ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

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

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.80 by jsr166, Wed Jan 16 01:59:47 2013 UTC vs.
Revision 1.125 by jsr166, Sun May 6 21:07:41 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);
243		}
244
245	+	/** Ensures that queue[0] exists, helping peek() and poll(). */
246	+	private static Object[] ensureNonEmpty(Object[] es) {
247	+	return (es.length > 0) ? es : new Object[1];
248	+	}
249	+
250		private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
251		if (c.getClass() == PriorityQueue.class) {
252	<	this.queue = c.toArray();
252	>	this.queue = ensureNonEmpty(c.toArray());
253		this.size = c.size();
254		} else {
255		initFromCollection(c);
#	Line 238 | Line 257 | public class PriorityQueue<E> extends Ab
257		}
258
259		private void initElementsFromCollection(Collection<? extends E> c) {
260	<	Object[] a = c.toArray();
260	>	Object[] es = c.toArray();
261	>	int len = es.length;
262		// If c.toArray incorrectly doesn't return Object[], copy it.
263	<	if (a.getClass() != Object[].class)
264	<	a = Arrays.copyOf(a, a.length, Object[].class);
245	<	int len = a.length;
263	>	if (es.getClass() != Object[].class)
264	>	es = Arrays.copyOf(es, len, Object[].class);
265		if (len == 1 || this.comparator != null)
266	<	for (int i = 0; i < len; i++)
267	<	if (a[i] == null)
266	>	for (Object e : es)
267	>	if (e == null)
268		throw new NullPointerException();
269	<	this.queue = a;
270	<	this.size = a.length;
269	>	this.queue = ensureNonEmpty(es);
270	>	this.size = len;
271		}
272
273		/**
#	Line 323 | Line 342 | public class PriorityQueue<E> extends Ab
342		int i = size;
343		if (i >= queue.length)
344		grow(i + 1);
345	+	siftUp(i, e);
346		size = i + 1;
327	–	if (i == 0)
328	–	queue[0] = e;
329	–	else
330	–	siftUp(i, e);
347		return true;
348		}
349
350		public E peek() {
351	<	return (size == 0) ? null : (E) queue[0];
351	>	return (E) queue[0];
352		}
353
354		private int indexOf(Object o) {
355		if (o != null) {
356	<	for (int i = 0; i < size; i++)
357	<	if (o.equals(queue[i]))
356	>	final Object[] es = queue;
357	>	for (int i = 0, n = size; i < n; i++)
358	>	if (o.equals(es[i]))
359		return i;
360		}
361		return -1;
#	Line 366 | Line 383 | public class PriorityQueue<E> extends Ab
383		}
384
385		/**
386	<	* Version of remove using reference equality, not equals.
370	<	* Needed by iterator.remove.
386	>	* Identity-based version for use in Itr.remove.
387		*
388		* @param o element to be removed from this queue, if present
373	–	* @return {@code true} if removed
389		*/
390	<	boolean removeEq(Object o) {
391	<	for (int i = 0; i < size; i++) {
392	<	if (o == queue[i]) {
390	>	void removeEq(Object o) {
391	>	final Object[] es = queue;
392	>	for (int i = 0, n = size; i < n; i++) {
393	>	if (o == es[i]) {
394		removeAt(i);
395	<	return true;
395	>	break;
396		}
397		}
382	–	return false;
398		}
399
400		/**
#	Line 391 | Line 406 | public class PriorityQueue<E> extends Ab
406		* @return {@code true} if this queue contains the specified element
407		*/
408		public boolean contains(Object o) {
409	<	return indexOf(o) != -1;
409	>	return indexOf(o) >= 0;
410		}
411
412		/**
#	Line 433 | Line 448 | public class PriorityQueue<E> extends Ab
448		* The following code can be used to dump the queue into a newly
449		* allocated array of {@code String}:
450		*
451	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
451	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
452		*
453		* Note that {@code toArray(new Object[0])} is identical in function to
454		* {@code toArray()}.
#	Line 448 | Line 463 | public class PriorityQueue<E> extends Ab
463		* @throws NullPointerException if the specified array is null
464		*/
465		public <T> T[] toArray(T[] a) {
466	+	final int size = this.size;
467		if (a.length < size)
468		// Make a new array of a's runtime type, but my contents:
469		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 472 | Line 488 | public class PriorityQueue<E> extends Ab
488		* Index (into queue array) of element to be returned by
489		* subsequent call to next.
490		*/
491	<	private int cursor = 0;
491	>	private int cursor;
492
493		/**
494		* Index of element returned by most recent call to next,
#	Line 492 | Line 508 | public class PriorityQueue<E> extends Ab
508		* We expect that most iterations, even those involving removals,
509		* will not need to store elements in this field.
510		*/
511	<	private ArrayDeque<E> forgetMeNot = null;
511	>	private ArrayDeque<E> forgetMeNot;
512
513		/**
514		* Element returned by the most recent call to next iff that
515		* element was drawn from the forgetMeNot list.
516		*/
517	<	private E lastRetElt = null;
517	>	private E lastRetElt;
518
519		/**
520		* The modCount value that the iterator believes that the backing
#	Line 507 | Line 523 | public class PriorityQueue<E> extends Ab
523		*/
524		private int expectedModCount = modCount;
525
526	+	Itr() {}                        // prevent access constructor creation
527	+
528		public boolean hasNext() {
529		return cursor < size ||
530		(forgetMeNot != null && !forgetMeNot.isEmpty());
#	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		public E poll() {
587	<	if (size == 0)
588	<	return null;
589	<	int s = --size;
590	<	modCount++;
591	<	E result = (E) queue[0];
592	<	E x = (E) queue[s];
593	<	queue[s] = null;
594	<	if (s != 0)
595	<	siftDown(0, x);
587	>	final Object[] es;
588	>	final E result;
589	>
590	>	if ((result = (E) ((es = queue)[0])) != null) {
591	>	modCount++;
592	>	final int n;
593	>	final E x = (E) es[(n = --size)];
594	>	es[n] = null;
595	>	if (n > 0) {
596	>	final Comparator<? super E> cmp;
597	>	if ((cmp = comparator) == null)
598	>	siftDownComparable(0, x, es, n);
599	>	else
600	>	siftDownUsingComparator(0, x, es, n, cmp);
601	>	}
602	>	}
603		return result;
604		}
605
#	Line 589 | Line 615 | public class PriorityQueue<E> extends Ab
615		* position before i. This fact is used by iterator.remove so as to
616		* avoid missing traversing elements.
617		*/
618	<	private E removeAt(int i) {
618	>	E removeAt(int i) {
619		// assert i >= 0 && i < size;
620		modCount++;
621		int s = --size;
#	Line 613 | Line 639 | public class PriorityQueue<E> extends Ab
639		* promoting x up the tree until it is greater than or equal to
640		* its parent, or is the root.
641		*
642	<	* To simplify and speed up coercions and comparisons. the
642	>	* To simplify and speed up coercions and comparisons, the
643		* Comparable and Comparator versions are separated into different
644		* methods that are otherwise identical. (Similarly for siftDown.)
645		*
#	Line 622 | Line 648 | public class PriorityQueue<E> extends Ab
648		*/
649		private void siftUp(int k, E x) {
650		if (comparator != null)
651	<	siftUpUsingComparator(k, x);
651	>	siftUpUsingComparator(k, x, queue, comparator);
652		else
653	<	siftUpComparable(k, x);
653	>	siftUpComparable(k, x, queue);
654		}
655
656	<	private void siftUpComparable(int k, E x) {
657	<	Comparable<? super E> key = (Comparable<? super E>) x;
656	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
657	>	Comparable<? super T> key = (Comparable<? super T>) x;
658		while (k > 0) {
659		int parent = (k - 1) >>> 1;
660	<	Object e = queue[parent];
661	<	if (key.compareTo((E) e) >= 0)
660	>	Object e = es[parent];
661	>	if (key.compareTo((T) e) >= 0)
662		break;
663	<	queue[k] = e;
663	>	es[k] = e;
664		k = parent;
665		}
666	<	queue[k] = key;
666	>	es[k] = key;
667		}
668
669	<	private void siftUpUsingComparator(int k, E x) {
669	>	private static <T> void siftUpUsingComparator(
670	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
671		while (k > 0) {
672		int parent = (k - 1) >>> 1;
673	<	Object e = queue[parent];
674	<	if (comparator.compare(x, (E) e) >= 0)
673	>	Object e = es[parent];
674	>	if (cmp.compare(x, (T) e) >= 0)
675		break;
676	<	queue[k] = e;
676	>	es[k] = e;
677		k = parent;
678		}
679	<	queue[k] = x;
679	>	es[k] = x;
680		}
681
682		/**
#	Line 662 | Line 689 | public class PriorityQueue<E> extends Ab
689		*/
690		private void siftDown(int k, E x) {
691		if (comparator != null)
692	<	siftDownUsingComparator(k, x);
692	>	siftDownUsingComparator(k, x, queue, size, comparator);
693		else
694	<	siftDownComparable(k, x);
694	>	siftDownComparable(k, x, queue, size);
695		}
696
697	<	private void siftDownComparable(int k, E x) {
698	<	Comparable<? super E> key = (Comparable<? super E>)x;
699	<	int half = size >>> 1;        // loop while a non-leaf
697	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
698	>	// assert n > 0;
699	>	Comparable<? super T> key = (Comparable<? super T>)x;
700	>	int half = n >>> 1;           // loop while a non-leaf
701		while (k < half) {
702		int child = (k << 1) + 1; // assume left child is least
703	<	Object c = queue[child];
703	>	Object c = es[child];
704		int right = child + 1;
705	<	if (right < size &&
706	<	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
707	<	c = queue[child = right];
708	<	if (key.compareTo((E) c) <= 0)
705	>	if (right < n &&
706	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
707	>	c = es[child = right];
708	>	if (key.compareTo((T) c) <= 0)
709		break;
710	<	queue[k] = c;
710	>	es[k] = c;
711		k = child;
712		}
713	<	queue[k] = key;
713	>	es[k] = key;
714		}
715
716	<	private void siftDownUsingComparator(int k, E x) {
717	<	int half = size >>> 1;
716	>	private static <T> void siftDownUsingComparator(
717	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
718	>	// assert n > 0;
719	>	int half = n >>> 1;
720		while (k < half) {
721		int child = (k << 1) + 1;
722	<	Object c = queue[child];
722	>	Object c = es[child];
723		int right = child + 1;
724	<	if (right < size &&
725	<	comparator.compare((E) c, (E) queue[right]) > 0)
726	<	c = queue[child = right];
697	<	if (comparator.compare(x, (E) c) <= 0)
724	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
725	>	c = es[child = right];
726	>	if (cmp.compare(x, (T) c) <= 0)
727		break;
728	<	queue[k] = c;
728	>	es[k] = c;
729		k = child;
730		}
731	<	queue[k] = x;
731	>	es[k] = x;
732		}
733
734		/**
735		* Establishes the heap invariant (described above) in the entire tree,
736		* assuming nothing about the order of the elements prior to the call.
737	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
738		*/
739		private void heapify() {
740	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
741	<	siftDown(i, (E) queue[i]);
740	>	final Object[] es = queue;
741	>	int n = size, i = (n >>> 1) - 1;
742	>	final Comparator<? super E> cmp;
743	>	if ((cmp = comparator) == null)
744	>	for (; i >= 0; i--)
745	>	siftDownComparable(i, (E) es[i], es, n);
746	>	else
747	>	for (; i >= 0; i--)
748	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
749		}
750
751		/**
#	Line 727 | Line 764 | public class PriorityQueue<E> extends Ab
764		/**
765		* Saves this queue to a stream (that is, serializes it).
766		*
767	+	* @param s the stream
768	+	* @throws java.io.IOException if an I/O error occurs
769		* @serialData The length of the array backing the instance is
770		*             emitted (int), followed by all of its elements
771		*             (each an {@code Object}) in the proper order.
#	Line 740 | Line 779 | public class PriorityQueue<E> extends Ab
779		s.writeInt(Math.max(2, size + 1));
780
781		// Write out all elements in the "proper order".
782	<	for (int i = 0; i < size; i++)
783	<	s.writeObject(queue[i]);
782	>	final Object[] es = queue;
783	>	for (int i = 0, n = size; i < n; i++)
784	>	s.writeObject(es[i]);
785		}
786
787		/**
788	<	* Reconstitutes this queue from a stream (that is, deserializes it).
788	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
789	>	* (that is, deserializes it).
790	>	*
791	>	* @param s the stream
792	>	* @throws ClassNotFoundException if the class of a serialized object
793	>	*         could not be found
794	>	* @throws java.io.IOException if an I/O error occurs
795		*/
796		private void readObject(java.io.ObjectInputStream s)
797		throws java.io.IOException, ClassNotFoundException {
#	Line 755 | Line 801 | public class PriorityQueue<E> extends Ab
801		// Read in (and discard) array length
802		s.readInt();
803
804	<	queue = new Object[size];
804	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
805	>	final Object[] es = queue = new Object[Math.max(size, 1)];
806
807		// Read in all elements.
808	<	for (int i = 0; i < size; i++)
809	<	queue[i] = s.readObject();
808	>	for (int i = 0, n = size; i < n; i++)
809	>	es[i] = s.readObject();
810
811		// Elements are guaranteed to be in "proper order", but the
812		// spec has never explained what that might be.
813		heapify();
814		}
815	+
816	+	/**
817	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
818	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
819	+	* queue. The spliterator does not traverse elements in any particular order
820	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
821	+	*
822	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
823	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
824	+	* Overriding implementations should document the reporting of additional
825	+	* characteristic values.
826	+	*
827	+	* @return a {@code Spliterator} over the elements in this queue
828	+	* @since 1.8
829	+	*/
830	+	public final Spliterator<E> spliterator() {
831	+	return new PriorityQueueSpliterator(0, -1, 0);
832	+	}
833	+
834	+	final class PriorityQueueSpliterator implements Spliterator<E> {
835	+	private int index;            // current index, modified on advance/split
836	+	private int fence;            // -1 until first use
837	+	private int expectedModCount; // initialized when fence set
838	+
839	+	/** Creates new spliterator covering the given range. */
840	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
841	+	this.index = origin;
842	+	this.fence = fence;
843	+	this.expectedModCount = expectedModCount;
844	+	}
845	+
846	+	private int getFence() { // initialize fence to size on first use
847	+	int hi;
848	+	if ((hi = fence) < 0) {
849	+	expectedModCount = modCount;
850	+	hi = fence = size;
851	+	}
852	+	return hi;
853	+	}
854	+
855	+	public PriorityQueueSpliterator trySplit() {
856	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
857	+	return (lo >= mid) ? null :
858	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
859	+	}
860	+
861	+	public void forEachRemaining(Consumer<? super E> action) {
862	+	if (action == null)
863	+	throw new NullPointerException();
864	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
865	+	final Object[] es = queue;
866	+	int i, hi; E e;
867	+	for (i = index, index = hi = fence; i < hi; i++) {
868	+	if ((e = (E) es[i]) == null)
869	+	break;      // must be CME
870	+	action.accept(e);
871	+	}
872	+	if (modCount != expectedModCount)
873	+	throw new ConcurrentModificationException();
874	+	}
875	+
876	+	public boolean tryAdvance(Consumer<? super E> action) {
877	+	if (action == null)
878	+	throw new NullPointerException();
879	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
880	+	int i;
881	+	if ((i = index) < fence) {
882	+	index = i + 1;
883	+	E e;
884	+	if ((e = (E) queue[i]) == null
885	+	|| modCount != expectedModCount)
886	+	throw new ConcurrentModificationException();
887	+	action.accept(e);
888	+	return true;
889	+	}
890	+	return false;
891	+	}
892	+
893	+	public long estimateSize() {
894	+	return getFence() - index;
895	+	}
896	+
897	+	public int characteristics() {
898	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
899	+	}
900	+	}
901	+
902	+	/**
903	+	* @throws NullPointerException {@inheritDoc}
904	+	*/
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		}

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines