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1 package com.daffodilwoods.database.general;
2
3 import java.util.Comparator  ;
4 import com.daffodilwoods.database.resource.*;
5 import java.lang.ref.*;
6 import com.daffodilwoods.daffodildb.utils.comparator.SuperComparator;
7
8 public class WeakOrderedKeyList extends OrderedKeyList
9 {
10 private SuperComparator comparator = null;
11
12 public ReferenceQueue queue = new ReferenceQueue();
13
14 public WeakOrderedKeyList(SuperComparator comparator) {
15 super(comparator);
16 this.comparator = comparator;
17 }
18
19 private void processQueue() throws DException {
20 try {
21 WeakKey wk;
22 while ((wk = (WeakKey)queue.poll()) != null) {
23 if(super.size() == 0)
24 return;
25 Object key = wk.getKey();
26 if(super.containsKey(key))
27 super.delete(key);
28 }
29 }catch(Exception e) {}
30 }
31
32 public boolean containsKey(Object key) throws DException {
33 processQueue();
34 return super.containsKey(key);
35 }
36
37 public boolean containsValue(Object value) throws DException {
38 return false;
39 }
40
41 public void put(Object key, Object value) throws DException {
42 processQueue();
43 WeakKey wk = WeakKey.create(value,queue); wk.setKey(key);
45 super.insert(key,wk);
46 }
47
48 public Object getKey() throws DException {
49 processQueue();
50 return super.getKey();
51 }
52
53 public void remove(Object key) throws DException {
54 try{
55 processQueue();
56 if(super.size() != 0)
57 super.delete(key);
58 }catch(Exception ex){}
59 }
60
61
62 public Object get() throws DException {
63 return ((WeakKey) super.getObject()).get();
64 }
65
66 public WeakOrderedKeyListIterator getWeakOrderedKeyListIterator() throws DException {
67 WeakOrderedKeyListIterator w = new WeakOrderedKeyListIterator();
68 return w;
69 }
70
71 public Object get(Object key) throws DException {
72 WeakKey weakKey1 = (WeakKey) super.getObject(key);
73 return weakKey1 == null ? null : weakKey1.get();
74 }
75
76 public static class WeakKey extends WeakReference {
77 private int hash;
79
80 private Object key;
81 public WeakKey(Object k) throws DException {
82 super(k);
83 hash = k.hashCode();
84 }
85
86 public static WeakKey create(Object k) throws DException {
87 if (k == null) return null;
88 else return new WeakKey(k);
89 }
90
91 public WeakKey(Object k, ReferenceQueue q) throws DException {
92 super(k, q);
93 hash = k.hashCode();
94 }
95
96 public static WeakKey create(Object k, ReferenceQueue q) throws DException {
97 if (k == null) return null;
98 else return new WeakKey(k, q);
99 }
100
101 public void setKey(Object key) throws DException {
102 this.key = key;
103 }
104
105 public Object getKey() throws DException {
106 return key;
107 }
108
109
111 public boolean equals(Object o) {
112 if (this == o) return true;
113 if (!(o instanceof WeakKey)) return false;
114 Object t = this.get();
115 Object u = ((WeakKey)o).get();
116 if ((t == null) || (u == null)) return false;
117 if (t == u) return true;
118 return t.equals(u);
119 }
120
121 public int hashCode() {
122 return hash;
123 }
124
125 public void clear() {}
126 }
127
128
129 public class WeakOrderedKeyListIterator {
130 Object current;
131
132 public WeakOrderedKeyListIterator() throws DException {
133 current = getTopKey();
134 }
135
136
137
141
142 public int getRowCount() throws DException {
143 return size();
144 }
145
146 public boolean top() throws DException {
147 current = getTopKey();
148 return current != null;
149 }
150
151 public boolean bottom() throws DException {
152 current = getBottomKey();
153 return current != null;
154 }
155
162
163 public boolean previous() throws DException {
164 Object p = getPreviousKey(current);
165 if(p == null)
166 return false;
167 current = p;
168 return true;
169 }
170
171 public boolean next() throws DException {
172 Object p = getNextKey(current);
173 if(p == null)
174 return false;
175 current = p;
176 return true;
177 }
178
179 public boolean isTop() throws DException {
180 if( current == null )
181 return false;
182 else {
183 Object p = getTopKey();
184 return (p != null && current == p);
185 }
186 }
187
188 public boolean isBottom() throws DException {
189 if( current == null )
190 return false;
191 else {
192 Object p = getBottomKey();
193 return (p != null && current == p) ;
194 }
195 }
196
197 public boolean isPrevious() throws DException {
198 return current == null ? false :
199 getPreviousKey(current) != null ;
200 }
201
202 public boolean isNext() throws DException {
203 return current == null ? false :
204 getNextKey(current) != null ;
205 }
206
207 public void moveToKey(Object key) throws DException
208 {
209 if(key == null)
210 throw new DException("DSE982",null);
211
212 current = key;
213 }
214
215 public Object getKey() throws DException {
216 return current;
217 }
218
219 public Object getObject() throws DException {
220 return WeakOrderedKeyList.this.get(current);
221 }
222
223 public Comparator getComparator() throws DException {
224 return getComparator();
225 }
226 }
227 public void moveToKey(Object key) {
228 super.moveToKey( key);
229 }
230 public int getRowCount() throws DException {
231 return super.getRowCount();
232 }
233 public Object getBottomKey() throws DException {
234 return super.getBottomKey();
235 }
236 public Object getPreviousKey(Object key) throws DException {
237 return super.getPreviousKey( key);
238 }
239 public Object getRootKey() throws DException {
240 return super.getRootKey();
241 }
242 public Object getTopKey() throws DException {
243 return super.getTopKey();
244 }
245 public Object getNextKey(Object key) throws DException {
246 return super.getNextKey( key);
247 }
248
249 }
250 |
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