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Java > Open Source Codes > org > gjt > sp > jedit > EditBus


1 /*
2  * EditBus.java - The EditBus
3  * :tabSize=8:indentSize=8:noTabs=false:
4  * :folding=explicit:collapseFolds=1:
5  *
6  * Copyright (C) 1999 Slava Pestov
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License
10  * as published by the Free Software Foundation; either version 2
11  * of the License, or any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
21  */
22
23 package org.gjt.sp.jedit;
24
25 import java.util.*;
26 import org.gjt.sp.util.Log;
27
28 /**
29  * jEdit's global event notification mechanism.<p>
30  *
31  * Plugins register with the EditBus to receive messages reflecting
32  * changes in the application's state, including changes in buffers,
33  * views and edit panes, changes in the set of properties maintained
34  * by the application, and the closing of the application.<p>
35  *
36  * The EditBus maintains a list of objects that have requested to receive
37  * messages. When a message is sent using this class, all registered
38  * components receive it in turn. Classes for objects that subscribe to
39  * the EditBus must implement the {@link EBComponent} interface, which
40  * defines the single method {@link EBComponent#handleMessage(EBMessage)}.<p>
41  *
42  * A plugin core class that extends the
43  * {@link EBPlugin} abstract class (and whose name ends with
44  * <code>Plugin</code> for identification purposes) will automatically be
45  * added to the EditBus during jEdit's startup routine. Any other
46  * class - for example, a dockable window that needs to receive
47  * notification of buffer changes - must perform its own registration by calling
48  * {@link #addToBus(EBComponent)} during its initialization.
49  * A convenient place to register in a class derived from <code>JComponent</code>
50  * would be in an implementation of the <code>JComponent</code> method
51  * <code>addNotify()</code>.<p>
52  *
53  * Message types sent by jEdit can be found in the
54  * {@link org.gjt.sp.jedit.msg} package.<p>
55  *
56  * Plugins can also send their own messages - any object can send a message to
57  * the EditBus by calling the static method {@link #send(EBMessage)}.
58  * Most plugins, however, only concern themselves with receiving, not
59  * sending, messages.
60  *
61  * @see org.gjt.sp.jedit.EBComponent
62  * @see org.gjt.sp.jedit.EBMessage
63  *
64  * @author Slava Pestov
65  * @author John Gellene (API documentation)
66  * @version $Id: EditBus.java 4669 2003-05-01 02:21:27Z spestov $
67  *
68  * @since jEdit 2.2pre6
69  */
70 public class EditBus
71 {
72     //{{{ addToBus() method
73 /**
74      * Adds a component to the bus. It will receive all messages sent
75      * on the bus.
76      *
77      * @param comp The component to add
78      */
79     public static void addToBus(EBComponent comp)
80     {
81         synchronized(components)
82         {
83             components.add(comp);
84             copyComponents = null;
85         }
86     } //}}}
87
88     //{{{ removeFromBus() method
89 /**
90      * Removes a component from the bus.
91      * @param comp The component to remove
92      */
93     public static void removeFromBus(EBComponent comp)
94     {
95         synchronized(components)
96         {
97             components.remove(comp);
98             copyComponents = null;
99         }
100     } //}}}
101
102     //{{{ getComponents() method
103 /**
104      * Returns an array of all components connected to the bus.
105      */
106     public static EBComponent[] getComponents()
107     {
108         synchronized(components)
109         {
110             if (copyComponents == null)
111             {
112                 copyComponents = (EBComponent[])components.toArray(
113                     new EBComponent[components.size()]);
114             }
115             return copyComponents;
116         }
117     } //}}}
118
119     //{{{ send() method
120 /**
121      * Sends a message to all components on the bus in turn.
122      * @param message The message
123      */
124     public static void send(EBMessage message)
125     {
126         Log.log(Log.DEBUG,EditBus.class,message.toString());
127
128         // To avoid any problems if components are added or removed
129 // while the message is being sent
130 EBComponent[] comps = getComponents();
131
132         for(int i = 0; i < comps.length; i++)
133         {
134             try
135             {
136                 EBComponent comp = comps[i];
137                 if(Debug.EB_TIMER)
138                 {
139                     long start = System.currentTimeMillis();
140                     comp.handleMessage(message);
141                     long time = (System.currentTimeMillis() - start);
142                     if(time != 0)
143                     {
144                         Log.log(Log.DEBUG,EditBus.class,comp + ": " + time + " ms");
145                     }
146                 }
147                 else
148                     comps[i].handleMessage(message);
149             }
150             catch(Throwable JavaDoc t)
151             {
152                 Log.log(Log.ERROR,EditBus.class,"Exception"
153                     + " while sending message on EditBus:");
154                 Log.log(Log.ERROR,EditBus.class,t);
155             }
156         }
157     } //}}}
158
159     //{{{ Private members
160 private static ArrayList components = new ArrayList();
161     private static EBComponent[] copyComponents;
162
163     // can't create new instances
164 private EditBus() {}
165     //}}}
166 }
167
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