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/* |
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* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. |
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* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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package java.util; |
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import java.util.function.Consumer; |
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import jdk.internal.misc.SharedSecrets; |
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/** |
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* An unbounded priority {@linkplain Queue queue} based on a priority heap. |
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* <p>This class and its iterator implement all of the |
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* <em>optional</em> methods of the {@link Collection} and {@link |
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* Iterator} interfaces. The Iterator provided in method {@link |
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* #iterator()} is <em>not</em> guaranteed to traverse the elements of |
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* #iterator()} and the Spliterator provided in method {@link #spliterator()} |
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* are <em>not</em> guaranteed to traverse the elements of |
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* the priority queue in any particular order. If you need ordered |
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* traversal, consider using {@code Arrays.sort(pq.toArray())}. |
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* |
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* ({@code peek}, {@code element}, and {@code size}). |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework"> |
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* Java Collections Framework</a>. |
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* |
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* @since 1.5 |
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*/ |
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private int expectedModCount = modCount; |
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Itr() {} // prevent access constructor creation |
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|
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public boolean hasNext() { |
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return cursor < size || |
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(forgetMeNot != null && !forgetMeNot.isEmpty()); |
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* promoting x up the tree until it is greater than or equal to |
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* its parent, or is the root. |
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* |
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* To simplify and speed up coercions and comparisons. the |
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* To simplify and speed up coercions and comparisons, the |
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* Comparable and Comparator versions are separated into different |
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* methods that are otherwise identical. (Similarly for siftDown.) |
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* |
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/** |
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* Establishes the heap invariant (described above) in the entire tree, |
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* assuming nothing about the order of the elements prior to the call. |
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* This classic algorithm due to Floyd (1964) is known to be O(size). |
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*/ |
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@SuppressWarnings("unchecked") |
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private void heapify() { |
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for (int i = (size >>> 1) - 1; i >= 0; i--) |
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siftDown(i, (E) queue[i]); |
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final Object[] es = queue; |
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int i = (size >>> 1) - 1; |
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if (comparator == null) |
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for (; i >= 0; i--) |
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siftDownComparable(i, (E) es[i]); |
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else |
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for (; i >= 0; i--) |
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siftDownUsingComparator(i, (E) es[i]); |
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} |
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/** |
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// Read in (and discard) array length |
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s.readInt(); |
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SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size); |
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queue = new Object[size]; |
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|
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// Read in all elements. |
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/** |
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* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
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* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
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* queue. |
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* queue. The spliterator does not traverse elements in any particular order |
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* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported). |
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* |
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* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
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* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}. |
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* @since 1.8 |
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*/ |
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public final Spliterator<E> spliterator() { |
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return new PriorityQueueSpliterator<>(this, 0, -1, 0); |
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return new PriorityQueueSpliterator(0, -1, 0); |
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} |
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static final class PriorityQueueSpliterator<E> implements Spliterator<E> { |
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/* |
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* This is very similar to ArrayList Spliterator, except for |
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* extra null checks. |
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*/ |
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private final PriorityQueue<E> pq; |
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final class PriorityQueueSpliterator implements Spliterator<E> { |
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private int index; // current index, modified on advance/split |
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private int fence; // -1 until first use |
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private int expectedModCount; // initialized when fence set |
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/** Creates new spliterator covering the given range. */ |
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PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence, |
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int expectedModCount) { |
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this.pq = pq; |
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PriorityQueueSpliterator(int origin, int fence, int expectedModCount) { |
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this.index = origin; |
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this.fence = fence; |
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this.expectedModCount = expectedModCount; |
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private int getFence() { // initialize fence to size on first use |
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int hi; |
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if ((hi = fence) < 0) { |
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expectedModCount = pq.modCount; |
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hi = fence = pq.size; |
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expectedModCount = modCount; |
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hi = fence = size; |
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} |
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return hi; |
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} |
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public PriorityQueueSpliterator<E> trySplit() { |
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public PriorityQueueSpliterator trySplit() { |
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int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; |
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return (lo >= mid) ? null : |
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new PriorityQueueSpliterator<>(pq, lo, index = mid, |
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expectedModCount); |
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new PriorityQueueSpliterator(lo, index = mid, expectedModCount); |
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} |
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@SuppressWarnings("unchecked") |
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public void forEachRemaining(Consumer<? super E> action) { |
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int i, hi, mc; // hoist accesses and checks from loop |
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PriorityQueue<E> q; Object[] a; |
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if (action == null) |
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throw new NullPointerException(); |
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if ((q = pq) != null && (a = q.queue) != null) { |
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if ((hi = fence) < 0) { |
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mc = q.modCount; |
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hi = q.size; |
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} |
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else |
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mc = expectedModCount; |
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if ((i = index) >= 0 && (index = hi) <= a.length) { |
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for (E e;; ++i) { |
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if (i < hi) { |
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if ((e = (E) a[i]) == null) // must be CME |
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break; |
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action.accept(e); |
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} |
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else if (q.modCount != mc) |
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break; |
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else |
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return; |
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} |
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} |
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if (fence < 0) { fence = size; expectedModCount = modCount; } |
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final Object[] a = queue; |
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int i, hi; E e; |
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for (i = index, index = hi = fence; i < hi; i++) { |
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if ((e = (E) a[i]) == null) |
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break; // must be CME |
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action.accept(e); |
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} |
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throw new ConcurrentModificationException(); |
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if (modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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} |
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@SuppressWarnings("unchecked") |
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public boolean tryAdvance(Consumer<? super E> action) { |
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if (action == null) |
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throw new NullPointerException(); |
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int hi = getFence(), lo = index; |
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if (lo >= 0 && lo < hi) { |
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index = lo + 1; |
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@SuppressWarnings("unchecked") E e = (E)pq.queue[lo]; |
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if (e == null) |
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if (fence < 0) { fence = size; expectedModCount = modCount; } |
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int i; |
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if ((i = index) < fence) { |
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index = i + 1; |
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E e; |
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if ((e = (E) queue[i]) == null |
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|| modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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action.accept(e); |
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if (pq.modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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return true; |
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} |
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return false; |
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} |
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public long estimateSize() { |
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return (long) (getFence() - index); |
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return getFence() - index; |
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} |
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public int characteristics() { |
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return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
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} |
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} |
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|
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/** |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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@SuppressWarnings("unchecked") |
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public void forEach(Consumer<? super E> action) { |
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Objects.requireNonNull(action); |
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final int expectedModCount = modCount; |
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final Object[] es = queue; |
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for (int i = 0, n = size; i < n; i++) |
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action.accept((E) es[i]); |
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if (expectedModCount != modCount) |
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throw new ConcurrentModificationException(); |
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} |
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} |
