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/* |
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* Copyright (c) 2003, 2018, 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 jdk.internal.misc.SharedSecrets; |
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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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* 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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public class PriorityQueue<E> extends AbstractQueue<E> |
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implements java.io.Serializable { |
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// OPENJDK @java.io.Serial |
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private static final long serialVersionUID = -7720805057305804111L; |
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private static final int DEFAULT_INITIAL_CAPACITY = 11; |
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* The comparator, or null if priority queue uses elements' |
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* natural ordering. |
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*/ |
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@SuppressWarnings("serial") // Conditionally serializable |
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private final Comparator<? super E> comparator; |
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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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* 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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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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* Inserts the specified element into this priority queue. |
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* |
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* emitted (int), followed by all of its elements |
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* (each an {@code Object}) in the proper order. |
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*/ |
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// OPENJDK @java.io.Serial |
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private void writeObject(java.io.ObjectOutputStream s) |
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throws java.io.IOException { |
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// Write out element count, and any hidden stuff |
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* could not be found |
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* @throws java.io.IOException if an I/O error occurs |
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*/ |
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// OPENJDK @java.io.Serial |
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private void readObject(java.io.ObjectInputStream s) |
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throws java.io.IOException, ClassNotFoundException { |
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// Read in size, and any hidden stuff |
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// Read in (and discard) array length |
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s.readInt(); |
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SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size); |
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jsr166.Platform.checkArray(s, Object[].class, size); |
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final Object[] es = queue = new Object[Math.max(size, 1)]; |
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// Read in all elements. |
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} |
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/** |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public boolean removeIf(Predicate<? super E> filter) { |
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Objects.requireNonNull(filter); |
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return bulkRemove(filter); |
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} |
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/** |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public boolean removeAll(Collection<?> c) { |
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Objects.requireNonNull(c); |
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return bulkRemove(e -> c.contains(e)); |
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} |
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|
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/** |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public boolean retainAll(Collection<?> c) { |
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Objects.requireNonNull(c); |
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return bulkRemove(e -> !c.contains(e)); |
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} |
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// A tiny bit set implementation |
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private static long[] nBits(int n) { |
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return new long[((n - 1) >> 6) + 1]; |
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} |
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private static void setBit(long[] bits, int i) { |
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bits[i >> 6] |= 1L << i; |
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} |
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private static boolean isClear(long[] bits, int i) { |
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return (bits[i >> 6] & (1L << i)) == 0; |
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} |
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/** Implementation of bulk remove methods. */ |
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private boolean bulkRemove(Predicate<? super E> filter) { |
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final int expectedModCount = ++modCount; |
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final Object[] es = queue; |
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final int end = size; |
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int i; |
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// Optimize for initial run of survivors |
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for (i = 0; i < end && !filter.test((E) es[i]); i++) |
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; |
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if (i >= end) { |
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if (modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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return false; |
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} |
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// Tolerate predicates that reentrantly access the collection for |
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// read (but writers still get CME), so traverse once to find |
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// elements to delete, a second pass to physically expunge. |
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final int beg = i; |
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final long[] deathRow = nBits(end - beg); |
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deathRow[0] = 1L; // set bit 0 |
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for (i = beg + 1; i < end; i++) |
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if (filter.test((E) es[i])) |
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setBit(deathRow, i - beg); |
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if (modCount != expectedModCount) |
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throw new ConcurrentModificationException(); |
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int w = beg; |
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for (i = beg; i < end; i++) |
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if (isClear(deathRow, i - beg)) |
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es[w++] = es[i]; |
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for (i = size = w; i < end; i++) |
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es[i] = null; |
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heapify(); |
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return true; |
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} |
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/** |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public void forEach(Consumer<? super E> action) { |