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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.73 by jsr166, Tue Jun 21 19:29:21 2011 UTC vs.
Revision 1.120 by jsr166, Sun Oct 22 17:44:03 2017 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
2	>	* Copyright (c) 2003, 2017, 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 25 | Line 25
25
26		package java.util;
27
28	+	import java.util.function.Consumer;
29	+	import jdk.internal.misc.SharedSecrets;
30	+
31		/**
32		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
33		* The elements of the priority queue are ordered according to their
#	Line 52 | Line 55 | package java.util;
55		* <p>This class and its iterator implement all of the
56		* <em>optional</em> methods of the {@link Collection} and {@link
57		* Iterator} interfaces.  The Iterator provided in method {@link
58	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
58	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
59	>	* are <em>not</em> guaranteed to traverse the elements of
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
67		* java.util.concurrent.PriorityBlockingQueue} class.
68		*
69		* <p>Implementation note: this implementation provides
70	<	* O(log(n)) time for the enqueing and dequeing methods
70	>	* O(log(n)) time for the enqueuing and dequeuing methods
71		* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
72		* linear time for the {@code remove(Object)} and {@code contains(Object)}
73		* methods; and constant time for the retrieval methods
74		* ({@code peek}, {@code element}, and {@code size}).
75		*
76		* <p>This class is a member of the
77	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
77	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
78		* Java Collections Framework</a>.
79		*
80		* @since 1.5
81		* @author Josh Bloch, Doug Lea
82	<	* @param <E> the type of elements held in this collection
82	>	* @param <E> the type of elements held in this queue
83		*/
84		public class PriorityQueue<E> extends AbstractQueue<E>
85		implements java.io.Serializable {
#	Line 92 | 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.
103		*/
104	<	private int size = 0;
104	>	int size;
105
106		/**
107		* The comparator, or null if priority queue uses elements'
#	Line 109 | 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;     // non-private to simplify nested class access
117
118		/**
119		* Creates a {@code PriorityQueue} with the default initial
#	Line 134 | Line 138 | public class PriorityQueue<E> extends Ab
138		}
139
140		/**
141	+	* Creates a {@code PriorityQueue} with the default initial capacity and
142	+	* whose elements are ordered according to the specified comparator.
143	+	*
144	+	* @param  comparator the comparator that will be used to order this
145	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
146	+	*         natural ordering} of the elements will be used.
147	+	* @since 1.8
148	+	*/
149	+	public PriorityQueue(Comparator<? super E> comparator) {
150	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
151	+	}
152	+
153	+	/**
154		* Creates a {@code PriorityQueue} with the specified initial capacity
155		* that orders its elements according to the specified comparator.
156		*
#	Line 243 | Line 260 | public class PriorityQueue<E> extends Ab
260		a = Arrays.copyOf(a, a.length, Object[].class);
261		int len = a.length;
262		if (len == 1 || this.comparator != null)
263	<	for (int i = 0; i < len; i++)
264	<	if (a[i] == null)
263	>	for (Object e : a)
264	>	if (e == null)
265		throw new NullPointerException();
266		this.queue = a;
267		this.size = a.length;
#	Line 322 | Line 339 | public class PriorityQueue<E> extends Ab
339		int i = size;
340		if (i >= queue.length)
341		grow(i + 1);
342	+	siftUp(i, e);
343		size = i + 1;
326	–	if (i == 0)
327	–	queue[0] = e;
328	–	else
329	–	siftUp(i, e);
344		return true;
345		}
346
347	+	@SuppressWarnings("unchecked")
348		public E peek() {
349		return (size == 0) ? null : (E) queue[0];
350		}
#	Line 390 | Line 405 | public class PriorityQueue<E> extends Ab
405		* @return {@code true} if this queue contains the specified element
406		*/
407		public boolean contains(Object o) {
408	<	return indexOf(o) != -1;
408	>	return indexOf(o) >= 0;
409		}
410
411		/**
#	Line 428 | Line 443 | public class PriorityQueue<E> extends Ab
443		* precise control over the runtime type of the output array, and may,
444		* under certain circumstances, be used to save allocation costs.
445		*
446	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
446	>	* <p>Suppose {@code x} is a queue known to contain only strings.
447		* The following code can be used to dump the queue into a newly
448	<	* allocated array of <tt>String</tt>:
448	>	* allocated array of {@code String}:
449		*
450	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
450	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
451		*
452	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
453	<	* <tt>toArray()</tt>.
452	>	* Note that {@code toArray(new Object[0])} is identical in function to
453	>	* {@code toArray()}.
454		*
455		* @param a the array into which the elements of the queue are to
456		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 446 | Line 461 | public class PriorityQueue<E> extends Ab
461		*         this queue
462		* @throws NullPointerException if the specified array is null
463		*/
464	+	@SuppressWarnings("unchecked")
465		public <T> T[] toArray(T[] a) {
466	+	final int size = this.size;
467		if (a.length < size)
468		// Make a new array of a's runtime type, but my contents:
469		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 471 | Line 488 | public class PriorityQueue<E> extends Ab
488		* Index (into queue array) of element to be returned by
489		* subsequent call to next.
490		*/
491	<	private int cursor = 0;
491	>	private int cursor;
492
493		/**
494		* Index of element returned by most recent call to next,
#	Line 491 | Line 508 | public class PriorityQueue<E> extends Ab
508		* We expect that most iterations, even those involving removals,
509		* will not need to store elements in this field.
510		*/
511	<	private ArrayDeque<E> forgetMeNot = null;
511	>	private ArrayDeque<E> forgetMeNot;
512
513		/**
514		* Element returned by the most recent call to next iff that
515		* element was drawn from the forgetMeNot list.
516		*/
517	<	private E lastRetElt = null;
517	>	private E lastRetElt;
518
519		/**
520		* The modCount value that the iterator believes that the backing
#	Line 506 | Line 523 | public class PriorityQueue<E> extends Ab
523		*/
524		private int expectedModCount = modCount;
525
526	+	Itr() {}                        // prevent access constructor creation
527	+
528		public boolean hasNext() {
529		return cursor < size ||
530		(forgetMeNot != null && !forgetMeNot.isEmpty());
531		}
532
533	+	@SuppressWarnings("unchecked")
534		public E next() {
535		if (expectedModCount != modCount)
536		throw new ConcurrentModificationException();
#	Line 535 | Line 555 | public class PriorityQueue<E> extends Ab
555		cursor--;
556		else {
557		if (forgetMeNot == null)
558	<	forgetMeNot = new ArrayDeque<E>();
558	>	forgetMeNot = new ArrayDeque<>();
559		forgetMeNot.add(moved);
560		}
561		} else if (lastRetElt != null) {
#	Line 563 | Line 583 | public class PriorityQueue<E> extends Ab
583		size = 0;
584		}
585
586	+	@SuppressWarnings("unchecked")
587		public E poll() {
588		if (size == 0)
589		return null;
#	Line 588 | Line 609 | public class PriorityQueue<E> extends Ab
609		* position before i. This fact is used by iterator.remove so as to
610		* avoid missing traversing elements.
611		*/
612	<	private E removeAt(int i) {
613	<	assert i >= 0 && i < size;
612	>	@SuppressWarnings("unchecked")
613	>	E removeAt(int i) {
614	>	// assert i >= 0 && i < size;
615		modCount++;
616		int s = --size;
617		if (s == i) // removed last element
#	Line 612 | Line 634 | public class PriorityQueue<E> extends Ab
634		* promoting x up the tree until it is greater than or equal to
635		* its parent, or is the root.
636		*
637	<	* To simplify and speed up coercions and comparisons. the
637	>	* To simplify and speed up coercions and comparisons, the
638		* Comparable and Comparator versions are separated into different
639		* methods that are otherwise identical. (Similarly for siftDown.)
640		*
#	Line 626 | Line 648 | public class PriorityQueue<E> extends Ab
648		siftUpComparable(k, x);
649		}
650
651	+	@SuppressWarnings("unchecked")
652		private void siftUpComparable(int k, E x) {
653		Comparable<? super E> key = (Comparable<? super E>) x;
654		while (k > 0) {
#	Line 639 | Line 662 | public class PriorityQueue<E> extends Ab
662		queue[k] = key;
663		}
664
665	+	@SuppressWarnings("unchecked")
666		private void siftUpUsingComparator(int k, E x) {
667		while (k > 0) {
668		int parent = (k - 1) >>> 1;
#	Line 666 | Line 690 | public class PriorityQueue<E> extends Ab
690		siftDownComparable(k, x);
691		}
692
693	+	@SuppressWarnings("unchecked")
694		private void siftDownComparable(int k, E x) {
695		Comparable<? super E> key = (Comparable<? super E>)x;
696		int half = size >>> 1;        // loop while a non-leaf
#	Line 684 | Line 709 | public class PriorityQueue<E> extends Ab
709		queue[k] = key;
710		}
711
712	+	@SuppressWarnings("unchecked")
713		private void siftDownUsingComparator(int k, E x) {
714		int half = size >>> 1;
715		while (k < half) {
#	Line 704 | Line 730 | public class PriorityQueue<E> extends Ab
730		/**
731		* Establishes the heap invariant (described above) in the entire tree,
732		* assuming nothing about the order of the elements prior to the call.
733	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
734		*/
735	+	@SuppressWarnings("unchecked")
736		private void heapify() {
737	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
738	<	siftDown(i, (E) queue[i]);
737	>	final Object[] es = queue;
738	>	int i = (size >>> 1) - 1;
739	>	if (comparator == null)
740	>	for (; i >= 0; i--)
741	>	siftDownComparable(i, (E) es[i]);
742	>	else
743	>	for (; i >= 0; i--)
744	>	siftDownUsingComparator(i, (E) es[i]);
745		}
746
747		/**
#	Line 724 | Line 758 | public class PriorityQueue<E> extends Ab
758		}
759
760		/**
761	<	* Saves the state of the instance to a stream (that
728	<	* is, serializes it).
761	>	* Saves this queue to a stream (that is, serializes it).
762		*
763	+	* @param s the stream
764	+	* @throws java.io.IOException if an I/O error occurs
765		* @serialData The length of the array backing the instance is
766		*             emitted (int), followed by all of its elements
767		*             (each an {@code Object}) in the proper order.
733	–	* @param s the stream
768		*/
769		private void writeObject(java.io.ObjectOutputStream s)
770	<	throws java.io.IOException{
770	>	throws java.io.IOException {
771		// Write out element count, and any hidden stuff
772		s.defaultWriteObject();
773
#	Line 750 | Line 784 | public class PriorityQueue<E> extends Ab
784		* (that is, deserializes it).
785		*
786		* @param s the stream
787	+	* @throws ClassNotFoundException if the class of a serialized object
788	+	*         could not be found
789	+	* @throws java.io.IOException if an I/O error occurs
790		*/
791		private void readObject(java.io.ObjectInputStream s)
792		throws java.io.IOException, ClassNotFoundException {
#	Line 759 | Line 796 | public class PriorityQueue<E> extends Ab
796		// Read in (and discard) array length
797		s.readInt();
798
799	+	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
800		queue = new Object[size];
801
802		// Read in all elements.
#	Line 769 | Line 807 | public class PriorityQueue<E> extends Ab
807		// spec has never explained what that might be.
808		heapify();
809		}
810	+
811	+	/**
812	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
813	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
814	+	* queue. The spliterator does not traverse elements in any particular order
815	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
816	+	*
817	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
818	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
819	+	* Overriding implementations should document the reporting of additional
820	+	* characteristic values.
821	+	*
822	+	* @return a {@code Spliterator} over the elements in this queue
823	+	* @since 1.8
824	+	*/
825	+	public final Spliterator<E> spliterator() {
826	+	return new PriorityQueueSpliterator(0, -1, 0);
827	+	}
828	+
829	+	final class PriorityQueueSpliterator implements Spliterator<E> {
830	+	private int index;            // current index, modified on advance/split
831	+	private int fence;            // -1 until first use
832	+	private int expectedModCount; // initialized when fence set
833	+
834	+	/** Creates new spliterator covering the given range. */
835	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
836	+	this.index = origin;
837	+	this.fence = fence;
838	+	this.expectedModCount = expectedModCount;
839	+	}
840	+
841	+	private int getFence() { // initialize fence to size on first use
842	+	int hi;
843	+	if ((hi = fence) < 0) {
844	+	expectedModCount = modCount;
845	+	hi = fence = size;
846	+	}
847	+	return hi;
848	+	}
849	+
850	+	public PriorityQueueSpliterator trySplit() {
851	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
852	+	return (lo >= mid) ? null :
853	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
854	+	}
855	+
856	+	@SuppressWarnings("unchecked")
857	+	public void forEachRemaining(Consumer<? super E> action) {
858	+	if (action == null)
859	+	throw new NullPointerException();
860	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
861	+	final Object[] a = queue;
862	+	int i, hi; E e;
863	+	for (i = index, index = hi = fence; i < hi; i++) {
864	+	if ((e = (E) a[i]) == null)
865	+	break;      // must be CME
866	+	action.accept(e);
867	+	}
868	+	if (modCount != expectedModCount)
869	+	throw new ConcurrentModificationException();
870	+	}
871	+
872	+	@SuppressWarnings("unchecked")
873	+	public boolean tryAdvance(Consumer<? super E> action) {
874	+	if (action == null)
875	+	throw new NullPointerException();
876	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
877	+	int i;
878	+	if ((i = index) < fence) {
879	+	index = i + 1;
880	+	E e;
881	+	if ((e = (E) queue[i]) == null
882	+	|| modCount != expectedModCount)
883	+	throw new ConcurrentModificationException();
884	+	action.accept(e);
885	+	return true;
886	+	}
887	+	return false;
888	+	}
889	+
890	+	public long estimateSize() {
891	+	return getFence() - index;
892	+	}
893	+
894	+	public int characteristics() {
895	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
896	+	}
897	+	}
898		}

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