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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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* ({@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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|
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/** Ensures that queue[0] exists, helping peek() and poll(). */ |
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private static Object[] ensureNonEmpty(Object[] es) { |
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return (es.length > 0) ? es : new Object[1]; |
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} |
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|
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private void initFromPriorityQueue(PriorityQueue<? extends E> c) { |
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if (c.getClass() == PriorityQueue.class) { |
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this.queue = c.toArray(); |
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this.queue = ensureNonEmpty(c.toArray()); |
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this.size = c.size(); |
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} else { |
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initFromCollection(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 = ensureNonEmpty(es); |
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this.size = len; |
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} |
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/** |
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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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return (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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* 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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(forgetMeNot != null && !forgetMeNot.isEmpty()); |
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} |
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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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int s = --size; |
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modCount++; |
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E result = (E) queue[0]; |
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E x = (E) queue[s]; |
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queue[s] = null; |
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if (s != 0) |
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siftDown(0, x); |
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final Object[] es; |
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final E result; |
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|
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if ((result = (E) ((es = queue)[0])) != null) { |
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modCount++; |
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final int n; |
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final E x = (E) es[(n = --size)]; |
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es[n] = null; |
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if (n > 0) { |
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final Comparator<? super E> cmp; |
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if ((cmp = comparator) == null) |
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siftDownComparable(0, x, es, n); |
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else |
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siftDownUsingComparator(0, x, es, n, cmp); |
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} |
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} |
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return result; |
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} |
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|
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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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*/ |
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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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@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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@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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@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) { |
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// assert n > 0; |
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Comparable<? super T> key = (Comparable<? super T>)x; |
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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 |
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Object c = queue[child]; |
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Object c = es[child]; |
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int right = child + 1; |
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if (right < size && |
706 |
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((Comparable<? super E>) c).compareTo((E) queue[right]) > 0) |
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c = queue[child = right]; |
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if (key.compareTo((E) c) <= 0) |
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if (right < n && |
706 |
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((Comparable<? super T>) c).compareTo((T) es[right]) > 0) |
707 |
> |
c = es[child = right]; |
708 |
> |
if (key.compareTo((T) c) <= 0) |
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break; |
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< |
queue[k] = c; |
710 |
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es[k] = c; |
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k = child; |
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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") |
717 |
< |
private void siftDownUsingComparator(int k, E x) { |
718 |
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int half = size >>> 1; |
716 |
> |
private static <T> void siftDownUsingComparator( |
717 |
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int k, T x, Object[] es, int n, Comparator<? super T> cmp) { |
718 |
> |
// assert n > 0; |
719 |
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int half = n >>> 1; |
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while (k < half) { |
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int child = (k << 1) + 1; |
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Object c = queue[child]; |
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Object c = es[child]; |
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int right = child + 1; |
724 |
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if (right < size && |
725 |
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comparator.compare((E) c, (E) queue[right]) > 0) |
726 |
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c = queue[child = right]; |
721 |
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if (comparator.compare(x, (E) c) <= 0) |
724 |
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if (right < n && cmp.compare((T) c, (T) es[right]) > 0) |
725 |
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c = es[child = right]; |
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> |
if (cmp.compare(x, (T) c) <= 0) |
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break; |
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queue[k] = c; |
728 |
> |
es[k] = c; |
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k = child; |
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} |
731 |
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queue[k] = x; |
731 |
> |
es[k] = x; |
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} |
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|
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/** |
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* assuming nothing about the order of the elements prior to the call. |
737 |
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* This classic algorithm due to Floyd (1964) is known to be O(size). |
738 |
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*/ |
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@SuppressWarnings("unchecked") |
739 |
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private void heapify() { |
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final Object[] es = queue; |
741 |
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int i = (size >>> 1) - 1; |
742 |
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if (comparator == null) |
741 |
> |
int n = size, i = (n >>> 1) - 1; |
742 |
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final Comparator<? super E> cmp; |
743 |
> |
if ((cmp = comparator) == null) |
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for (; i >= 0; i--) |
745 |
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siftDownComparable(i, (E) es[i]); |
745 |
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siftDownComparable(i, (E) es[i], es, n); |
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else |
747 |
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for (; i >= 0; i--) |
748 |
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siftDownUsingComparator(i, (E) es[i]); |
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siftDownUsingComparator(i, (E) es[i], es, n, cmp); |
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} |
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|
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/** |
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s.writeInt(Math.max(2, size + 1)); |
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|
781 |
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// Write out all elements in the "proper order". |
782 |
< |
for (int i = 0; i < size; i++) |
783 |
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s.writeObject(queue[i]); |
782 |
> |
final Object[] es = queue; |
783 |
> |
for (int i = 0, n = size; i < n; i++) |
784 |
> |
s.writeObject(es[i]); |
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} |
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|
787 |
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/** |
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// Read in (and discard) array length |
802 |
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s.readInt(); |
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|
804 |
< |
queue = new Object[size]; |
804 |
> |
SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size); |
805 |
> |
final Object[] es = queue = new Object[Math.max(size, 1)]; |
806 |
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|
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// Read in all elements. |
808 |
< |
for (int i = 0; i < size; i++) |
809 |
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queue[i] = s.readObject(); |
808 |
> |
for (int i = 0, n = size; i < n; i++) |
809 |
> |
es[i] = s.readObject(); |
810 |
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|
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// Elements are guaranteed to be in "proper order", but the |
812 |
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// spec has never explained what that might be. |
858 |
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new PriorityQueueSpliterator(lo, index = mid, expectedModCount); |
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} |
860 |
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|
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– |
@SuppressWarnings("unchecked") |
861 |
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public void forEachRemaining(Consumer<? super E> action) { |
862 |
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if (action == null) |
863 |
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throw new NullPointerException(); |
864 |
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if (fence < 0) { fence = size; expectedModCount = modCount; } |
865 |
< |
final Object[] a = queue; |
865 |
> |
final Object[] es = queue; |
866 |
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int i, hi; E e; |
867 |
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for (i = index, index = hi = fence; i < hi; i++) { |
868 |
< |
if ((e = (E) a[i]) == null) |
868 |
> |
if ((e = (E) es[i]) == null) |
869 |
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break; // must be CME |
870 |
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action.accept(e); |
871 |
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} |
873 |
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throw new ConcurrentModificationException(); |
874 |
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} |
875 |
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|
870 |
– |
@SuppressWarnings("unchecked") |
876 |
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public boolean tryAdvance(Consumer<? super E> action) { |
877 |
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if (action == null) |
878 |
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throw new NullPointerException(); |
898 |
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return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
899 |
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} |
900 |
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} |
901 |
+ |
|
902 |
+ |
/** |
903 |
+ |
* @throws NullPointerException {@inheritDoc} |
904 |
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*/ |
905 |
+ |
public void forEach(Consumer<? super E> action) { |
906 |
+ |
Objects.requireNonNull(action); |
907 |
+ |
final int expectedModCount = modCount; |
908 |
+ |
final Object[] es = queue; |
909 |
+ |
for (int i = 0, n = size; i < n; i++) |
910 |
+ |
action.accept((E) es[i]); |
911 |
+ |
if (expectedModCount != modCount) |
912 |
+ |
throw new ConcurrentModificationException(); |
913 |
+ |
} |
914 |
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} |