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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.70 by jsr166, Mon May 10 20:11:01 2010 UTC vs.
Revision 1.118 by jsr166, Thu Dec 29 23:14:34 2016 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright 2003-2006 Sun Microsystems, Inc.  All Rights Reserved.
2	>	* Copyright (c) 2003, 2013, 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
28	+	import java.util.function.Consumer;
29	+
30		/**
31		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
32		* The elements of the priority queue are ordered according to their
#	Line 52 | Line 54 | package java.util;
54		* <p>This class and its iterator implement all of the
55		* <em>optional</em> methods of the {@link Collection} and {@link
56		* Iterator} interfaces.  The Iterator provided in method {@link
57	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
57	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
58	>	* are <em>not</em> guaranteed to traverse the elements of
59		* the priority queue in any particular order. If you need ordered
60		* traversal, consider using {@code Arrays.sort(pq.toArray())}.
61		*
62	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
62	>	* <p><strong>Note that this implementation is not synchronized.</strong>
63		* Multiple threads should not access a {@code PriorityQueue}
64		* instance concurrently if any of the threads modifies the queue.
65		* Instead, use the thread-safe {@link
66		* java.util.concurrent.PriorityBlockingQueue} class.
67		*
68		* <p>Implementation note: this implementation provides
69	<	* O(log(n)) time for the enqueing and dequeing methods
69	>	* O(log(n)) time for the enqueuing and dequeuing methods
70		* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
71		* linear time for the {@code remove(Object)} and {@code contains(Object)}
72		* methods; and constant time for the retrieval methods
#	Line 75 | Line 78 | package java.util;
78		*
79		* @since 1.5
80		* @author Josh Bloch, Doug Lea
81	<	* @param <E> the type of elements held in this collection
81	>	* @param <E> the type of elements held in this queue
82		*/
83		public class PriorityQueue<E> extends AbstractQueue<E>
84		implements java.io.Serializable {
#	Line 92 | Line 95 | public class PriorityQueue<E> extends Ab
95		* heap and each descendant d of n, n <= d.  The element with the
96		* lowest value is in queue[0], assuming the queue is nonempty.
97		*/
98	<	private transient Object[] queue;
98	>	transient Object[] queue; // non-private to simplify nested class access
99
100		/**
101		* The number of elements in the priority queue.
102		*/
103	<	private int size = 0;
103	>	int size;
104
105		/**
106		* The comparator, or null if priority queue uses elements'
#	Line 109 | Line 112 | public class PriorityQueue<E> extends Ab
112		* The number of times this priority queue has been
113		* <i>structurally modified</i>.  See AbstractList for gory details.
114		*/
115	<	private transient int modCount = 0;
115	>	transient int modCount;     // non-private to simplify nested class access
116
117		/**
118		* Creates a {@code PriorityQueue} with the default initial
#	Line 134 | Line 137 | public class PriorityQueue<E> extends Ab
137		}
138
139		/**
140	+	* Creates a {@code PriorityQueue} with the default initial capacity and
141	+	* whose elements are ordered according to the specified comparator.
142	+	*
143	+	* @param  comparator the comparator that will be used to order this
144	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
145	+	*         natural ordering} of the elements will be used.
146	+	* @since 1.8
147	+	*/
148	+	public PriorityQueue(Comparator<? super E> comparator) {
149	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
150	+	}
151	+
152	+	/**
153		* Creates a {@code PriorityQueue} with the specified initial capacity
154		* that orders its elements according to the specified comparator.
155		*
#	Line 243 | Line 259 | public class PriorityQueue<E> extends Ab
259		a = Arrays.copyOf(a, a.length, Object[].class);
260		int len = a.length;
261		if (len == 1 || this.comparator != null)
262	<	for (int i = 0; i < len; i++)
263	<	if (a[i] == null)
262	>	for (Object e : a)
263	>	if (e == null)
264		throw new NullPointerException();
265		this.queue = a;
266		this.size = a.length;
#	Line 322 | Line 338 | public class PriorityQueue<E> extends Ab
338		int i = size;
339		if (i >= queue.length)
340		grow(i + 1);
341	+	siftUp(i, e);
342		size = i + 1;
326	–	if (i == 0)
327	–	queue[0] = e;
328	–	else
329	–	siftUp(i, e);
343		return true;
344		}
345
346	+	@SuppressWarnings("unchecked")
347		public E peek() {
348	<	if (size == 0)
335	<	return null;
336	<	return (E) queue[0];
348	>	return (size == 0) ? null : (E) queue[0];
349		}
350
351		private int indexOf(Object o) {
#	Line 392 | Line 404 | public class PriorityQueue<E> extends Ab
404		* @return {@code true} if this queue contains the specified element
405		*/
406		public boolean contains(Object o) {
407	<	return indexOf(o) != -1;
407	>	return indexOf(o) >= 0;
408		}
409
410		/**
#	Line 430 | Line 442 | public class PriorityQueue<E> extends Ab
442		* precise control over the runtime type of the output array, and may,
443		* under certain circumstances, be used to save allocation costs.
444		*
445	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
445	>	* <p>Suppose {@code x} is a queue known to contain only strings.
446		* The following code can be used to dump the queue into a newly
447	<	* allocated array of <tt>String</tt>:
447	>	* allocated array of {@code String}:
448		*
449	<	* <pre>
438	<	*     String[] y = x.toArray(new String[0]);</pre>
449	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
450		*
451	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
452	<	* <tt>toArray()</tt>.
451	>	* Note that {@code toArray(new Object[0])} is identical in function to
452	>	* {@code toArray()}.
453		*
454		* @param a the array into which the elements of the queue are to
455		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 449 | Line 460 | public class PriorityQueue<E> extends Ab
460		*         this queue
461		* @throws NullPointerException if the specified array is null
462		*/
463	+	@SuppressWarnings("unchecked")
464		public <T> T[] toArray(T[] a) {
465	+	final int size = this.size;
466		if (a.length < size)
467		// Make a new array of a's runtime type, but my contents:
468		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 474 | Line 487 | public class PriorityQueue<E> extends Ab
487		* Index (into queue array) of element to be returned by
488		* subsequent call to next.
489		*/
490	<	private int cursor = 0;
490	>	private int cursor;
491
492		/**
493		* Index of element returned by most recent call to next,
#	Line 494 | Line 507 | public class PriorityQueue<E> extends Ab
507		* We expect that most iterations, even those involving removals,
508		* will not need to store elements in this field.
509		*/
510	<	private ArrayDeque<E> forgetMeNot = null;
510	>	private ArrayDeque<E> forgetMeNot;
511
512		/**
513		* Element returned by the most recent call to next iff that
514		* element was drawn from the forgetMeNot list.
515		*/
516	<	private E lastRetElt = null;
516	>	private E lastRetElt;
517
518		/**
519		* The modCount value that the iterator believes that the backing
#	Line 509 | Line 522 | public class PriorityQueue<E> extends Ab
522		*/
523		private int expectedModCount = modCount;
524
525	+	Itr() {}                        // prevent access constructor creation
526	+
527		public boolean hasNext() {
528		return cursor < size ||
529		(forgetMeNot != null && !forgetMeNot.isEmpty());
530		}
531
532	+	@SuppressWarnings("unchecked")
533		public E next() {
534		if (expectedModCount != modCount)
535		throw new ConcurrentModificationException();
#	Line 538 | Line 554 | public class PriorityQueue<E> extends Ab
554		cursor--;
555		else {
556		if (forgetMeNot == null)
557	<	forgetMeNot = new ArrayDeque<E>();
557	>	forgetMeNot = new ArrayDeque<>();
558		forgetMeNot.add(moved);
559		}
560		} else if (lastRetElt != null) {
#	Line 566 | Line 582 | public class PriorityQueue<E> extends Ab
582		size = 0;
583		}
584
585	+	@SuppressWarnings("unchecked")
586		public E poll() {
587		if (size == 0)
588		return null;
#	Line 591 | Line 608 | public class PriorityQueue<E> extends Ab
608		* position before i. This fact is used by iterator.remove so as to
609		* avoid missing traversing elements.
610		*/
611	<	private E removeAt(int i) {
612	<	assert i >= 0 && i < size;
611	>	@SuppressWarnings("unchecked")
612	>	E removeAt(int i) {
613	>	// assert i >= 0 && i < size;
614		modCount++;
615		int s = --size;
616		if (s == i) // removed last element
#	Line 615 | Line 633 | public class PriorityQueue<E> extends Ab
633		* promoting x up the tree until it is greater than or equal to
634		* its parent, or is the root.
635		*
636	<	* To simplify and speed up coercions and comparisons. the
636	>	* To simplify and speed up coercions and comparisons, the
637		* Comparable and Comparator versions are separated into different
638		* methods that are otherwise identical. (Similarly for siftDown.)
639		*
#	Line 629 | Line 647 | public class PriorityQueue<E> extends Ab
647		siftUpComparable(k, x);
648		}
649
650	+	@SuppressWarnings("unchecked")
651		private void siftUpComparable(int k, E x) {
652		Comparable<? super E> key = (Comparable<? super E>) x;
653		while (k > 0) {
#	Line 642 | Line 661 | public class PriorityQueue<E> extends Ab
661		queue[k] = key;
662		}
663
664	+	@SuppressWarnings("unchecked")
665		private void siftUpUsingComparator(int k, E x) {
666		while (k > 0) {
667		int parent = (k - 1) >>> 1;
#	Line 669 | Line 689 | public class PriorityQueue<E> extends Ab
689		siftDownComparable(k, x);
690		}
691
692	+	@SuppressWarnings("unchecked")
693		private void siftDownComparable(int k, E x) {
694		Comparable<? super E> key = (Comparable<? super E>)x;
695		int half = size >>> 1;        // loop while a non-leaf
#	Line 687 | Line 708 | public class PriorityQueue<E> extends Ab
708		queue[k] = key;
709		}
710
711	+	@SuppressWarnings("unchecked")
712		private void siftDownUsingComparator(int k, E x) {
713		int half = size >>> 1;
714		while (k < half) {
#	Line 707 | Line 729 | public class PriorityQueue<E> extends Ab
729		/**
730		* Establishes the heap invariant (described above) in the entire tree,
731		* assuming nothing about the order of the elements prior to the call.
732	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
733		*/
734	+	@SuppressWarnings("unchecked")
735		private void heapify() {
736	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
737	<	siftDown(i, (E) queue[i]);
736	>	final Object[] es = queue;
737	>	int i = (size >>> 1) - 1;
738	>	if (comparator == null)
739	>	for (; i >= 0; i--)
740	>	siftDownComparable(i, (E) es[i]);
741	>	else
742	>	for (; i >= 0; i--)
743	>	siftDownUsingComparator(i, (E) es[i]);
744		}
745
746		/**
#	Line 727 | Line 757 | public class PriorityQueue<E> extends Ab
757		}
758
759		/**
760	<	* Saves the state of the instance to a stream (that
731	<	* is, serializes it).
760	>	* Saves this queue to a stream (that is, serializes it).
761		*
762	+	* @param s the stream
763	+	* @throws java.io.IOException if an I/O error occurs
764		* @serialData The length of the array backing the instance is
765		*             emitted (int), followed by all of its elements
766		*             (each an {@code Object}) in the proper order.
736	–	* @param s the stream
767		*/
768		private void writeObject(java.io.ObjectOutputStream s)
769	<	throws java.io.IOException{
769	>	throws java.io.IOException {
770		// Write out element count, and any hidden stuff
771		s.defaultWriteObject();
772
#	Line 753 | Line 783 | public class PriorityQueue<E> extends Ab
783		* (that is, deserializes it).
784		*
785		* @param s the stream
786	+	* @throws ClassNotFoundException if the class of a serialized object
787	+	*         could not be found
788	+	* @throws java.io.IOException if an I/O error occurs
789		*/
790		private void readObject(java.io.ObjectInputStream s)
791		throws java.io.IOException, ClassNotFoundException {
#	Line 772 | Line 805 | public class PriorityQueue<E> extends Ab
805		// spec has never explained what that might be.
806		heapify();
807		}
808	+
809	+	/**
810	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
811	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
812	+	* queue. The spliterator does not traverse elements in any particular order
813	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
814	+	*
815	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
816	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
817	+	* Overriding implementations should document the reporting of additional
818	+	* characteristic values.
819	+	*
820	+	* @return a {@code Spliterator} over the elements in this queue
821	+	* @since 1.8
822	+	*/
823	+	public final Spliterator<E> spliterator() {
824	+	return new PriorityQueueSpliterator(0, -1, 0);
825	+	}
826	+
827	+	final class PriorityQueueSpliterator implements Spliterator<E> {
828	+	private int index;            // current index, modified on advance/split
829	+	private int fence;            // -1 until first use
830	+	private int expectedModCount; // initialized when fence set
831	+
832	+	/** Creates new spliterator covering the given range. */
833	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
834	+	this.index = origin;
835	+	this.fence = fence;
836	+	this.expectedModCount = expectedModCount;
837	+	}
838	+
839	+	private int getFence() { // initialize fence to size on first use
840	+	int hi;
841	+	if ((hi = fence) < 0) {
842	+	expectedModCount = modCount;
843	+	hi = fence = size;
844	+	}
845	+	return hi;
846	+	}
847	+
848	+	public PriorityQueueSpliterator trySplit() {
849	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
850	+	return (lo >= mid) ? null :
851	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
852	+	}
853	+
854	+	@SuppressWarnings("unchecked")
855	+	public void forEachRemaining(Consumer<? super E> action) {
856	+	if (action == null)
857	+	throw new NullPointerException();
858	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
859	+	final Object[] a = queue;
860	+	int i, hi; E e;
861	+	for (i = index, index = hi = fence; i < hi; i++) {
862	+	if ((e = (E) a[i]) == null)
863	+	break;      // must be CME
864	+	action.accept(e);
865	+	}
866	+	if (modCount != expectedModCount)
867	+	throw new ConcurrentModificationException();
868	+	}
869	+
870	+	@SuppressWarnings("unchecked")
871	+	public boolean tryAdvance(Consumer<? super E> action) {
872	+	if (action == null)
873	+	throw new NullPointerException();
874	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
875	+	int i;
876	+	if ((i = index) < fence) {
877	+	index = i + 1;
878	+	E e;
879	+	if ((e = (E) queue[i]) == null
880	+	|| modCount != expectedModCount)
881	+	throw new ConcurrentModificationException();
882	+	action.accept(e);
883	+	return true;
884	+	}
885	+	return false;
886	+	}
887	+
888	+	public long estimateSize() {
889	+	return getFence() - index;
890	+	}
891	+
892	+	public int characteristics() {
893	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
894	+	}
895	+	}
896		}

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