Skip to main content
aboutsummaryrefslogtreecommitdiffstats
blob: 0db7e07b7049c5e9ee3bfd5a50a2f60e5164bc54 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
/*******************************************************************************
 * Copyright (c) 2000, 2012 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.osgi.framework.util;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * A set data structure which only accepts {@link KeyedElement} objects as elements of the set. 
 * Unlike typical set implementations this set requires each element to provide its own key.  This helps
 * reduce the overhead of storing the keys of each individual element<p>
 * This class in not thread safe, clients must ensure synchronization when modifying an object of this type.
 * @since 3.2 
 */
// This class was moved from  /org.eclipse.osgi/core/framework/org/eclipse/osgi/framework/internal/core/KeyedHashSet.java
public class KeyedHashSet {
	public static final int MINIMUM_SIZE = 7;
	int elementCount = 0;
	KeyedElement[] elements;
	private boolean replace;
	private int capacity;

	/**
	 * Constructs an KeyedHashSet which allows elements to be replaced and with the minimum initial capacity.
	 */
	public KeyedHashSet() {
		this(MINIMUM_SIZE, true);
	}

	/**
	 * Constructs an KeyedHashSet with the minimum initial capacity.
	 * @param replace true if this set allows elements to be replaced
	 */
	public KeyedHashSet(boolean replace) {
		this(MINIMUM_SIZE, replace);
	}

	/**
	 * Constructs an KeyedHashSet which allows elements to be replaced.
	 * @param capacity the initial capacity of this set
	 */
	public KeyedHashSet(int capacity) {
		this(capacity, true);
	}

	/**
	 * Constructs an KeyedHashSet
	 * @param capacity the initial capacity of this set
	 * @param replace true if this set allows elements to be replaced
	 */
	public KeyedHashSet(int capacity, boolean replace) {
		elements = new KeyedElement[Math.max(MINIMUM_SIZE, capacity * 2)];
		this.replace = replace;
		this.capacity = capacity;
	}

	/**
	 * Constructs a new KeyedHashSet and copies to specified KeyedHashSet's contents to the new KeyedHashSet.
	 * @param original the KeyedHashSet to copy
	 */
	public KeyedHashSet(KeyedHashSet original) {
		elements = new KeyedElement[original.elements.length];
		System.arraycopy(original.elements, 0, elements, 0, original.elements.length);
		elementCount = original.elementCount;
		replace = original.replace;
		capacity = original.capacity;
	}

	/**
	 * Adds an element to this set. If an element with the same key already exists,
	 * replaces it depending on the replace flag.
	 * @return true if the element was added/stored, false otherwise
	 */
	public boolean add(KeyedElement element) {
		int hash = hash(element);

		// search for an empty slot at the end of the array
		for (int i = hash; i < elements.length; i++) {
			if (elements[i] == null) {
				elements[i] = element;
				elementCount++;
				// grow if necessary
				if (shouldGrow())
					expand();
				return true;
			}
			if (elements[i].compare(element)) {
				if (replace)
					elements[i] = element;
				return replace;
			}
		}

		// search for an empty slot at the beginning of the array
		for (int i = 0; i < hash - 1; i++) {
			if (elements[i] == null) {
				elements[i] = element;
				elementCount++;
				// grow if necessary
				if (shouldGrow())
					expand();
				return true;
			}
			if (elements[i].compare(element)) {
				if (replace)
					elements[i] = element;
				return replace;
			}
		}

		// if we didn't find a free slot, then try again with the expanded set
		expand();
		return add(element);
	}

	/**
	 * Adds the specified list of elements to this set.  Some elements may not
	 * get added if the replace flag is set.
	 * @param toAdd the list of elements to add to this set.
	 */
	public void addAll(KeyedElement[] toAdd) {
		for (int i = 0; i < toAdd.length; i++)
			add(toAdd[i]);
	}

	/**
	 * Returns true if the specified element exists in this set.
	 * @param element the requested element
	 * @return true if the specified element exists in this set; false otherwise.
	 */
	public boolean contains(KeyedElement element) {
		return get(element) != null;
	}

	/**
	 * Returns true if an element with the specified key exists in this set.
	 * @param key the key of the requested element
	 * @return true if an element with the specified key exists in this set; false otherwise
	 */
	public boolean containsKey(Object key) {
		return getByKey(key) != null;
	}

	/**
	 * Returns all elements that exist in this set
	 * @return all elements that exist in this set
	 */
	public KeyedElement[] elements() {
		return (KeyedElement[]) elements(new KeyedElement[elementCount]);
	}

	/**
	 * Copies all elements that exist in this set into the specified array.  No size 
	 * checking is done.  If the specified array is to small an ArrayIndexOutOfBoundsException
	 * will be thrown.
	 * @param result the array to copy the existing elements into.
	 * @return the specified array.
	 * @throws ArrayIndexOutOfBoundsException if the specified array is to small.
	 */
	public Object[] elements(Object[] result) {
		int j = 0;
		for (int i = 0; i < elements.length; i++) {
			KeyedElement element = elements[i];
			if (element != null)
				result[j++] = element;
		}
		return result;
	}

	/**
	 * The array isn't large enough so double its size and rehash
	 * all its current values.
	 */
	protected void expand() {
		if (elements.length == Integer.MAX_VALUE) {
			throw new OutOfMemoryError();
		}
		KeyedElement[] oldElements = elements;
		int newSize = elements.length * 2;
		if (newSize < 0) {
			// overflowed; set to max
			newSize = Integer.MAX_VALUE;
		}
		elements = new KeyedElement[newSize];

		int maxArrayIndex = elements.length - 1;
		for (int i = 0; i < oldElements.length; i++) {
			KeyedElement element = oldElements[i];
			if (element != null) {
				int hash = hash(element);
				while (elements[hash] != null) {
					hash++;
					if (hash > maxArrayIndex)
						hash = 0;
				}
				elements[hash] = element;
			}
		}
	}

	/**
	 * Returns the element with the specified key, or null if not found.
	 * @param key the requested element's key
	 * @return the element with the specified key, or null if not found.
	 */
	public KeyedElement getByKey(Object key) {
		if (elementCount == 0)
			return null;
		int hash = keyHash(key);

		// search the last half of the array
		for (int i = hash; i < elements.length; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return null;
			if (element.getKey().equals(key))
				return element;
		}

		// search the beginning of the array
		for (int i = 0; i < hash - 1; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return null;
			if (element.getKey().equals(key))
				return element;
		}

		// nothing found so return null
		return null;
	}

	/**
	 * Returns the element which compares to the specified element, or null if not found.
	 * @see KeyedElement#compare(KeyedElement)
	 * @param otherElement the requested element 
	 * @return the element which compares to the specified element, or null if not found.
	 */
	public KeyedElement get(KeyedElement otherElement) {
		if (elementCount == 0)
			return null;
		int hash = hash(otherElement);

		// search the last half of the array
		for (int i = hash; i < elements.length; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return null;
			if (element.compare(otherElement))
				return element;
		}

		// search the beginning of the array
		for (int i = 0; i < hash - 1; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return null;
			if (element.compare(otherElement))
				return element;
		}

		// nothing found so return null
		return null;
	}

	/**
	 * Returns true if this set is empty
	 * @return true if this set is empty
	 */
	public boolean isEmpty() {
		return elementCount == 0;
	}

	/**
	 * The element at the given index has been removed so move
	 * elements to keep the set properly hashed.
	 * @param anIndex the index that has been removed
	 */
	protected void rehashTo(int anIndex) {

		int target = anIndex;
		int index = anIndex + 1;
		if (index >= elements.length)
			index = 0;
		KeyedElement element = elements[index];
		while (element != null) {
			int hashIndex = hash(element);
			boolean match;
			if (index < target)
				match = !(hashIndex > target || hashIndex <= index);
			else
				match = !(hashIndex > target && hashIndex <= index);
			if (match) {
				elements[target] = element;
				target = index;
			}
			index++;
			if (index >= elements.length)
				index = 0;
			element = elements[index];
		}
		elements[target] = null;
	}

	/**
	 * Removes the element with the specified key
	 * @param key the requested element's key
	 * @return true if an element was removed
	 */
	public boolean removeByKey(Object key) {
		if (elementCount == 0)
			return false;
		int hash = keyHash(key);

		for (int i = hash; i < elements.length; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return false;
			if (element.getKey().equals(key)) {
				rehashTo(i);
				elementCount--;
				return true;
			}
		}

		for (int i = 0; i < hash - 1; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return false;
			if (element.getKey().equals(key)) {
				rehashTo(i);
				elementCount--;
				return true;
			}
		}

		return true;
	}

	/**
	 * Removes the element which compares to the specified element
	 * @param toRemove the requested element to remove
	 * @return true if an element was removed
	 */
	public boolean remove(KeyedElement toRemove) {
		if (elementCount == 0)
			return false;

		int hash = hash(toRemove);

		for (int i = hash; i < elements.length; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return false;
			if (element.compare(toRemove)) {
				rehashTo(i);
				elementCount--;
				return true;
			}
		}

		for (int i = 0; i < hash - 1; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				return false;
			if (element.compare(toRemove)) {
				rehashTo(i);
				elementCount--;
				return true;
			}
		}
		return false;
	}

	private int hash(KeyedElement element) {
		return Math.abs(element.getKeyHashCode()) % elements.length;
	}

	private int keyHash(Object key) {
		return Math.abs(key.hashCode()) % elements.length;
	}

	/**
	 * Removes all of the specified elements from this set
	 * @param toRemove the requested elements to remove
	 */
	public void removeAll(KeyedElement[] toRemove) {
		for (int i = 0; i < toRemove.length; i++)
			remove(toRemove[i]);
	}

	private boolean shouldGrow() {
		return elementCount > elements.length * 0.75;
	}

	/**
	 * Returns the number of elements in this set
	 * @return the number of elements in this set
	 */
	public int size() {
		return elementCount;
	}

	public String toString() {
		StringBuffer result = new StringBuffer(100);
		result.append("{"); //$NON-NLS-1$
		boolean first = true;
		for (int i = 0; i < elements.length; i++) {
			if (elements[i] != null) {
				if (first)
					first = false;
				else
					result.append(", "); //$NON-NLS-1$
				result.append(elements[i]);
			}
		}
		result.append("}"); //$NON-NLS-1$
		return result.toString();
	}

	/**
	 * Returns the number of collisions this set currently has
	 * @return the number of collisions this set currently has
	 */
	public int countCollisions() {
		int result = 0;
		int lastHash = 0;
		boolean found = false;
		for (int i = 0; i < elements.length; i++) {
			KeyedElement element = elements[i];
			if (element == null)
				found = false;
			else {
				int hash = hash(element);
				if (found)
					if (lastHash == hash)
						result++;
					else
						found = false;
				else {
					lastHash = hash;
					found = true;
				}
			}
		}
		return result;
	}

	/**
	 * Returns an iterator of elements in this set
	 * @return an iterator of elements in this set
	 */
	public Iterator<KeyedElement> iterator() {
		return new EquinoxSetIterator();
	}

	class EquinoxSetIterator implements Iterator<KeyedElement> {
		private int currentIndex = -1;
		private int found;

		public boolean hasNext() {
			return found < elementCount;
		}

		public KeyedElement next() {
			if (!hasNext())
				throw new NoSuchElementException();
			while (++currentIndex < elements.length)
				if (elements[currentIndex] != null) {
					found++;
					return elements[currentIndex];
				}
			// this would mean we have less elements than we thought
			throw new NoSuchElementException();
		}

		public void remove() {
			// as allowed by the API
			throw new UnsupportedOperationException();
		}
	}

	/**
	 * Clears all elements from this set
	 */
	public void clear() {
		elements = new KeyedElement[Math.max(MINIMUM_SIZE, capacity * 2)];
		elementCount = 0;
	}
}

Back to the top