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

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.11 by dholmes, Mon Jul 28 04:11:54 2003 UTC vs.
Revision 1.16 by tim, Thu Jul 31 15:44:41 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}:
6	>	* specified in the same manner as {@link TreeSet} and {@link TreeMap}:
7		* 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
12	<	* head is one of those elements. A priority queue does not permit
11	>	* specified ordering. If multiple elements are tied for least value, the
12	>	* head is one of those elements. A priority queue does not permit
13		* <tt>null</tt> elements.
14	<	*
14	>	*
15		* <p>The {@link #remove()} and {@link #poll()} methods remove and
16		* return the head of the queue.
17		*
#	Line 38 | Line 38
38		* @author Josh Bloch
39		*/
40		public class PriorityQueue<E> extends AbstractQueue<E>
41	<	implements Queue<E>, Sorted, java.io.Serializable {
41	>	implements Queue<E>, java.io.Serializable {
42
43		private static final int DEFAULT_INITIAL_CAPACITY = 11;
44
#	Line 55 | Line 55 | public class PriorityQueue<E> extends Ab
55		*
56		* queue.length must be >= 2, even if size == 0.
57		*/
58	<	private transient E[] queue;
58	>	private transient Object[] queue;
59
60		/**
61		* The number of elements in the priority queue.
#	Line 66 | Line 66 | public class PriorityQueue<E> extends Ab
66		* The comparator, or null if priority queue uses elements'
67		* natural ordering.
68		*/
69	<	private final Comparator<E> comparator;
69	>	private final Comparator<? super E> comparator;
70
71		/**
72		* The number of times this priority queue has been
#	Line 102 | Line 102 | public class PriorityQueue<E> extends Ab
102		* @param comparator the comparator used to order this priority queue.
103		* If <tt>null</tt> then the order depends on the elements' natural
104		* ordering.
105	+	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
106	+	* than 1
107		*/
108	<	public PriorityQueue(int initialCapacity, Comparator<E> comparator) {
108	>	public PriorityQueue(int initialCapacity, Comparator<? super E> comparator) {
109		if (initialCapacity < 1)
110	<	initialCapacity = 1;
111	<	queue = (E[]) new Object[initialCapacity + 1];
110	>	throw new IllegalArgumentException();
111	>	this.queue = new Object[initialCapacity + 1];
112		this.comparator = comparator;
113		}
114
115		/**
116		* Create a <tt>PriorityQueue</tt> containing the elements in the specified
117		* collection.  The priority queue has an initial capacity of 110% of the
118	<	* size of the specified collection. If the specified collection
118	>	* size of the specified collection; or 1 if the collection is empty.
119	>	* If the specified collection
120		* implements the {@link Sorted} interface, the priority queue will be
121		* sorted according to the same comparator, or according to its elements'
122		* natural order if the collection is sorted according to its elements'
#	Line 121 | Line 124 | public class PriorityQueue<E> extends Ab
124		* <tt>Sorted</tt>, the priority queue is ordered according to
125		* its elements' natural order.
126		*
127	<	* @param initialElements the collection whose elements are to be placed
127	>	* @param c the collection whose elements are to be placed
128		*        into this priority queue.
129		* @throws ClassCastException if elements of the specified collection
130		*         cannot be compared to one another according to the priority
131		*         queue's ordering.
132	<	* @throws NullPointerException if the specified collection or an
133	<	*         element of the specified collection is <tt>null</tt>.
132	>	* @throws NullPointerException if <tt>c</tt> or any element within it
133	>	* is <tt>null</tt>
134		*/
135	<	public PriorityQueue(Collection<E> initialElements) {
136	<	int sz = initialElements.size();
135	>	public PriorityQueue(Collection<? extends E> c) {
136	>	int sz = c.size();
137		int initialCapacity = (int)Math.min((sz * 110L) / 100,
138		Integer.MAX_VALUE - 1);
139		if (initialCapacity < 1)
140		initialCapacity = 1;
138	–	queue = (E[]) new Object[initialCapacity + 1];
141
142	<	if (initialElements instanceof Sorted) {
143	<	comparator = ((Sorted)initialElements).comparator();
144	<	for (Iterator<E> i = initialElements.iterator(); i.hasNext(); )
142	>	this.queue = new Object[initialCapacity + 1];
143	>
144	>	if (c instanceof Sorted) {
145	>	// FIXME: this code assumes too much
146	>	this.comparator = (Comparator<? super E>) ((Sorted)c).comparator();
147	>	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
148		queue[++size] = i.next();
149		} else {
150		comparator = null;
151	<	for (Iterator<E> i = initialElements.iterator(); i.hasNext(); )
151	>	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
152		add(i.next());
153		}
154		}
#	Line 168 | Line 173 | public class PriorityQueue<E> extends Ab
173
174		// Grow backing store if necessary
175		while (size >= queue.length) {
176	<	E[] newQueue = (E[]) new Object[2 * queue.length];
176	>	Object[] newQueue = new Object[2 * queue.length];
177		System.arraycopy(queue, 0, newQueue, 0, queue.length);
178		queue = newQueue;
179		}
#	Line 181 | Line 186 | public class PriorityQueue<E> extends Ab
186		public E poll() {
187		if (size == 0)
188		return null;
189	<	return remove(1);
189	>	return (E) remove(1);
190		}
191
192		public E peek() {
193	<	return queue[1];
193	>	return (E) queue[1];
194		}
195
196		// Collection Methods
#	Line 194 | Line 199 | public class PriorityQueue<E> extends Ab
199
200		/**
201		* @throws NullPointerException if the specified element is <tt>null</tt>.
202	+	* @throws ClassCastException if the specified element cannot be compared
203	+	* with elements currently in the priority queue according
204	+	* to the priority queue's ordering.
205		*/
206		public boolean add(E element) {
207		return super.add(element);
#	Line 201 | Line 209 | public class PriorityQueue<E> extends Ab
209
210		/**
211		* @throws NullPointerException if any element is <tt>null</tt>.
212	+	* @throws ClassCastException if any element cannot be compared
213	+	* with elements currently in the priority queue according
214	+	* to the priority queue's ordering.
215		*/
216	<	public boolean addAll(Collection c) {
216	>	public boolean addAll(Collection<? extends E> c) {
217		return super.addAll(c);
218		}
219
220	<	/**
210	<	* @throws NullPointerException if the specified element is <tt>null</tt>.
211	<	*/
212	<	public boolean remove(E o) {
220	>	public boolean remove(Object o) {
221		if (o == null)
222	<	throw new NullPointerException();
222	>	return false;
223
224		if (comparator == null) {
225		for (int i = 1; i <= size; i++) {
226	<	if (((Comparable)queue[i]).compareTo(o) == 0) {
226	>	if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) {
227		remove(i);
228		return true;
229		}
230		}
231		} else {
232		for (int i = 1; i <= size; i++) {
233	<	if (comparator.compare(queue[i], o) == 0) {
233	>	if (comparator.compare((E)queue[i], (E)o) == 0) {
234		remove(i);
235		return true;
236		}
#	Line 231 | Line 239 | public class PriorityQueue<E> extends Ab
239		return false;
240		}
241
234	–	/**
235	–	* Returns an iterator over the elements in this priority queue.  The
236	–	* elements of the priority queue will be returned by this iterator in the
237	–	* order specified by the queue, which is to say the order they would be
238	–	* returned by repeated calls to <tt>poll</tt>.
239	–	*
240	–	* @return an <tt>Iterator</tt> over the elements in this priority queue.
241	–	*/
242		public Iterator<E> iterator() {
243		return new Itr();
244		}
#	Line 272 | Line 272 | public class PriorityQueue<E> extends Ab
272		checkForComodification();
273		if (cursor > size)
274		throw new NoSuchElementException();
275	<	E result = queue[cursor];
275	>	E result = (E) queue[cursor];
276		lastRet = cursor++;
277		return result;
278		}
#	Line 328 | Line 328 | public class PriorityQueue<E> extends Ab
328		assert i <= size;
329		modCount++;
330
331	<	E result = queue[i];
331	>	E result = (E) queue[i];
332		queue[i] = queue[size];
333		queue[size--] = null;  // Drop extra ref to prevent memory leak
334		if (i <= size)
#	Line 349 | Line 349 | public class PriorityQueue<E> extends Ab
349		if (comparator == null) {
350		while (k > 1) {
351		int j = k >> 1;
352	<	if (((Comparable)queue[j]).compareTo(queue[k]) <= 0)
352	>	if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0)
353		break;
354	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
354	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
355		k = j;
356		}
357		} else {
358		while (k > 1) {
359		int j = k >> 1;
360	<	if (comparator.compare(queue[j], queue[k]) <= 0)
360	>	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
361		break;
362	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
362	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
363		k = j;
364		}
365		}
#	Line 378 | Line 378 | public class PriorityQueue<E> extends Ab
378		int j;
379		if (comparator == null) {
380		while ((j = k << 1) <= size) {
381	<	if (j<size && ((Comparable)queue[j]).compareTo(queue[j+1]) > 0)
381	>	if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
382		j++; // j indexes smallest kid
383	<	if (((Comparable)queue[k]).compareTo(queue[j]) <= 0)
383	>	if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
384		break;
385	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
385	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
386		k = j;
387		}
388		} else {
389		while ((j = k << 1) <= size) {
390	<	if (j < size && comparator.compare(queue[j], queue[j+1]) > 0)
390	>	if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
391		j++; // j indexes smallest kid
392	<	if (comparator.compare(queue[k], queue[j]) <= 0)
392	>	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
393		break;
394	<	E tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
394	>	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
395		k = j;
396		}
397		}
398		}
399
400	<	public Comparator comparator() {
400	>	public Comparator<? super E> comparator() {
401		return comparator;
402		}
403
#	Line 435 | Line 435 | public class PriorityQueue<E> extends Ab
435
436		// Read in array length and allocate array
437		int arrayLength = s.readInt();
438	<	queue = (E[]) new Object[arrayLength];
438	>	queue = new Object[arrayLength];
439
440		// Read in all elements in the proper order.
441		for (int i=0; i<size; i++)
442	<	queue[i] = (E)s.readObject();
442	>	queue[i] = s.readObject();
443		}
444
445		}

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