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root/jsr166/jsr166/src/main/java/util/PriorityQueue.java

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.15 by dholmes, Thu Jul 31 07:18:02 2003 UTC vs.
Revision 1.22 by dl, Tue Aug 5 12:11:08 2003 UTC

#	Line 3 | Line 3
3		/**
4		* An unbounded priority queue based on a priority heap.  This queue orders
5		* elements according to an order specified at construction time, which is
6	<	* specified in the same manner as {@link TreeSet} and {@link TreeMap}:
7	<	* elements are ordered
6	>	* specified in the same manner as {@link java.util.TreeSet} and
7	>	* {@link java.util.TreeMap}: elements are ordered
8		* either according to their <i>natural order</i> (see {@link Comparable}), or
9	<	* according to a {@link Comparator}, depending on which constructor is used.
10	<	* The <em>head</em> of this queue is the least element with respect to the
11	<	* specified ordering. If multiple elements are tied for least value, the
9	>	* according to a {@link java.util.Comparator}, depending on which
10	>	* constructor is used.
11	>	* <p>The <em>head</em> of this queue is the <em>least</em> element with
12	>	* respect to the specified ordering.
13	>	* If multiple elements are tied for least value, the
14		* head is one of those elements. A priority queue does not permit
15		* <tt>null</tt> elements.
16		*
#	Line 20 | Line 22
22		*
23		* <p>A priority queue has a <i>capacity</i>.  The capacity is the
24		* size of the array used internally to store the elements on the
25	<	* queue.  It is always at least as large as the queue size.  As
25	>	* queue.
26	>	* It is always at least as large as the queue size.  As
27		* elements are added to a priority queue, its capacity grows
28		* automatically.  The details of the growth policy are not specified.
29		*
#	Line 55 | Line 58 | public class PriorityQueue<E> extends Ab
58		*
59		* queue.length must be >= 2, even if size == 0.
60		*/
61	<	private transient E[] queue;
61	>	private transient Object[] queue;
62
63		/**
64		* The number of elements in the priority queue.
#	Line 66 | Line 69 | public class PriorityQueue<E> extends Ab
69		* The comparator, or null if priority queue uses elements'
70		* natural ordering.
71		*/
72	<	private final Comparator<E> comparator;
72	>	private final Comparator<? super E> comparator;
73
74		/**
75		* The number of times this priority queue has been
#	Line 75 | Line 78 | public class PriorityQueue<E> extends Ab
78		private transient int modCount = 0;
79
80		/**
81	<	* Create a <tt>PriorityQueue</tt> with the default initial capacity
81	>	* Creates a <tt>PriorityQueue</tt> with the default initial capacity
82		* (11) that orders its elements according to their natural
83		* ordering (using <tt>Comparable</tt>.)
84		*/
#	Line 84 | Line 87 | public class PriorityQueue<E> extends Ab
87		}
88
89		/**
90	<	* Create a <tt>PriorityQueue</tt> with the specified initial capacity
90	>	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
91		* that orders its elements according to their natural ordering
92		* (using <tt>Comparable</tt>.)
93		*
#	Line 95 | Line 98 | public class PriorityQueue<E> extends Ab
98		}
99
100		/**
101	<	* Create a <tt>PriorityQueue</tt> with the specified initial capacity
101	>	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
102		* that orders its elements according to the specified comparator.
103		*
104		* @param initialCapacity the initial capacity for this priority queue.
#	Line 105 | Line 108 | public class PriorityQueue<E> extends Ab
108		* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
109		* than 1
110		*/
111	<	public PriorityQueue(int initialCapacity, Comparator<E> comparator) {
111	>	public PriorityQueue(int initialCapacity, Comparator<? super E> comparator) {
112		if (initialCapacity < 1)
113		throw new IllegalArgumentException();
114	<	queue = (E[]) new Object[initialCapacity + 1];
114	>	this.queue = new Object[initialCapacity + 1];
115		this.comparator = comparator;
116		}
117
118		/**
119	<	* Create a <tt>PriorityQueue</tt> containing the elements in the specified
120	<	* collection.  The priority queue has an initial capacity of 110% of the
121	<	* size of the specified collection; or 1 if the collection is empty.
122	<	* If the specified collection
123	<	* implements the {@link Sorted} interface, the priority queue will be
124	<	* sorted according to the same comparator, or according to its elements'
125	<	* natural order if the collection is sorted according to its elements'
126	<	* natural order.  If the specified collection does not implement
127	<	* <tt>Sorted</tt>, the priority queue is ordered according to
128	<	* its elements' natural order.
119	>	* Common code to initialize underlying queue array across
120	>	* constructors below.
121	>	*/
122	>	private void initializeArray(Collection<? extends E> c) {
123	>	int sz = c.size();
124	>	int initialCapacity = (int)Math.min((sz * 110L) / 100,
125	>	Integer.MAX_VALUE - 1);
126	>	if (initialCapacity < 1)
127	>	initialCapacity = 1;
128	>
129	>	this.queue = new Object[initialCapacity + 1];
130	>	}
131	>
132	>	/**
133	>	* Initially fill elements of the queue array under the
134	>	* knowledge that it is sorted or is another PQ, in which
135	>	* case we can just place the elements without fixups.
136	>	*/
137	>	private void fillFromSorted(Collection<? extends E> c) {
138	>	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
139	>	queue[++size] = i.next();
140	>	}
141	>
142	>
143	>	/**
144	>	* Initially fill elements of the queue array that is
145	>	* not to our knowledge sorted, so we must add them
146	>	* one by one.
147	>	*/
148	>	private void fillFromUnsorted(Collection<? extends E> c) {
149	>	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
150	>	add(i.next());
151	>	}
152	>
153	>	/**
154	>	* Creates a <tt>PriorityQueue</tt> containing the elements in the
155	>	* specified collection.  The priority queue has an initial
156	>	* capacity of 110% of the size of the specified collection or 1
157	>	* if the collection is empty.  If the specified collection is an
158	>	* instance of a {@link SortedSet} or is another
159	>	* <tt>PriorityQueue</tt>, the priority queue will be sorted
160	>	* according to the same comparator, or according to its elements'
161	>	* natural order if the collection is sorted according to its
162	>	* elements' natural order.  Otherwise, the priority queue is
163	>	* ordered according to its elements' natural order.
164		*
165		* @param c the collection whose elements are to be placed
166		*        into this priority queue.
#	Line 132 | Line 170 | public class PriorityQueue<E> extends Ab
170		* @throws NullPointerException if <tt>c</tt> or any element within it
171		* is <tt>null</tt>
172		*/
173	<	public PriorityQueue(Collection<E> c) {
174	<	int sz = c.size();
175	<	int initialCapacity = (int)Math.min((sz * 110L) / 100,
176	<	Integer.MAX_VALUE - 1);
177	<	if (initialCapacity < 1)
178	<	initialCapacity = 1;
179	<
180	<	queue = (E[]) new Object[initialCapacity + 1];
181	<
182	<	if (c instanceof Sorted) {
183	<	// FIXME: this code assumes too much
184	<	comparator = ((Sorted)c).comparator();
185	<	for (Iterator<E> i = c.iterator(); i.hasNext(); )
148	<	queue[++size] = i.next();
149	<	} else {
173	>	public PriorityQueue(Collection<? extends E> c) {
174	>	initializeArray(c);
175	>	if (c instanceof SortedSet<? extends E>) {
176	>	SortedSet<? extends E> s = (SortedSet<? extends E>) c;
177	>	comparator = (Comparator<? super E>)s.comparator();
178	>	fillFromSorted(s);
179	>	}
180	>	else if (c instanceof PriorityQueue<? extends E>) {
181	>	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
182	>	comparator = (Comparator<? super E>)s.comparator();
183	>	fillFromSorted(s);
184	>	}
185	>	else {
186		comparator = null;
187	<	for (Iterator<E> i = c.iterator(); i.hasNext(); )
152	<	add(i.next());
187	>	fillFromUnsorted(c);
188		}
189		}
190
191	+	/**
192	+	* Creates a <tt>PriorityQueue</tt> containing the elements in the
193	+	* specified collection.  The priority queue has an initial
194	+	* capacity of 110% of the size of the specified collection or 1
195	+	* if the collection is empty.  This priority queue will be sorted
196	+	* according to the same comparator as the given collection, or
197	+	* according to its elements' natural order if the collection is
198	+	* sorted according to its elements' natural order.
199	+	*
200	+	* @param c the collection whose elements are to be placed
201	+	*        into this priority queue.
202	+	* @throws ClassCastException if elements of the specified collection
203	+	*         cannot be compared to one another according to the priority
204	+	*         queue's ordering.
205	+	* @throws NullPointerException if <tt>c</tt> or any element within it
206	+	* is <tt>null</tt>
207	+	*/
208	+	public PriorityQueue(PriorityQueue<? extends E> c) {
209	+	initializeArray(c);
210	+	comparator = (Comparator<? super E>)c.comparator();
211	+	fillFromSorted(c);
212	+	}
213	+
214	+	/**
215	+	* Creates a <tt>PriorityQueue</tt> containing the elements in the
216	+	* specified collection.  The priority queue has an initial
217	+	* capacity of 110% of the size of the specified collection or 1
218	+	* if the collection is empty.  This priority queue will be sorted
219	+	* according to the same comparator as the given collection, or
220	+	* according to its elements' natural order if the collection is
221	+	* sorted according to its elements' natural order.
222	+	*
223	+	* @param c the collection whose elements are to be placed
224	+	*        into this priority queue.
225	+	* @throws ClassCastException if elements of the specified collection
226	+	*         cannot be compared to one another according to the priority
227	+	*         queue's ordering.
228	+	* @throws NullPointerException if <tt>c</tt> or any element within it
229	+	* is <tt>null</tt>
230	+	*/
231	+	public PriorityQueue(SortedSet<? extends E> c) {
232	+	initializeArray(c);
233	+	comparator = (Comparator<? super E>)c.comparator();
234	+	fillFromSorted(c);
235	+	}
236	+
237	+	/**
238	+	* Resize array, if necessary, to be able to hold given index
239	+	*/
240	+	private void grow(int index) {
241	+	int newlen = queue.length;
242	+	if (index < newlen) // don't need to grow
243	+	return;
244	+	if (index == Integer.MAX_VALUE)
245	+	throw new OutOfMemoryError();
246	+	while (newlen <= index) {
247	+	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
248	+	newlen = Integer.MAX_VALUE;
249	+	else
250	+	newlen <<= 2;
251	+	}
252	+	Object[] newQueue = new Object[newlen];
253	+	System.arraycopy(queue, 0, newQueue, 0, queue.length);
254	+	queue = newQueue;
255	+	}
256	+
257		// Queue Methods
258
259		/**
260		* Add the specified element to this priority queue.
261		*
161	–	* @param element the element to add.
262		* @return <tt>true</tt>
263		* @throws ClassCastException if the specified element cannot be compared
264		* with elements currently in the priority queue according
265		* to the priority queue's ordering.
266	<	* @throws NullPointerException if the specified element is null.
266	>	* @throws NullPointerException if the specified element is <tt>null</tt>.
267		*/
268	<	public boolean offer(E element) {
269	<	if (element == null)
268	>	public boolean offer(E o) {
269	>	if (o == null)
270		throw new NullPointerException();
271		modCount++;
272		++size;
273
274		// Grow backing store if necessary
275	<	while (size >= queue.length) {
276	<	E[] newQueue = (E[]) new Object[2 * queue.length];
177	<	System.arraycopy(queue, 0, newQueue, 0, queue.length);
178	<	queue = newQueue;
179	<	}
275	>	if (size >= queue.length)
276	>	grow(size);
277
278	<	queue[size] = element;
278	>	queue[size] = o;
279		fixUp(size);
280		return true;
281		}
#	Line 186 | Line 283 | public class PriorityQueue<E> extends Ab
283		public E poll() {
284		if (size == 0)
285		return null;
286	<	return remove(1);
286	>	return (E) remove(1);
287		}
288
289		public E peek() {
290	<	return queue[1];
290	>	return (E) queue[1];
291		}
292
293		// Collection Methods
#	Line 203 | Line 300 | public class PriorityQueue<E> extends Ab
300		* with elements currently in the priority queue according
301		* to the priority queue's ordering.
302		*/
303	<	public boolean add(E element) {
304	<	return super.add(element);
303	>	public boolean add(E o) {
304	>	return super.add(o);
305		}
306
307		/**
211	–	* @throws NullPointerException if any element is <tt>null</tt>.
308		* @throws ClassCastException if any element cannot be compared
309		* with elements currently in the priority queue according
310		* to the priority queue's ordering.
311	+	* @throws NullPointerException if <tt>c</tt> or any element in <tt>c</tt>
312	+	* is <tt>null</tt>
313		*/
314		public boolean addAll(Collection<? extends E> c) {
315		return super.addAll(c);
#	Line 223 | Line 321 | public class PriorityQueue<E> extends Ab
321
322		if (comparator == null) {
323		for (int i = 1; i <= size; i++) {
324	<	if (((Comparable)queue[i]).compareTo(o) == 0) {
324	>	if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) {
325		remove(i);
326		return true;
327		}
328		}
329		} else {
330		for (int i = 1; i <= size; i++) {
331	<	if (comparator.compare(queue[i], (E)o) == 0) {
331	>	if (comparator.compare((E)queue[i], (E)o) == 0) {
332		remove(i);
333		return true;
334		}
#	Line 272 | Line 370 | public class PriorityQueue<E> extends Ab
370		checkForComodification();
371		if (cursor > size)
372		throw new NoSuchElementException();
373	<	E result = queue[cursor];
373	>	E result = (E) queue[cursor];
374		lastRet = cursor++;
375		return result;
376		}
#	Line 328 | Line 426 | public class PriorityQueue<E> extends Ab
426		assert i <= size;
427		modCount++;
428
429	<	E result = queue[i];
429	>	E result = (E) queue[i];
430		queue[i] = queue[size];
431		queue[size--] = null;  // Drop extra ref to prevent memory leak
432		if (i <= size)
#	Line 349 | Line 447 | public class PriorityQueue<E> extends Ab
447		if (comparator == null) {
448		while (k > 1) {
449		int j = k >> 1;
450	<	if (((Comparable)queue[j]).compareTo(queue[k]) <= 0)
450	>	if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0)
451		break;
452	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
452	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
453		k = j;
454		}
455		} else {
456		while (k > 1) {
457		int j = k >> 1;
458	<	if (comparator.compare(queue[j], queue[k]) <= 0)
458	>	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
459		break;
460	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
460	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
461		k = j;
462		}
463		}
#	Line 378 | Line 476 | public class PriorityQueue<E> extends Ab
476		int j;
477		if (comparator == null) {
478		while ((j = k << 1) <= size) {
479	<	if (j<size && ((Comparable)queue[j]).compareTo(queue[j+1]) > 0)
479	>	if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
480		j++; // j indexes smallest kid
481	<	if (((Comparable)queue[k]).compareTo(queue[j]) <= 0)
481	>	if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
482		break;
483	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
483	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
484		k = j;
485		}
486		} else {
487		while ((j = k << 1) <= size) {
488	<	if (j < size && comparator.compare(queue[j], queue[j+1]) > 0)
488	>	if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
489		j++; // j indexes smallest kid
490	<	if (comparator.compare(queue[k], queue[j]) <= 0)
490	>	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
491		break;
492	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
492	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
493		k = j;
494		}
495		}
496		}
497
498	<	public Comparator comparator() {
498	>	public Comparator<? super E> comparator() {
499		return comparator;
500		}
501
#	Line 410 | Line 508 | public class PriorityQueue<E> extends Ab
508		* <tt>Object</tt>) in the proper order.
509		* @param s the stream
510		*/
511	<	private synchronized void writeObject(java.io.ObjectOutputStream s)
511	>	private void writeObject(java.io.ObjectOutputStream s)
512		throws java.io.IOException{
513		// Write out element count, and any hidden stuff
514		s.defaultWriteObject();
#	Line 428 | Line 526 | public class PriorityQueue<E> extends Ab
526		* deserialize it).
527		* @param s the stream
528		*/
529	<	private synchronized void readObject(java.io.ObjectInputStream s)
529	>	private void readObject(java.io.ObjectInputStream s)
530		throws java.io.IOException, ClassNotFoundException {
531		// Read in size, and any hidden stuff
532		s.defaultReadObject();
533
534		// Read in array length and allocate array
535		int arrayLength = s.readInt();
536	<	queue = (E[]) new Object[arrayLength];
536	>	queue = new Object[arrayLength];
537
538		// Read in all elements in the proper order.
539		for (int i=0; i<size; i++)
540	<	queue[i] = (E)s.readObject();
540	>	queue[i] = s.readObject();
541		}
542
543		}

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