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Java > Open Source Codes > org > fjank > jcache > collection > SetProxy


1 /* Open Source Java Caching Service
2 * Copyright (C) 2002 Frank Karlstrøm
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
7 *
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16 *
17 * The author can be contacted by email: fjankk@users.sourceforge.net
18 */
19 package org.fjank.jcache.collection;
20
21 import java.util.Collection JavaDoc;
22 import java.util.Iterator JavaDoc;
23 import java.util.Map JavaDoc;
24 import java.util.Set JavaDoc;
25 import java.util.Map.Entry;
26 import org.fjank.jcache.CacheGroup;
27 import org.fjank.jcache.CacheObject;
28
29 /**A proxy for a key set returned from the Map implementation.
30  * @author Frank Karlstrøm
31  *
32  */
33 public class SetProxy implements Set JavaDoc {
34     
35     private class SetProxyIterator implements Iterator JavaDoc {
36         private SetProxyIterator(Iterator JavaDoc iter) {
37             this.wrappedIter=iter;
38         }
39         private final Iterator JavaDoc wrappedIter;
40         private Object JavaDoc currObj;
41         public boolean hasNext() {
42             return wrappedIter.hasNext();
43         }
44         public Object JavaDoc next() {
45            this.currObj= wrappedIter.next();
46            return currObj;
47         }
48         public void remove() {
49            rmv(currObj);
50         }
51
52     }
53     private CacheGroup group;
54
55     private Set JavaDoc set;
56
57     /**Creates a new keySetProxy.
58      * @param set the set to be a proxy for.
59      * @param group
60      */
61     public SetProxy(Set JavaDoc set, CacheGroup group) {
62         this.set=set;
63         this.group=group;
64     }
65     /**the implementation of this operation will always
66      * throw UnsupportedOperatioinException
67      * @param o the object to add.
68      * @return a boolean indicating wether the operation failed or not.
69      */
70     public boolean add(Object JavaDoc o) {
71         throw new UnsupportedOperationException JavaDoc();
72     }
73
74     /**the implementation of this operation will always
75      * throw UnsupportedOperationException
76      * @param c the collection to add objects from.
77      * @return a boolean indicating wether the operation failed or not.
78      */
79     public boolean addAll(Collection JavaDoc c) {
80         throw new UnsupportedOperationException JavaDoc();
81     }
82
83     /**
84      * Clears this set, which will clear the cache of all objects.
85      * This method behaves the same as invalidate on CacheAccess.
86      * @see javax.util.jcache.CacheAccess#invalidate()
87      */
88     public void clear() {
89         group.invalidate();
90     }
91
92     /**Returns a boolean indicating wether the object exists
93      * in the cache or not.
94      * @param o the object to check the existence for.
95      * @return <code>true</code> if the object is present in the cache, <code>false</code> otherwise.
96      */
97     public boolean contains(Object JavaDoc o) {
98         return set.contains(o);
99     }
100
101     
102     public boolean containsAll(Collection JavaDoc c) {
103         return set.containsAll(c);
104     }
105
106     public boolean isEmpty() {
107         return set.isEmpty();
108     }
109
110
111     public Iterator JavaDoc iterator() {
112         return new SetProxyIterator(set.iterator());
113     }
114     private void rmv(Object JavaDoc o) {
115         remove(o);
116     }
117
118     public boolean remove(Object JavaDoc o) {
119         if(!set.contains(o)) return false;
120         if(o instanceof Map.Entry JavaDoc) {
121             Map.Entry JavaDoc entry = (Entry) o;
122             CacheObject obj = (CacheObject) entry.getValue();
123             obj.invalidate();
124             return true;
125         }
126         CacheObject obj = (CacheObject) group.get(o);
127         if(obj==null) return false;
128         obj.invalidate();
129         return true;
130     }
131
132     public boolean removeAll(Collection JavaDoc c) {
133         /*naive implementation, but it works.*/
134         boolean changed = false;
135         for (Iterator JavaDoc iter = c.iterator(); iter.hasNext();) {
136             if(remove(iter.next())) {
137                 changed=true;
138             }
139         }
140         return changed;
141     }
142
143     /**
144      * @param c
145      * @return
146      */
147     public boolean retainAll(Collection JavaDoc c) {
148         /*naive implementation, but it works.*/
149         boolean changed = false;
150         for (Iterator JavaDoc iter = set.iterator(); iter.hasNext();) {
151             Object JavaDoc tmp = iter.next();
152             if(!c.contains(tmp)) {
153                 if(remove(tmp)) {
154                     changed=true;
155                 }
156             }
157         }
158         return changed;
159     }
160
161     /**
162      * @return
163      */
164     public int size() {
165         return set.size();
166     }
167
168     /**
169      * @return
170      */
171     public Object JavaDoc[] toArray() {
172         return set.toArray();
173     }
174
175     /**
176      * @param a
177      * @return
178      */
179     public Object JavaDoc[] toArray(Object JavaDoc[] a) {
180         return set.toArray(a);
181     }
182
183     /* (non-Javadoc)
184      * @see java.lang.Object#toString()
185      */
186     public String JavaDoc toString() {
187         return set.toString();
188     }
189
190 }
191
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