--- jsr166/src/main/java/util/PriorityQueue.java 2014/04/11 21:15:44 1.99
+++ jsr166/src/main/java/util/PriorityQueue.java 2018/05/06 02:08:36 1.122
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2018, 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
@@ -24,8 +24,9 @@
*/
package java.util;
+
import java.util.function.Consumer;
-import java.util.stream.Stream;
+import jdk.internal.misc.SharedSecrets;
/**
* An unbounded priority {@linkplain Queue queue} based on a priority heap.
@@ -54,7 +55,8 @@ import java.util.stream.Stream;
* This class and its iterator implement all of the
* optional methods of the {@link Collection} and {@link
* Iterator} interfaces. The Iterator provided in method {@link
- * #iterator()} is not guaranteed to traverse the elements of
+ * #iterator()} and the Spliterator provided in method {@link #spliterator()}
+ * are not guaranteed to traverse the elements of
* the priority queue in any particular order. If you need ordered
* traversal, consider using {@code Arrays.sort(pq.toArray())}.
*
@@ -72,12 +74,12 @@ import java.util.stream.Stream;
* ({@code peek}, {@code element}, and {@code size}).
*
*
This class is a member of the
- *
+ *
* Java Collections Framework.
*
* @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 {
@@ -99,7 +101,7 @@ public class PriorityQueue extends Ab
/**
* The number of elements in the priority queue.
*/
- private int size;
+ int size;
/**
* The comparator, or null if priority queue uses elements'
@@ -111,7 +113,7 @@ 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
@@ -136,6 +138,19 @@ 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 comparator) {
+ this(DEFAULT_INITIAL_CAPACITY, comparator);
+ }
+
+ /**
* Creates a {@code PriorityQueue} with the specified initial capacity
* that orders its elements according to the specified comparator.
*
@@ -245,8 +260,8 @@ 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;
@@ -324,11 +339,8 @@ 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;
}
@@ -393,7 +405,7 @@ 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;
}
/**
@@ -435,7 +447,7 @@ 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()}.
@@ -511,6 +523,8 @@ public class PriorityQueue extends Ab
*/
private int expectedModCount = modCount;
+ Itr() {} // prevent access constructor creation
+
public boolean hasNext() {
return cursor < size ||
(forgetMeNot != null && !forgetMeNot.isEmpty());
@@ -596,7 +610,7 @@ 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;
@@ -620,7 +634,7 @@ public class PriorityQueue extends Ab
* promoting x up the tree until it is greater than or equal to
* its parent, or is the root.
*
- * To simplify and speed up coercions and comparisons. the
+ * To simplify and speed up coercions and comparisons, the
* Comparable and Comparator versions are separated into different
* methods that are otherwise identical. (Similarly for siftDown.)
*
@@ -716,11 +730,18 @@ public class PriorityQueue extends Ab
/**
* Establishes the heap invariant (described above) in the entire tree,
* assuming nothing about the order of the elements prior to the call.
+ * This classic algorithm due to Floyd (1964) is known to be O(size).
*/
@SuppressWarnings("unchecked")
private void heapify() {
- for (int i = (size >>> 1) - 1; i >= 0; i--)
- siftDown(i, (E) queue[i]);
+ final Object[] es = queue;
+ int i = (size >>> 1) - 1;
+ if (comparator == null)
+ for (; i >= 0; i--)
+ siftDownComparable(i, (E) es[i]);
+ else
+ for (; i >= 0; i--)
+ siftDownUsingComparator(i, (E) es[i]);
}
/**
@@ -739,11 +760,11 @@ 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
- * @throws java.io.IOException if an I/O error occurs
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
@@ -775,6 +796,7 @@ public class PriorityQueue extends Ab
// Read in (and discard) array length
s.readInt();
+ SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
queue = new Object[size];
// Read in all elements.
@@ -786,24 +808,31 @@ public class PriorityQueue extends Ab
heapify();
}
- public Spliterator spliterator() {
- return new PriorityQueueSpliterator(this, 0, -1, 0);
- }
-
/**
- * This is very similar to ArrayList Spliterator, except for extra
- * null checks.
+ * Creates a late-binding
+ * and fail-fast {@link Spliterator} over the elements in this
+ * queue. The spliterator does not traverse elements in any particular order
+ * (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
+ *
+ * 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
*/
- static final class PriorityQueueSpliterator implements Spliterator {
- private final PriorityQueue pq;
+ public final Spliterator spliterator() {
+ return new PriorityQueueSpliterator(0, -1, 0);
+ }
+
+ final class PriorityQueueSpliterator implements Spliterator {
private int index; // current index, modified on advance/split
private int fence; // -1 until first use
private int expectedModCount; // initialized when fence set
- /** Creates new spliterator covering the given range */
- PriorityQueueSpliterator(PriorityQueue pq, int origin, int fence,
- int expectedModCount) {
- this.pq = pq;
+ /** Creates new spliterator covering the given range. */
+ PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
this.index = origin;
this.fence = fence;
this.expectedModCount = expectedModCount;
@@ -812,70 +841,72 @@ public class PriorityQueue extends Ab
private int getFence() { // initialize fence to size on first use
int hi;
if ((hi = fence) < 0) {
- expectedModCount = pq.modCount;
- hi = fence = pq.size;
+ expectedModCount = modCount;
+ hi = fence = size;
}
return hi;
}
- public Spliterator trySplit() {
+ public PriorityQueueSpliterator trySplit() {
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
return (lo >= mid) ? null :
- new PriorityQueueSpliterator(pq, lo, index = mid,
- expectedModCount);
+ new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
}
@SuppressWarnings("unchecked")
public void forEachRemaining(Consumer action) {
- int i, hi, mc; // hoist accesses and checks from loop
- PriorityQueue q; Object[] a;
if (action == null)
throw new NullPointerException();
- 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;
- }
- }
+ if (fence < 0) { fence = size; expectedModCount = modCount; }
+ final Object[] a = queue;
+ int i, hi; E e;
+ for (i = index, index = hi = fence; i < hi; i++) {
+ if ((e = (E) a[i]) == null)
+ break; // must be CME
+ action.accept(e);
}
- throw new ConcurrentModificationException();
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
}
+ @SuppressWarnings("unchecked")
public boolean tryAdvance(Consumer action) {
- int hi = getFence(), lo = index;
- if (lo >= 0 && lo < hi) {
- index = lo + 1;
- @SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
- if (e == null)
+ if (action == null)
+ throw new NullPointerException();
+ if (fence < 0) { fence = size; expectedModCount = modCount; }
+ int i;
+ if ((i = index) < fence) {
+ index = i + 1;
+ E e;
+ if ((e = (E) queue[i]) == null
+ || modCount != expectedModCount)
throw new ConcurrentModificationException();
action.accept(e);
- if (pq.modCount != expectedModCount)
- throw new ConcurrentModificationException();
return true;
}
return false;
}
public long estimateSize() {
- return (long) (getFence() - index);
+ return getFence() - index;
}
public int characteristics() {
return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
}
}
+
+ /**
+ * @throws NullPointerException {@inheritDoc}
+ */
+ @SuppressWarnings("unchecked")
+ public void forEach(Consumer action) {
+ Objects.requireNonNull(action);
+ final int expectedModCount = modCount;
+ final Object[] es = queue;
+ for (int i = 0, n = size; i < n; i++)
+ action.accept((E) es[i]);
+ if (expectedModCount != modCount)
+ throw new ConcurrentModificationException();
+ }
}