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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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* @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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@SuppressWarnings("unchecked") |
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public class PriorityQueue<E> extends AbstractQueue<E> |
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implements java.io.Serializable { |
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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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if (c instanceof SortedSet<?>) { |
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SortedSet<? extends E> ss = (SortedSet<? extends E>) c; |
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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") |
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public PriorityQueue(PriorityQueue<? extends E> c) { |
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this.comparator = (Comparator<? super E>) c.comparator(); |
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initFromPriorityQueue(c); |
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* @throws NullPointerException if the specified sorted set 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(SortedSet<? extends E> c) { |
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this.comparator = (Comparator<? super E>) c.comparator(); |
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initElementsFromCollection(c); |
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} |
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private void initElementsFromCollection(Collection<? extends E> c) { |
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Object[] a = c.toArray(); |
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Object[] es = c.toArray(); |
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int len = es.length; |
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// If c.toArray incorrectly doesn't return Object[], copy it. |
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if (a.getClass() != Object[].class) |
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a = Arrays.copyOf(a, a.length, Object[].class); |
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int len = a.length; |
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if (es.getClass() != Object[].class) |
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es = Arrays.copyOf(es, len, Object[].class); |
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if (len == 1 || this.comparator != null) |
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for (Object e : a) |
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for (Object e : es) |
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if (e == null) |
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throw new NullPointerException(); |
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this.queue = a; |
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this.size = a.length; |
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this.queue = es; |
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this.size = len; |
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} |
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/** |
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int i = size; |
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if (i >= queue.length) |
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grow(i + 1); |
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siftUp(i, e); |
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size = i + 1; |
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if (i == 0) |
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queue[0] = e; |
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else |
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siftUp(i, e); |
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return true; |
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} |
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|
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@SuppressWarnings("unchecked") |
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public E peek() { |
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return (size == 0) ? null : (E) queue[0]; |
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} |
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|
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private int indexOf(Object o) { |
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if (o != null) { |
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for (int i = 0; i < size; i++) |
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if (o.equals(queue[i])) |
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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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if (o.equals(es[i])) |
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return i; |
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} |
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return -1; |
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} |
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|
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/** |
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* Version of remove using reference equality, not equals. |
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* Needed by iterator.remove. |
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* Identity-based version for use in Itr.remove. |
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* |
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* @param o element to be removed from this queue, if present |
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* @return {@code true} if removed |
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*/ |
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boolean removeEq(Object o) { |
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for (int i = 0; i < size; i++) { |
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if (o == queue[i]) { |
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void removeEq(Object o) { |
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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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if (o == es[i]) { |
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removeAt(i); |
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return true; |
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break; |
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} |
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} |
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return false; |
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} |
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/** |
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* this queue |
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* @throws NullPointerException if the specified array is null |
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*/ |
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@SuppressWarnings("unchecked") |
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public <T> T[] toArray(T[] a) { |
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final int size = this.size; |
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if (a.length < size) |
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*/ |
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private int expectedModCount = modCount; |
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|
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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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} |
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@SuppressWarnings("unchecked") |
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public E next() { |
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if (expectedModCount != modCount) |
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throw new ConcurrentModificationException(); |
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*/ |
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public void clear() { |
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modCount++; |
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for (int i = 0; i < size; i++) |
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queue[i] = null; |
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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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es[i] = null; |
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size = 0; |
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} |
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|
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@SuppressWarnings("unchecked") |
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public E poll() { |
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if (size == 0) |
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return null; |
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* position before i. This fact is used by iterator.remove so as to |
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* avoid missing traversing elements. |
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*/ |
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@SuppressWarnings("unchecked") |
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E removeAt(int i) { |
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// assert i >= 0 && i < size; |
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modCount++; |
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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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private void siftUp(int k, E x) { |
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if (comparator != null) |
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siftUpUsingComparator(k, x); |
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siftUpUsingComparator(k, x, queue, comparator); |
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else |
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siftUpComparable(k, x); |
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siftUpComparable(k, x, queue); |
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} |
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|
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@SuppressWarnings("unchecked") |
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private void siftUpComparable(int k, E x) { |
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Comparable<? super E> key = (Comparable<? super E>) x; |
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private static <T> void siftUpComparable(int k, T x, Object[] es) { |
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Comparable<? super T> key = (Comparable<? super T>) x; |
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while (k > 0) { |
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int parent = (k - 1) >>> 1; |
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Object e = queue[parent]; |
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if (key.compareTo((E) e) >= 0) |
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Object e = es[parent]; |
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if (key.compareTo((T) e) >= 0) |
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break; |
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queue[k] = e; |
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es[k] = e; |
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k = parent; |
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} |
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queue[k] = key; |
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es[k] = key; |
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} |
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|
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@SuppressWarnings("unchecked") |
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private void siftUpUsingComparator(int k, E x) { |
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> |
private static <T> void siftUpUsingComparator( |
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int k, T x, Object[] es, Comparator<? super T> cmp) { |
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while (k > 0) { |
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int parent = (k - 1) >>> 1; |
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Object e = queue[parent]; |
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if (comparator.compare(x, (E) e) >= 0) |
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Object e = es[parent]; |
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if (cmp.compare(x, (T) e) >= 0) |
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break; |
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queue[k] = e; |
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es[k] = e; |
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k = parent; |
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} |
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queue[k] = x; |
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es[k] = x; |
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} |
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/** |
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*/ |
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private void siftDown(int k, E x) { |
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if (comparator != null) |
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siftDownUsingComparator(k, x); |
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siftDownUsingComparator(k, x, queue, size, comparator); |
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else |
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siftDownComparable(k, x); |
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siftDownComparable(k, x, queue, size); |
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} |
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|
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@SuppressWarnings("unchecked") |
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< |
private void siftDownComparable(int k, E x) { |
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Comparable<? super E> key = (Comparable<? super E>)x; |
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< |
int half = size >>> 1; // loop while a non-leaf |
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> |
private static <T> void siftDownComparable(int k, T x, Object[] es, int n) { |
686 |
> |
// assert n > 0; |
687 |
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Comparable<? super T> key = (Comparable<? super T>)x; |
688 |
> |
int half = n >>> 1; // loop while a non-leaf |
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while (k < half) { |
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int child = (k << 1) + 1; // assume left child is least |
691 |
< |
Object c = queue[child]; |
691 |
> |
Object c = es[child]; |
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int right = child + 1; |
693 |
< |
if (right < size && |
694 |
< |
((Comparable<? super E>) c).compareTo((E) queue[right]) > 0) |
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< |
c = queue[child = right]; |
696 |
< |
if (key.compareTo((E) c) <= 0) |
693 |
> |
if (right < n && |
694 |
> |
((Comparable<? super T>) c).compareTo((T) es[right]) > 0) |
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> |
c = es[child = right]; |
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> |
if (key.compareTo((T) c) <= 0) |
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break; |
698 |
< |
queue[k] = c; |
698 |
> |
es[k] = c; |
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k = child; |
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} |
701 |
< |
queue[k] = key; |
701 |
> |
es[k] = key; |
702 |
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} |
703 |
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|
704 |
< |
@SuppressWarnings("unchecked") |
705 |
< |
private void siftDownUsingComparator(int k, E x) { |
706 |
< |
int half = size >>> 1; |
704 |
> |
private static <T> void siftDownUsingComparator( |
705 |
> |
int k, T x, Object[] es, int n, Comparator<? super T> cmp) { |
706 |
> |
// assert n > 0; |
707 |
> |
int half = n >>> 1; |
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while (k < half) { |
709 |
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int child = (k << 1) + 1; |
710 |
< |
Object c = queue[child]; |
710 |
> |
Object c = es[child]; |
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int right = child + 1; |
712 |
< |
if (right < size && |
713 |
< |
comparator.compare((E) c, (E) queue[right]) > 0) |
714 |
< |
c = queue[child = right]; |
721 |
< |
if (comparator.compare(x, (E) c) <= 0) |
712 |
> |
if (right < n && cmp.compare((T) c, (T) es[right]) > 0) |
713 |
> |
c = es[child = right]; |
714 |
> |
if (cmp.compare(x, (T) c) <= 0) |
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break; |
716 |
< |
queue[k] = c; |
716 |
> |
es[k] = c; |
717 |
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k = child; |
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} |
719 |
< |
queue[k] = x; |
719 |
> |
es[k] = x; |
720 |
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} |
721 |
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|
722 |
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/** |
723 |
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* Establishes the heap invariant (described above) in the entire tree, |
724 |
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* assuming nothing about the order of the elements prior to the call. |
725 |
+ |
* This classic algorithm due to Floyd (1964) is known to be O(size). |
726 |
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*/ |
733 |
– |
@SuppressWarnings("unchecked") |
727 |
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private void heapify() { |
728 |
< |
for (int i = (size >>> 1) - 1; i >= 0; i--) |
729 |
< |
siftDown(i, (E) queue[i]); |
728 |
> |
final Object[] es = queue; |
729 |
> |
int n = size, i = (n >>> 1) - 1; |
730 |
> |
Comparator<? super E> cmp = comparator; |
731 |
> |
if (cmp == null) |
732 |
> |
for (; i >= 0; i--) |
733 |
> |
siftDownComparable(i, (E) es[i], es, n); |
734 |
> |
else |
735 |
> |
for (; i >= 0; i--) |
736 |
> |
siftDownUsingComparator(i, (E) es[i], es, n, cmp); |
737 |
|
} |
738 |
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|
739 |
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/** |
752 |
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/** |
753 |
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* Saves this queue to a stream (that is, serializes it). |
754 |
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* |
755 |
+ |
* @param s the stream |
756 |
+ |
* @throws java.io.IOException if an I/O error occurs |
757 |
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* @serialData The length of the array backing the instance is |
758 |
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* emitted (int), followed by all of its elements |
759 |
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* (each an {@code Object}) in the proper order. |
758 |
– |
* @param s the stream |
759 |
– |
* @throws java.io.IOException if an I/O error occurs |
760 |
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*/ |
761 |
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private void writeObject(java.io.ObjectOutputStream s) |
762 |
|
throws java.io.IOException { |
767 |
|
s.writeInt(Math.max(2, size + 1)); |
768 |
|
|
769 |
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// Write out all elements in the "proper order". |
770 |
< |
for (int i = 0; i < size; i++) |
771 |
< |
s.writeObject(queue[i]); |
770 |
> |
final Object[] es = queue; |
771 |
> |
for (int i = 0, n = size; i < n; i++) |
772 |
> |
s.writeObject(es[i]); |
773 |
|
} |
774 |
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|
775 |
|
/** |
789 |
|
// Read in (and discard) array length |
790 |
|
s.readInt(); |
791 |
|
|
792 |
+ |
SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size); |
793 |
|
queue = new Object[size]; |
794 |
|
|
795 |
|
// Read in all elements. |
796 |
< |
for (int i = 0; i < size; i++) |
797 |
< |
queue[i] = s.readObject(); |
796 |
> |
final Object[] es = queue; |
797 |
> |
for (int i = 0, n = size; i < n; i++) |
798 |
> |
es[i] = s.readObject(); |
799 |
|
|
800 |
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// Elements are guaranteed to be in "proper order", but the |
801 |
|
// spec has never explained what that might be. |
805 |
|
/** |
806 |
|
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
807 |
|
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
808 |
< |
* queue. |
808 |
> |
* queue. The spliterator does not traverse elements in any particular order |
809 |
> |
* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported). |
810 |
|
* |
811 |
|
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
812 |
|
* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}. |
817 |
|
* @since 1.8 |
818 |
|
*/ |
819 |
|
public final Spliterator<E> spliterator() { |
820 |
< |
return new PriorityQueueSpliterator<>(this, 0, -1, 0); |
820 |
> |
return new PriorityQueueSpliterator(0, -1, 0); |
821 |
|
} |
822 |
|
|
823 |
< |
static final class PriorityQueueSpliterator<E> implements Spliterator<E> { |
820 |
< |
/* |
821 |
< |
* This is very similar to ArrayList Spliterator, except for |
822 |
< |
* extra null checks. |
823 |
< |
*/ |
824 |
< |
private final PriorityQueue<E> pq; |
823 |
> |
final class PriorityQueueSpliterator implements Spliterator<E> { |
824 |
|
private int index; // current index, modified on advance/split |
825 |
|
private int fence; // -1 until first use |
826 |
|
private int expectedModCount; // initialized when fence set |
827 |
|
|
828 |
< |
/** Creates new spliterator covering the given range */ |
829 |
< |
PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence, |
831 |
< |
int expectedModCount) { |
832 |
< |
this.pq = pq; |
828 |
> |
/** Creates new spliterator covering the given range. */ |
829 |
> |
PriorityQueueSpliterator(int origin, int fence, int expectedModCount) { |
830 |
|
this.index = origin; |
831 |
|
this.fence = fence; |
832 |
|
this.expectedModCount = expectedModCount; |
835 |
|
private int getFence() { // initialize fence to size on first use |
836 |
|
int hi; |
837 |
|
if ((hi = fence) < 0) { |
838 |
< |
expectedModCount = pq.modCount; |
839 |
< |
hi = fence = pq.size; |
838 |
> |
expectedModCount = modCount; |
839 |
> |
hi = fence = size; |
840 |
|
} |
841 |
|
return hi; |
842 |
|
} |
843 |
|
|
844 |
< |
public PriorityQueueSpliterator<E> trySplit() { |
844 |
> |
public PriorityQueueSpliterator trySplit() { |
845 |
|
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; |
846 |
|
return (lo >= mid) ? null : |
847 |
< |
new PriorityQueueSpliterator<>(pq, lo, index = mid, |
851 |
< |
expectedModCount); |
847 |
> |
new PriorityQueueSpliterator(lo, index = mid, expectedModCount); |
848 |
|
} |
849 |
|
|
854 |
– |
@SuppressWarnings("unchecked") |
850 |
|
public void forEachRemaining(Consumer<? super E> action) { |
856 |
– |
int i, hi, mc; // hoist accesses and checks from loop |
857 |
– |
PriorityQueue<E> q; Object[] a; |
851 |
|
if (action == null) |
852 |
|
throw new NullPointerException(); |
853 |
< |
if ((q = pq) != null && (a = q.queue) != null) { |
854 |
< |
if ((hi = fence) < 0) { |
855 |
< |
mc = q.modCount; |
856 |
< |
hi = q.size; |
857 |
< |
} |
858 |
< |
else |
859 |
< |
mc = expectedModCount; |
867 |
< |
if ((i = index) >= 0 && (index = hi) <= a.length) { |
868 |
< |
for (E e;; ++i) { |
869 |
< |
if (i < hi) { |
870 |
< |
if ((e = (E) a[i]) == null) // must be CME |
871 |
< |
break; |
872 |
< |
action.accept(e); |
873 |
< |
} |
874 |
< |
else if (q.modCount != mc) |
875 |
< |
break; |
876 |
< |
else |
877 |
< |
return; |
878 |
< |
} |
879 |
< |
} |
853 |
> |
if (fence < 0) { fence = size; expectedModCount = modCount; } |
854 |
> |
final Object[] es = queue; |
855 |
> |
int i, hi; E e; |
856 |
> |
for (i = index, index = hi = fence; i < hi; i++) { |
857 |
> |
if ((e = (E) es[i]) == null) |
858 |
> |
break; // must be CME |
859 |
> |
action.accept(e); |
860 |
|
} |
861 |
< |
throw new ConcurrentModificationException(); |
861 |
> |
if (modCount != expectedModCount) |
862 |
> |
throw new ConcurrentModificationException(); |
863 |
|
} |
864 |
|
|
865 |
|
public boolean tryAdvance(Consumer<? super E> action) { |
866 |
|
if (action == null) |
867 |
|
throw new NullPointerException(); |
868 |
< |
int hi = getFence(), lo = index; |
869 |
< |
if (lo >= 0 && lo < hi) { |
870 |
< |
index = lo + 1; |
871 |
< |
@SuppressWarnings("unchecked") E e = (E)pq.queue[lo]; |
872 |
< |
if (e == null) |
868 |
> |
if (fence < 0) { fence = size; expectedModCount = modCount; } |
869 |
> |
int i; |
870 |
> |
if ((i = index) < fence) { |
871 |
> |
index = i + 1; |
872 |
> |
E e; |
873 |
> |
if ((e = (E) queue[i]) == null |
874 |
> |
|| modCount != expectedModCount) |
875 |
|
throw new ConcurrentModificationException(); |
876 |
|
action.accept(e); |
894 |
– |
if (pq.modCount != expectedModCount) |
895 |
– |
throw new ConcurrentModificationException(); |
877 |
|
return true; |
878 |
|
} |
879 |
|
return false; |
880 |
|
} |
881 |
|
|
882 |
|
public long estimateSize() { |
883 |
< |
return (long) (getFence() - index); |
883 |
> |
return getFence() - index; |
884 |
|
} |
885 |
|
|
886 |
|
public int characteristics() { |
887 |
|
return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
888 |
|
} |
889 |
|
} |
890 |
+ |
|
891 |
+ |
/** |
892 |
+ |
* @throws NullPointerException {@inheritDoc} |
893 |
+ |
*/ |
894 |
+ |
public void forEach(Consumer<? super E> action) { |
895 |
+ |
Objects.requireNonNull(action); |
896 |
+ |
final int expectedModCount = modCount; |
897 |
+ |
final Object[] es = queue; |
898 |
+ |
for (int i = 0, n = size; i < n; i++) |
899 |
+ |
action.accept((E) es[i]); |
900 |
+ |
if (expectedModCount != modCount) |
901 |
+ |
throw new ConcurrentModificationException(); |
902 |
+ |
} |
903 |
|
} |