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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.68 by jsr166, Sun May 18 23:47:56 2008 UTC vs.
Revision 1.84 by jsr166, Sat Jan 19 18:11:56 2013 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright 2003-2006 Sun Microsystems, Inc.  All Rights Reserved.
2	>	* Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3		* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5		* This code is free software; you can redistribute it and/or modify it
6		* under the terms of the GNU General Public License version 2 only, as
7	<	* published by the Free Software Foundation.  Sun designates this
7	>	* published by the Free Software Foundation.  Oracle designates this
8		* particular file as subject to the "Classpath" exception as provided
9	<	* by Sun in the LICENSE file that accompanied this code.
9	>	* by Oracle in the LICENSE file that accompanied this code.
10		*
11		* This code is distributed in the hope that it will be useful, but WITHOUT
12		* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
#	Line 18 | Line 18
18		* 2 along with this work; if not, write to the Free Software Foundation,
19		* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20		*
21	<	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22	<	* CA 95054 USA or visit www.sun.com if you need additional information or
23	<	* have any questions.
21	>	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22	>	* or visit www.oracle.com if you need additional information or have any
23	>	* questions.
24		*/
25
26		package java.util;
27	+	import java.util.stream.Stream;
28	+	import java.util.Spliterator;
29	+	import java.util.stream.Streams;
30	+	import java.util.function.Block;
31
32		/**
33		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
#	Line 56 | Line 60 | package java.util;
60		* the priority queue in any particular order. If you need ordered
61		* traversal, consider using {@code Arrays.sort(pq.toArray())}.
62		*
63	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
63	>	* <p><strong>Note that this implementation is not synchronized.</strong>
64		* Multiple threads should not access a {@code PriorityQueue}
65		* instance concurrently if any of the threads modifies the queue.
66		* Instead, use the thread-safe {@link
#	Line 74 | Line 78 | package java.util;
78		* Java Collections Framework</a>.
79		*
80		* @since 1.5
77	–	* @version %I%, %G%
81		* @author Josh Bloch, Doug Lea
82		* @param <E> the type of elements held in this collection
83		*/
#	Line 93 | Line 96 | public class PriorityQueue<E> extends Ab
96		* heap and each descendant d of n, n <= d.  The element with the
97		* lowest value is in queue[0], assuming the queue is nonempty.
98		*/
99	<	private transient Object[] queue;
99	>	transient Object[] queue; // non-private to simplify nested class access
100
101		/**
102		* The number of elements in the priority queue.
#	Line 110 | Line 113 | public class PriorityQueue<E> extends Ab
113		* The number of times this priority queue has been
114		* <i>structurally modified</i>.  See AbstractList for gory details.
115		*/
116	<	private transient int modCount = 0;
116	>	transient int modCount = 0; // non-private to simplify nested class access
117
118		/**
119		* Creates a {@code PriorityQueue} with the default initial
#	Line 171 | Line 174 | public class PriorityQueue<E> extends Ab
174		* @throws NullPointerException if the specified collection or any
175		*         of its elements are null
176		*/
177	+	@SuppressWarnings("unchecked")
178		public PriorityQueue(Collection<? extends E> c) {
179	<	initFromCollection(c);
180	<	if (c instanceof SortedSet)
181	<	comparator = (Comparator<? super E>)
182	<	((SortedSet<? extends E>)c).comparator();
183	<	else if (c instanceof PriorityQueue)
184	<	comparator = (Comparator<? super E>)
185	<	((PriorityQueue<? extends E>)c).comparator();
179	>	if (c instanceof SortedSet<?>) {
180	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
181	>	this.comparator = (Comparator<? super E>) ss.comparator();
182	>	initElementsFromCollection(ss);
183	>	}
184	>	else if (c instanceof PriorityQueue<?>) {
185	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
186	>	this.comparator = (Comparator<? super E>) pq.comparator();
187	>	initFromPriorityQueue(pq);
188	>	}
189		else {
190	<	comparator = null;
191	<	heapify();
190	>	this.comparator = null;
191	>	initFromCollection(c);
192		}
193		}
194
#	Line 199 | Line 206 | public class PriorityQueue<E> extends Ab
206		* @throws NullPointerException if the specified priority queue or any
207		*         of its elements are null
208		*/
209	+	@SuppressWarnings("unchecked")
210		public PriorityQueue(PriorityQueue<? extends E> c) {
211	<	comparator = (Comparator<? super E>)c.comparator();
212	<	initFromCollection(c);
211	>	this.comparator = (Comparator<? super E>) c.comparator();
212	>	initFromPriorityQueue(c);
213		}
214
215		/**
#	Line 217 | Line 225 | public class PriorityQueue<E> extends Ab
225		* @throws NullPointerException if the specified sorted set or any
226		*         of its elements are null
227		*/
228	+	@SuppressWarnings("unchecked")
229		public PriorityQueue(SortedSet<? extends E> c) {
230	<	comparator = (Comparator<? super E>)c.comparator();
231	<	initFromCollection(c);
230	>	this.comparator = (Comparator<? super E>) c.comparator();
231	>	initElementsFromCollection(c);
232	>	}
233	>
234	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
235	>	if (c.getClass() == PriorityQueue.class) {
236	>	this.queue = c.toArray();
237	>	this.size = c.size();
238	>	} else {
239	>	initFromCollection(c);
240	>	}
241	>	}
242	>
243	>	private void initElementsFromCollection(Collection<? extends E> c) {
244	>	Object[] a = c.toArray();
245	>	// If c.toArray incorrectly doesn't return Object[], copy it.
246	>	if (a.getClass() != Object[].class)
247	>	a = Arrays.copyOf(a, a.length, Object[].class);
248	>	int len = a.length;
249	>	if (len == 1 || this.comparator != null)
250	>	for (int i = 0; i < len; i++)
251	>	if (a[i] == null)
252	>	throw new NullPointerException();
253	>	this.queue = a;
254	>	this.size = a.length;
255		}
256
257		/**
#	Line 228 | Line 260 | public class PriorityQueue<E> extends Ab
260		* @param c the collection
261		*/
262		private void initFromCollection(Collection<? extends E> c) {
263	<	Object[] a = c.toArray();
264	<	// If c.toArray incorrectly doesn't return Object[], copy it.
233	<	if (a.getClass() != Object[].class)
234	<	a = Arrays.copyOf(a, a.length, Object[].class);
235	<	queue = a;
236	<	size = a.length;
263	>	initElementsFromCollection(c);
264	>	heapify();
265		}
266
267		/**
268	+	* The maximum size of array to allocate.
269	+	* Some VMs reserve some header words in an array.
270	+	* Attempts to allocate larger arrays may result in
271	+	* OutOfMemoryError: Requested array size exceeds VM limit
272	+	*/
273	+	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
274	+
275	+	/**
276		* Increases the capacity of the array.
277		*
278		* @param minCapacity the desired minimum capacity
279		*/
280		private void grow(int minCapacity) {
245	–	if (minCapacity < 0) // overflow
246	–	throw new OutOfMemoryError();
281		int oldCapacity = queue.length;
282		// Double size if small; else grow by 50%
283	<	int newCapacity = ((oldCapacity < 64)?
284	<	((oldCapacity + 1) * 2):
285	<	((oldCapacity / 2) * 3));
286	<	if (newCapacity < 0) // overflow
287	<	newCapacity = Integer.MAX_VALUE;
288	<	if (newCapacity < minCapacity)
255	<	newCapacity = minCapacity;
283	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
284	>	(oldCapacity + 2) :
285	>	(oldCapacity >> 1));
286	>	// overflow-conscious code
287	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
288	>	newCapacity = hugeCapacity(minCapacity);
289		queue = Arrays.copyOf(queue, newCapacity);
290		}
291
292	+	private static int hugeCapacity(int minCapacity) {
293	+	if (minCapacity < 0) // overflow
294	+	throw new OutOfMemoryError();
295	+	return (minCapacity > MAX_ARRAY_SIZE) ?
296	+	Integer.MAX_VALUE :
297	+	MAX_ARRAY_SIZE;
298	+	}
299	+
300		/**
301		* Inserts the specified element into this priority queue.
302		*
#	Line 293 | Line 334 | public class PriorityQueue<E> extends Ab
334		return true;
335		}
336
337	+	@SuppressWarnings("unchecked")
338		public E peek() {
339	<	if (size == 0)
298	<	return null;
299	<	return (E) queue[0];
339	>	return (size == 0) ? null : (E) queue[0];
340		}
341
342		private int indexOf(Object o) {
#	Line 393 | Line 433 | public class PriorityQueue<E> extends Ab
433		* precise control over the runtime type of the output array, and may,
434		* under certain circumstances, be used to save allocation costs.
435		*
436	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
436	>	* <p>Suppose {@code x} is a queue known to contain only strings.
437		* The following code can be used to dump the queue into a newly
438	<	* allocated array of <tt>String</tt>:
438	>	* allocated array of {@code String}:
439		*
440	<	* <pre>
401	<	*     String[] y = x.toArray(new String[0]);</pre>
440	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
441		*
442	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
443	<	* <tt>toArray()</tt>.
442	>	* Note that {@code toArray(new Object[0])} is identical in function to
443	>	* {@code toArray()}.
444		*
445		* @param a the array into which the elements of the queue are to
446		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 412 | Line 451 | public class PriorityQueue<E> extends Ab
451		*         this queue
452		* @throws NullPointerException if the specified array is null
453		*/
454	+	@SuppressWarnings("unchecked")
455		public <T> T[] toArray(T[] a) {
456		if (a.length < size)
457		// Make a new array of a's runtime type, but my contents:
#	Line 477 | Line 517 | public class PriorityQueue<E> extends Ab
517		(forgetMeNot != null && !forgetMeNot.isEmpty());
518		}
519
520	+	@SuppressWarnings("unchecked")
521		public E next() {
522		if (expectedModCount != modCount)
523		throw new ConcurrentModificationException();
#	Line 529 | Line 570 | public class PriorityQueue<E> extends Ab
570		size = 0;
571		}
572
573	+	@SuppressWarnings("unchecked")
574		public E poll() {
575		if (size == 0)
576		return null;
#	Line 554 | Line 596 | public class PriorityQueue<E> extends Ab
596		* position before i. This fact is used by iterator.remove so as to
597		* avoid missing traversing elements.
598		*/
599	+	@SuppressWarnings("unchecked")
600		private E removeAt(int i) {
601	<	assert i >= 0 && i < size;
601	>	// assert i >= 0 && i < size;
602		modCount++;
603		int s = --size;
604		if (s == i) // removed last element
#	Line 592 | Line 635 | public class PriorityQueue<E> extends Ab
635		siftUpComparable(k, x);
636		}
637
638	+	@SuppressWarnings("unchecked")
639		private void siftUpComparable(int k, E x) {
640		Comparable<? super E> key = (Comparable<? super E>) x;
641		while (k > 0) {
#	Line 605 | Line 649 | public class PriorityQueue<E> extends Ab
649		queue[k] = key;
650		}
651
652	+	@SuppressWarnings("unchecked")
653		private void siftUpUsingComparator(int k, E x) {
654		while (k > 0) {
655		int parent = (k - 1) >>> 1;
#	Line 632 | Line 677 | public class PriorityQueue<E> extends Ab
677		siftDownComparable(k, x);
678		}
679
680	+	@SuppressWarnings("unchecked")
681		private void siftDownComparable(int k, E x) {
682		Comparable<? super E> key = (Comparable<? super E>)x;
683		int half = size >>> 1;        // loop while a non-leaf
#	Line 650 | Line 696 | public class PriorityQueue<E> extends Ab
696		queue[k] = key;
697		}
698
699	+	@SuppressWarnings("unchecked")
700		private void siftDownUsingComparator(int k, E x) {
701		int half = size >>> 1;
702		while (k < half) {
#	Line 671 | Line 718 | public class PriorityQueue<E> extends Ab
718		* Establishes the heap invariant (described above) in the entire tree,
719		* assuming nothing about the order of the elements prior to the call.
720		*/
721	+	@SuppressWarnings("unchecked")
722		private void heapify() {
723		for (int i = (size >>> 1) - 1; i >= 0; i--)
724		siftDown(i, (E) queue[i]);
#	Line 690 | Line 738 | public class PriorityQueue<E> extends Ab
738		}
739
740		/**
741	<	* Saves the state of the instance to a stream (that
694	<	* is, serializes it).
741	>	* Saves this queue to a stream (that is, serializes it).
742		*
743		* @serialData The length of the array backing the instance is
744		*             emitted (int), followed by all of its elements
#	Line 699 | Line 746 | public class PriorityQueue<E> extends Ab
746		* @param s the stream
747		*/
748		private void writeObject(java.io.ObjectOutputStream s)
749	<	throws java.io.IOException{
749	>	throws java.io.IOException {
750		// Write out element count, and any hidden stuff
751		s.defaultWriteObject();
752
#	Line 735 | Line 782 | public class PriorityQueue<E> extends Ab
782		// spec has never explained what that might be.
783		heapify();
784		}
785	+
786	+	// wrapping constructor in method avoids transient javac problems
787	+	final PriorityQueueSpliterator<E> spliterator(int origin, int fence,
788	+	int expectedModCount) {
789	+	return new PriorityQueueSpliterator<E>(this, origin, fence,
790	+	expectedModCount);
791	+	}
792	+
793	+	public Stream<E> stream() {
794	+	int flags = Streams.STREAM_IS_SIZED;
795	+	return Streams.stream
796	+	(() -> spliterator(0, size, modCount), flags);
797	+	}
798	+	public Stream<E> parallelStream() {
799	+	int flags = Streams.STREAM_IS_SIZED;
800	+	return Streams.parallelStream
801	+	(() -> spliterator(0, size, modCount), flags);
802	+	}
803	+
804	+	/** Index-based split-by-two Spliterator */
805	+	static final class PriorityQueueSpliterator<E>
806	+	implements Spliterator<E>, Iterator<E> {
807	+	private final PriorityQueue<E> pq;
808	+	private int index;           // current index, modified on advance/split
809	+	private final int fence;     // one past last index
810	+	private final int expectedModCount; // for comodification checks
811	+
812	+	/** Create new spliterator covering the given  range */
813	+	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
814	+	int expectedModCount) {
815	+	this.pq = pq; this.index = origin; this.fence = fence;
816	+	this.expectedModCount = expectedModCount;
817	+	}
818	+
819	+	public PriorityQueueSpliterator<E> trySplit() {
820	+	int lo = index, mid = (lo + fence) >>> 1;
821	+	return (lo >= mid) ? null :
822	+	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
823	+	expectedModCount);
824	+	}
825	+
826	+	public void forEach(Block<? super E> block) {
827	+	Object[] a; int i, hi; // hoist accesses and checks from loop
828	+	if (block == null)
829	+	throw new NullPointerException();
830	+	if ((a = pq.queue).length >= (hi = fence) &&
831	+	(i = index) >= 0 && i < hi) {
832	+	index = hi;
833	+	do {
834	+	@SuppressWarnings("unchecked") E e = (E) a[i];
835	+	block.accept(e);
836	+	} while (++i < hi);
837	+	if (pq.modCount != expectedModCount)
838	+	throw new ConcurrentModificationException();
839	+	}
840	+	}
841	+
842	+	public boolean tryAdvance(Block<? super E> block) {
843	+	if (index >= 0 && index < fence) {
844	+	if (pq.modCount != expectedModCount)
845	+	throw new ConcurrentModificationException();
846	+	@SuppressWarnings("unchecked") E e =
847	+	(E)pq.queue[index++];
848	+	block.accept(e);
849	+	return true;
850	+	}
851	+	return false;
852	+	}
853	+
854	+	public long estimateSize() { return (long)(fence - index); }
855	+	public boolean hasExactSize() { return true; }
856	+	public boolean hasExactSplits() { return true; }
857	+
858	+	// Iterator support
859	+	public Iterator<E> iterator() { return this; }
860	+	public void remove() { throw new UnsupportedOperationException(); }
861	+	public boolean hasNext() { return index >= 0 && index < fence; }
862	+
863	+	public E next() {
864	+	if (index < 0 || index >= fence)
865	+	throw new NoSuchElementException();
866	+	if (pq.modCount != expectedModCount)
867	+	throw new ConcurrentModificationException();
868	+	@SuppressWarnings("unchecked") E e =
869	+	(E) pq.queue[index++];
870	+	return e;
871	+	}
872	+	}
873		}

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