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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.78 by jsr166, Sun Nov 18 18:03:10 2012 UTC vs.
Revision 1.123 by jsr166, Sun May 6 16:26:03 2018 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
2	>	* Copyright (c) 2003, 2018, 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		*
#	Line 63 | Line 67 | package java.util;
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		*/
80	–	@SuppressWarnings("unchecked")
84		public class PriorityQueue<E> extends AbstractQueue<E>
85		implements java.io.Serializable {
86
#	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.
103		*/
104	<	private int size = 0;
104	>	int size;
105
106		/**
107		* The comparator, or null if priority queue uses elements'
#	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;     // non-private to simplify nested class access
117
118		/**
119		* Creates a {@code PriorityQueue} with the default initial
#	Line 135 | 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 244 | 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 323 | 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;
327	–	if (i == 0)
328	–	queue[0] = e;
329	–	else
330	–	siftUp(i, e);
344		return true;
345		}
346
347	+	@SuppressWarnings("unchecked")
348		public E peek() {
349		return (size == 0) ? null : (E) queue[0];
350		}
351
352		private int indexOf(Object o) {
353		if (o != null) {
354	<	for (int i = 0; i < size; i++)
355	<	if (o.equals(queue[i]))
354	>	final Object[] es = queue;
355	>	for (int i = 0, n = size; i < n; i++)
356	>	if (o.equals(es[i]))
357		return i;
358		}
359		return -1;
#	Line 366 | Line 381 | public class PriorityQueue<E> extends Ab
381		}
382
383		/**
384	<	* Version of remove using reference equality, not equals.
370	<	* Needed by iterator.remove.
384	>	* Identity-based version for use in Itr.remove.
385		*
386		* @param o element to be removed from this queue, if present
373	–	* @return {@code true} if removed
387		*/
388	<	boolean removeEq(Object o) {
389	<	for (int i = 0; i < size; i++) {
390	<	if (o == queue[i]) {
388	>	void removeEq(Object o) {
389	>	final Object[] es = queue;
390	>	for (int i = 0, n = size; i < n; i++) {
391	>	if (o == es[i]) {
392		removeAt(i);
393	<	return true;
393	>	break;
394		}
395		}
382	–	return false;
396		}
397
398		/**
#	Line 391 | 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 429 | 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> {@code 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 447 | 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 472 | 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 492 | 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 507 | 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 536 | 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 559 | Line 577 | public class PriorityQueue<E> extends Ab
577		*/
578		public void clear() {
579		modCount++;
580	<	for (int i = 0; i < size; i++)
581	<	queue[i] = null;
580	>	final Object[] es = queue;
581	>	for (int i = 0, n = size; i < n; i++)
582	>	es[i] = null;
583		size = 0;
584		}
585
586	+	@SuppressWarnings("unchecked")
587		public E poll() {
588		if (size == 0)
589		return null;
#	Line 589 | 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) {
612	>	@SuppressWarnings("unchecked")
613	>	E removeAt(int i) {
614		// assert i >= 0 && i < size;
615		modCount++;
616		int s = --size;
#	Line 613 | 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 627 | 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 640 | 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 667 | 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 685 | 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 705 | 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 727 | Line 760 | public class PriorityQueue<E> extends Ab
760		/**
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.
#	Line 740 | Line 775 | public class PriorityQueue<E> extends Ab
775		s.writeInt(Math.max(2, size + 1));
776
777		// Write out all elements in the "proper order".
778	<	for (int i = 0; i < size; i++)
779	<	s.writeObject(queue[i]);
778	>	final Object[] es = queue;
779	>	for (int i = 0, n = size; i < n; i++)
780	>	s.writeObject(es[i]);
781		}
782
783		/**
784	<	* Reconstitutes this queue from a stream (that is, deserializes it).
784	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
785	>	* (that is, deserializes it).
786	>	*
787	>	* @param s the stream
788	>	* @throws ClassNotFoundException if the class of a serialized object
789	>	*         could not be found
790	>	* @throws java.io.IOException if an I/O error occurs
791		*/
792		private void readObject(java.io.ObjectInputStream s)
793		throws java.io.IOException, ClassNotFoundException {
#	Line 755 | Line 797 | public class PriorityQueue<E> extends Ab
797		// Read in (and discard) array length
798		s.readInt();
799
800	+	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
801		queue = new Object[size];
802
803		// Read in all elements.
804	<	for (int i = 0; i < size; i++)
805	<	queue[i] = s.readObject();
804	>	final Object[] es = queue;
805	>	for (int i = 0, n = size; i < n; i++)
806	>	es[i] = s.readObject();
807
808		// Elements are guaranteed to be in "proper order", but the
809		// spec has never explained what that might be.
810		heapify();
811		}
812	+
813	+	/**
814	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
815	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
816	+	* queue. The spliterator does not traverse elements in any particular order
817	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
818	+	*
819	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
820	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
821	+	* Overriding implementations should document the reporting of additional
822	+	* characteristic values.
823	+	*
824	+	* @return a {@code Spliterator} over the elements in this queue
825	+	* @since 1.8
826	+	*/
827	+	public final Spliterator<E> spliterator() {
828	+	return new PriorityQueueSpliterator(0, -1, 0);
829	+	}
830	+
831	+	final class PriorityQueueSpliterator implements Spliterator<E> {
832	+	private int index;            // current index, modified on advance/split
833	+	private int fence;            // -1 until first use
834	+	private int expectedModCount; // initialized when fence set
835	+
836	+	/** Creates new spliterator covering the given range. */
837	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
838	+	this.index = origin;
839	+	this.fence = fence;
840	+	this.expectedModCount = expectedModCount;
841	+	}
842	+
843	+	private int getFence() { // initialize fence to size on first use
844	+	int hi;
845	+	if ((hi = fence) < 0) {
846	+	expectedModCount = modCount;
847	+	hi = fence = size;
848	+	}
849	+	return hi;
850	+	}
851	+
852	+	public PriorityQueueSpliterator trySplit() {
853	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
854	+	return (lo >= mid) ? null :
855	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
856	+	}
857	+
858	+	@SuppressWarnings("unchecked")
859	+	public void forEachRemaining(Consumer<? super E> action) {
860	+	if (action == null)
861	+	throw new NullPointerException();
862	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
863	+	final Object[] a = queue;
864	+	int i, hi; E e;
865	+	for (i = index, index = hi = fence; i < hi; i++) {
866	+	if ((e = (E) a[i]) == null)
867	+	break;      // must be CME
868	+	action.accept(e);
869	+	}
870	+	if (modCount != expectedModCount)
871	+	throw new ConcurrentModificationException();
872	+	}
873	+
874	+	@SuppressWarnings("unchecked")
875	+	public boolean tryAdvance(Consumer<? super E> action) {
876	+	if (action == null)
877	+	throw new NullPointerException();
878	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
879	+	int i;
880	+	if ((i = index) < fence) {
881	+	index = i + 1;
882	+	E e;
883	+	if ((e = (E) queue[i]) == null
884	+	|| modCount != expectedModCount)
885	+	throw new ConcurrentModificationException();
886	+	action.accept(e);
887	+	return true;
888	+	}
889	+	return false;
890	+	}
891	+
892	+	public long estimateSize() {
893	+	return getFence() - index;
894	+	}
895	+
896	+	public int characteristics() {
897	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
898	+	}
899	+	}
900	+
901	+	/**
902	+	* @throws NullPointerException {@inheritDoc}
903	+	*/
904	+	@SuppressWarnings("unchecked")
905	+	public void forEach(Consumer<? super E> action) {
906	+	Objects.requireNonNull(action);
907	+	final int expectedModCount = modCount;
908	+	final Object[] es = queue;
909	+	for (int i = 0, n = size; i < n; i++)
910	+	action.accept((E) es[i]);
911	+	if (expectedModCount != modCount)
912	+	throw new ConcurrentModificationException();
913	+	}
914		}

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