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

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.82 by jsr166, Wed Jan 16 21:18:50 2013 UTC vs.
Revision 1.112 by jsr166, Tue Nov 29 18:11:28 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	<	import java.util.stream.Stream;
28	<	import java.util.Spliterator;
29	<	import java.util.stream.Streams;
30	<	import java.util.function.Block;
27	>
28	>	import java.util.function.Consumer;
29
30		/**
31		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
#	Line 56 | Line 54 | import java.util.function.Block;
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 67 | Line 66 | import java.util.function.Block;
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 79 | Line 78 | import java.util.function.Block;
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 101 | 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 113 | 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 138 | 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 247 | 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 326 | 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;
330	–	if (i == 0)
331	–	queue[0] = e;
332	–	else
333	–	siftUp(i, e);
343		return true;
344		}
345
#	Line 395 | 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 437 | 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 451 | 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 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 541 | Line 552 | public class PriorityQueue<E> extends Ab
552		cursor--;
553		else {
554		if (forgetMeNot == null)
555	<	forgetMeNot = new ArrayDeque<E>();
555	>	forgetMeNot = new ArrayDeque<>();
556		forgetMeNot.add(moved);
557		}
558		} else if (lastRetElt != null) {
#	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() {
#	Line 739 | Line 751 | public class PriorityQueue<E> extends Ab
751		/**
752		* Saves this queue to a stream (that is, serializes it).
753		*
754	+	* @param s the stream
755	+	* @throws java.io.IOException if an I/O error occurs
756		* @serialData The length of the array backing the instance is
757		*             emitted (int), followed by all of its elements
758		*             (each an {@code Object}) in the proper order.
745	–	* @param s the stream
759		*/
760		private void writeObject(java.io.ObjectOutputStream s)
761		throws java.io.IOException {
#	Line 762 | Line 775 | public class PriorityQueue<E> extends Ab
775		* (that is, deserializes it).
776		*
777		* @param s the stream
778	+	* @throws ClassNotFoundException if the class of a serialized object
779	+	*         could not be found
780	+	* @throws java.io.IOException if an I/O error occurs
781		*/
782		private void readObject(java.io.ObjectInputStream s)
783		throws java.io.IOException, ClassNotFoundException {
#	Line 782 | Line 798 | public class PriorityQueue<E> extends Ab
798		heapify();
799		}
800
801	<	// wrapping constructor in method avoids transient javac problems
802	<	final PriorityQueueSpliterator<E> spliterator(int origin, int fence,
803	<	int expectedModCount) {
804	<	return new PriorityQueueSpliterator(this, origin, fence,
805	<	expectedModCount);
806	<	}
807	<
808	<	public Stream<E> stream() {
809	<	int flags = Streams.STREAM_IS_SIZED;
810	<	return Streams.stream
811	<	(() -> spliterator(0, size, modCount), flags);
812	<	}
813	<	public Stream<E> parallelStream() {
814	<	int flags = Streams.STREAM_IS_SIZED;
815	<	return Streams.parallelStream
816	<	(() -> spliterator(0, size, modCount), flags);
817	<	}
818	<
819	<	/** Index-based split-by-two Spliterator */
820	<	static final class PriorityQueueSpliterator<E>
821	<	implements Spliterator<E>, Iterator<E> {
801	>	/**
802	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
803	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
804	>	* queue. The spliterator does not traverse elements in any particular order
805	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
806	>	*
807	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
808	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
809	>	* Overriding implementations should document the reporting of additional
810	>	* characteristic values.
811	>	*
812	>	* @return a {@code Spliterator} over the elements in this queue
813	>	* @since 1.8
814	>	*/
815	>	public final Spliterator<E> spliterator() {
816	>	return new PriorityQueueSpliterator<>(this, 0, -1, 0);
817	>	}
818	>
819	>	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
820	>	/*
821	>	* This is very similar to ArrayList Spliterator, except for
822	>	* extra null checks.
823	>	*/
824		private final PriorityQueue<E> pq;
825	<	private int index;           // current index, modified on advance/split
826	<	private final int fence;     // one past last index
827	<	private final int expectedModCount; // for comodification checks
825	>	private int index;            // current index, modified on advance/split
826	>	private int fence;            // -1 until first use
827	>	private int expectedModCount; // initialized when fence set
828
829	<	/** Create new spliterator covering the given  range */
829	>	/** Creates new spliterator covering the given range. */
830		PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
831	<	int expectedModCount) {
832	<	this.pq = pq; this.index = origin; this.fence = fence;
831	>	int expectedModCount) {
832	>	this.pq = pq;
833	>	this.index = origin;
834	>	this.fence = fence;
835		this.expectedModCount = expectedModCount;
836		}
837
838	+	private int getFence() { // initialize fence to size on first use
839	+	int hi;
840	+	if ((hi = fence) < 0) {
841	+	expectedModCount = pq.modCount;
842	+	hi = fence = pq.size;
843	+	}
844	+	return hi;
845	+	}
846	+
847		public PriorityQueueSpliterator<E> trySplit() {
848	<	int lo = index, mid = (lo + fence) >>> 1;
848	>	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
849		return (lo >= mid) ? null :
850	<	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
851	<	expectedModCount);
850	>	new PriorityQueueSpliterator<>(pq, lo, index = mid,
851	>	expectedModCount);
852		}
853
854	<	public void forEach(Block<? super E> block) {
855	<	Object[] a; int i, hi; // hoist accesses and checks from loop
856	<	if (block == null)
854	>	@SuppressWarnings("unchecked")
855	>	public void forEachRemaining(Consumer<? super E> action) {
856	>	int i, hi, mc; // hoist accesses and checks from loop
857	>	PriorityQueue<E> q; Object[] a;
858	>	if (action == null)
859		throw new NullPointerException();
860	<	if ((a = pq.queue).length >= (hi = fence) &&
861	<	(i = index) >= 0 && i < hi) {
862	<	index = hi;
863	<	do {
864	<	@SuppressWarnings("unchecked") E e = (E) a[i];
865	<	block.accept(e);
866	<	} while (++i < hi);
867	<	if (pq.modCount != expectedModCount)
868	<	throw new ConcurrentModificationException();
860	>	if ((q = pq) != null && (a = q.queue) != null) {
861	>	if ((hi = fence) < 0) {
862	>	mc = q.modCount;
863	>	hi = q.size;
864	>	}
865	>	else
866	>	mc = expectedModCount;
867	>	if ((i = index) >= 0 && (index = hi) <= a.length) {
868	>	for (E e;; ++i) {
869	>	if (i < hi) {
870	>	if ((e = (E) a[i]) == null) // must be CME
871	>	break;
872	>	action.accept(e);
873	>	}
874	>	else if (q.modCount != mc)
875	>	break;
876	>	else
877	>	return;
878	>	}
879	>	}
880		}
881	+	throw new ConcurrentModificationException();
882		}
883
884	<	public boolean tryAdvance(Block<? super E> block) {
885	<	if (index >= 0 && index < fence) {
884	>	public boolean tryAdvance(Consumer<? super E> action) {
885	>	if (action == null)
886	>	throw new NullPointerException();
887	>	int hi = getFence(), lo = index;
888	>	if (lo >= 0 && lo < hi) {
889	>	index = lo + 1;
890	>	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
891	>	if (e == null)
892	>	throw new ConcurrentModificationException();
893	>	action.accept(e);
894		if (pq.modCount != expectedModCount)
895		throw new ConcurrentModificationException();
845	–	@SuppressWarnings("unchecked") E e =
846	–	(E)pq.queue[index++];
847	–	block.accept(e);
896		return true;
897		}
898		return false;
899		}
900
901	<	public long estimateSize() { return (long)(fence - index); }
902	<	public boolean hasExactSize() { return true; }
903	<	public boolean hasExactSplits() { return true; }
856	<
857	<	// Iterator support
858	<	public Iterator<E> iterator() { return this; }
859	<	public void remove() { throw new UnsupportedOperationException(); }
860	<	public boolean hasNext() { return index >= 0 && index < fence; }
901	>	public long estimateSize() {
902	>	return (long) (getFence() - index);
903	>	}
904
905	<	public E next() {
906	<	if (index < 0 || index >= fence)
864	<	throw new NoSuchElementException();
865	<	if (pq.modCount != expectedModCount)
866	<	throw new ConcurrentModificationException();
867	<	@SuppressWarnings("unchecked") E e =
868	<	(E) pq.queue[index++];
869	<	return e;
905	>	public int characteristics() {
906	>	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
907		}
908		}
909		}

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