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

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.97 by jsr166, Thu Jul 18 18:21:22 2013 UTC vs.
Revision 1.115 by jsr166, Fri Dec 2 07:11:36 2016 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2012, Oracle and/or its affiliates. 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
#	Line 24 | Line 24
24		*/
25
26		package java.util;
27	+
28		import java.util.function.Consumer;
28	–	import java.util.stream.Stream;
29
30		/**
31		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
#	Line 54 | Line 54 | import java.util.stream.Stream;
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		*
#	Line 65 | Line 66 | import java.util.stream.Stream;
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 77 | Line 78 | import java.util.stream.Stream;
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 99 | Line 100 | public class PriorityQueue<E> extends Ab
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 111 | 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	<	transient int modCount = 0; // non-private to simplify nested class access
115	>	transient int modCount;     // non-private to simplify nested class access
116
117		/**
118		* Creates a {@code PriorityQueue} with the default initial
#	Line 136 | 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 245 | 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 324 | 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;
328	–	if (i == 0)
329	–	queue[0] = e;
330	–	else
331	–	siftUp(i, e);
343		return true;
344		}
345
#	Line 393 | 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 435 | Line 446 | public class PriorityQueue<E> extends Ab
446		* The following code can be used to dump the queue into a newly
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 {@code toArray(new Object[0])} is identical in function to
452		* {@code toArray()}.
#	Line 476 | 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 496 | 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 596 | Line 607 | public class PriorityQueue<E> extends Ab
607		* avoid missing traversing elements.
608		*/
609		@SuppressWarnings("unchecked")
610	<	private E removeAt(int i) {
610	>	E removeAt(int i) {
611		// assert i >= 0 && i < size;
612		modCount++;
613		int s = --size;
#	Line 716 | Line 727 | public class PriorityQueue<E> extends Ab
727		/**
728		* Establishes the heap invariant (described above) in the entire tree,
729		* assuming nothing about the order of the elements prior to the call.
730	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
731		*/
732		@SuppressWarnings("unchecked")
733		private void heapify() {
734	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
735	<	siftDown(i, (E) queue[i]);
734	>	final Object[] es = queue;
735	>	final int half = (size >>> 1) - 1;
736	>	if (comparator == null)
737	>	for (int i = half; i >= 0; i--)
738	>	siftDownComparable(i, (E) es[i]);
739	>	else
740	>	for (int i = half; i >= 0; i--)
741	>	siftDownUsingComparator(i, (E) es[i]);
742		}
743
744		/**
#	Line 739 | Line 757 | public class PriorityQueue<E> extends Ab
757		/**
758		* Saves this queue to a stream (that is, serializes it).
759		*
760	+	* @param s the stream
761	+	* @throws java.io.IOException if an I/O error occurs
762		* @serialData The length of the array backing the instance is
763		*             emitted (int), followed by all of its elements
764		*             (each an {@code Object}) in the proper order.
745	–	* @param s the stream
746	–	* @throws java.io.IOException if an I/O error occurs
765		*/
766		private void writeObject(java.io.ObjectOutputStream s)
767		throws java.io.IOException {
#	Line 786 | Line 804 | public class PriorityQueue<E> extends Ab
804		heapify();
805		}
806
789	–	public Spliterator<E> spliterator() {
790	–	return new PriorityQueueSpliterator<E>(this, 0, -1, 0);
791	–	}
792	–
807		/**
808	<	* This is very similar to ArrayList Spliterator, except for extra
809	<	* null checks.
808	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
809	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
810	>	* queue. The spliterator does not traverse elements in any particular order
811	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
812	>	*
813	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
814	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
815	>	* Overriding implementations should document the reporting of additional
816	>	* characteristic values.
817	>	*
818	>	* @return a {@code Spliterator} over the elements in this queue
819	>	* @since 1.8
820		*/
821	<	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
822	<	private final PriorityQueue<E> pq;
821	>	public final Spliterator<E> spliterator() {
822	>	return new PriorityQueueSpliterator(0, -1, 0);
823	>	}
824	>
825	>	final class PriorityQueueSpliterator implements Spliterator<E> {
826		private int index;            // current index, modified on advance/split
827		private int fence;            // -1 until first use
828		private int expectedModCount; // initialized when fence set
829
830	<	/** Creates new spliterator covering the given range */
831	<	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
805	<	int expectedModCount) {
806	<	this.pq = pq;
830	>	/** Creates new spliterator covering the given range. */
831	>	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
832		this.index = origin;
833		this.fence = fence;
834		this.expectedModCount = expectedModCount;
#	Line 812 | Line 837 | public class PriorityQueue<E> extends Ab
837		private int getFence() { // initialize fence to size on first use
838		int hi;
839		if ((hi = fence) < 0) {
840	<	expectedModCount = pq.modCount;
841	<	hi = fence = pq.size;
840	>	expectedModCount = modCount;
841	>	hi = fence = size;
842		}
843		return hi;
844		}
845
846	<	public Spliterator<E> trySplit() {
846	>	public PriorityQueueSpliterator trySplit() {
847		int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
848		return (lo >= mid) ? null :
849	<	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
825	<	expectedModCount);
849	>	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
850		}
851
852		@SuppressWarnings("unchecked")
853		public void forEachRemaining(Consumer<? super E> action) {
830	–	int i, hi, mc; // hoist accesses and checks from loop
831	–	PriorityQueue<E> q; Object[] a;
854		if (action == null)
855		throw new NullPointerException();
856	<	if ((q = pq) != null && (a = q.queue) != null) {
857	<	if ((hi = fence) < 0) {
858	<	mc = q.modCount;
859	<	hi = q.size;
860	<	}
861	<	else
862	<	mc = expectedModCount;
841	<	if ((i = index) >= 0 && (index = hi) <= a.length) {
842	<	for (E e;; ++i) {
843	<	if (i < hi) {
844	<	if ((e = (E) a[i]) == null) // must be CME
845	<	break;
846	<	action.accept(e);
847	<	}
848	<	else if (q.modCount != mc)
849	<	break;
850	<	else
851	<	return;
852	<	}
853	<	}
856	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
857	>	final Object[] a = queue;
858	>	int i, hi; E e;
859	>	for (i = index, index = hi = fence; i < hi; i++) {
860	>	if ((e = (E) a[i]) == null)
861	>	break;      // must be CME
862	>	action.accept(e);
863		}
864	<	throw new ConcurrentModificationException();
864	>	if (modCount != expectedModCount)
865	>	throw new ConcurrentModificationException();
866		}
867
868	+	@SuppressWarnings("unchecked")
869		public boolean tryAdvance(Consumer<? super E> action) {
870	<	int hi = getFence(), lo = index;
871	<	if (lo >= 0 && lo < hi) {
872	<	index = lo + 1;
873	<	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
874	<	if (e == null)
870	>	if (action == null)
871	>	throw new NullPointerException();
872	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
873	>	int i;
874	>	if ((i = index) < fence) {
875	>	index = i + 1;
876	>	E e;
877	>	if ((e = (E) queue[i]) == null
878	>	|| modCount != expectedModCount)
879		throw new ConcurrentModificationException();
880		action.accept(e);
866	–	if (pq.modCount != expectedModCount)
867	–	throw new ConcurrentModificationException();
881		return true;
882		}
883		return false;
884		}
885
886		public long estimateSize() {
887	<	return (long) (getFence() - index);
887	>	return getFence() - index;
888		}
889
890		public int characteristics() {

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