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*/ |
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|
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package java.util; |
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+ |
|
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+ |
import java.util.function.Consumer; |
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import java.util.stream.Stream; |
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import java.util.Spliterator; |
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import java.util.stream.Streams; |
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import java.util.function.Block; |
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|
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/** |
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* An unbounded priority {@linkplain Queue queue} based on a priority heap. |
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* java.util.concurrent.PriorityBlockingQueue} class. |
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* |
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* <p>Implementation note: this implementation provides |
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< |
* O(log(n)) time for the enqueing and dequeing methods |
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> |
* O(log(n)) time for the enqueuing and dequeuing methods |
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* ({@code offer}, {@code poll}, {@code remove()} and {@code add}); |
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* linear time for the {@code remove(Object)} and {@code contains(Object)} |
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* methods; and constant time for the retrieval methods |
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* |
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* @since 1.5 |
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* @author Josh Bloch, Doug Lea |
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* @param <E> the type of elements held in this collection |
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> |
* @param <E> the type of elements held in this queue |
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*/ |
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public class PriorityQueue<E> extends AbstractQueue<E> |
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implements java.io.Serializable { |
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/** |
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* The number of elements in the priority queue. |
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*/ |
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private int size = 0; |
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> |
private int size; |
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|
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/** |
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* The comparator, or null if priority queue uses elements' |
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* @return {@code true} if this queue contains the specified element |
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*/ |
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public boolean contains(Object o) { |
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< |
return indexOf(o) != -1; |
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> |
return indexOf(o) >= 0; |
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|
} |
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|
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|
/** |
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* this queue |
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* @throws NullPointerException if the specified array is null |
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|
*/ |
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+ |
@SuppressWarnings("unchecked") |
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public <T> T[] toArray(T[] a) { |
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final int size = this.size; |
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if (a.length < size) |
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// Make a new array of a's runtime type, but my contents: |
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return (T[]) Arrays.copyOf(queue, size, a.getClass()); |
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* Index (into queue array) of element to be returned by |
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* subsequent call to next. |
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*/ |
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private int cursor = 0; |
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> |
private int cursor; |
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|
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/** |
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* Index of element returned by most recent call to next, |
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* We expect that most iterations, even those involving removals, |
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* will not need to store elements in this field. |
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*/ |
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< |
private ArrayDeque<E> forgetMeNot = null; |
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> |
private ArrayDeque<E> forgetMeNot; |
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|
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/** |
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* Element returned by the most recent call to next iff that |
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* element was drawn from the forgetMeNot list. |
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*/ |
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< |
private E lastRetElt = null; |
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> |
private E lastRetElt; |
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|
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/** |
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* The modCount value that the iterator believes that the backing |
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cursor--; |
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else { |
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if (forgetMeNot == null) |
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< |
forgetMeNot = new ArrayDeque<E>(); |
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> |
forgetMeNot = new ArrayDeque<>(); |
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|
forgetMeNot.add(moved); |
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|
} |
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} else if (lastRetElt != null) { |
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* emitted (int), followed by all of its elements |
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|
* (each an {@code Object}) in the proper order. |
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* @param s the stream |
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+ |
* @throws java.io.IOException if an I/O error occurs |
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|
*/ |
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|
private void writeObject(java.io.ObjectOutputStream s) |
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|
throws java.io.IOException { |
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|
* (that is, deserializes it). |
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|
* |
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|
* @param s the stream |
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* @throws ClassNotFoundException if the class of a serialized object |
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* could not be found |
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* @throws java.io.IOException if an I/O error occurs |
| 770 |
|
*/ |
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|
private void readObject(java.io.ObjectInputStream s) |
| 772 |
|
throws java.io.IOException, ClassNotFoundException { |
| 787 |
|
heapify(); |
| 788 |
|
} |
| 789 |
|
|
| 790 |
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// wrapping constructor in method avoids transient javac problems |
| 791 |
< |
final PriorityQueueSpliterator<E> spliterator(int origin, int fence, |
| 792 |
< |
int expectedModCount) { |
| 793 |
< |
return new PriorityQueueSpliterator<E>(this, origin, fence, |
| 794 |
< |
expectedModCount); |
| 795 |
< |
} |
| 796 |
< |
|
| 797 |
< |
public Stream<E> stream() { |
| 798 |
< |
int flags = Streams.STREAM_IS_SIZED; |
| 794 |
< |
return Streams.stream |
| 795 |
< |
(() -> spliterator(0, size, modCount), flags); |
| 796 |
< |
} |
| 797 |
< |
public Stream<E> parallelStream() { |
| 798 |
< |
int flags = Streams.STREAM_IS_SIZED; |
| 799 |
< |
return Streams.parallelStream |
| 800 |
< |
(() -> spliterator(0, size, modCount), flags); |
| 801 |
< |
} |
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< |
|
| 803 |
< |
/** Index-based split-by-two Spliterator */ |
| 804 |
< |
static final class PriorityQueueSpliterator<E> |
| 805 |
< |
implements Spliterator<E>, Iterator<E> { |
| 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> { |
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|
private final PriorityQueue<E> pq; |
| 800 |
< |
private int index; // current index, modified on advance/split |
| 801 |
< |
private final int fence; // one past last index |
| 802 |
< |
private final int expectedModCount; // for comodification checks |
| 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 |
< |
/** Create new spliterator covering the given range */ |
| 804 |
> |
/** Creates new spliterator covering the given range */ |
| 805 |
|
PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence, |
| 806 |
|
int expectedModCount) { |
| 807 |
< |
this.pq = pq; this.index = origin; this.fence = fence; |
| 807 |
> |
this.pq = pq; |
| 808 |
> |
this.index = origin; |
| 809 |
> |
this.fence = fence; |
| 810 |
|
this.expectedModCount = expectedModCount; |
| 811 |
|
} |
| 812 |
|
|
| 813 |
< |
public PriorityQueueSpliterator<E> trySplit() { |
| 814 |
< |
int lo = index, mid = (lo + fence) >>> 1; |
| 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); |
| 826 |
> |
expectedModCount); |
| 827 |
|
} |
| 828 |
|
|
| 829 |
< |
public void forEach(Block<? super E> block) { |
| 830 |
< |
Object[] a; int i, hi; // hoist accesses and checks from loop |
| 831 |
< |
if (block == null) |
| 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 ((a = pq.queue).length >= (hi = fence) && |
| 836 |
< |
(i = index) >= 0 && i < hi) { |
| 837 |
< |
index = hi; |
| 838 |
< |
do { |
| 839 |
< |
@SuppressWarnings("unchecked") E e = (E) a[i]; |
| 840 |
< |
block.accept(e); |
| 841 |
< |
} while (++i < hi); |
| 842 |
< |
if (pq.modCount != expectedModCount) |
| 843 |
< |
throw new ConcurrentModificationException(); |
| 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(Block<? super E> block) { |
| 860 |
< |
if (index >= 0 && index < fence) { |
| 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(); |
| 845 |
– |
@SuppressWarnings("unchecked") E e = |
| 846 |
– |
(E)pq.queue[index++]; |
| 847 |
– |
block.accept(e); |
| 869 |
|
return true; |
| 870 |
|
} |
| 871 |
|
return false; |
| 872 |
|
} |
| 873 |
|
|
| 874 |
< |
public long estimateSize() { return (long)(fence - index); } |
| 875 |
< |
public boolean hasExactSize() { return true; } |
| 876 |
< |
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; } |
| 874 |
> |
public long estimateSize() { |
| 875 |
> |
return (long) (getFence() - index); |
| 876 |
> |
} |
| 877 |
|
|
| 878 |
< |
public E next() { |
| 879 |
< |
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; |
| 878 |
> |
public int characteristics() { |
| 879 |
> |
return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
| 880 |
|
} |
| 881 |
|
} |
| 882 |
|
} |
