
             twoTest, notifyMeTwice, null, null );
             
         NSNotificationCenter.defaultCenter().postNotification(
             "aMessage", aSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "aMessage", bSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "bMessage", aSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "bMessage", bSource );
         System.out.println( "---" );
         
         NSNotificationCenter.defaultCenter().removeObserver( 
             oneTest, null, aSource );
 
         NSNotificationCenter.defaultCenter().postNotification(
             "aMessage", aSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "aMessage", bSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "bMessage", aSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "bMessage", bSource );
         System.out.println( "---" );
 
         NSNotificationCenter.defaultCenter().removeObserver( 
             null );
 
         NSNotificationCenter.defaultCenter().postNotification(
             "aMessage", aSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "aMessage", bSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "bMessage", aSource );
         System.out.println();
         NSNotificationCenter.defaultCenter().postNotification(
             "bMessage", bSource );
         System.out.println( "---" );
     }
     
     static private class OneTest
     {
         public void notifyMeOnce( NSNotification aNotification )
         {
             System.out.println( "OneTest.notifyMeOnce: " + aNotification );   
         }
     }
 
     static private class TwoTest
     {
         public void notifyMeOnce( NSNotification aNotification )
         {
             System.out.println( "TwoTest.notifyMeOnce: " + aNotification );   
         }
         public void notifyMeTwice( NSNotification aNotification )
         {
             System.out.println( "TwoTest.notifyMeTwice: " + aNotification );   
         }
     }
 */
 }
 
 
 
 /*
  * $Log$
  * Revision 1.2  2006/02/16 13:15:00  cgruber
  * Check in all sources in eclipse-friendly maven-enabled packages.
  *
  * Revision 1.11  2003/06/03 14:51:15  mpowers
  * Added commented-out println for debugging.
  *
  * Revision 1.10  2003/03/27 21:46:00  mpowers
  * Better handling for null parameters on subscribe.
  * Better handling for null parameters on post.
  *
  * Revision 1.9  2003/01/28 19:44:38  mpowers
  * Now comparing strings by value not reference.
  *
  * Revision 1.8  2001/06/29 16:14:23  mpowers
  * Fixed a javac compiler error that jikes allowed: shoe's on the other foot!
  *
  * Revision 1.7  2001/06/07 22:09:03  mpowers
  * Exceptions during a notification are no longer being thrown
  * so we can assure that all notifications get handled.
  * Instead, we're printing stack traces...
  *
  * Revision 1.6  2001/04/09 21:41:50  mpowers
  * Better debugging.
  *
  * Revision 1.5  2001/03/15 21:09:06  mpowers
  * Fixed notifications with null objects.
  *
  * Revision 1.4  2001/02/21 21:18:34  mpowers
  * Clarified need to retain references.
  *
  * Revision 1.3  2001/02/21 18:31:07  mpowers
  * Finished and tested implementation of NSNotificationCenter.
  *
  * Revision 1.1.1.1  2000/12/21 15:47:39  mpowers
  * Contributing wotonomy.
  *
  * Revision 1.3  2000/12/20 16:25:38  michael
  * Added log to all files.
  *
  *
  */
 

1		/*
2		Wotonomy: OpenStep design patterns for pure Java applications.
3		Copyright (C) 2000 Blacksmith, Inc.
4
5		This library is free software; you can redistribute it and/or
6		modify it under the terms of the GNU Lesser General Public
7		License as published by the Free Software Foundation; either
8		version 2.1 of the License, or (at your option) any later version.
9
10		This library is distributed in the hope that it will be useful,
11		but WITHOUT ANY WARRANTY; without even the implied warranty of
12		MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13		Lesser General Public License for more details.
14
15		You should have received a copy of the GNU Lesser General Public
16		License along with this library; if not, see http://www.gnu.org
17		*/
18
19		package net.wotonomy.foundation;
20
21		import java.lang.ref.ReferenceQueue;
22		import java.lang.ref.WeakReference;
23		import java.util.Hashtable;
24		import java.util.Iterator;
25		import java.util.LinkedList;
26		import java.util.List;
27		import java.util.Map;
28		import java.util.Vector;
29
30		import net.wotonomy.foundation.internal.WotonomyException;
31
32		/**
33		* NSNotificationCenter broadcasts NSNotifications to
34		* registered observers. Observers can register for all
35		* notifications of a specific type, or all notifications
36		* about a specific object, or both. Observers specify
37		* the method that will be called when they are notified.
38		* A global notification center can be accessed with
39		* defaultCenter(), but other centers can be created and
40		* used independently of the default center. <br><br>
41		*
42		* This implementation uses weak references for observers
43		* and observables. The advantage to this approach is
44		* that you do not need to explicitly unregister observers
45		* or observables; they will be unregistered when they are
46		* garbage-collected. Note that you will need to retain
47		* a reference to any objects you register or they may
48		* become unregistered if no other object references them.
49		*
50		* @author michael@mpowers.net
51		* @author $Author: cgruber $
52		* @version $Revision: 893 $
53		*/
54	0	public class NSNotificationCenter
55		{
56		/**
57		* Null marker class simplifies equals() logic
58		* for CompoundKey class below.
59		*/
60	0	public static final Object NullMarker = new Object();
61
62	0	private static NSNotificationCenter defaultCenter = null;
63
64		/**
65		* A Map of (name,object) pairs to a List
66		* of (observer,selector) pairs.
67		*/
68		private Hashtable observers; // thread-safe
69
70		/**
71		* Default constructor creates a new notification center.
72		*/
73	0	public NSNotificationCenter()
74	0	{
75	0	observers = new Hashtable();
76	0	}
77
78		/**
79		* Returns the system default center, creating one
80		* if it has not yet been created.
81		*/
82		static public NSNotificationCenter defaultCenter()
83		{
84	0	if ( defaultCenter == null )
85		{
86	0	defaultCenter = new NSNotificationCenter();
87		}
88	0	return defaultCenter;
89		}
90
91		/**
92		* Addes the specified observer to the notification queue for
93		* notifications with the specified name or the specified
94		* object or both.
95		* @param anObserver The observer that wishes to be notified.
96		* @param aSelector The selector that will be invoked.
97		* Must have exactly one argument, to which a notification
98		* will be passed.
99		* @param notificationName The name of the notifications for
100		* which the observer will be notified. If null, will notify
101		* only based on matching anObject.
102		* @param anObject The object of the notifications for which
103		* the observer will be notified. If null, will notify
104		* only based on matching notificationName.
105		*/
106		public void addObserver(
107		Object anObserver, NSSelector aSelector,
108		String notificationName, Object anObject )
109		{
110		// remove freed objects
111	0	processKeyQueue();
112
113	0	Object name = notificationName;
114	0	if ( name == null )
115		{
116	0	name = NullMarker;
117		}
118	0	if ( anObject == null )
119		{
120	0	anObject = NullMarker;
121		}
122	0	Object key = new CompoundKey( name, anObject );
123	0	Object value = new CompoundValue( anObserver, aSelector );
124	0	List list = (List) observers.get( key );
125	0	if ( list == null )
126		{
127		// create new list with value and put it in map
128	0	list = new Vector(); // thread-safe
129	0	list.add( value );
130	0	observers.put( new CompoundKey(
131	0	name, anObject, keyQueue ), list );
132	0	}
133		else
134		{
135		// add only if not already in list
136	0	if ( ! list.contains( value ) )
137		{
138	0	list.add( value );
139		}
140		}
141	0	}
142
143		/**
144		* Posts the specified notification. Notifies all registered
145		* observers that match either the notification name or
146		* the notification object, or both.
147		* @param aNotification The notification that will be passed
148		* to the observers selector.
149		*/
150		public void postNotification(
151		NSNotification aNotification )
152		{
153	0	List mergedList = new LinkedList();
154		Object key, observerList;
155
156	0	Object name = aNotification.name();
157	0	Object object = aNotification.object();
158
159	0	if ( name != null )
160		{
161	0	if ( object != null )
162		{ // both are specified
163	0	observerList = observers.get( new CompoundKey( name, object ) );
164	0	if ( observerList != null )
165		{
166	0	mergedList.addAll( (List) observerList );
167		}
168	0	observerList = observers.get( new CompoundKey( name, NullMarker ) );
169	0	if ( observerList != null )
170		{
171	0	mergedList.addAll( (List) observerList );
172		}
173	0	observerList = observers.get( new CompoundKey( NullMarker, object ) );
174	0	if ( observerList != null )
175		{
176	0	mergedList.addAll( (List) observerList );
177	0	}
178		}
179		else
180		{ // object is null
181	0	observerList = observers.get( new CompoundKey( name, NullMarker ) );
182	0	if ( observerList != null )
183		{
184	0	mergedList.addAll( (List) observerList );
185	0	}
186		}
187		}
188		else
189	0	if ( object != null )
190		{ // name is null
191	0	observerList = observers.get( new CompoundKey( NullMarker, object ) );
192	0	if ( observerList != null )
193		{
194	0	mergedList.addAll( (List) observerList );
195		}
196		}
197
198	0	key = new CompoundKey(
199	0	NullMarker, NullMarker );
200	0	observerList = observers.get( key );
201	0	if ( observerList != null )
202		{
203	0	mergedList.addAll( (List) observerList );
204		}
205
206		CompoundValue value;
207	0	Iterator it = mergedList.iterator();
208	0	while ( it.hasNext() )
209		{
210	0	value = (CompoundValue) it.next();
211	0	if ( value.get() == null )
212		{
213	0	it.remove();
214	0	}
215		else
216		{
217		try
218		{
219	0	value.selector().invoke(
220	0	value.get(),
221	0	new Object[] { aNotification } );
222		}
223	0	catch ( Exception exc )
224		{
225	0	WotonomyException w = new WotonomyException(
226	0	"Error notifying object: " + value.get() + " : " + aNotification, exc );
227		// throw w;
228	0	w.printStackTrace();
229	0	postNotification( "Error notifying object", this, new NSDictionary( "exception", w ) );
230	0	}
231		}
232	0	}
233
234	0	}
235
236		/**
237		* Posts a notification created from the specified name
238		* and object. Calls postNotification( NSNotification ).
239		* @param notificationName a String key to distinguish
240		* this notification.
241		* @param anObject any object, by convention this is
242		* the originator of the notification.
243		*/
244		public void postNotification(
245		String notificationName, Object anObject )
246		{
247	0	postNotification( new NSNotification(
248	0	notificationName, anObject ) );
249	0	}
250
251		/**
252		* Posts a notification created from the specified name,
253		* object, and info. Calls postNotification( NSNotification ).
254		* @param notificationName a String key to distinguish
255		* this notification.
256		* @param anObject any object, by convention this is
257		* the originator of the notification.
258		* @param userInfo a Map containing information specific
259		* to the originator of the notification and that may
260		* be of interest to a knowledgable observer.
261		*/
262		public void postNotification(
263		String notificationName, Object anObject, Map userInfo )
264		{
265	0	postNotification( new NSNotification(
266	0	notificationName, anObject, userInfo ) );
267	0	}
268
269		/**
270		* Unregisters the specified observer from all notification
271		* queues for which it is registered.
272		* @param anObserver The observer to be unregistered.
273		*/
274		public void removeObserver(
275		Object anObserver )
276		{
277		// remove freed objects
278	0	processKeyQueue();
279
280	0	Iterator it = new LinkedList( observers.keySet() ).iterator();
281	0	while ( it.hasNext() )
282		{
283	0	removeObserver( anObserver, it.next() );
284	0	}
285	0	}
286
287		/**
288		* Unregisters the specified observer from all notifications
289		* queues associated with the specified name or object or both.
290		* @param anObserver The observer to be unregistered, if null
291		* will unregister all observers for the specified notification
292		* name and object.
293		* @param notificationName The name of the notification for which
294		* the observer will be unregistered, if null will unregister
295		* the specified observer for all notifications with the
296		* specified object.
297		* @param anObject The object for the notification for which
298		* the observer will be unregistered, if null will unregister
299		* the specified observer for all objects with the specified
300		* notification.
301		*/
302		public void removeObserver(
303		Object anObserver, String notificationName, Object anObject )
304		{
305		// remove freed objects
306	0	processKeyQueue();
307
308		// get key matches
309	0	List keys = matchingKeys( notificationName, anObject );
310
311		// remove specified observer from each matching key
312	0	Iterator it = keys.iterator();
313	0	while ( it.hasNext() )
314		{
315	0	removeObserver( anObserver, it.next() );
316	0	}
317	0	}
318
319		/**
320		* Returns all keys that match the specified name and object,
321		* but in this case null parameters are considered wildcards.
322		* Pass NullMarkers if you want to explicitly match nulls.
323		*/
324		private List matchingKeys( String name, Object object )
325		{
326	0	List result = new LinkedList();
327
328		boolean willAdd;
329		CompoundKey key;
330	0	Iterator it = observers.keySet().iterator();
331	0	while ( it.hasNext() )
332		{
333	0	key = (CompoundKey) it.next();
334	0	willAdd = false;
335	0	if ( ( name == null ) \|\| ( name == key.name() ) )
336		{
337	0	if ( ( object == null ) \|\| ( object == key.get() ) )
338		{
339	0	willAdd = true;
340		}
341		}
342	0	if ( willAdd )
343		{
344	0	result.add( key );
345	0	}
346		}
347	0	return result;
348		}
349
350		/**
351		* Removes the specified observer from the list referenced
352		* by the specified key in the observer map.
353		*/
354		private void removeObserver(
355		Object anObserver, Object key )
356		{
357		// if observer null, remove all observers for key
358	0	if ( anObserver == null )
359		{
360	0	observers.remove( key );
361	0	return;
362		}
363
364	0	List list = (List) observers.get( key );
365	0	if ( list == null ) return;
366
367		// remove specified observer from list
368		Object observer;
369	0	Iterator it = list.iterator();
370	0	while ( it.hasNext() )
371		{
372	0	observer = ((CompoundValue)it.next()).get();
373	0	if ( ( observer == null ) \|\| ( anObserver == observer ) )
374		{
375		// remove if match or freed object
376	0	it.remove();
377
378		// do not return; process entire list
379	0	}
380		}
381	0	if ( list.size() == 0 )
382		{
383	0	observers.remove( key );
384		}
385	0	}
386
387		/* Reference queues for cleared WeakKeys */
388	0	private ReferenceQueue keyQueue = new ReferenceQueue();
389
390		/**
391		* Removes any keys whose object has been garbage collected.
392		* (Garbage collected values are removed as they are encountered.)
393		*/
394		private void processKeyQueue()
395		{
396		CompoundKey ck;
397	0	while ((ck = (CompoundKey)keyQueue.poll()) != null)
398		{
399		//System.out.println( "EOObserverCenter.processQueue: removing object" );
400	0	observers.remove(ck);
401	0	}
402	0	}
403
404		/**
405		* Key combining a name with an object.
406		* The object is weakly referenced, and keys
407		* are deallocated by reference queue.
408		* equals() compares by reference.
409		*/
410		private static class CompoundKey extends WeakReference
411		{
412		private Object name;
413		private int hashCode;
414
415		/**
416		* Creates compound key.
417		* Neither name nor object may be null.
418		* Use NullMarker to represent null
419		* in either name or object.
420		*/
421		public CompoundKey (
422		Object aName, Object anObject )
423		{
424	0	super( anObject );
425	0	name = aName;
426	0	hashCode = aName.hashCode() + anObject.hashCode();
427	0	}
428
429		/**
430		* Creates compound key with queue.
431		* Neither name nor object may be null.
432		* Use NullMarker to represent null
433		* in either name or object.
434		*/
435		public CompoundKey (
436		Object aName, Object anObject, ReferenceQueue aQueue )
437		{
438	0	super( anObject, aQueue );
439	0	name = aName;
440	0	hashCode = aName.hashCode() + anObject.hashCode();
441	0	}
442
443		public Object name()
444		{
445	0	return name;
446		}
447
448		public int hashCode()
449		{
450	0	return hashCode;
451		}
452
453		public boolean equals( Object anObject )
454		{
455	0	if ( this == anObject ) return true;
456		// assumes only used with other compound keys
457	0	CompoundKey key = (CompoundKey) anObject;
458	0	if ( name == key.name \|\| ( name != null && name.equals( key.name ) ) )
459		{
460	0	Object object = get();
461	0	if ( object != null )
462		{
463		// compares by reference
464	0	if ( object == ( key.get() ) )
465		{
466	0	return true;
467		}
468		}
469		}
470	0	return false;
471		}
472
473		public String toString()
474		{
475	0	return "[CompoundKey:"+name()+":"+get()+"]";
476		}
477		}
478
479		/**
480		* Value combining an object with a selector.
481		* The object is weakly referenced, and null
482		* values are not allowed.
483		*/
484		private static class CompoundValue extends WeakReference
485		{
486		private NSSelector selector;
487		private int hashCode;
488
489		public CompoundValue( Object anObject, NSSelector aSelector )
490		{
491	0	super( anObject );
492	0	hashCode = anObject.hashCode();
493	0	selector = aSelector;
494	0	}
495
496		public NSSelector selector()
497		{
498	0	return selector;
499		}
500
501		public int hashCode()
502		{
503	0	return hashCode;
504		}
505
506		public boolean equals( Object anObject )
507		{
508	0	if ( this == anObject ) return true;
509		// assumes only used with other compound values
510	0	CompoundValue value = (CompoundValue) anObject;
511	0	if ( selector == value.selector \|\|
512	0	( selector != null && selector.equals( value.selector ) ) )
513		{
514	0	Object object = get();
515	0	if ( object != null )
516		{
517	0	if ( object == value.get() )
518		{
519	0	return true;
520		}
521		}
522		}
523	0	return false;
524		}
525
526		public String toString()
527		{
528	0	return "[CompoundValue:"+get()+":"+selector().name()+"]";
529		}
530		}
531		/*
532		public static void main( String[] argv )
533		{
534		Object aSource = "aSource";
535		Object bSource = "bSource";
536
537		Object oneTest = new OneTest();
538		Object twoTest = new TwoTest();
539		NSSelector notifyMeOnce =
540		new NSSelector( "notifyMeOnce",
541		new Class[] { NSNotification.class } );
542		NSSelector notifyMeTwice =
543		new NSSelector( "notifyMeTwice",
544		new Class[] { NSNotification.class } );
545
546		NSNotificationCenter.defaultCenter().addObserver(
547		oneTest, notifyMeOnce, "aMessage", null );
548
549		NSNotificationCenter.defaultCenter().addObserver(
550		oneTest, notifyMeOnce, null, aSource );
551
552		NSNotificationCenter.defaultCenter().addObserver(
553		twoTest, notifyMeOnce, "aMessage", aSource );
554
555		NSNotificationCenter.defaultCenter().addObserver(
556		twoTest, notifyMeTwice, null, null );
557
558		NSNotificationCenter.defaultCenter().postNotification(
559		"aMessage", aSource );
560		System.out.println();
561		NSNotificationCenter.defaultCenter().postNotification(
562		"aMessage", bSource );
563		System.out.println();
564		NSNotificationCenter.defaultCenter().postNotification(
565		"bMessage", aSource );
566		System.out.println();
567		NSNotificationCenter.defaultCenter().postNotification(
568		"bMessage", bSource );
569		System.out.println( "---" );
570
571		NSNotificationCenter.defaultCenter().removeObserver(
572		oneTest, null, aSource );
573
574		NSNotificationCenter.defaultCenter().postNotification(
575		"aMessage", aSource );
576		System.out.println();
577		NSNotificationCenter.defaultCenter().postNotification(
578		"aMessage", bSource );
579		System.out.println();
580		NSNotificationCenter.defaultCenter().postNotification(
581		"bMessage", aSource );
582		System.out.println();
583		NSNotificationCenter.defaultCenter().postNotification(
584		"bMessage", bSource );
585		System.out.println( "---" );
586
587		NSNotificationCenter.defaultCenter().removeObserver(
588		null );
589
590		NSNotificationCenter.defaultCenter().postNotification(
591		"aMessage", aSource );
592		System.out.println();
593		NSNotificationCenter.defaultCenter().postNotification(
594		"aMessage", bSource );
595		System.out.println();
596		NSNotificationCenter.defaultCenter().postNotification(
597		"bMessage", aSource );
598		System.out.println();
599		NSNotificationCenter.defaultCenter().postNotification(
600		"bMessage", bSource );
601		System.out.println( "---" );
602		}
603
604		static private class OneTest
605		{
606		public void notifyMeOnce( NSNotification aNotification )
607		{
608		System.out.println( "OneTest.notifyMeOnce: " + aNotification );
609		}
610		}
611
612		static private class TwoTest
613		{
614		public void notifyMeOnce( NSNotification aNotification )
615		{
616		System.out.println( "TwoTest.notifyMeOnce: " + aNotification );
617		}
618		public void notifyMeTwice( NSNotification aNotification )
619		{
620		System.out.println( "TwoTest.notifyMeTwice: " + aNotification );
621		}
622		}
623		*/
624		}
625
626
627
628		/*
629		* $Log$
630		* Revision 1.2 2006/02/16 13:15:00 cgruber
631		* Check in all sources in eclipse-friendly maven-enabled packages.
632		*
633		* Revision 1.11 2003/06/03 14:51:15 mpowers
634		* Added commented-out println for debugging.
635		*
636		* Revision 1.10 2003/03/27 21:46:00 mpowers
637		* Better handling for null parameters on subscribe.
638		* Better handling for null parameters on post.
639		*
640		* Revision 1.9 2003/01/28 19:44:38 mpowers
641		* Now comparing strings by value not reference.
642		*
643		* Revision 1.8 2001/06/29 16:14:23 mpowers
644		* Fixed a javac compiler error that jikes allowed: shoe's on the other foot!
645		*
646		* Revision 1.7 2001/06/07 22:09:03 mpowers
647		* Exceptions during a notification are no longer being thrown
648		* so we can assure that all notifications get handled.
649		* Instead, we're printing stack traces...
650		*
651		* Revision 1.6 2001/04/09 21:41:50 mpowers
652		* Better debugging.
653		*
654		* Revision 1.5 2001/03/15 21:09:06 mpowers
655		* Fixed notifications with null objects.
656		*
657		* Revision 1.4 2001/02/21 21:18:34 mpowers
658		* Clarified need to retain references.
659		*
660		* Revision 1.3 2001/02/21 18:31:07 mpowers
661		* Finished and tested implementation of NSNotificationCenter.
662		*
663		* Revision 1.1.1.1 2000/12/21 15:47:39 mpowers
664		* Contributing wotonomy.
665		*
666		* Revision 1.3 2000/12/20 16:25:38 michael
667		* Added log to all files.
668		*
669		*
670		*/
671