--- jsr166/src/main/java/util/PriorityQueue.java 2013/01/16 15:06:10 1.81
+++ jsr166/src/main/java/util/PriorityQueue.java 2016/08/24 21:46:18 1.110
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -24,10 +24,8 @@
*/
package java.util;
-import java.util.stream.Stream;
-import java.util.Spliterator;
-import java.util.stream.Streams;
-import java.util.function.Block;
+
+import java.util.function.Consumer;
/**
* An unbounded priority {@linkplain Queue queue} based on a priority heap.
@@ -60,14 +58,14 @@ import java.util.function.Block;
* the priority queue in any particular order. If you need ordered
* traversal, consider using {@code Arrays.sort(pq.toArray())}.
*
- *
Note that this implementation is not synchronized.
+ *
Note that this implementation is not synchronized.
* Multiple threads should not access a {@code PriorityQueue}
* instance concurrently if any of the threads modifies the queue.
* Instead, use the thread-safe {@link
* java.util.concurrent.PriorityBlockingQueue} class.
*
*
Implementation note: this implementation provides
- * O(log(n)) time for the enqueing and dequeing methods
+ * O(log(n)) time for the enqueuing and dequeuing methods
* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
* linear time for the {@code remove(Object)} and {@code contains(Object)}
* methods; and constant time for the retrieval methods
@@ -79,7 +77,7 @@ import java.util.function.Block;
*
* @since 1.5
* @author Josh Bloch, Doug Lea
- * @param the type of elements held in this collection
+ * @param the type of elements held in this queue
*/
public class PriorityQueue extends AbstractQueue
implements java.io.Serializable {
@@ -101,7 +99,7 @@ public class PriorityQueue extends Ab
/**
* The number of elements in the priority queue.
*/
- private int size = 0;
+ int size;
/**
* The comparator, or null if priority queue uses elements'
@@ -113,7 +111,7 @@ public class PriorityQueue extends Ab
* The number of times this priority queue has been
* structurally modified. See AbstractList for gory details.
*/
- transient int modCount = 0; // non-private to simplify nested class access
+ transient int modCount; // non-private to simplify nested class access
/**
* Creates a {@code PriorityQueue} with the default initial
@@ -138,6 +136,19 @@ public class PriorityQueue extends Ab
}
/**
+ * Creates a {@code PriorityQueue} with the default initial capacity and
+ * whose elements are ordered according to the specified comparator.
+ *
+ * @param comparator the comparator that will be used to order this
+ * priority queue. If {@code null}, the {@linkplain Comparable
+ * natural ordering} of the elements will be used.
+ * @since 1.8
+ */
+ public PriorityQueue(Comparator super E> comparator) {
+ this(DEFAULT_INITIAL_CAPACITY, comparator);
+ }
+
+ /**
* Creates a {@code PriorityQueue} with the specified initial capacity
* that orders its elements according to the specified comparator.
*
@@ -247,8 +258,8 @@ public class PriorityQueue extends Ab
a = Arrays.copyOf(a, a.length, Object[].class);
int len = a.length;
if (len == 1 || this.comparator != null)
- for (int i = 0; i < len; i++)
- if (a[i] == null)
+ for (Object e : a)
+ if (e == null)
throw new NullPointerException();
this.queue = a;
this.size = a.length;
@@ -326,11 +337,8 @@ public class PriorityQueue extends Ab
int i = size;
if (i >= queue.length)
grow(i + 1);
+ siftUp(i, e);
size = i + 1;
- if (i == 0)
- queue[0] = e;
- else
- siftUp(i, e);
return true;
}
@@ -395,7 +403,7 @@ public class PriorityQueue extends Ab
* @return {@code true} if this queue contains the specified element
*/
public boolean contains(Object o) {
- return indexOf(o) != -1;
+ return indexOf(o) >= 0;
}
/**
@@ -437,7 +445,7 @@ public class PriorityQueue extends Ab
* The following code can be used to dump the queue into a newly
* allocated array of {@code String}:
*
- * {@code String[] y = x.toArray(new String[0]);}
+ * {@code String[] y = x.toArray(new String[0]);}
*
* Note that {@code toArray(new Object[0])} is identical in function to
* {@code toArray()}.
@@ -451,7 +459,9 @@ public class PriorityQueue extends Ab
* this queue
* @throws NullPointerException if the specified array is null
*/
+ @SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
+ final int size = this.size;
if (a.length < size)
// Make a new array of a's runtime type, but my contents:
return (T[]) Arrays.copyOf(queue, size, a.getClass());
@@ -476,7 +486,7 @@ public class PriorityQueue extends Ab
* Index (into queue array) of element to be returned by
* subsequent call to next.
*/
- private int cursor = 0;
+ private int cursor;
/**
* Index of element returned by most recent call to next,
@@ -496,13 +506,13 @@ public class PriorityQueue extends Ab
* We expect that most iterations, even those involving removals,
* will not need to store elements in this field.
*/
- private ArrayDeque forgetMeNot = null;
+ private ArrayDeque forgetMeNot;
/**
* Element returned by the most recent call to next iff that
* element was drawn from the forgetMeNot list.
*/
- private E lastRetElt = null;
+ private E lastRetElt;
/**
* The modCount value that the iterator believes that the backing
@@ -541,7 +551,7 @@ public class PriorityQueue extends Ab
cursor--;
else {
if (forgetMeNot == null)
- forgetMeNot = new ArrayDeque();
+ forgetMeNot = new ArrayDeque<>();
forgetMeNot.add(moved);
}
} else if (lastRetElt != null) {
@@ -596,7 +606,7 @@ public class PriorityQueue extends Ab
* avoid missing traversing elements.
*/
@SuppressWarnings("unchecked")
- private E removeAt(int i) {
+ E removeAt(int i) {
// assert i >= 0 && i < size;
modCount++;
int s = --size;
@@ -739,10 +749,11 @@ public class PriorityQueue extends Ab
/**
* Saves this queue to a stream (that is, serializes it).
*
+ * @param s the stream
+ * @throws java.io.IOException if an I/O error occurs
* @serialData The length of the array backing the instance is
* emitted (int), followed by all of its elements
* (each an {@code Object}) in the proper order.
- * @param s the stream
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
@@ -762,6 +773,9 @@ public class PriorityQueue extends Ab
* (that is, deserializes it).
*
* @param s the stream
+ * @throws ClassNotFoundException if the class of a serialized object
+ * could not be found
+ * @throws java.io.IOException if an I/O error occurs
*/
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
@@ -782,91 +796,111 @@ public class PriorityQueue extends Ab
heapify();
}
- // wrapping constructor in method avoids transient javac problems
- final PriorityQueueSpliterator spliterator(int origin, int fence,
- int expectedModCount) {
- return new PriorityQueueSpliterator(this, origin, fence,
- expectedModCount);
- }
-
- public Stream stream() {
- int flags = Streams.STREAM_IS_SIZED;
- return Streams.stream
- (() -> spliterator(0, size, modCount), flags);
- }
- public Stream parallelStream() {
- int flags = Streams.STREAM_IS_SIZED;
- return Streams.parallelStream
- (() -> spliterator(0, size, modCount), flags);
- }
-
- /** Index-based split-by-two Spliterator */
- static final class PriorityQueueSpliterator
- implements Spliterator, Iterator {
+ /**
+ * Creates a late-binding
+ * and fail-fast {@link Spliterator} over the elements in this
+ * queue.
+ *
+ * The {@code Spliterator} reports {@link Spliterator#SIZED},
+ * {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
+ * Overriding implementations should document the reporting of additional
+ * characteristic values.
+ *
+ * @return a {@code Spliterator} over the elements in this queue
+ * @since 1.8
+ */
+ public final Spliterator spliterator() {
+ return new PriorityQueueSpliterator<>(this, 0, -1, 0);
+ }
+
+ static final class PriorityQueueSpliterator implements Spliterator {
+ /*
+ * This is very similar to ArrayList Spliterator, except for
+ * extra null checks.
+ */
private final PriorityQueue pq;
- private int index; // current index, modified on advance/split
- private final int fence; // one past last index
- private final int expectedModCount; // for comodification checks
+ private int index; // current index, modified on advance/split
+ private int fence; // -1 until first use
+ private int expectedModCount; // initialized when fence set
- /** Create new spliterator covering the given range */
+ /** Creates new spliterator covering the given range. */
PriorityQueueSpliterator(PriorityQueue pq, int origin, int fence,
- int expectedModCount) {
- this.pq = pq; this.index = origin; this.fence = fence;
+ int expectedModCount) {
+ this.pq = pq;
+ this.index = origin;
+ this.fence = fence;
this.expectedModCount = expectedModCount;
}
+ private int getFence() { // initialize fence to size on first use
+ int hi;
+ if ((hi = fence) < 0) {
+ expectedModCount = pq.modCount;
+ hi = fence = pq.size;
+ }
+ return hi;
+ }
+
public PriorityQueueSpliterator trySplit() {
- int lo = index, mid = (lo + fence) >>> 1;
+ int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
return (lo >= mid) ? null :
- new PriorityQueueSpliterator(pq, lo, index = mid,
- expectedModCount);
+ new PriorityQueueSpliterator<>(pq, lo, index = mid,
+ expectedModCount);
}
- public void forEach(Block super E> block) {
- Object[] a; int i, hi; // hoist accesses and checks from loop
- if (block == null)
+ @SuppressWarnings("unchecked")
+ public void forEachRemaining(Consumer super E> action) {
+ int i, hi, mc; // hoist accesses and checks from loop
+ PriorityQueue q; Object[] a;
+ if (action == null)
throw new NullPointerException();
- if ((a = pq.queue).length >= (hi = fence) &&
- (i = index) >= 0 && i < hi) {
- index = hi;
- do {
- @SuppressWarnings("unchecked") E e = (E) a[i];
- block.accept(e);
- } while (++i < hi);
- if (pq.modCount != expectedModCount)
- throw new ConcurrentModificationException();
+ if ((q = pq) != null && (a = q.queue) != null) {
+ if ((hi = fence) < 0) {
+ mc = q.modCount;
+ hi = q.size;
+ }
+ else
+ mc = expectedModCount;
+ if ((i = index) >= 0 && (index = hi) <= a.length) {
+ for (E e;; ++i) {
+ if (i < hi) {
+ if ((e = (E) a[i]) == null) // must be CME
+ break;
+ action.accept(e);
+ }
+ else if (q.modCount != mc)
+ break;
+ else
+ return;
+ }
+ }
}
+ throw new ConcurrentModificationException();
}
- public boolean tryAdvance(Block super E> block) {
- if (index >= 0 && index < fence) {
+ public boolean tryAdvance(Consumer super E> action) {
+ if (action == null)
+ throw new NullPointerException();
+ int hi = getFence(), lo = index;
+ if (lo >= 0 && lo < hi) {
+ index = lo + 1;
+ @SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
+ if (e == null)
+ throw new ConcurrentModificationException();
+ action.accept(e);
if (pq.modCount != expectedModCount)
throw new ConcurrentModificationException();
- @SuppressWarnings("unchecked") E e =
- (E)pq.queue[index++];
- block.accept(e);
return true;
}
return false;
}
- public long estimateSize() { return (long)(fence - index); }
- public boolean hasExactSize() { return true; }
- public boolean hasExactSplits() { return true; }
-
- // Iterator support
- public Iterator iterator() { return this; }
- public void remove() { throw new UnsupportedOperationException(); }
- public boolean hasNext() { return index >= 0 && index < fence; }
+ public long estimateSize() {
+ return (long) (getFence() - index);
+ }
- public E next() {
- if (index < 0 || index >= fence)
- throw new NoSuchElementException();
- if (pq.modCount != expectedModCount)
- throw new ConcurrentModificationException();
- @SuppressWarnings("unchecked") E e =
- (E) pq.queue[index++];
- return e;
+ public int characteristics() {
+ return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
}
}
}