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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.79 by jsr166, Sat Dec 15 22:26:29 2012 UTC vs.
Revision 1.124 by jsr166, Sun May 6 19:35:51 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 70 | Line 74 | package java.util;
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		@SuppressWarnings("unchecked")
85		public class PriorityQueue<E> extends AbstractQueue<E>
#	Line 93 | Line 97 | public class PriorityQueue<E> extends Ab
97		* heap and each descendant d of n, n <= d.  The element with the
98		* lowest value is in queue[0], assuming the queue is nonempty.
99		*/
100	<	private transient Object[] queue;
100	>	transient Object[] queue; // non-private to simplify nested class access
101
102		/**
103		* The number of elements in the priority queue.
104		*/
105	<	private int size = 0;
105	>	int size;
106
107		/**
108		* The comparator, or null if priority queue uses elements'
#	Line 110 | Line 114 | public class PriorityQueue<E> extends Ab
114		* The number of times this priority queue has been
115		* <i>structurally modified</i>.  See AbstractList for gory details.
116		*/
117	<	private transient int modCount = 0;
117	>	transient int modCount;     // non-private to simplify nested class access
118
119		/**
120		* Creates a {@code PriorityQueue} with the default initial
#	Line 135 | Line 139 | public class PriorityQueue<E> extends Ab
139		}
140
141		/**
142	+	* Creates a {@code PriorityQueue} with the default initial capacity and
143	+	* whose elements are ordered according to the specified comparator.
144	+	*
145	+	* @param  comparator the comparator that will be used to order this
146	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
147	+	*         natural ordering} of the elements will be used.
148	+	* @since 1.8
149	+	*/
150	+	public PriorityQueue(Comparator<? super E> comparator) {
151	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
152	+	}
153	+
154	+	/**
155		* Creates a {@code PriorityQueue} with the specified initial capacity
156		* that orders its elements according to the specified comparator.
157		*
#	Line 171 | Line 188 | public class PriorityQueue<E> extends Ab
188		* @throws NullPointerException if the specified collection or any
189		*         of its elements are null
190		*/
174	–	@SuppressWarnings("unchecked")
191		public PriorityQueue(Collection<? extends E> c) {
192		if (c instanceof SortedSet<?>) {
193		SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
#	Line 203 | Line 219 | public class PriorityQueue<E> extends Ab
219		* @throws NullPointerException if the specified priority queue or any
220		*         of its elements are null
221		*/
206	–	@SuppressWarnings("unchecked")
222		public PriorityQueue(PriorityQueue<? extends E> c) {
223		this.comparator = (Comparator<? super E>) c.comparator();
224		initFromPriorityQueue(c);
#	Line 222 | Line 237 | public class PriorityQueue<E> extends Ab
237		* @throws NullPointerException if the specified sorted set or any
238		*         of its elements are null
239		*/
225	–	@SuppressWarnings("unchecked")
240		public PriorityQueue(SortedSet<? extends E> c) {
241		this.comparator = (Comparator<? super E>) c.comparator();
242		initElementsFromCollection(c);
#	Line 238 | Line 252 | public class PriorityQueue<E> extends Ab
252		}
253
254		private void initElementsFromCollection(Collection<? extends E> c) {
255	<	Object[] a = c.toArray();
255	>	Object[] es = c.toArray();
256	>	int len = es.length;
257		// If c.toArray incorrectly doesn't return Object[], copy it.
258	<	if (a.getClass() != Object[].class)
259	<	a = Arrays.copyOf(a, a.length, Object[].class);
245	<	int len = a.length;
258	>	if (es.getClass() != Object[].class)
259	>	es = Arrays.copyOf(es, len, Object[].class);
260		if (len == 1 || this.comparator != null)
261	<	for (int i = 0; i < len; i++)
262	<	if (a[i] == null)
261	>	for (Object e : es)
262	>	if (e == null)
263		throw new NullPointerException();
264	<	this.queue = a;
265	<	this.size = a.length;
264	>	this.queue = es;
265	>	this.size = len;
266		}
267
268		/**
#	Line 323 | Line 337 | public class PriorityQueue<E> extends Ab
337		int i = size;
338		if (i >= queue.length)
339		grow(i + 1);
340	+	siftUp(i, e);
341		size = i + 1;
327	–	if (i == 0)
328	–	queue[0] = e;
329	–	else
330	–	siftUp(i, e);
342		return true;
343		}
344
#	Line 337 | Line 348 | public class PriorityQueue<E> extends Ab
348
349		private int indexOf(Object o) {
350		if (o != null) {
351	<	for (int i = 0; i < size; i++)
352	<	if (o.equals(queue[i]))
351	>	final Object[] es = queue;
352	>	for (int i = 0, n = size; i < n; i++)
353	>	if (o.equals(es[i]))
354		return i;
355		}
356		return -1;
#	Line 366 | Line 378 | public class PriorityQueue<E> extends Ab
378		}
379
380		/**
381	<	* Version of remove using reference equality, not equals.
370	<	* Needed by iterator.remove.
381	>	* Identity-based version for use in Itr.remove.
382		*
383		* @param o element to be removed from this queue, if present
373	–	* @return {@code true} if removed
384		*/
385	<	boolean removeEq(Object o) {
386	<	for (int i = 0; i < size; i++) {
387	<	if (o == queue[i]) {
385	>	void removeEq(Object o) {
386	>	final Object[] es = queue;
387	>	for (int i = 0, n = size; i < n; i++) {
388	>	if (o == es[i]) {
389		removeAt(i);
390	<	return true;
390	>	break;
391		}
392		}
382	–	return false;
393		}
394
395		/**
#	Line 391 | Line 401 | public class PriorityQueue<E> extends Ab
401		* @return {@code true} if this queue contains the specified element
402		*/
403		public boolean contains(Object o) {
404	<	return indexOf(o) != -1;
404	>	return indexOf(o) >= 0;
405		}
406
407		/**
#	Line 429 | Line 439 | public class PriorityQueue<E> extends Ab
439		* precise control over the runtime type of the output array, and may,
440		* under certain circumstances, be used to save allocation costs.
441		*
442	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
442	>	* <p>Suppose {@code x} is a queue known to contain only strings.
443		* The following code can be used to dump the queue into a newly
444	<	* allocated array of <tt>String</tt>:
444	>	* allocated array of {@code String}:
445		*
446	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
446	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
447		*
448	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
449	<	* <tt>toArray()</tt>.
448	>	* Note that {@code toArray(new Object[0])} is identical in function to
449	>	* {@code toArray()}.
450		*
451		* @param a the array into which the elements of the queue are to
452		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 448 | Line 458 | public class PriorityQueue<E> extends Ab
458		* @throws NullPointerException if the specified array is null
459		*/
460		public <T> T[] toArray(T[] a) {
461	+	final int size = this.size;
462		if (a.length < size)
463		// Make a new array of a's runtime type, but my contents:
464		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 472 | Line 483 | public class PriorityQueue<E> extends Ab
483		* Index (into queue array) of element to be returned by
484		* subsequent call to next.
485		*/
486	<	private int cursor = 0;
486	>	private int cursor;
487
488		/**
489		* Index of element returned by most recent call to next,
#	Line 492 | Line 503 | public class PriorityQueue<E> extends Ab
503		* We expect that most iterations, even those involving removals,
504		* will not need to store elements in this field.
505		*/
506	<	private ArrayDeque<E> forgetMeNot = null;
506	>	private ArrayDeque<E> forgetMeNot;
507
508		/**
509		* Element returned by the most recent call to next iff that
510		* element was drawn from the forgetMeNot list.
511		*/
512	<	private E lastRetElt = null;
512	>	private E lastRetElt;
513
514		/**
515		* The modCount value that the iterator believes that the backing
#	Line 507 | Line 518 | public class PriorityQueue<E> extends Ab
518		*/
519		private int expectedModCount = modCount;
520
521	+	Itr() {}                        // prevent access constructor creation
522	+
523		public boolean hasNext() {
524		return cursor < size ||
525		(forgetMeNot != null && !forgetMeNot.isEmpty());
#	Line 536 | Line 549 | public class PriorityQueue<E> extends Ab
549		cursor--;
550		else {
551		if (forgetMeNot == null)
552	<	forgetMeNot = new ArrayDeque<E>();
552	>	forgetMeNot = new ArrayDeque<>();
553		forgetMeNot.add(moved);
554		}
555		} else if (lastRetElt != null) {
#	Line 559 | Line 572 | public class PriorityQueue<E> extends Ab
572		*/
573		public void clear() {
574		modCount++;
575	<	for (int i = 0; i < size; i++)
576	<	queue[i] = null;
575	>	final Object[] es = queue;
576	>	for (int i = 0, n = size; i < n; i++)
577	>	es[i] = null;
578		size = 0;
579		}
580
#	Line 589 | Line 603 | public class PriorityQueue<E> extends Ab
603		* position before i. This fact is used by iterator.remove so as to
604		* avoid missing traversing elements.
605		*/
606	<	private E removeAt(int i) {
606	>	E removeAt(int i) {
607		// assert i >= 0 && i < size;
608		modCount++;
609		int s = --size;
#	Line 613 | Line 627 | public class PriorityQueue<E> extends Ab
627		* promoting x up the tree until it is greater than or equal to
628		* its parent, or is the root.
629		*
630	<	* To simplify and speed up coercions and comparisons. the
630	>	* To simplify and speed up coercions and comparisons, the
631		* Comparable and Comparator versions are separated into different
632		* methods that are otherwise identical. (Similarly for siftDown.)
633		*
#	Line 622 | Line 636 | public class PriorityQueue<E> extends Ab
636		*/
637		private void siftUp(int k, E x) {
638		if (comparator != null)
639	<	siftUpUsingComparator(k, x);
639	>	siftUpUsingComparator(k, x, queue, comparator);
640		else
641	<	siftUpComparable(k, x);
641	>	siftUpComparable(k, x, queue);
642		}
643
644	<	private void siftUpComparable(int k, E x) {
645	<	Comparable<? super E> key = (Comparable<? super E>) x;
644	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
645	>	Comparable<? super T> key = (Comparable<? super T>) x;
646		while (k > 0) {
647		int parent = (k - 1) >>> 1;
648	<	Object e = queue[parent];
649	<	if (key.compareTo((E) e) >= 0)
648	>	Object e = es[parent];
649	>	if (key.compareTo((T) e) >= 0)
650		break;
651	<	queue[k] = e;
651	>	es[k] = e;
652		k = parent;
653		}
654	<	queue[k] = key;
654	>	es[k] = key;
655		}
656
657	<	private void siftUpUsingComparator(int k, E x) {
657	>	private static <T> void siftUpUsingComparator(
658	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
659		while (k > 0) {
660		int parent = (k - 1) >>> 1;
661	<	Object e = queue[parent];
662	<	if (comparator.compare(x, (E) e) >= 0)
661	>	Object e = es[parent];
662	>	if (cmp.compare(x, (T) e) >= 0)
663		break;
664	<	queue[k] = e;
664	>	es[k] = e;
665		k = parent;
666		}
667	<	queue[k] = x;
667	>	es[k] = x;
668		}
669
670		/**
#	Line 662 | Line 677 | public class PriorityQueue<E> extends Ab
677		*/
678		private void siftDown(int k, E x) {
679		if (comparator != null)
680	<	siftDownUsingComparator(k, x);
680	>	siftDownUsingComparator(k, x, queue, size, comparator);
681		else
682	<	siftDownComparable(k, x);
682	>	siftDownComparable(k, x, queue, size);
683		}
684
685	<	private void siftDownComparable(int k, E x) {
686	<	Comparable<? super E> key = (Comparable<? super E>)x;
687	<	int half = size >>> 1;        // loop while a non-leaf
685	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
686	>	// assert n > 0;
687	>	Comparable<? super T> key = (Comparable<? super T>)x;
688	>	int half = n >>> 1;           // loop while a non-leaf
689		while (k < half) {
690		int child = (k << 1) + 1; // assume left child is least
691	<	Object c = queue[child];
691	>	Object c = es[child];
692		int right = child + 1;
693	<	if (right < size &&
694	<	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
695	<	c = queue[child = right];
696	<	if (key.compareTo((E) c) <= 0)
693	>	if (right < n &&
694	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
695	>	c = es[child = right];
696	>	if (key.compareTo((T) c) <= 0)
697		break;
698	<	queue[k] = c;
698	>	es[k] = c;
699		k = child;
700		}
701	<	queue[k] = key;
701	>	es[k] = key;
702		}
703
704	<	private void siftDownUsingComparator(int k, E x) {
705	<	int half = size >>> 1;
704	>	private static <T> void siftDownUsingComparator(
705	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
706	>	// assert n > 0;
707	>	int half = n >>> 1;
708		while (k < half) {
709		int child = (k << 1) + 1;
710	<	Object c = queue[child];
710	>	Object c = es[child];
711		int right = child + 1;
712	<	if (right < size &&
713	<	comparator.compare((E) c, (E) queue[right]) > 0)
714	<	c = queue[child = right];
697	<	if (comparator.compare(x, (E) c) <= 0)
712	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
713	>	c = es[child = right];
714	>	if (cmp.compare(x, (T) c) <= 0)
715		break;
716	<	queue[k] = c;
716	>	es[k] = c;
717		k = child;
718		}
719	<	queue[k] = x;
719	>	es[k] = x;
720		}
721
722		/**
723		* Establishes the heap invariant (described above) in the entire tree,
724		* assuming nothing about the order of the elements prior to the call.
725	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
726		*/
727		private void heapify() {
728	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
729	<	siftDown(i, (E) queue[i]);
728	>	final Object[] es = queue;
729	>	int n = size, i = (n >>> 1) - 1;
730	>	Comparator<? super E> cmp = comparator;
731	>	if (cmp == null)
732	>	for (; i >= 0; i--)
733	>	siftDownComparable(i, (E) es[i], es, n);
734	>	else
735	>	for (; i >= 0; i--)
736	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
737		}
738
739		/**
#	Line 727 | Line 752 | public class PriorityQueue<E> extends Ab
752		/**
753		* Saves this queue to a stream (that is, serializes it).
754		*
755	+	* @param s the stream
756	+	* @throws java.io.IOException if an I/O error occurs
757		* @serialData The length of the array backing the instance is
758		*             emitted (int), followed by all of its elements
759		*             (each an {@code Object}) in the proper order.
#	Line 740 | Line 767 | public class PriorityQueue<E> extends Ab
767		s.writeInt(Math.max(2, size + 1));
768
769		// Write out all elements in the "proper order".
770	<	for (int i = 0; i < size; i++)
771	<	s.writeObject(queue[i]);
770	>	final Object[] es = queue;
771	>	for (int i = 0, n = size; i < n; i++)
772	>	s.writeObject(es[i]);
773		}
774
775		/**
776	<	* Reconstitutes this queue from a stream (that is, deserializes it).
776	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
777	>	* (that is, deserializes it).
778	>	*
779	>	* @param s the stream
780	>	* @throws ClassNotFoundException if the class of a serialized object
781	>	*         could not be found
782	>	* @throws java.io.IOException if an I/O error occurs
783		*/
784		private void readObject(java.io.ObjectInputStream s)
785		throws java.io.IOException, ClassNotFoundException {
#	Line 755 | Line 789 | public class PriorityQueue<E> extends Ab
789		// Read in (and discard) array length
790		s.readInt();
791
792	+	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
793		queue = new Object[size];
794
795		// Read in all elements.
796	<	for (int i = 0; i < size; i++)
797	<	queue[i] = s.readObject();
796	>	final Object[] es = queue;
797	>	for (int i = 0, n = size; i < n; i++)
798	>	es[i] = s.readObject();
799
800		// Elements are guaranteed to be in "proper order", but the
801		// spec has never explained what that might be.
802		heapify();
803		}
804	+
805	+	/**
806	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
807	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
808	+	* queue. The spliterator does not traverse elements in any particular order
809	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
810	+	*
811	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
812	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
813	+	* Overriding implementations should document the reporting of additional
814	+	* characteristic values.
815	+	*
816	+	* @return a {@code Spliterator} over the elements in this queue
817	+	* @since 1.8
818	+	*/
819	+	public final Spliterator<E> spliterator() {
820	+	return new PriorityQueueSpliterator(0, -1, 0);
821	+	}
822	+
823	+	final class PriorityQueueSpliterator implements Spliterator<E> {
824	+	private int index;            // current index, modified on advance/split
825	+	private int fence;            // -1 until first use
826	+	private int expectedModCount; // initialized when fence set
827	+
828	+	/** Creates new spliterator covering the given range. */
829	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
830	+	this.index = origin;
831	+	this.fence = fence;
832	+	this.expectedModCount = expectedModCount;
833	+	}
834	+
835	+	private int getFence() { // initialize fence to size on first use
836	+	int hi;
837	+	if ((hi = fence) < 0) {
838	+	expectedModCount = modCount;
839	+	hi = fence = size;
840	+	}
841	+	return hi;
842	+	}
843	+
844	+	public PriorityQueueSpliterator trySplit() {
845	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
846	+	return (lo >= mid) ? null :
847	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
848	+	}
849	+
850	+	public void forEachRemaining(Consumer<? super E> action) {
851	+	if (action == null)
852	+	throw new NullPointerException();
853	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
854	+	final Object[] es = queue;
855	+	int i, hi; E e;
856	+	for (i = index, index = hi = fence; i < hi; i++) {
857	+	if ((e = (E) es[i]) == null)
858	+	break;      // must be CME
859	+	action.accept(e);
860	+	}
861	+	if (modCount != expectedModCount)
862	+	throw new ConcurrentModificationException();
863	+	}
864	+
865	+	public boolean tryAdvance(Consumer<? super E> action) {
866	+	if (action == null)
867	+	throw new NullPointerException();
868	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
869	+	int i;
870	+	if ((i = index) < fence) {
871	+	index = i + 1;
872	+	E e;
873	+	if ((e = (E) queue[i]) == null
874	+	|| modCount != expectedModCount)
875	+	throw new ConcurrentModificationException();
876	+	action.accept(e);
877	+	return true;
878	+	}
879	+	return false;
880	+	}
881	+
882	+	public long estimateSize() {
883	+	return getFence() - index;
884	+	}
885	+
886	+	public int characteristics() {
887	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
888	+	}
889	+	}
890	+
891	+	/**
892	+	* @throws NullPointerException {@inheritDoc}
893	+	*/
894	+	public void forEach(Consumer<? super E> action) {
895	+	Objects.requireNonNull(action);
896	+	final int expectedModCount = modCount;
897	+	final Object[] es = queue;
898	+	for (int i = 0, n = size; i < n; i++)
899	+	action.accept((E) es[i]);
900	+	if (expectedModCount != modCount)
901	+	throw new ConcurrentModificationException();
902	+	}
903		}

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