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1
11 package org.eclipse.core.internal.runtime;
12
13 import java.lang.ref.*;
14
15
20 public class ReferenceHashSet {
21
22 private interface HashedReference {
23 int hashCode();
24
25 Object  get();
26 }
27
28 private class HashableWeakReference extends WeakReference implements HashedReference {
29 public int hashCode;
30
31 public HashableWeakReference(Object referent, ReferenceQueue queue) {
32 super(referent, queue);
33 this.hashCode = referent.hashCode();
34 }
35
36 public boolean equals(Object obj) {
37 if (!(obj instanceof HashableWeakReference))
38 return false;
39 Object referent = super.get();
40 Object other = ((HashableWeakReference) obj).get();
41 if (referent == null)
42 return other == null;
43 return referent.equals(other);
44 }
45
46 public int hashCode() {
47 return this.hashCode;
48 }
49
50 public String toString() {
51 Object referent = super.get();
52 if (referent == null)
53 return "[hashCode=" + this.hashCode + "] <referent was garbage collected>"; return "[hashCode=" + this.hashCode + "] " + referent.toString(); }
56 }
57
58 private class HashableSoftReference extends SoftReference implements HashedReference {
59 public int hashCode;
60
61 public HashableSoftReference(Object referent, ReferenceQueue queue) {
62 super(referent, queue);
63 this.hashCode = referent.hashCode();
64 }
65
66 public boolean equals(Object obj) {
67 if (!(obj instanceof HashableWeakReference))
68 return false;
69 Object referent = super.get();
70 Object other = ((HashableWeakReference) obj).get();
71 if (referent == null)
72 return other == null;
73 return referent.equals(other);
74 }
75
76 public int hashCode() {
77 return this.hashCode;
78 }
79
80 public String toString() {
81 Object referent = super.get();
82 if (referent == null)
83 return "[hashCode=" + this.hashCode + "] <referent was garbage collected>"; return "[hashCode=" + this.hashCode + "] " + referent.toString(); }
86 }
87
88 private class StrongReference implements HashedReference {
89 private Object referent;
90
91 public StrongReference(Object referent, ReferenceQueue queue) {
92 this.referent = referent;
93 }
94
95 public int hashCode() {
96 return referent.hashCode();
97 }
98
99 public Object get() {
100 return referent;
101 }
102
103 public boolean equals(Object obj) {
104 return referent.equals(obj);
105 }
106 }
107
108 HashedReference[] values;
109
110 public int elementSize;
112 int threshold;
113
114 ReferenceQueue referenceQueue = new ReferenceQueue();
115
116 public ReferenceHashSet() {
117 this(5);
118 }
119
120 public ReferenceHashSet(int size) {
121 this.elementSize = 0;
122 this.threshold = size; int extraRoom = (int) (size * 1.75f);
125 if (this.threshold == extraRoom)
126 extraRoom++;
127 this.values = new HashedReference[extraRoom];
128 }
129
130
133 final public static int HARD = 0;
134
135
138 final public static int SOFT = 1;
139
140
143 final public static int WEAK = 2;
144
145 private HashedReference toReference(int type, Object referent) {
146 switch (type) {
147 case HARD :
148 return new StrongReference(referent, referenceQueue);
149 case SOFT :
150 return new HashableSoftReference(referent, referenceQueue);
151 case WEAK :
152 return new HashableWeakReference(referent, referenceQueue);
153 default :
154 throw new Error ();
155 }
156 }
157
158
163 public Object add(Object obj, int referenceType) {
164 cleanupGarbageCollectedValues();
165 int index = (obj.hashCode() & 0x7FFFFFFF) % this.values.length;
166 HashedReference currentValue;
167 while ((currentValue = this.values[index]) != null) {
168 Object referent;
169 if (obj.equals(referent = currentValue.get())) {
170 return referent;
171 }
172 index = (index + 1) % this.values.length;
173 }
174 this.values[index] = toReference(referenceType, obj);
175
176 if (++this.elementSize > this.threshold)
178 rehash();
179
180 return obj;
181 }
182
183 private void addValue(HashedReference value) {
184 Object obj = value.get();
185 if (obj == null)
186 return;
187 int valuesLength = this.values.length;
188 int index = (value.hashCode() & 0x7FFFFFFF) % valuesLength;
189 HashedReference currentValue;
190 while ((currentValue = this.values[index]) != null) {
191 if (obj.equals(currentValue.get())) {
192 return;
193 }
194 index = (index + 1) % valuesLength;
195 }
196 this.values[index] = value;
197
198 if (++this.elementSize > this.threshold)
200 rehash();
201 }
202
203 private void cleanupGarbageCollectedValues() {
204 HashedReference toBeRemoved;
205 while ((toBeRemoved = (HashedReference) this.referenceQueue.poll()) != null) {
206 int hashCode = toBeRemoved.hashCode();
207 int valuesLength = this.values.length;
208 int index = (hashCode & 0x7FFFFFFF) % valuesLength;
209 HashedReference currentValue;
210 while ((currentValue = this.values[index]) != null) {
211 if (currentValue == toBeRemoved) {
212 int sameHash = index;
215 int current;
216 while ((currentValue = this.values[current = (sameHash + 1) % valuesLength]) != null && currentValue.hashCode() == hashCode)
217 sameHash = current;
218 this.values[index] = this.values[sameHash];
219 this.values[sameHash] = null;
220 this.elementSize--;
221 break;
222 }
223 index = (index + 1) % valuesLength;
224 }
225 }
226 }
227
228 public boolean contains(Object obj) {
229 return get(obj) != null;
230 }
231
232
236 public Object get(Object obj) {
237 cleanupGarbageCollectedValues();
238 int valuesLength = this.values.length;
239 int index = (obj.hashCode() & 0x7FFFFFFF) % valuesLength;
240 HashedReference currentValue;
241 while ((currentValue = this.values[index]) != null) {
242 Object referent;
243 if (obj.equals(referent = currentValue.get())) {
244 return referent;
245 }
246 index = (index + 1) % valuesLength;
247 }
248 return null;
249 }
250
251 private void rehash() {
252 ReferenceHashSet newHashSet = new ReferenceHashSet(this.elementSize * 2); newHashSet.referenceQueue = this.referenceQueue;
254 HashedReference currentValue;
255 for (int i = 0, length = this.values.length; i < length; i++)
256 if ((currentValue = this.values[i]) != null)
257 newHashSet.addValue(currentValue);
258
259 this.values = newHashSet.values;
260 this.threshold = newHashSet.threshold;
261 this.elementSize = newHashSet.elementSize;
262 }
263
264
268 public Object remove(Object obj) {
269 cleanupGarbageCollectedValues();
270 int valuesLength = this.values.length;
271 int index = (obj.hashCode() & 0x7FFFFFFF) % valuesLength;
272 HashedReference currentValue;
273 while ((currentValue = this.values[index]) != null) {
274 Object referent;
275 if (obj.equals(referent = currentValue.get())) {
276 this.elementSize--;
277 this.values[index] = null;
278 rehash();
279 return referent;
280 }
281 index = (index + 1) % valuesLength;
282 }
283 return null;
284 }
285
286 public int size() {
287 return this.elementSize;
288 }
289
290 public String toString() {
291 StringBuffer buffer = new StringBuffer ("{"); for (int i = 0, length = this.values.length; i < length; i++) {
293 HashedReference value = this.values[i];
294 if (value != null) {
295 Object ref = value.get();
296 if (ref != null) {
297 buffer.append(ref.toString());
298 buffer.append(", "); }
300 }
301 }
302 buffer.append("}"); return buffer.toString();
304 }
305
306 public Object [] toArray() {
307 cleanupGarbageCollectedValues();
308 Object [] result = new Object [elementSize];
309 int resultSize = 0;
310 for (int i = 0; i < values.length; i++) {
311 if (values[i] == null)
312 continue;
313 Object tmp = values[i].get();
314 if (tmp != null)
315 result[resultSize++] = tmp;
316 }
317 if (result.length == resultSize)
318 return result;
319 Object [] finalResult = new Object [resultSize];
320 System.arraycopy(result, 0, finalResult, 0, resultSize);
321 return finalResult;
322 }
323 }
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