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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.71 by jsr166, Sun Sep 5 21:32:19 2010 UTC vs.
Revision 1.102 by jsr166, Wed Dec 31 07:54:13 2014 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
2	>	* Copyright (c) 2003, 2012, 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 java.util.stream.Stream;
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 56 | Line 59 | package java.util;
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	>	private 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 = 0; // non-private to simplify nested class access
116
117		/**
118		* Creates a {@code PriorityQueue} with the default initial
#	Line 330 | Line 333 | public class PriorityQueue<E> extends Ab
333		return true;
334		}
335
336	+	@SuppressWarnings("unchecked")
337		public E peek() {
338	<	if (size == 0)
335	<	return null;
336	<	return (E) queue[0];
338	>	return (size == 0) ? null : (E) queue[0];
339		}
340
341		private int indexOf(Object o) {
#	Line 392 | Line 394 | public class PriorityQueue<E> extends Ab
394		* @return {@code true} if this queue contains the specified element
395		*/
396		public boolean contains(Object o) {
397	<	return indexOf(o) != -1;
397	>	return indexOf(o) >= 0;
398		}
399
400		/**
#	Line 430 | Line 432 | public class PriorityQueue<E> extends Ab
432		* precise control over the runtime type of the output array, and may,
433		* under certain circumstances, be used to save allocation costs.
434		*
435	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
435	>	* <p>Suppose {@code x} is a queue known to contain only strings.
436		* The following code can be used to dump the queue into a newly
437	<	* allocated array of <tt>String</tt>:
437	>	* allocated array of {@code String}:
438		*
439	<	* <pre>
438	<	*     String[] y = x.toArray(new String[0]);</pre>
439	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
440		*
441	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
442	<	* <tt>toArray()</tt>.
441	>	* Note that {@code toArray(new Object[0])} is identical in function to
442	>	* {@code toArray()}.
443		*
444		* @param a the array into which the elements of the queue are to
445		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 449 | Line 450 | public class PriorityQueue<E> extends Ab
450		*         this queue
451		* @throws NullPointerException if the specified array is null
452		*/
453	+	@SuppressWarnings("unchecked")
454		public <T> T[] toArray(T[] a) {
455	+	final int size = this.size;
456		if (a.length < size)
457		// Make a new array of a's runtime type, but my contents:
458		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 474 | Line 477 | public class PriorityQueue<E> extends Ab
477		* Index (into queue array) of element to be returned by
478		* subsequent call to next.
479		*/
480	<	private int cursor = 0;
480	>	private int cursor;
481
482		/**
483		* Index of element returned by most recent call to next,
#	Line 494 | Line 497 | public class PriorityQueue<E> extends Ab
497		* We expect that most iterations, even those involving removals,
498		* will not need to store elements in this field.
499		*/
500	<	private ArrayDeque<E> forgetMeNot = null;
500	>	private ArrayDeque<E> forgetMeNot;
501
502		/**
503		* Element returned by the most recent call to next iff that
504		* element was drawn from the forgetMeNot list.
505		*/
506	<	private E lastRetElt = null;
506	>	private E lastRetElt;
507
508		/**
509		* The modCount value that the iterator believes that the backing
#	Line 514 | Line 517 | public class PriorityQueue<E> extends Ab
517		(forgetMeNot != null && !forgetMeNot.isEmpty());
518		}
519
520	+	@SuppressWarnings("unchecked")
521		public E next() {
522		if (expectedModCount != modCount)
523		throw new ConcurrentModificationException();
#	Line 538 | Line 542 | public class PriorityQueue<E> extends Ab
542		cursor--;
543		else {
544		if (forgetMeNot == null)
545	<	forgetMeNot = new ArrayDeque<E>();
545	>	forgetMeNot = new ArrayDeque<>();
546		forgetMeNot.add(moved);
547		}
548		} else if (lastRetElt != null) {
#	Line 566 | Line 570 | public class PriorityQueue<E> extends Ab
570		size = 0;
571		}
572
573	+	@SuppressWarnings("unchecked")
574		public E poll() {
575		if (size == 0)
576		return null;
#	Line 591 | Line 596 | public class PriorityQueue<E> extends Ab
596		* position before i. This fact is used by iterator.remove so as to
597		* avoid missing traversing elements.
598		*/
599	+	@SuppressWarnings("unchecked")
600		private E removeAt(int i) {
601	<	assert i >= 0 && i < size;
601	>	// assert i >= 0 && i < size;
602		modCount++;
603		int s = --size;
604		if (s == i) // removed last element
#	Line 629 | Line 635 | public class PriorityQueue<E> extends Ab
635		siftUpComparable(k, x);
636		}
637
638	+	@SuppressWarnings("unchecked")
639		private void siftUpComparable(int k, E x) {
640		Comparable<? super E> key = (Comparable<? super E>) x;
641		while (k > 0) {
#	Line 642 | Line 649 | public class PriorityQueue<E> extends Ab
649		queue[k] = key;
650		}
651
652	+	@SuppressWarnings("unchecked")
653		private void siftUpUsingComparator(int k, E x) {
654		while (k > 0) {
655		int parent = (k - 1) >>> 1;
#	Line 669 | Line 677 | public class PriorityQueue<E> extends Ab
677		siftDownComparable(k, x);
678		}
679
680	+	@SuppressWarnings("unchecked")
681		private void siftDownComparable(int k, E x) {
682		Comparable<? super E> key = (Comparable<? super E>)x;
683		int half = size >>> 1;        // loop while a non-leaf
#	Line 687 | Line 696 | public class PriorityQueue<E> extends Ab
696		queue[k] = key;
697		}
698
699	+	@SuppressWarnings("unchecked")
700		private void siftDownUsingComparator(int k, E x) {
701		int half = size >>> 1;
702		while (k < half) {
#	Line 708 | Line 718 | public class PriorityQueue<E> extends Ab
718		* Establishes the heap invariant (described above) in the entire tree,
719		* assuming nothing about the order of the elements prior to the call.
720		*/
721	+	@SuppressWarnings("unchecked")
722		private void heapify() {
723		for (int i = (size >>> 1) - 1; i >= 0; i--)
724		siftDown(i, (E) queue[i]);
#	Line 727 | Line 738 | public class PriorityQueue<E> extends Ab
738		}
739
740		/**
741	<	* Saves the state of the instance to a stream (that
731	<	* is, serializes it).
741	>	* Saves this queue to a stream (that is, serializes it).
742		*
743		* @serialData The length of the array backing the instance is
744		*             emitted (int), followed by all of its elements
745		*             (each an {@code Object}) in the proper order.
746		* @param s the stream
747	+	* @throws java.io.IOException if an I/O error occurs
748		*/
749		private void writeObject(java.io.ObjectOutputStream s)
750	<	throws java.io.IOException{
750	>	throws java.io.IOException {
751		// Write out element count, and any hidden stuff
752		s.defaultWriteObject();
753
#	Line 753 | Line 764 | public class PriorityQueue<E> extends Ab
764		* (that is, deserializes it).
765		*
766		* @param s the stream
767	+	* @throws ClassNotFoundException if the class of a serialized object
768	+	*         could not be found
769	+	* @throws java.io.IOException if an I/O error occurs
770		*/
771		private void readObject(java.io.ObjectInputStream s)
772		throws java.io.IOException, ClassNotFoundException {
#	Line 772 | Line 786 | public class PriorityQueue<E> extends Ab
786		// spec has never explained what that might be.
787		heapify();
788		}
789	+
790	+	public Spliterator<E> spliterator() {
791	+	return new PriorityQueueSpliterator<E>(this, 0, -1, 0);
792	+	}
793	+
794	+	/**
795	+	* This is very similar to ArrayList Spliterator, except for extra
796	+	* null checks.
797	+	*/
798	+	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
799	+	private final PriorityQueue<E> pq;
800	+	private int index;            // current index, modified on advance/split
801	+	private int fence;            // -1 until first use
802	+	private int expectedModCount; // initialized when fence set
803	+
804	+	/** Creates new spliterator covering the given range */
805	+	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
806	+	int expectedModCount) {
807	+	this.pq = pq;
808	+	this.index = origin;
809	+	this.fence = fence;
810	+	this.expectedModCount = expectedModCount;
811	+	}
812	+
813	+	private int getFence() { // initialize fence to size on first use
814	+	int hi;
815	+	if ((hi = fence) < 0) {
816	+	expectedModCount = pq.modCount;
817	+	hi = fence = pq.size;
818	+	}
819	+	return hi;
820	+	}
821	+
822	+	public Spliterator<E> trySplit() {
823	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
824	+	return (lo >= mid) ? null :
825	+	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
826	+	expectedModCount);
827	+	}
828	+
829	+	@SuppressWarnings("unchecked")
830	+	public void forEachRemaining(Consumer<? super E> action) {
831	+	int i, hi, mc; // hoist accesses and checks from loop
832	+	PriorityQueue<E> q; Object[] a;
833	+	if (action == null)
834	+	throw new NullPointerException();
835	+	if ((q = pq) != null && (a = q.queue) != null) {
836	+	if ((hi = fence) < 0) {
837	+	mc = q.modCount;
838	+	hi = q.size;
839	+	}
840	+	else
841	+	mc = expectedModCount;
842	+	if ((i = index) >= 0 && (index = hi) <= a.length) {
843	+	for (E e;; ++i) {
844	+	if (i < hi) {
845	+	if ((e = (E) a[i]) == null) // must be CME
846	+	break;
847	+	action.accept(e);
848	+	}
849	+	else if (q.modCount != mc)
850	+	break;
851	+	else
852	+	return;
853	+	}
854	+	}
855	+	}
856	+	throw new ConcurrentModificationException();
857	+	}
858	+
859	+	public boolean tryAdvance(Consumer<? super E> action) {
860	+	int hi = getFence(), lo = index;
861	+	if (lo >= 0 && lo < hi) {
862	+	index = lo + 1;
863	+	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
864	+	if (e == null)
865	+	throw new ConcurrentModificationException();
866	+	action.accept(e);
867	+	if (pq.modCount != expectedModCount)
868	+	throw new ConcurrentModificationException();
869	+	return true;
870	+	}
871	+	return false;
872	+	}
873	+
874	+	public long estimateSize() {
875	+	return (long) (getFence() - index);
876	+	}
877	+
878	+	public int characteristics() {
879	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
880	+	}
881	+	}
882		}

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