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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, 2019, 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 java.util.function.Predicate; |
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// OPENJDK import jdk.internal.access.SharedSecrets; |
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import jdk.internal.util.ArraysSupport; |
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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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* ({@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}/java/util/package-summary.html#CollectionsFramework"> |
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* <a href="{@docRoot}/java.base/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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|
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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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|
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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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/** |
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} |
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|
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/** |
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* The maximum size of array to allocate. |
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* Some VMs reserve some header words in an array. |
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* Attempts to allocate larger arrays may result in |
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* OutOfMemoryError: Requested array size exceeds VM limit |
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*/ |
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private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
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|
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/** |
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* Increases the capacity of the array. |
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* |
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* @param minCapacity the desired minimum capacity |
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private void grow(int minCapacity) { |
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int oldCapacity = queue.length; |
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// Double size if small; else grow by 50% |
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int newCapacity = oldCapacity + ((oldCapacity < 64) ? |
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(oldCapacity + 2) : |
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(oldCapacity >> 1)); |
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// overflow-conscious code |
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if (newCapacity - MAX_ARRAY_SIZE > 0) |
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newCapacity = hugeCapacity(minCapacity); |
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int newCapacity = ArraysSupport.newLength(oldCapacity, |
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minCapacity - oldCapacity, /* minimum growth */ |
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oldCapacity < 64 ? oldCapacity + 2 : oldCapacity >> 1 |
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/* preferred growth */); |
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queue = Arrays.copyOf(queue, newCapacity); |
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} |
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|
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private static int hugeCapacity(int minCapacity) { |
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if (minCapacity < 0) // overflow |
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throw new OutOfMemoryError(); |
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return (minCapacity > MAX_ARRAY_SIZE) ? |
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Integer.MAX_VALUE : |
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MAX_ARRAY_SIZE; |
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} |
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|
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/** |
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* Inserts the specified element into this priority queue. |
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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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/** |
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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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/** |
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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; |
564 |
> |
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; |
577 |
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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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final Object[] es = queue; |
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modCount++; |
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int s = --size; |
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if (s == i) // removed last element |
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queue[i] = null; |
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es[i] = null; |
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else { |
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E moved = (E) queue[s]; |
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queue[s] = null; |
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E moved = (E) es[s]; |
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es[s] = null; |
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siftDown(i, moved); |
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< |
if (queue[i] == moved) { |
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> |
if (es[i] == moved) { |
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siftUp(i, moved); |
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if (queue[i] != moved) |
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if (es[i] != moved) |
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return moved; |
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} |
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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) |
636 |
< |
siftUpUsingComparator(k, x); |
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siftUpUsingComparator(k, x, queue, comparator); |
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else |
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siftUpComparable(k, x); |
638 |
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siftUpComparable(k, x, queue); |
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} |
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|
641 |
< |
@SuppressWarnings("unchecked") |
642 |
< |
private void siftUpComparable(int k, E x) { |
652 |
< |
Comparable<? super E> key = (Comparable<? super E>) x; |
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> |
private static <T> void siftUpComparable(int k, T x, Object[] es) { |
642 |
> |
Comparable<? super T> key = (Comparable<? super T>) x; |
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while (k > 0) { |
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int parent = (k - 1) >>> 1; |
645 |
< |
Object e = queue[parent]; |
646 |
< |
if (key.compareTo((E) e) >= 0) |
645 |
> |
Object e = es[parent]; |
646 |
> |
if (key.compareTo((T) e) >= 0) |
647 |
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break; |
648 |
< |
queue[k] = e; |
648 |
> |
es[k] = e; |
649 |
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k = parent; |
650 |
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} |
651 |
< |
queue[k] = key; |
651 |
> |
es[k] = key; |
652 |
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} |
653 |
|
|
654 |
< |
@SuppressWarnings("unchecked") |
655 |
< |
private void siftUpUsingComparator(int k, E x) { |
654 |
> |
private static <T> void siftUpUsingComparator( |
655 |
> |
int k, T x, Object[] es, Comparator<? super T> cmp) { |
656 |
|
while (k > 0) { |
657 |
|
int parent = (k - 1) >>> 1; |
658 |
< |
Object e = queue[parent]; |
659 |
< |
if (comparator.compare(x, (E) e) >= 0) |
658 |
> |
Object e = es[parent]; |
659 |
> |
if (cmp.compare(x, (T) e) >= 0) |
660 |
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break; |
661 |
< |
queue[k] = e; |
661 |
> |
es[k] = e; |
662 |
|
k = parent; |
663 |
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} |
664 |
< |
queue[k] = x; |
664 |
> |
es[k] = x; |
665 |
|
} |
666 |
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|
667 |
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/** |
674 |
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*/ |
675 |
|
private void siftDown(int k, E x) { |
676 |
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if (comparator != null) |
677 |
< |
siftDownUsingComparator(k, x); |
677 |
> |
siftDownUsingComparator(k, x, queue, size, comparator); |
678 |
|
else |
679 |
< |
siftDownComparable(k, x); |
679 |
> |
siftDownComparable(k, x, queue, size); |
680 |
|
} |
681 |
|
|
682 |
< |
@SuppressWarnings("unchecked") |
683 |
< |
private void siftDownComparable(int k, E x) { |
684 |
< |
Comparable<? super E> key = (Comparable<? super E>)x; |
685 |
< |
int half = size >>> 1; // loop while a non-leaf |
682 |
> |
private static <T> void siftDownComparable(int k, T x, Object[] es, int n) { |
683 |
> |
// assert n > 0; |
684 |
> |
Comparable<? super T> key = (Comparable<? super T>)x; |
685 |
> |
int half = n >>> 1; // loop while a non-leaf |
686 |
|
while (k < half) { |
687 |
|
int child = (k << 1) + 1; // assume left child is least |
688 |
< |
Object c = queue[child]; |
688 |
> |
Object c = es[child]; |
689 |
|
int right = child + 1; |
690 |
< |
if (right < size && |
691 |
< |
((Comparable<? super E>) c).compareTo((E) queue[right]) > 0) |
692 |
< |
c = queue[child = right]; |
693 |
< |
if (key.compareTo((E) c) <= 0) |
690 |
> |
if (right < n && |
691 |
> |
((Comparable<? super T>) c).compareTo((T) es[right]) > 0) |
692 |
> |
c = es[child = right]; |
693 |
> |
if (key.compareTo((T) c) <= 0) |
694 |
|
break; |
695 |
< |
queue[k] = c; |
695 |
> |
es[k] = c; |
696 |
|
k = child; |
697 |
|
} |
698 |
< |
queue[k] = key; |
698 |
> |
es[k] = key; |
699 |
|
} |
700 |
|
|
701 |
< |
@SuppressWarnings("unchecked") |
702 |
< |
private void siftDownUsingComparator(int k, E x) { |
703 |
< |
int half = size >>> 1; |
701 |
> |
private static <T> void siftDownUsingComparator( |
702 |
> |
int k, T x, Object[] es, int n, Comparator<? super T> cmp) { |
703 |
> |
// assert n > 0; |
704 |
> |
int half = n >>> 1; |
705 |
|
while (k < half) { |
706 |
|
int child = (k << 1) + 1; |
707 |
< |
Object c = queue[child]; |
707 |
> |
Object c = es[child]; |
708 |
|
int right = child + 1; |
709 |
< |
if (right < size && |
710 |
< |
comparator.compare((E) c, (E) queue[right]) > 0) |
711 |
< |
c = queue[child = right]; |
721 |
< |
if (comparator.compare(x, (E) c) <= 0) |
709 |
> |
if (right < n && cmp.compare((T) c, (T) es[right]) > 0) |
710 |
> |
c = es[child = right]; |
711 |
> |
if (cmp.compare(x, (T) c) <= 0) |
712 |
|
break; |
713 |
< |
queue[k] = c; |
713 |
> |
es[k] = c; |
714 |
|
k = child; |
715 |
|
} |
716 |
< |
queue[k] = x; |
716 |
> |
es[k] = x; |
717 |
|
} |
718 |
|
|
719 |
|
/** |
721 |
|
* assuming nothing about the order of the elements prior to the call. |
722 |
|
* This classic algorithm due to Floyd (1964) is known to be O(size). |
723 |
|
*/ |
734 |
– |
@SuppressWarnings("unchecked") |
724 |
|
private void heapify() { |
725 |
|
final Object[] es = queue; |
726 |
< |
int i = (size >>> 1) - 1; |
727 |
< |
if (comparator == null) |
726 |
> |
int n = size, i = (n >>> 1) - 1; |
727 |
> |
final Comparator<? super E> cmp; |
728 |
> |
if ((cmp = comparator) == null) |
729 |
|
for (; i >= 0; i--) |
730 |
< |
siftDownComparable(i, (E) es[i]); |
730 |
> |
siftDownComparable(i, (E) es[i], es, n); |
731 |
|
else |
732 |
|
for (; i >= 0; i--) |
733 |
< |
siftDownUsingComparator(i, (E) es[i]); |
733 |
> |
siftDownUsingComparator(i, (E) es[i], es, n, cmp); |
734 |
|
} |
735 |
|
|
736 |
|
/** |
764 |
|
s.writeInt(Math.max(2, size + 1)); |
765 |
|
|
766 |
|
// Write out all elements in the "proper order". |
767 |
< |
for (int i = 0; i < size; i++) |
768 |
< |
s.writeObject(queue[i]); |
767 |
> |
final Object[] es = queue; |
768 |
> |
for (int i = 0, n = size; i < n; i++) |
769 |
> |
s.writeObject(es[i]); |
770 |
|
} |
771 |
|
|
772 |
|
/** |
786 |
|
// Read in (and discard) array length |
787 |
|
s.readInt(); |
788 |
|
|
789 |
< |
queue = new Object[size]; |
789 |
> |
jsr166.Platform.checkArray(s, Object[].class, size); |
790 |
> |
final Object[] es = queue = new Object[Math.max(size, 1)]; |
791 |
|
|
792 |
|
// Read in all elements. |
793 |
< |
for (int i = 0; i < size; i++) |
794 |
< |
queue[i] = s.readObject(); |
793 |
> |
for (int i = 0, n = size; i < n; i++) |
794 |
> |
es[i] = s.readObject(); |
795 |
|
|
796 |
|
// Elements are guaranteed to be in "proper order", but the |
797 |
|
// spec has never explained what that might be. |
843 |
|
new PriorityQueueSpliterator(lo, index = mid, expectedModCount); |
844 |
|
} |
845 |
|
|
854 |
– |
@SuppressWarnings("unchecked") |
846 |
|
public void forEachRemaining(Consumer<? super E> action) { |
847 |
|
if (action == null) |
848 |
|
throw new NullPointerException(); |
849 |
|
if (fence < 0) { fence = size; expectedModCount = modCount; } |
850 |
< |
final Object[] a = queue; |
850 |
> |
final Object[] es = queue; |
851 |
|
int i, hi; E e; |
852 |
|
for (i = index, index = hi = fence; i < hi; i++) { |
853 |
< |
if ((e = (E) a[i]) == null) |
853 |
> |
if ((e = (E) es[i]) == null) |
854 |
|
break; // must be CME |
855 |
|
action.accept(e); |
856 |
|
} |
858 |
|
throw new ConcurrentModificationException(); |
859 |
|
} |
860 |
|
|
870 |
– |
@SuppressWarnings("unchecked") |
861 |
|
public boolean tryAdvance(Consumer<? super E> action) { |
862 |
|
if (action == null) |
863 |
|
throw new NullPointerException(); |
883 |
|
return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
884 |
|
} |
885 |
|
} |
886 |
+ |
|
887 |
+ |
/** |
888 |
+ |
* @throws NullPointerException {@inheritDoc} |
889 |
+ |
*/ |
890 |
+ |
public boolean removeIf(Predicate<? super E> filter) { |
891 |
+ |
Objects.requireNonNull(filter); |
892 |
+ |
return bulkRemove(filter); |
893 |
+ |
} |
894 |
+ |
|
895 |
+ |
/** |
896 |
+ |
* @throws NullPointerException {@inheritDoc} |
897 |
+ |
*/ |
898 |
+ |
public boolean removeAll(Collection<?> c) { |
899 |
+ |
Objects.requireNonNull(c); |
900 |
+ |
return bulkRemove(e -> c.contains(e)); |
901 |
+ |
} |
902 |
+ |
|
903 |
+ |
/** |
904 |
+ |
* @throws NullPointerException {@inheritDoc} |
905 |
+ |
*/ |
906 |
+ |
public boolean retainAll(Collection<?> c) { |
907 |
+ |
Objects.requireNonNull(c); |
908 |
+ |
return bulkRemove(e -> !c.contains(e)); |
909 |
+ |
} |
910 |
+ |
|
911 |
+ |
// A tiny bit set implementation |
912 |
+ |
|
913 |
+ |
private static long[] nBits(int n) { |
914 |
+ |
return new long[((n - 1) >> 6) + 1]; |
915 |
+ |
} |
916 |
+ |
private static void setBit(long[] bits, int i) { |
917 |
+ |
bits[i >> 6] |= 1L << i; |
918 |
+ |
} |
919 |
+ |
private static boolean isClear(long[] bits, int i) { |
920 |
+ |
return (bits[i >> 6] & (1L << i)) == 0; |
921 |
+ |
} |
922 |
+ |
|
923 |
+ |
/** Implementation of bulk remove methods. */ |
924 |
+ |
private boolean bulkRemove(Predicate<? super E> filter) { |
925 |
+ |
final int expectedModCount = ++modCount; |
926 |
+ |
final Object[] es = queue; |
927 |
+ |
final int end = size; |
928 |
+ |
int i; |
929 |
+ |
// Optimize for initial run of survivors |
930 |
+ |
for (i = 0; i < end && !filter.test((E) es[i]); i++) |
931 |
+ |
; |
932 |
+ |
if (i >= end) { |
933 |
+ |
if (modCount != expectedModCount) |
934 |
+ |
throw new ConcurrentModificationException(); |
935 |
+ |
return false; |
936 |
+ |
} |
937 |
+ |
// Tolerate predicates that reentrantly access the collection for |
938 |
+ |
// read (but writers still get CME), so traverse once to find |
939 |
+ |
// elements to delete, a second pass to physically expunge. |
940 |
+ |
final int beg = i; |
941 |
+ |
final long[] deathRow = nBits(end - beg); |
942 |
+ |
deathRow[0] = 1L; // set bit 0 |
943 |
+ |
for (i = beg + 1; i < end; i++) |
944 |
+ |
if (filter.test((E) es[i])) |
945 |
+ |
setBit(deathRow, i - beg); |
946 |
+ |
if (modCount != expectedModCount) |
947 |
+ |
throw new ConcurrentModificationException(); |
948 |
+ |
int w = beg; |
949 |
+ |
for (i = beg; i < end; i++) |
950 |
+ |
if (isClear(deathRow, i - beg)) |
951 |
+ |
es[w++] = es[i]; |
952 |
+ |
for (i = size = w; i < end; i++) |
953 |
+ |
es[i] = null; |
954 |
+ |
heapify(); |
955 |
+ |
return true; |
956 |
+ |
} |
957 |
+ |
|
958 |
+ |
/** |
959 |
+ |
* @throws NullPointerException {@inheritDoc} |
960 |
+ |
*/ |
961 |
+ |
public void forEach(Consumer<? super E> action) { |
962 |
+ |
Objects.requireNonNull(action); |
963 |
+ |
final int expectedModCount = modCount; |
964 |
+ |
final Object[] es = queue; |
965 |
+ |
for (int i = 0, n = size; i < n; i++) |
966 |
+ |
action.accept((E) es[i]); |
967 |
+ |
if (expectedModCount != modCount) |
968 |
+ |
throw new ConcurrentModificationException(); |
969 |
+ |
} |
970 |
|
} |