gomp-20050608-branch/libjava/classpath/gnu/classpath/jdwp/event/Event.java

   1 /* Event.java -- a base class for all event types
   2    Copyright (C) 2005 Free Software Foundation
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 terms of your choice, provided that you also meet, for each linked
  32 independent module, the terms and conditions of the license of that
  33 module.  An independent module is a module which is not derived from
  34 or based on this library.  If you modify this library, you may extend
  35 this exception to your version of the library, but you are not
  36 obligated to do so.  If you do not wish to do so, delete this
  37 exception statement from your version. */
  38
  39
  40 package gnu.classpath.jdwp.event;
  41
  42 import gnu.classpath.jdwp.JdwpConstants;
  43 import gnu.classpath.jdwp.transport.JdwpCommandPacket;
  44 import gnu.classpath.jdwp.transport.JdwpPacket;
  45
  46 import java.io.DataOutputStream;
  47 import java.io.IOException;
  48
  49 /**
  50  * This class is a base class for all VM->debugger event
  51  * notifications.
  52  *
  53  * @author Keith Seitz  (keiths@redhat.com)
  54  */
  55 public abstract class Event
  56 {
  57   // The kind of event represented by this event
  58   private byte _eventKind;
  59
  60   /**
  61    * Constructs an <code>Event</code> of the given kind
  62    *
  63    * @param kind  the type of event
  64    */
  65   public Event (byte kind)
  66   {
  67     _eventKind = kind;
  68   }
  69
  70   /**
  71    * Returns the event type of this event
  72    *
  73    * @returns  the event kind
  74    */
  75   public byte getEventKind ()
  76   {
  77     return _eventKind;
  78   }
  79
  80   /**
  81    * Abstract function used by implementing classes to fill in the
  82    * event-specific data. Note that request ID is automatically added
  83    * by this class (since it appears in all event notifications).
  84    *
  85    * @param outStream  the stream to which to write data
  86    */
  87   protected abstract void _writeData (DataOutputStream outStream)
  88     throws IOException;
  89
  90   /**
  91    * Returns a specific filtering parameter for this event. For example,
  92    * most events may be filtered by thread. Consequently, a call to this
  93    * method with <code>ThreadId.class</code> should return a
  94    * <code>Thread</code>.
  95    *
  96    * @param type  the type of parameter to return
  97    * @returns the parameter (not the ID) or <code>null</code> if none is
  98    *          is defined for this event
  99    */
 100   public abstract Object getParameter (Class type);
 101
 102   /**
 103    * Converts this event into to a JDWP packet
 104    *
 105    * @param dos     the stream to which to write data
 106    * @param request the request the wanted this notification
 107    * @returns a <code>JdwpPacket</code> of the events
 108    */
 109   public JdwpPacket toPacket (DataOutputStream dos, EventRequest request)
 110   {
 111     JdwpPacket pkt;
 112     try
 113       {
 114         dos.writeByte (request.getSuspendPolicy ());
 115         dos.writeInt (1);
 116         dos.writeByte (_eventKind);
 117         dos.writeInt (request.getId ());
 118         _writeData (dos);
 119
 120         pkt = new JdwpCommandPacket (JdwpConstants.CommandSet.Event.CS_VALUE,
 121                                      JdwpConstants.CommandSet.Event.COMPOSITE);
 122       }
 123     catch (IOException ioe)
 124       {
 125         pkt = null;
 126       }
 127
 128     return pkt;
 129   }
 130 }