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Java > Open Source Codes > ch > ethz > prose > Aspect


1  //
2 // This file is part of the prose package.
3 //
4 // The contents of this file are subject to the Mozilla Public License
5 // Version 1.1 (the "License"); you may not use this file except in
6 // compliance with the License. You may obtain a copy of the License at
7 // http://www.mozilla.org/MPL/
8 //
9 // Software distributed under the License is distributed on an "AS IS" basis,
10 // WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
11 // for the specific language governing rights and limitations under the
12 // License.
13 //
14 // The Original Code is prose.
15 //
16 // The Initial Developer of the Original Code is Andrei Popovici. Portions
17 // created by Andrei Popovici are Copyright (C) 2002 Andrei Popovici.
18 // All Rights Reserved.
19 //
20 // Contributor(s):
21 // $Id: Aspect.java,v 1.1.1.1 2003/07/02 15:30:50 apopovic Exp $
22 // =====================================================================
23 //
24 // (history at end)
25 //
26
27 package ch.ethz.prose;
28 import java.io.Serializable JavaDoc;
29 import java.util.List JavaDoc;
30
31 import ch.ethz.prose.crosscut.Crosscut;
32
33
34 /** Class aspect is the
35  *
36  */
37 public
38 abstract class Aspect implements Insertable,Serializable JavaDoc {
39
40   /** This method is called <em>before and after</em> this
41    * aspect is inserted into an <code>AspectManager</code>.
42    * By overriding the default (which is a no-op), one can
43    * define setup actions. If this method throws an exception,
44    * the aspect insertion fails.
45    */
46   public void insertionAction(boolean isBefore) {}
47
48
49   /** this method is called before and after the withdrawal of an aspect.
50    */
51   public void withdrawalAction(boolean isBefore){}
52
53
54   /** Aspects are associated to objects. This method generates a 'random'
55    * object.
56    */
57   public static Object JavaDoc generateUniqueAssociation()
58     {
59       return "" + System.currentTimeMillis() + birthDayCount++;
60     }
61
62   protected static long birthDayCount = 0;
63   private List JavaDoc ownedCrosscutList= null;
64   protected Object JavaDoc aspectID = null;
65   private boolean aspectIDisSet = false;
66   protected int priority = 0;
67
68   /** Associate aspect with a given object. Note that
69    * the associated has in PROSE the same role as the 'perObject', 'perVM',
70    * etc. role in other languages and frameworks. For one given object,
71    * just ONE aspect instance may be inserted in PROSE at a given time.
72    * With this, if you specify the name "foo" as an associated object, any insertion
73    * of a second aspect associated to "foo" results in an exception.
74    * In other words, a unique name means a 'per VM' aspect. However,
75    * you may associate aspects to the elements o1..oN of a vector
76    * of your choice. In this case, it will be a 'per Object' aspect.
77    * An aspect not explicitely associated to an id is associated to a random
78    * object.
79    */
80   public synchronized void associateTo(Object JavaDoc id)
81     {
82       if (aspectIDisSet)
83     throw new IllegalStateException JavaDoc("reset of IDs not allowed in aspects");
84
85       if (id == null)
86     throw new IllegalArgumentException JavaDoc("null ids not accepted as arguments");
87
88       this.aspectIDisSet = true;
89       this.aspectID = id;
90     }
91
92   /** Create an aspect with an automatically generated association. Note that
93    * the aspects associations have in PROSE the same role as the 'perObject', 'perVM',
94    * etc. role in other languages and frameworks.
95    */
96   public Aspect()
97     {
98       aspectID = generateUniqueAssociation();
99     }
100
101     /** Return a list of crosscuts owned by this Aspect. Note that this
102      * method returns the same list of objects during
103      * the existence of asspect. This list is initialized using the
104      * <code>crosscuts</code> template method.
105      *
106      */
107     public List JavaDoc getCrosscuts()
108     {
109     if (ownedCrosscutList != null)
110         return ownedCrosscutList;
111
112
113     Crosscut[] ownedCrosscuts = crosscuts();
114     ownedCrosscutList = new java.util.Vector JavaDoc();
115
116     for (int i = 0; i < ownedCrosscuts.length; i++)
117         {
118         ownedCrosscuts[i].setOwner(this);
119         ownedCrosscutList.add(ownedCrosscuts[i]);
120         }
121
122     return ownedCrosscutList;
123     }
124
125
126
127   /** Get the priority of this aspect. Advices (indireclty) belonging
128    * to this aspect are executed from low priority values to
129    * high prioirity values. The default priority is 0.
130    *
131    */
132   public int getPriority()
133     {
134       return priority;
135     }
136
137
138   /** Set the priority of this aspect. Advices (indireclty) belonging
139    * to this aspect are executed from low priority values to
140    * high prioirity values. The default priority is 0.
141    */
142   public void setPriority(int prio)
143     {
144       this.priority = prio;
145     }
146
147
148
149   /** Return the object associated to this aspect */
150   public Object JavaDoc getAssociatedObject()
151     {
152       return aspectID;
153     }
154
155   /** This is a template meethod. Users must define
156    * this method to return a list of crosscut objects
157    * that belong to this aspect
158    */
159   protected abstract Crosscut[] crosscuts();
160
161   /**
162    * Indicates whether some other object is "equal to" this one. The
163    * result is <code>true</code> if and only if <code>obj</code> is
164    * not <code>null</code> and is a instance of
165    * <code>DefaultAspect</code> and has equal contents as this
166    * object.
167    * @param obj other object with which to compare
168    * @return <code>true</code> iff <code>obj</code> is equal to this
169    * <code>DefaultAspect</code>
170    */
171   public boolean equals(Object JavaDoc obj)
172     {
173       return
174     obj instanceof Aspect &&
175     aspectID.equals( ((Aspect) obj).aspectID);
176     }
177
178   /**
179    * Returns a hashcode for this object.
180    * @return hashcode value
181    */
182   public int hashCode()
183     {
184       return (int)aspectID.hashCode();
185     }
186
187
188   public String JavaDoc toString()
189     {
190       return "Aspect [" + aspectID + "]";
191     }
192
193 }
194
195
196 //======================================================================
197 //
198 // $Log: Aspect.java,v $
199 // Revision 1.1.1.1 2003/07/02 15:30:50 apopovic
200 // Imported from ETH Zurich
201 //
202 // Revision 1.6 2003/06/07 15:33:54 popovici
203 // Compile bug fix: getCrosscuts couldnt have been final
204 //
205 // Revision 1.5 2003/05/26 13:28:48 popovici
206 // Documentation Improvements
207 //
208 // Revision 1.4 2003/05/25 11:44:20 popovici
209 // default association now over the new method 'generateUniqueAssociation'
210 //
211 // Revision 1.3 2003/05/20 16:05:01 popovici
212 //
213 // New QueryManager replaces functionality in AspectManager (better Soc)
214 // New 'Surrogate' classes for usage in the QueryManager
215 // The 'RemoteAspectManager' and tools modified to use the Surrogates and the QueryManager
216 //
217 // Revision 1.2 2003/05/06 15:13:34 popovici
218 // aspectId renamed to 'associated object'
219 //
220 // Revision 1.1 2003/05/05 13:58:29 popovici
221 // renaming from runes to prose
222 //
223 // Revision 1.4 2003/04/29 12:41:03 popovici
224 // Feature added:
225 // - the 'setPriority' in class insertable allows now Aspects and Crosscuts to have a priority.
226 // Notitification is done from low int priorities to high int priorities.
227 // - the 'setAspectID' introduced to replace constuctor; used to be cumberstone for subclasses
228 //
229 // Revision 1.3 2003/04/27 13:21:32 popovici
230 // Aspects now have identities. Equality is based
231 // either on an ad-hoc identity, or on a specific
232 // name given by the user
233 //
234 // Revision 1.2 2003/04/17 15:43:45 popovici
235 // crosscuts renamed to 'getCrosscuts'
236 // createCrosscuts renamed to 'crosscuts'
237 //
238 // Revision 1.1 2003/04/17 15:15:09 popovici
239 // Extension->Aspect renaming
240 //
241 // Revision 1.6 2003/04/17 12:49:41 popovici
242 // Refactoring of the crosscut package
243 // ExceptionCut renamed to ThrowCut
244 // McutSignature is now SignaturePattern
245 //
246 // Revision 1.5 2003/04/17 08:47:12 popovici
247 // Important functionality additions
248 // - Cflow specializers
249 // - Restructuring of the MethodCut, SetCut, ThrowCut, and GetCut (they are much smaller)
250 // - Transactional capabilities
251 // - Total refactoring of Specializer evaluation, which permits fine-grained distinction
252 // between static and dynamic specializers.
253 // - Functionality pulled up in abstract classes
254 // - Uniformization of advice methods patterns and names
255 //
256 // Revision 1.4 2003/03/04 18:36:36 popovici
257 // Organization of imprts
258 //
259 // Revision 1.3 2002/03/28 13:48:33 popovici
260 // Mozilla-ified
261 //
262 // Revision 1.2 2002/02/21 12:36:47 popovici
263 // Interface 'Insertable' added. Extensions and crosscuts
264 // are now insertable objects.
265 //
266 // Revision 1.1.1.1 2001/11/29 18:13:15 popovici
267 // Sources from runes
268 //
269 // Revision 1.1.2.3 2001/02/07 11:47:01 popovici
270 // Abstract methods 'insertionAction' and 'withdrawalAction' added.
271 //
272 // Revision 1.1.2.2 2001/02/05 13:27:21 mrmuller
273 // needs to implement Serializable, so that Extensions can be passed by value
274 //
275 // Revision 1.1.2.1 2000/10/24 17:44:51 popovici
276 // Documentation added.
277 //
278 // Revision 1.1 2000/10/16 11:53:24 popovici
279 // Initial Revision
280 //
281
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