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package java.util; |
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/* |
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* Copyright (c) 2003, 2013, 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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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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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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|
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/** |
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* An unbounded priority {@linkplain Queue queue} based on a priority heap. |
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* This queue orders |
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* elements according to an order specified at construction time, which is |
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* specified in the same manner as {@link java.util.TreeSet} and |
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* {@link java.util.TreeMap}: elements are ordered |
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* either according to their <i>natural order</i> (see {@link Comparable}), or |
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* according to a {@link java.util.Comparator}, depending on which |
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* constructor is used. |
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* <p>The <em>head</em> of this queue is the <em>least</em> element with |
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* respect to the specified ordering. |
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* If multiple elements are tied for least value, the |
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* head is one of those elements. A priority queue does not permit |
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* <tt>null</tt> elements. |
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* |
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* <p>The {@link #remove()} and {@link #poll()} methods remove and |
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* return the head of the queue. |
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* |
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* <p>The {@link #element()} and {@link #peek()} methods return, but do |
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* not delete, the head of the queue. |
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* |
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* <p>A priority queue has a <i>capacity</i>. The capacity is the |
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* size of the array used internally to store the elements on the |
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* queue. |
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* It is always at least as large as the queue size. As |
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* elements are added to a priority queue, its capacity grows |
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* automatically. The details of the growth policy are not specified. |
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* |
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* <p>Implementation note: this implementation provides O(log(n)) time |
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* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>, |
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* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the |
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* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and |
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* constant time for the retrieval methods (<tt>peek</tt>, |
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* <tt>element</tt>, and <tt>size</tt>). |
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* An unbounded priority {@linkplain Queue queue} based on a priority heap. |
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* The elements of the priority queue are ordered according to their |
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* {@linkplain Comparable natural ordering}, or by a {@link Comparator} |
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* provided at queue construction time, depending on which constructor is |
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* used. A priority queue does not permit {@code null} elements. |
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* A priority queue relying on natural ordering also does not permit |
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* insertion of non-comparable objects (doing so may result in |
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* {@code ClassCastException}). |
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* |
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* <p>The <em>head</em> of this queue is the <em>least</em> element |
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* with respect to the specified ordering. If multiple elements are |
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* tied for least value, the head is one of those elements -- ties are |
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* broken arbitrarily. The queue retrieval operations {@code poll}, |
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* {@code remove}, {@code peek}, and {@code element} access the |
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* element at the head of the queue. |
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* |
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* <p>A priority queue is unbounded, but has an internal |
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* <i>capacity</i> governing the size of an array used to store the |
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* elements on the queue. It is always at least as large as the queue |
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* size. As elements are added to a priority queue, its capacity |
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* grows automatically. The details of the growth policy are not |
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* specified. |
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* |
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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()} 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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* <p><strong>Note that this implementation is not synchronized.</strong> |
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* Multiple threads should not access a {@code PriorityQueue} |
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* instance concurrently if any of the threads modifies the queue. |
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* Instead, use the thread-safe {@link |
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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 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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* ({@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}/../guide/collections/index.html"> |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @since 1.5 |
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* @author Josh Bloch |
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* @author Josh Bloch, Doug Lea |
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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 Queue<E>, java.io.Serializable { |
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implements java.io.Serializable { |
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|
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private static final long serialVersionUID = -7720805057305804111L; |
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|
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private static final int DEFAULT_INITIAL_CAPACITY = 11; |
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|
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/** |
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* Priority queue represented as a balanced binary heap: the two children |
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* of queue[n] are queue[2*n] and queue[2*n + 1]. The priority queue is |
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* ordered by comparator, or by the elements' natural ordering, if |
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* comparator is null: For each node n in the heap and each descendant d |
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* of n, n <= d. |
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* |
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* The element with the lowest value is in queue[1], assuming the queue is |
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* nonempty. (A one-based array is used in preference to the traditional |
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* zero-based array to simplify parent and child calculations.) |
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* |
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* queue.length must be >= 2, even if size == 0. |
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* Priority queue represented as a balanced binary heap: the two |
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* children of queue[n] are queue[2*n+1] and queue[2*(n+1)]. The |
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* priority queue is ordered by comparator, or by the elements' |
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* natural ordering, if comparator is null: For each node n in the |
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* heap and each descendant d of n, n <= d. The element with the |
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* lowest value is in queue[0], assuming the queue is nonempty. |
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*/ |
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private transient Object[] queue; |
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transient Object[] queue; // non-private to simplify nested class access |
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|
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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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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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* The number of times this priority queue has been |
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* <i>structurally modified</i>. See AbstractList for gory details. |
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*/ |
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private transient int modCount = 0; |
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transient int modCount; // non-private to simplify nested class access |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> with the default initial capacity |
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* (11) that orders its elements according to their natural |
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* ordering (using <tt>Comparable</tt>). |
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* Creates a {@code PriorityQueue} with the default initial |
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* capacity (11) that orders its elements according to their |
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* {@linkplain Comparable natural ordering}. |
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*/ |
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public PriorityQueue() { |
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this(DEFAULT_INITIAL_CAPACITY, null); |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> with the specified initial capacity |
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* that orders its elements according to their natural ordering |
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* (using <tt>Comparable</tt>). |
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* |
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* @param initialCapacity the initial capacity for this priority queue. |
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* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
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* than 1 |
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* Creates a {@code PriorityQueue} with the specified initial |
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* capacity that orders its elements according to their |
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* {@linkplain Comparable natural ordering}. |
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* |
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* @param initialCapacity the initial capacity for this priority queue |
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* @throws IllegalArgumentException if {@code initialCapacity} is less |
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* than 1 |
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*/ |
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public PriorityQueue(int initialCapacity) { |
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this(initialCapacity, null); |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> with the specified initial capacity |
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* that orders its elements according to the specified comparator. |
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* Creates a {@code PriorityQueue} with the default initial capacity and |
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* whose elements are ordered according to the specified comparator. |
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* |
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* @param initialCapacity the initial capacity for this priority queue. |
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* @param comparator the comparator used to order this priority queue. |
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* If <tt>null</tt> then the order depends on the elements' natural |
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* ordering. |
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* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
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* than 1 |
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* @param comparator the comparator that will be used to order this |
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* priority queue. If {@code null}, the {@linkplain Comparable |
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* natural ordering} of the elements will be used. |
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* @since 1.8 |
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*/ |
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public PriorityQueue(int initialCapacity, |
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Comparator<? super E> comparator) { |
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if (initialCapacity < 1) |
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throw new IllegalArgumentException(); |
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this.queue = new Object[initialCapacity + 1]; |
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this.comparator = comparator; |
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public PriorityQueue(Comparator<? super E> comparator) { |
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this(DEFAULT_INITIAL_CAPACITY, comparator); |
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} |
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|
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/** |
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* Common code to initialize underlying queue array across |
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* constructors below. |
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* Creates a {@code PriorityQueue} with the specified initial capacity |
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* that orders its elements according to the specified comparator. |
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* |
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* @param initialCapacity the initial capacity for this priority queue |
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* @param comparator the comparator that will be used to order this |
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* priority queue. If {@code null}, the {@linkplain Comparable |
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* natural ordering} of the elements will be used. |
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* @throws IllegalArgumentException if {@code initialCapacity} is |
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* less than 1 |
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*/ |
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private void initializeArray(Collection<? extends E> c) { |
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int sz = c.size(); |
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int initialCapacity = (int)Math.min((sz * 110L) / 100, |
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Integer.MAX_VALUE - 1); |
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public PriorityQueue(int initialCapacity, |
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Comparator<? super E> comparator) { |
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// Note: This restriction of at least one is not actually needed, |
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// but continues for 1.5 compatibility |
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if (initialCapacity < 1) |
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initialCapacity = 1; |
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|
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this.queue = new Object[initialCapacity + 1]; |
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} |
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|
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/** |
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* Initially fill elements of the queue array under the |
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* knowledge that it is sorted or is another PQ, in which |
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* case we can just place the elements without fixups. |
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*/ |
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private void fillFromSorted(Collection<? extends E> c) { |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
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queue[++size] = i.next(); |
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} |
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|
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|
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/** |
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* Initially fill elements of the queue array that is |
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* not to our knowledge sorted, so we must add them |
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* one by one. |
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*/ |
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private void fillFromUnsorted(Collection<? extends E> c) { |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
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add(i.next()); |
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throw new IllegalArgumentException(); |
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this.queue = new Object[initialCapacity]; |
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this.comparator = comparator; |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> containing the elements in the |
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* specified collection. The priority queue has an initial |
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* capacity of 110% of the size of the specified collection or 1 |
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* if the collection is empty. If the specified collection is an |
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* instance of a {@link java.util.SortedSet} or is another |
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* <tt>PriorityQueue</tt>, the priority queue will be sorted |
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* according to the same comparator, or according to its elements' |
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* natural order if the collection is sorted according to its |
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* elements' natural order. Otherwise, the priority queue is |
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* ordered according to its elements' natural order. |
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* Creates a {@code PriorityQueue} containing the elements in the |
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* specified collection. If the specified collection is an instance of |
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* a {@link SortedSet} or is another {@code PriorityQueue}, this |
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* priority queue will be ordered according to the same ordering. |
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* Otherwise, this priority queue will be ordered according to the |
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* {@linkplain Comparable natural ordering} of its elements. |
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* |
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* @param c the collection whose elements are to be placed |
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* into this priority queue. |
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* @param c the collection whose elements are to be placed |
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* into this priority queue |
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* @throws ClassCastException if elements of the specified collection |
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* cannot be compared to one another according to the priority |
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* queue's ordering. |
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* @throws NullPointerException if <tt>c</tt> or any element within it |
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* is <tt>null</tt> |
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* queue's ordering |
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* @throws NullPointerException if the specified collection or any |
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* of its elements are null |
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*/ |
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@SuppressWarnings("unchecked") |
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public PriorityQueue(Collection<? extends E> c) { |
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initializeArray(c); |
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if (c instanceof SortedSet<? extends E>) { |
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SortedSet<? extends E> s = (SortedSet<? extends E>) c; |
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comparator = (Comparator<? super E>)s.comparator(); |
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fillFromSorted(s); |
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} |
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< |
else if (c instanceof PriorityQueue<? extends E>) { |
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PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c; |
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comparator = (Comparator<? super E>)s.comparator(); |
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fillFromSorted(s); |
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if (c instanceof SortedSet<?>) { |
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SortedSet<? extends E> ss = (SortedSet<? extends E>) c; |
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this.comparator = (Comparator<? super E>) ss.comparator(); |
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initElementsFromCollection(ss); |
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} |
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else if (c instanceof PriorityQueue<?>) { |
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PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c; |
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this.comparator = (Comparator<? super E>) pq.comparator(); |
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initFromPriorityQueue(pq); |
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} |
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else { |
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comparator = null; |
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fillFromUnsorted(c); |
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this.comparator = null; |
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initFromCollection(c); |
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} |
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} |
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|
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/** |
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< |
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
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* specified collection. The priority queue has an initial |
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* capacity of 110% of the size of the specified collection or 1 |
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* if the collection is empty. This priority queue will be sorted |
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* according to the same comparator as the given collection, or |
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* according to its elements' natural order if the collection is |
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* sorted according to its elements' natural order. |
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> |
* Creates a {@code PriorityQueue} containing the elements in the |
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* specified priority queue. This priority queue will be |
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* ordered according to the same ordering as the given priority |
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* queue. |
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|
* |
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* @param c the collection whose elements are to be placed |
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* into this priority queue. |
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* @throws ClassCastException if elements of the specified collection |
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* cannot be compared to one another according to the priority |
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* queue's ordering. |
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* @throws NullPointerException if <tt>c</tt> or any element within it |
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* is <tt>null</tt> |
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> |
* @param c the priority queue whose elements are to be placed |
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> |
* into this priority queue |
215 |
> |
* @throws ClassCastException if elements of {@code c} cannot be |
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> |
* compared to one another according to {@code c}'s |
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> |
* ordering |
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> |
* @throws NullPointerException if the specified priority queue or any |
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> |
* of its elements are null |
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|
*/ |
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+ |
@SuppressWarnings("unchecked") |
222 |
|
public PriorityQueue(PriorityQueue<? extends E> c) { |
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< |
initializeArray(c); |
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< |
comparator = (Comparator<? super E>)c.comparator(); |
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< |
fillFromSorted(c); |
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> |
this.comparator = (Comparator<? super E>) c.comparator(); |
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> |
initFromPriorityQueue(c); |
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} |
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|
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/** |
228 |
< |
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
229 |
< |
* specified collection. The priority queue has an initial |
230 |
< |
* capacity of 110% of the size of the specified collection or 1 |
222 |
< |
* if the collection is empty. This priority queue will be sorted |
223 |
< |
* according to the same comparator as the given collection, or |
224 |
< |
* according to its elements' natural order if the collection is |
225 |
< |
* sorted according to its elements' natural order. |
228 |
> |
* Creates a {@code PriorityQueue} containing the elements in the |
229 |
> |
* specified sorted set. This priority queue will be ordered |
230 |
> |
* according to the same ordering as the given sorted set. |
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|
* |
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< |
* @param c the collection whose elements are to be placed |
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* into this priority queue. |
234 |
< |
* @throws ClassCastException if elements of the specified collection |
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< |
* cannot be compared to one another according to the priority |
236 |
< |
* queue's ordering. |
237 |
< |
* @throws NullPointerException if <tt>c</tt> or any element within it |
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< |
* is <tt>null</tt> |
232 |
> |
* @param c the sorted set whose elements are to be placed |
233 |
> |
* into this priority queue |
234 |
> |
* @throws ClassCastException if elements of the specified sorted |
235 |
> |
* set cannot be compared to one another according to the |
236 |
> |
* sorted set's ordering |
237 |
> |
* @throws NullPointerException if the specified sorted set or any |
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> |
* of its elements are null |
239 |
|
*/ |
240 |
+ |
@SuppressWarnings("unchecked") |
241 |
|
public PriorityQueue(SortedSet<? extends E> c) { |
242 |
< |
initializeArray(c); |
243 |
< |
comparator = (Comparator<? super E>)c.comparator(); |
238 |
< |
fillFromSorted(c); |
242 |
> |
this.comparator = (Comparator<? super E>) c.comparator(); |
243 |
> |
initElementsFromCollection(c); |
244 |
|
} |
245 |
|
|
246 |
< |
/** |
247 |
< |
* Resize array, if necessary, to be able to hold given index |
248 |
< |
*/ |
249 |
< |
private void grow(int index) { |
250 |
< |
int newlen = queue.length; |
251 |
< |
if (index < newlen) // don't need to grow |
247 |
< |
return; |
248 |
< |
if (index == Integer.MAX_VALUE) |
249 |
< |
throw new OutOfMemoryError(); |
250 |
< |
while (newlen <= index) { |
251 |
< |
if (newlen >= Integer.MAX_VALUE / 2) // avoid overflow |
252 |
< |
newlen = Integer.MAX_VALUE; |
253 |
< |
else |
254 |
< |
newlen <<= 2; |
246 |
> |
private void initFromPriorityQueue(PriorityQueue<? extends E> c) { |
247 |
> |
if (c.getClass() == PriorityQueue.class) { |
248 |
> |
this.queue = c.toArray(); |
249 |
> |
this.size = c.size(); |
250 |
> |
} else { |
251 |
> |
initFromCollection(c); |
252 |
|
} |
256 |
– |
Object[] newQueue = new Object[newlen]; |
257 |
– |
System.arraycopy(queue, 0, newQueue, 0, queue.length); |
258 |
– |
queue = newQueue; |
253 |
|
} |
260 |
– |
|
261 |
– |
// Queue Methods |
262 |
– |
|
254 |
|
|
255 |
+ |
private void initElementsFromCollection(Collection<? extends E> c) { |
256 |
+ |
Object[] a = c.toArray(); |
257 |
+ |
// If c.toArray incorrectly doesn't return Object[], copy it. |
258 |
+ |
if (a.getClass() != Object[].class) |
259 |
+ |
a = Arrays.copyOf(a, a.length, Object[].class); |
260 |
+ |
int len = a.length; |
261 |
+ |
if (len == 1 || this.comparator != null) |
262 |
+ |
for (Object e : a) |
263 |
+ |
if (e == null) |
264 |
+ |
throw new NullPointerException(); |
265 |
+ |
this.queue = a; |
266 |
+ |
this.size = a.length; |
267 |
+ |
} |
268 |
|
|
269 |
|
/** |
270 |
< |
* Add the specified element to this priority queue. |
270 |
> |
* Initializes queue array with elements from the given Collection. |
271 |
|
* |
272 |
< |
* @return <tt>true</tt> |
269 |
< |
* @throws ClassCastException if the specified element cannot be compared |
270 |
< |
* with elements currently in the priority queue according |
271 |
< |
* to the priority queue's ordering. |
272 |
< |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
272 |
> |
* @param c the collection |
273 |
|
*/ |
274 |
< |
public boolean offer(E o) { |
275 |
< |
if (o == null) |
276 |
< |
throw new NullPointerException(); |
277 |
< |
modCount++; |
278 |
< |
++size; |
279 |
< |
|
280 |
< |
// Grow backing store if necessary |
281 |
< |
if (size >= queue.length) |
282 |
< |
grow(size); |
283 |
< |
|
284 |
< |
queue[size] = o; |
285 |
< |
fixUp(size); |
286 |
< |
return true; |
274 |
> |
private void initFromCollection(Collection<? extends E> c) { |
275 |
> |
initElementsFromCollection(c); |
276 |
> |
heapify(); |
277 |
|
} |
278 |
|
|
279 |
< |
public E poll() { |
280 |
< |
if (size == 0) |
281 |
< |
return null; |
282 |
< |
return (E) remove(1); |
283 |
< |
} |
279 |
> |
/** |
280 |
> |
* The maximum size of array to allocate. |
281 |
> |
* Some VMs reserve some header words in an array. |
282 |
> |
* Attempts to allocate larger arrays may result in |
283 |
> |
* OutOfMemoryError: Requested array size exceeds VM limit |
284 |
> |
*/ |
285 |
> |
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
286 |
|
|
287 |
< |
public E peek() { |
288 |
< |
return (E) queue[1]; |
287 |
> |
/** |
288 |
> |
* Increases the capacity of the array. |
289 |
> |
* |
290 |
> |
* @param minCapacity the desired minimum capacity |
291 |
> |
*/ |
292 |
> |
private void grow(int minCapacity) { |
293 |
> |
int oldCapacity = queue.length; |
294 |
> |
// Double size if small; else grow by 50% |
295 |
> |
int newCapacity = oldCapacity + ((oldCapacity < 64) ? |
296 |
> |
(oldCapacity + 2) : |
297 |
> |
(oldCapacity >> 1)); |
298 |
> |
// overflow-conscious code |
299 |
> |
if (newCapacity - MAX_ARRAY_SIZE > 0) |
300 |
> |
newCapacity = hugeCapacity(minCapacity); |
301 |
> |
queue = Arrays.copyOf(queue, newCapacity); |
302 |
|
} |
303 |
|
|
304 |
< |
// Collection Methods - the first two override to update docs |
304 |
> |
private static int hugeCapacity(int minCapacity) { |
305 |
> |
if (minCapacity < 0) // overflow |
306 |
> |
throw new OutOfMemoryError(); |
307 |
> |
return (minCapacity > MAX_ARRAY_SIZE) ? |
308 |
> |
Integer.MAX_VALUE : |
309 |
> |
MAX_ARRAY_SIZE; |
310 |
> |
} |
311 |
|
|
312 |
|
/** |
313 |
< |
* Adds the specified element to this queue. |
303 |
< |
* @return <tt>true</tt> (as per the general contract of |
304 |
< |
* <tt>Collection.add</tt>). |
313 |
> |
* Inserts the specified element into this priority queue. |
314 |
|
* |
315 |
< |
* @throws NullPointerException {@inheritDoc} |
316 |
< |
* @throws ClassCastException if the specified element cannot be compared |
317 |
< |
* with elements currently in the priority queue according |
318 |
< |
* to the priority queue's ordering. |
315 |
> |
* @return {@code true} (as specified by {@link Collection#add}) |
316 |
> |
* @throws ClassCastException if the specified element cannot be |
317 |
> |
* compared with elements currently in this priority queue |
318 |
> |
* according to the priority queue's ordering |
319 |
> |
* @throws NullPointerException if the specified element is null |
320 |
|
*/ |
321 |
< |
public boolean add(E o) { |
322 |
< |
return super.add(o); |
321 |
> |
public boolean add(E e) { |
322 |
> |
return offer(e); |
323 |
|
} |
324 |
|
|
315 |
– |
|
325 |
|
/** |
326 |
< |
* Adds all of the elements in the specified collection to this queue. |
327 |
< |
* The behavior of this operation is undefined if |
328 |
< |
* the specified collection is modified while the operation is in |
329 |
< |
* progress. (This implies that the behavior of this call is undefined if |
330 |
< |
* the specified collection is this queue, and this queue is nonempty.) |
331 |
< |
* <p> |
332 |
< |
* This implementation iterates over the specified collection, and adds |
324 |
< |
* each object returned by the iterator to this collection, in turn. |
325 |
< |
* @throws NullPointerException {@inheritDoc} |
326 |
< |
* @throws ClassCastException if any element cannot be compared |
327 |
< |
* with elements currently in the priority queue according |
328 |
< |
* to the priority queue's ordering. |
326 |
> |
* Inserts the specified element into this priority queue. |
327 |
> |
* |
328 |
> |
* @return {@code true} (as specified by {@link Queue#offer}) |
329 |
> |
* @throws ClassCastException if the specified element cannot be |
330 |
> |
* compared with elements currently in this priority queue |
331 |
> |
* according to the priority queue's ordering |
332 |
> |
* @throws NullPointerException if the specified element is null |
333 |
|
*/ |
334 |
< |
public boolean addAll(Collection<? extends E> c) { |
335 |
< |
return super.addAll(c); |
334 |
> |
public boolean offer(E e) { |
335 |
> |
if (e == null) |
336 |
> |
throw new NullPointerException(); |
337 |
> |
modCount++; |
338 |
> |
int i = size; |
339 |
> |
if (i >= queue.length) |
340 |
> |
grow(i + 1); |
341 |
> |
siftUp(i, e); |
342 |
> |
size = i + 1; |
343 |
> |
return true; |
344 |
|
} |
345 |
|
|
346 |
+ |
@SuppressWarnings("unchecked") |
347 |
+ |
public E peek() { |
348 |
+ |
return (size == 0) ? null : (E) queue[0]; |
349 |
+ |
} |
350 |
+ |
|
351 |
+ |
private int indexOf(Object o) { |
352 |
+ |
if (o != null) { |
353 |
+ |
for (int i = 0; i < size; i++) |
354 |
+ |
if (o.equals(queue[i])) |
355 |
+ |
return i; |
356 |
+ |
} |
357 |
+ |
return -1; |
358 |
+ |
} |
359 |
|
|
360 |
< |
/** |
361 |
< |
* Removes a single instance of the specified element from this |
362 |
< |
* queue, if it is present. More formally, |
363 |
< |
* removes an element <tt>e</tt> such that <tt>(o==null ? e==null : |
364 |
< |
* o.equals(e))</tt>, if the queue contains one or more such |
365 |
< |
* elements. Returns <tt>true</tt> if the queue contained the |
341 |
< |
* specified element (or equivalently, if the queue changed as a |
360 |
> |
/** |
361 |
> |
* Removes a single instance of the specified element from this queue, |
362 |
> |
* if it is present. More formally, removes an element {@code e} such |
363 |
> |
* that {@code o.equals(e)}, if this queue contains one or more such |
364 |
> |
* elements. Returns {@code true} if and only if this queue contained |
365 |
> |
* the specified element (or equivalently, if this queue changed as a |
366 |
|
* result of the call). |
367 |
|
* |
368 |
< |
* <p>This implementation iterates over the queue looking for the |
369 |
< |
* specified element. If it finds the element, it removes the element |
346 |
< |
* from the queue using the iterator's remove method.<p> |
347 |
< |
* |
368 |
> |
* @param o element to be removed from this queue, if present |
369 |
> |
* @return {@code true} if this queue changed as a result of the call |
370 |
|
*/ |
371 |
|
public boolean remove(Object o) { |
372 |
< |
if (o == null) |
372 |
> |
int i = indexOf(o); |
373 |
> |
if (i == -1) |
374 |
|
return false; |
375 |
+ |
else { |
376 |
+ |
removeAt(i); |
377 |
+ |
return true; |
378 |
+ |
} |
379 |
+ |
} |
380 |
|
|
381 |
< |
if (comparator == null) { |
382 |
< |
for (int i = 1; i <= size; i++) { |
383 |
< |
if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) { |
384 |
< |
remove(i); |
385 |
< |
return true; |
386 |
< |
} |
387 |
< |
} |
388 |
< |
} else { |
389 |
< |
for (int i = 1; i <= size; i++) { |
390 |
< |
if (comparator.compare((E)queue[i], (E)o) == 0) { |
391 |
< |
remove(i); |
392 |
< |
return true; |
365 |
< |
} |
381 |
> |
/** |
382 |
> |
* Version of remove using reference equality, not equals. |
383 |
> |
* Needed by iterator.remove. |
384 |
> |
* |
385 |
> |
* @param o element to be removed from this queue, if present |
386 |
> |
* @return {@code true} if removed |
387 |
> |
*/ |
388 |
> |
boolean removeEq(Object o) { |
389 |
> |
for (int i = 0; i < size; i++) { |
390 |
> |
if (o == queue[i]) { |
391 |
> |
removeAt(i); |
392 |
> |
return true; |
393 |
|
} |
394 |
|
} |
395 |
|
return false; |
396 |
|
} |
397 |
|
|
398 |
|
/** |
399 |
+ |
* Returns {@code true} if this queue contains the specified element. |
400 |
+ |
* More formally, returns {@code true} if and only if this queue contains |
401 |
+ |
* at least one element {@code e} such that {@code o.equals(e)}. |
402 |
+ |
* |
403 |
+ |
* @param o object to be checked for containment in this queue |
404 |
+ |
* @return {@code true} if this queue contains the specified element |
405 |
+ |
*/ |
406 |
+ |
public boolean contains(Object o) { |
407 |
+ |
return indexOf(o) >= 0; |
408 |
+ |
} |
409 |
+ |
|
410 |
+ |
/** |
411 |
+ |
* Returns an array containing all of the elements in this queue. |
412 |
+ |
* The elements are in no particular order. |
413 |
+ |
* |
414 |
+ |
* <p>The returned array will be "safe" in that no references to it are |
415 |
+ |
* maintained by this queue. (In other words, this method must allocate |
416 |
+ |
* a new array). The caller is thus free to modify the returned array. |
417 |
+ |
* |
418 |
+ |
* <p>This method acts as bridge between array-based and collection-based |
419 |
+ |
* APIs. |
420 |
+ |
* |
421 |
+ |
* @return an array containing all of the elements in this queue |
422 |
+ |
*/ |
423 |
+ |
public Object[] toArray() { |
424 |
+ |
return Arrays.copyOf(queue, size); |
425 |
+ |
} |
426 |
+ |
|
427 |
+ |
/** |
428 |
+ |
* Returns an array containing all of the elements in this queue; the |
429 |
+ |
* runtime type of the returned array is that of the specified array. |
430 |
+ |
* The returned array elements are in no particular order. |
431 |
+ |
* If the queue fits in the specified array, it is returned therein. |
432 |
+ |
* Otherwise, a new array is allocated with the runtime type of the |
433 |
+ |
* specified array and the size of this queue. |
434 |
+ |
* |
435 |
+ |
* <p>If the queue fits in the specified array with room to spare |
436 |
+ |
* (i.e., the array has more elements than the queue), the element in |
437 |
+ |
* the array immediately following the end of the collection is set to |
438 |
+ |
* {@code null}. |
439 |
+ |
* |
440 |
+ |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
441 |
+ |
* array-based and collection-based APIs. Further, this method allows |
442 |
+ |
* precise control over the runtime type of the output array, and may, |
443 |
+ |
* under certain circumstances, be used to save allocation costs. |
444 |
+ |
* |
445 |
+ |
* <p>Suppose {@code x} is a queue known to contain only strings. |
446 |
+ |
* The following code can be used to dump the queue into a newly |
447 |
+ |
* allocated array of {@code String}: |
448 |
+ |
* |
449 |
+ |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
450 |
+ |
* |
451 |
+ |
* Note that {@code toArray(new Object[0])} is identical in function to |
452 |
+ |
* {@code toArray()}. |
453 |
+ |
* |
454 |
+ |
* @param a the array into which the elements of the queue are to |
455 |
+ |
* be stored, if it is big enough; otherwise, a new array of the |
456 |
+ |
* same runtime type is allocated for this purpose. |
457 |
+ |
* @return an array containing all of the elements in this queue |
458 |
+ |
* @throws ArrayStoreException if the runtime type of the specified array |
459 |
+ |
* is not a supertype of the runtime type of every element in |
460 |
+ |
* this queue |
461 |
+ |
* @throws NullPointerException if the specified array is null |
462 |
+ |
*/ |
463 |
+ |
@SuppressWarnings("unchecked") |
464 |
+ |
public <T> T[] toArray(T[] a) { |
465 |
+ |
final int size = this.size; |
466 |
+ |
if (a.length < size) |
467 |
+ |
// Make a new array of a's runtime type, but my contents: |
468 |
+ |
return (T[]) Arrays.copyOf(queue, size, a.getClass()); |
469 |
+ |
System.arraycopy(queue, 0, a, 0, size); |
470 |
+ |
if (a.length > size) |
471 |
+ |
a[size] = null; |
472 |
+ |
return a; |
473 |
+ |
} |
474 |
+ |
|
475 |
+ |
/** |
476 |
|
* Returns an iterator over the elements in this queue. The iterator |
477 |
|
* does not return the elements in any particular order. |
478 |
|
* |
479 |
< |
* @return an iterator over the elements in this queue. |
479 |
> |
* @return an iterator over the elements in this queue |
480 |
|
*/ |
481 |
|
public Iterator<E> iterator() { |
482 |
|
return new Itr(); |
483 |
|
} |
484 |
|
|
485 |
< |
private class Itr implements Iterator<E> { |
485 |
> |
private final class Itr implements Iterator<E> { |
486 |
|
/** |
487 |
|
* Index (into queue array) of element to be returned by |
488 |
|
* subsequent call to next. |
489 |
|
*/ |
490 |
< |
private int cursor = 1; |
490 |
> |
private int cursor; |
491 |
> |
|
492 |
> |
/** |
493 |
> |
* Index of element returned by most recent call to next, |
494 |
> |
* unless that element came from the forgetMeNot list. |
495 |
> |
* Set to -1 if element is deleted by a call to remove. |
496 |
> |
*/ |
497 |
> |
private int lastRet = -1; |
498 |
> |
|
499 |
> |
/** |
500 |
> |
* A queue of elements that were moved from the unvisited portion of |
501 |
> |
* the heap into the visited portion as a result of "unlucky" element |
502 |
> |
* removals during the iteration. (Unlucky element removals are those |
503 |
> |
* that require a siftup instead of a siftdown.) We must visit all of |
504 |
> |
* the elements in this list to complete the iteration. We do this |
505 |
> |
* after we've completed the "normal" iteration. |
506 |
> |
* |
507 |
> |
* We expect that most iterations, even those involving removals, |
508 |
> |
* will not need to store elements in this field. |
509 |
> |
*/ |
510 |
> |
private ArrayDeque<E> forgetMeNot; |
511 |
|
|
512 |
|
/** |
513 |
< |
* Index of element returned by most recent call to next or |
514 |
< |
* previous. Reset to 0 if this element is deleted by a call |
391 |
< |
* to remove. |
513 |
> |
* Element returned by the most recent call to next iff that |
514 |
> |
* element was drawn from the forgetMeNot list. |
515 |
|
*/ |
516 |
< |
private int lastRet = 0; |
516 |
> |
private E lastRetElt; |
517 |
|
|
518 |
|
/** |
519 |
|
* The modCount value that the iterator believes that the backing |
520 |
< |
* List should have. If this expectation is violated, the iterator |
520 |
> |
* Queue should have. If this expectation is violated, the iterator |
521 |
|
* has detected concurrent modification. |
522 |
|
*/ |
523 |
|
private int expectedModCount = modCount; |
524 |
|
|
525 |
|
public boolean hasNext() { |
526 |
< |
return cursor <= size; |
526 |
> |
return cursor < size || |
527 |
> |
(forgetMeNot != null && !forgetMeNot.isEmpty()); |
528 |
|
} |
529 |
|
|
530 |
+ |
@SuppressWarnings("unchecked") |
531 |
|
public E next() { |
532 |
< |
checkForComodification(); |
533 |
< |
if (cursor > size) |
534 |
< |
throw new NoSuchElementException(); |
535 |
< |
E result = (E) queue[cursor]; |
536 |
< |
lastRet = cursor++; |
537 |
< |
return result; |
532 |
> |
if (expectedModCount != modCount) |
533 |
> |
throw new ConcurrentModificationException(); |
534 |
> |
if (cursor < size) |
535 |
> |
return (E) queue[lastRet = cursor++]; |
536 |
> |
if (forgetMeNot != null) { |
537 |
> |
lastRet = -1; |
538 |
> |
lastRetElt = forgetMeNot.poll(); |
539 |
> |
if (lastRetElt != null) |
540 |
> |
return lastRetElt; |
541 |
> |
} |
542 |
> |
throw new NoSuchElementException(); |
543 |
|
} |
544 |
|
|
545 |
|
public void remove() { |
546 |
< |
if (lastRet == 0) |
546 |
> |
if (expectedModCount != modCount) |
547 |
> |
throw new ConcurrentModificationException(); |
548 |
> |
if (lastRet != -1) { |
549 |
> |
E moved = PriorityQueue.this.removeAt(lastRet); |
550 |
> |
lastRet = -1; |
551 |
> |
if (moved == null) |
552 |
> |
cursor--; |
553 |
> |
else { |
554 |
> |
if (forgetMeNot == null) |
555 |
> |
forgetMeNot = new ArrayDeque<>(); |
556 |
> |
forgetMeNot.add(moved); |
557 |
> |
} |
558 |
> |
} else if (lastRetElt != null) { |
559 |
> |
PriorityQueue.this.removeEq(lastRetElt); |
560 |
> |
lastRetElt = null; |
561 |
> |
} else { |
562 |
|
throw new IllegalStateException(); |
563 |
< |
checkForComodification(); |
419 |
< |
|
420 |
< |
PriorityQueue.this.remove(lastRet); |
421 |
< |
if (lastRet < cursor) |
422 |
< |
cursor--; |
423 |
< |
lastRet = 0; |
563 |
> |
} |
564 |
|
expectedModCount = modCount; |
565 |
|
} |
426 |
– |
|
427 |
– |
final void checkForComodification() { |
428 |
– |
if (modCount != expectedModCount) |
429 |
– |
throw new ConcurrentModificationException(); |
430 |
– |
} |
566 |
|
} |
567 |
|
|
568 |
|
public int size() { |
570 |
|
} |
571 |
|
|
572 |
|
/** |
573 |
< |
* Remove all elements from the priority queue. |
573 |
> |
* Removes all of the elements from this priority queue. |
574 |
> |
* The queue will be empty after this call returns. |
575 |
|
*/ |
576 |
|
public void clear() { |
577 |
|
modCount++; |
578 |
< |
|
443 |
< |
// Null out element references to prevent memory leak |
444 |
< |
for (int i=1; i<=size; i++) |
578 |
> |
for (int i = 0; i < size; i++) |
579 |
|
queue[i] = null; |
446 |
– |
|
580 |
|
size = 0; |
581 |
|
} |
582 |
|
|
583 |
< |
/** |
584 |
< |
* Removes and returns the ith element from queue. Recall |
585 |
< |
* that queue is one-based, so 1 <= i <= size. |
586 |
< |
* |
587 |
< |
* XXX: Could further special-case i==size, but is it worth it? |
455 |
< |
* XXX: Could special-case i==0, but is it worth it? |
456 |
< |
*/ |
457 |
< |
private E remove(int i) { |
458 |
< |
assert i <= size; |
583 |
> |
@SuppressWarnings("unchecked") |
584 |
> |
public E poll() { |
585 |
> |
if (size == 0) |
586 |
> |
return null; |
587 |
> |
int s = --size; |
588 |
|
modCount++; |
589 |
< |
|
590 |
< |
E result = (E) queue[i]; |
591 |
< |
queue[i] = queue[size]; |
592 |
< |
queue[size--] = null; // Drop extra ref to prevent memory leak |
593 |
< |
if (i <= size) |
465 |
< |
fixDown(i); |
589 |
> |
E result = (E) queue[0]; |
590 |
> |
E x = (E) queue[s]; |
591 |
> |
queue[s] = null; |
592 |
> |
if (s != 0) |
593 |
> |
siftDown(0, x); |
594 |
|
return result; |
595 |
|
} |
596 |
|
|
597 |
|
/** |
598 |
< |
* Establishes the heap invariant (described above) assuming the heap |
599 |
< |
* satisfies the invariant except possibly for the leaf-node indexed by k |
600 |
< |
* (which may have a nextExecutionTime less than its parent's). |
601 |
< |
* |
602 |
< |
* This method functions by "promoting" queue[k] up the hierarchy |
603 |
< |
* (by swapping it with its parent) repeatedly until queue[k] |
604 |
< |
* is greater than or equal to its parent. |
605 |
< |
*/ |
606 |
< |
private void fixUp(int k) { |
607 |
< |
if (comparator == null) { |
608 |
< |
while (k > 1) { |
609 |
< |
int j = k >> 1; |
610 |
< |
if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0) |
611 |
< |
break; |
612 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
613 |
< |
k = j; |
614 |
< |
} |
615 |
< |
} else { |
616 |
< |
while (k > 1) { |
617 |
< |
int j = k >> 1; |
618 |
< |
if (comparator.compare((E)queue[j], (E)queue[k]) <= 0) |
619 |
< |
break; |
620 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
621 |
< |
k = j; |
622 |
< |
} |
623 |
< |
} |
496 |
< |
} |
497 |
< |
|
498 |
< |
/** |
499 |
< |
* Establishes the heap invariant (described above) in the subtree |
500 |
< |
* rooted at k, which is assumed to satisfy the heap invariant except |
501 |
< |
* possibly for node k itself (which may be greater than its children). |
502 |
< |
* |
503 |
< |
* This method functions by "demoting" queue[k] down the hierarchy |
504 |
< |
* (by swapping it with its smaller child) repeatedly until queue[k] |
505 |
< |
* is less than or equal to its children. |
506 |
< |
*/ |
507 |
< |
private void fixDown(int k) { |
508 |
< |
int j; |
509 |
< |
if (comparator == null) { |
510 |
< |
while ((j = k << 1) <= size) { |
511 |
< |
if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0) |
512 |
< |
j++; // j indexes smallest kid |
513 |
< |
if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0) |
514 |
< |
break; |
515 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
516 |
< |
k = j; |
517 |
< |
} |
518 |
< |
} else { |
519 |
< |
while ((j = k << 1) <= size) { |
520 |
< |
if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0) |
521 |
< |
j++; // j indexes smallest kid |
522 |
< |
if (comparator.compare((E)queue[k], (E)queue[j]) <= 0) |
523 |
< |
break; |
524 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
525 |
< |
k = j; |
598 |
> |
* Removes the ith element from queue. |
599 |
> |
* |
600 |
> |
* Normally this method leaves the elements at up to i-1, |
601 |
> |
* inclusive, untouched. Under these circumstances, it returns |
602 |
> |
* null. Occasionally, in order to maintain the heap invariant, |
603 |
> |
* it must swap a later element of the list with one earlier than |
604 |
> |
* i. Under these circumstances, this method returns the element |
605 |
> |
* that was previously at the end of the list and is now at some |
606 |
> |
* position before i. This fact is used by iterator.remove so as to |
607 |
> |
* avoid missing traversing elements. |
608 |
> |
*/ |
609 |
> |
@SuppressWarnings("unchecked") |
610 |
> |
E removeAt(int i) { |
611 |
> |
// assert i >= 0 && i < size; |
612 |
> |
modCount++; |
613 |
> |
int s = --size; |
614 |
> |
if (s == i) // removed last element |
615 |
> |
queue[i] = null; |
616 |
> |
else { |
617 |
> |
E moved = (E) queue[s]; |
618 |
> |
queue[s] = null; |
619 |
> |
siftDown(i, moved); |
620 |
> |
if (queue[i] == moved) { |
621 |
> |
siftUp(i, moved); |
622 |
> |
if (queue[i] != moved) |
623 |
> |
return moved; |
624 |
|
} |
625 |
|
} |
626 |
+ |
return null; |
627 |
|
} |
628 |
|
|
530 |
– |
|
629 |
|
/** |
630 |
< |
* Returns the comparator used to order this collection, or <tt>null</tt> |
631 |
< |
* if this collection is sorted according to its elements natural ordering |
632 |
< |
* (using <tt>Comparable</tt>). |
633 |
< |
* |
634 |
< |
* @return the comparator used to order this collection, or <tt>null</tt> |
635 |
< |
* if this collection is sorted according to its elements natural ordering. |
630 |
> |
* Inserts item x at position k, maintaining heap invariant by |
631 |
> |
* promoting x up the tree until it is greater than or equal to |
632 |
> |
* its parent, or is the root. |
633 |
> |
* |
634 |
> |
* To simplify and speed up coercions and comparisons, the |
635 |
> |
* Comparable and Comparator versions are separated into different |
636 |
> |
* methods that are otherwise identical. (Similarly for siftDown.) |
637 |
> |
* |
638 |
> |
* @param k the position to fill |
639 |
> |
* @param x the item to insert |
640 |
> |
*/ |
641 |
> |
private void siftUp(int k, E x) { |
642 |
> |
if (comparator != null) |
643 |
> |
siftUpUsingComparator(k, x); |
644 |
> |
else |
645 |
> |
siftUpComparable(k, x); |
646 |
> |
} |
647 |
> |
|
648 |
> |
@SuppressWarnings("unchecked") |
649 |
> |
private void siftUpComparable(int k, E x) { |
650 |
> |
Comparable<? super E> key = (Comparable<? super E>) x; |
651 |
> |
while (k > 0) { |
652 |
> |
int parent = (k - 1) >>> 1; |
653 |
> |
Object e = queue[parent]; |
654 |
> |
if (key.compareTo((E) e) >= 0) |
655 |
> |
break; |
656 |
> |
queue[k] = e; |
657 |
> |
k = parent; |
658 |
> |
} |
659 |
> |
queue[k] = key; |
660 |
> |
} |
661 |
> |
|
662 |
> |
@SuppressWarnings("unchecked") |
663 |
> |
private void siftUpUsingComparator(int k, E x) { |
664 |
> |
while (k > 0) { |
665 |
> |
int parent = (k - 1) >>> 1; |
666 |
> |
Object e = queue[parent]; |
667 |
> |
if (comparator.compare(x, (E) e) >= 0) |
668 |
> |
break; |
669 |
> |
queue[k] = e; |
670 |
> |
k = parent; |
671 |
> |
} |
672 |
> |
queue[k] = x; |
673 |
> |
} |
674 |
> |
|
675 |
> |
/** |
676 |
> |
* Inserts item x at position k, maintaining heap invariant by |
677 |
> |
* demoting x down the tree repeatedly until it is less than or |
678 |
> |
* equal to its children or is a leaf. |
679 |
> |
* |
680 |
> |
* @param k the position to fill |
681 |
> |
* @param x the item to insert |
682 |
> |
*/ |
683 |
> |
private void siftDown(int k, E x) { |
684 |
> |
if (comparator != null) |
685 |
> |
siftDownUsingComparator(k, x); |
686 |
> |
else |
687 |
> |
siftDownComparable(k, x); |
688 |
> |
} |
689 |
> |
|
690 |
> |
@SuppressWarnings("unchecked") |
691 |
> |
private void siftDownComparable(int k, E x) { |
692 |
> |
Comparable<? super E> key = (Comparable<? super E>)x; |
693 |
> |
int half = size >>> 1; // loop while a non-leaf |
694 |
> |
while (k < half) { |
695 |
> |
int child = (k << 1) + 1; // assume left child is least |
696 |
> |
Object c = queue[child]; |
697 |
> |
int right = child + 1; |
698 |
> |
if (right < size && |
699 |
> |
((Comparable<? super E>) c).compareTo((E) queue[right]) > 0) |
700 |
> |
c = queue[child = right]; |
701 |
> |
if (key.compareTo((E) c) <= 0) |
702 |
> |
break; |
703 |
> |
queue[k] = c; |
704 |
> |
k = child; |
705 |
> |
} |
706 |
> |
queue[k] = key; |
707 |
> |
} |
708 |
> |
|
709 |
> |
@SuppressWarnings("unchecked") |
710 |
> |
private void siftDownUsingComparator(int k, E x) { |
711 |
> |
int half = size >>> 1; |
712 |
> |
while (k < half) { |
713 |
> |
int child = (k << 1) + 1; |
714 |
> |
Object c = queue[child]; |
715 |
> |
int right = child + 1; |
716 |
> |
if (right < size && |
717 |
> |
comparator.compare((E) c, (E) queue[right]) > 0) |
718 |
> |
c = queue[child = right]; |
719 |
> |
if (comparator.compare(x, (E) c) <= 0) |
720 |
> |
break; |
721 |
> |
queue[k] = c; |
722 |
> |
k = child; |
723 |
> |
} |
724 |
> |
queue[k] = x; |
725 |
> |
} |
726 |
> |
|
727 |
> |
/** |
728 |
> |
* Establishes the heap invariant (described above) in the entire tree, |
729 |
> |
* assuming nothing about the order of the elements prior to the call. |
730 |
> |
* This classic algorithm due to Floyd (1964) is known to be O(size). |
731 |
> |
*/ |
732 |
> |
@SuppressWarnings("unchecked") |
733 |
> |
private void heapify() { |
734 |
> |
final Object[] es = queue; |
735 |
> |
final int half = (size >>> 1) - 1; |
736 |
> |
if (comparator == null) |
737 |
> |
for (int i = half; i >= 0; i--) |
738 |
> |
siftDownComparable(i, (E) es[i]); |
739 |
> |
else |
740 |
> |
for (int i = half; i >= 0; i--) |
741 |
> |
siftDownUsingComparator(i, (E) es[i]); |
742 |
> |
} |
743 |
> |
|
744 |
> |
/** |
745 |
> |
* Returns the comparator used to order the elements in this |
746 |
> |
* queue, or {@code null} if this queue is sorted according to |
747 |
> |
* the {@linkplain Comparable natural ordering} of its elements. |
748 |
> |
* |
749 |
> |
* @return the comparator used to order this queue, or |
750 |
> |
* {@code null} if this queue is sorted according to the |
751 |
> |
* natural ordering of its elements |
752 |
|
*/ |
753 |
|
public Comparator<? super E> comparator() { |
754 |
|
return comparator; |
755 |
|
} |
756 |
|
|
757 |
|
/** |
758 |
< |
* Save the state of the instance to a stream (that |
545 |
< |
* is, serialize it). |
758 |
> |
* Saves this queue to a stream (that is, serializes it). |
759 |
|
* |
547 |
– |
* @serialData The length of the array backing the instance is |
548 |
– |
* emitted (int), followed by all of its elements (each an |
549 |
– |
* <tt>Object</tt>) in the proper order. |
760 |
|
* @param s the stream |
761 |
+ |
* @throws java.io.IOException if an I/O error occurs |
762 |
+ |
* @serialData The length of the array backing the instance is |
763 |
+ |
* emitted (int), followed by all of its elements |
764 |
+ |
* (each an {@code Object}) in the proper order. |
765 |
|
*/ |
766 |
|
private void writeObject(java.io.ObjectOutputStream s) |
767 |
< |
throws java.io.IOException{ |
767 |
> |
throws java.io.IOException { |
768 |
|
// Write out element count, and any hidden stuff |
769 |
|
s.defaultWriteObject(); |
770 |
|
|
771 |
< |
// Write out array length |
772 |
< |
s.writeInt(queue.length); |
771 |
> |
// Write out array length, for compatibility with 1.5 version |
772 |
> |
s.writeInt(Math.max(2, size + 1)); |
773 |
|
|
774 |
< |
// Write out all elements in the proper order. |
775 |
< |
for (int i=0; i<size; i++) |
774 |
> |
// Write out all elements in the "proper order". |
775 |
> |
for (int i = 0; i < size; i++) |
776 |
|
s.writeObject(queue[i]); |
777 |
|
} |
778 |
|
|
779 |
|
/** |
780 |
< |
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
781 |
< |
* deserialize it). |
780 |
> |
* Reconstitutes the {@code PriorityQueue} instance from a stream |
781 |
> |
* (that is, deserializes it). |
782 |
> |
* |
783 |
|
* @param s the stream |
784 |
+ |
* @throws ClassNotFoundException if the class of a serialized object |
785 |
+ |
* could not be found |
786 |
+ |
* @throws java.io.IOException if an I/O error occurs |
787 |
|
*/ |
788 |
|
private void readObject(java.io.ObjectInputStream s) |
789 |
|
throws java.io.IOException, ClassNotFoundException { |
790 |
|
// Read in size, and any hidden stuff |
791 |
|
s.defaultReadObject(); |
792 |
|
|
793 |
< |
// Read in array length and allocate array |
794 |
< |
int arrayLength = s.readInt(); |
795 |
< |
queue = new Object[arrayLength]; |
793 |
> |
// Read in (and discard) array length |
794 |
> |
s.readInt(); |
795 |
> |
|
796 |
> |
queue = new Object[size]; |
797 |
|
|
798 |
< |
// Read in all elements in the proper order. |
799 |
< |
for (int i=0; i<size; i++) |
798 |
> |
// Read in all elements. |
799 |
> |
for (int i = 0; i < size; i++) |
800 |
|
queue[i] = s.readObject(); |
801 |
+ |
|
802 |
+ |
// Elements are guaranteed to be in "proper order", but the |
803 |
+ |
// spec has never explained what that might be. |
804 |
+ |
heapify(); |
805 |
|
} |
806 |
|
|
807 |
< |
} |
807 |
> |
/** |
808 |
> |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
809 |
> |
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
810 |
> |
* queue. The spliterator does not traverse elements in any particular order |
811 |
> |
* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported). |
812 |
> |
* |
813 |
> |
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
814 |
> |
* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}. |
815 |
> |
* Overriding implementations should document the reporting of additional |
816 |
> |
* characteristic values. |
817 |
> |
* |
818 |
> |
* @return a {@code Spliterator} over the elements in this queue |
819 |
> |
* @since 1.8 |
820 |
> |
*/ |
821 |
> |
public final Spliterator<E> spliterator() { |
822 |
> |
return new PriorityQueueSpliterator(0, -1, 0); |
823 |
> |
} |
824 |
> |
|
825 |
> |
final class PriorityQueueSpliterator implements Spliterator<E> { |
826 |
> |
private int index; // current index, modified on advance/split |
827 |
> |
private int fence; // -1 until first use |
828 |
> |
private int expectedModCount; // initialized when fence set |
829 |
> |
|
830 |
> |
/** Creates new spliterator covering the given range. */ |
831 |
> |
PriorityQueueSpliterator(int origin, int fence, int expectedModCount) { |
832 |
> |
this.index = origin; |
833 |
> |
this.fence = fence; |
834 |
> |
this.expectedModCount = expectedModCount; |
835 |
> |
} |
836 |
> |
|
837 |
> |
private int getFence() { // initialize fence to size on first use |
838 |
> |
int hi; |
839 |
> |
if ((hi = fence) < 0) { |
840 |
> |
expectedModCount = modCount; |
841 |
> |
hi = fence = size; |
842 |
> |
} |
843 |
> |
return hi; |
844 |
> |
} |
845 |
> |
|
846 |
> |
public PriorityQueueSpliterator trySplit() { |
847 |
> |
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; |
848 |
> |
return (lo >= mid) ? null : |
849 |
> |
new PriorityQueueSpliterator(lo, index = mid, expectedModCount); |
850 |
> |
} |
851 |
> |
|
852 |
> |
@SuppressWarnings("unchecked") |
853 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
854 |
> |
if (action == null) |
855 |
> |
throw new NullPointerException(); |
856 |
> |
if (fence < 0) { fence = size; expectedModCount = modCount; } |
857 |
> |
final Object[] a = queue; |
858 |
> |
int i, hi; E e; |
859 |
> |
for (i = index, index = hi = fence; i < hi; i++) { |
860 |
> |
if ((e = (E) a[i]) == null) |
861 |
> |
break; // must be CME |
862 |
> |
action.accept(e); |
863 |
> |
} |
864 |
> |
if (modCount != expectedModCount) |
865 |
> |
throw new ConcurrentModificationException(); |
866 |
> |
} |
867 |
> |
|
868 |
> |
@SuppressWarnings("unchecked") |
869 |
> |
public boolean tryAdvance(Consumer<? super E> action) { |
870 |
> |
if (action == null) |
871 |
> |
throw new NullPointerException(); |
872 |
> |
if (fence < 0) { fence = size; expectedModCount = modCount; } |
873 |
> |
int i; |
874 |
> |
if ((i = index) < fence) { |
875 |
> |
index = i + 1; |
876 |
> |
E e; |
877 |
> |
if ((e = (E) queue[i]) == null |
878 |
> |
|| modCount != expectedModCount) |
879 |
> |
throw new ConcurrentModificationException(); |
880 |
> |
action.accept(e); |
881 |
> |
return true; |
882 |
> |
} |
883 |
> |
return false; |
884 |
> |
} |
885 |
|
|
886 |
+ |
public long estimateSize() { |
887 |
+ |
return getFence() - index; |
888 |
+ |
} |
889 |
+ |
|
890 |
+ |
public int characteristics() { |
891 |
+ |
return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
892 |
+ |
} |
893 |
+ |
} |
894 |
+ |
} |