/*
* Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
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*
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*
*/
package java.util;
import java.util.function.
Consumer;
import sun.misc.
SharedSecrets;
/**
* An unbounded priority {@linkplain Queue queue} based on a priority heap.
* The elements of the priority queue are ordered according to their
* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
* provided at queue construction time, depending on which constructor is
* used. A priority queue does not permit {@code null} elements.
* A priority queue relying on natural ordering also does not permit
* insertion of non-comparable objects (doing so may result in
* {@code ClassCastException}).
*
* <p>The <em>head</em> of this queue is the <em>least</em> element
* with respect to the specified ordering. If multiple elements are
* tied for least value, the head is one of those elements -- ties are
* broken arbitrarily. The queue retrieval operations {@code poll},
* {@code remove}, {@code peek}, and {@code element} access the
* element at the head of the queue.
*
* <p>A priority queue is unbounded, but has an internal
* <i>capacity</i> governing the size of an array used to store the
* elements on the queue. It is always at least as large as the queue
* size. As elements are added to a priority queue, its capacity
* grows automatically. The details of the growth policy are not
* specified.
*
* <p>This class and its iterator implement all of the
* <em>optional</em> methods of the {@link Collection} and {@link
* Iterator} interfaces. The Iterator provided in method {@link
* #iterator()} is <em>not</em> guaranteed to traverse the elements of
* the priority queue in any particular order. If you need ordered
* traversal, consider using {@code Arrays.sort(pq.toArray())}.
*
* <p><strong>Note that this implementation is not synchronized.</strong>
* Multiple threads should not access a {@code PriorityQueue}
* instance concurrently if any of the threads modifies the queue.
* Instead, use the thread-safe {@link
* java.util.concurrent.PriorityBlockingQueue} class.
*
* <p>Implementation note: this implementation provides
* O(log(n)) time for the enqueuing and dequeuing methods
* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
* linear time for the {@code remove(Object)} and {@code contains(Object)}
* methods; and constant time for the retrieval methods
* ({@code peek}, {@code element}, and {@code size}).
*
* <p>This class is a member of the
* <a href="{@docRoot}/../technotes/guides/collections/index.html">
* Java Collections Framework</a>.
*
* @since 1.5
* @author Josh Bloch, Doug Lea
* @param <E> the type of elements held in this collection
*/
public class
PriorityQueue<E> extends
AbstractQueue<E>
implements java.io.
Serializable {
private static final long
serialVersionUID = -7720805057305804111L;
private static final int
DEFAULT_INITIAL_CAPACITY = 11;
/**
* Priority queue represented as a balanced binary heap: the two
* children of queue[n] are queue[2*n+1] and queue[2*(n+1)]. The
* priority queue is ordered by comparator, or by the elements'
* natural ordering, if comparator is null: For each node n in the
* heap and each descendant d of n, n <= d. The element with the
* lowest value is in queue[0], assuming the queue is nonempty.
*/
transient
Object[]
queue; // non-private to simplify nested class access
/**
* The number of elements in the priority queue.
*/
private int
size = 0;
/**
* The comparator, or null if priority queue uses elements'
* natural ordering.
*/
private final
Comparator<? super E>
comparator;
/**
* The number of times this priority queue has been
* <i>structurally modified</i>. See AbstractList for gory details.
*/
transient int
modCount = 0; // non-private to simplify nested class access
/**
* Creates a {@code PriorityQueue} with the default initial
* capacity (11) that orders its elements according to their
* {@linkplain Comparable natural ordering}.
*/
public
PriorityQueue() {
this(
DEFAULT_INITIAL_CAPACITY, null);
}
/**
* Creates a {@code PriorityQueue} with the specified initial
* capacity that orders its elements according to their
* {@linkplain Comparable natural ordering}.
*
* @param initialCapacity the initial capacity for this priority queue
* @throws IllegalArgumentException if {@code initialCapacity} is less
* than 1
*/
public
PriorityQueue(int
initialCapacity) {
this(
initialCapacity, null);
}
/**
* Creates a {@code PriorityQueue} with the default initial capacity and
* whose elements are ordered according to the specified comparator.
*
* @param comparator the comparator that will be used to order this
* priority queue. If {@code null}, the {@linkplain Comparable
* natural ordering} of the elements will be used.
* @since 1.8
*/
public
PriorityQueue(
Comparator<? super E>
comparator) {
this(
DEFAULT_INITIAL_CAPACITY,
comparator);
}
/**
* Creates a {@code PriorityQueue} with the specified initial capacity
* that orders its elements according to the specified comparator.
*
* @param initialCapacity the initial capacity for this priority queue
* @param comparator the comparator that will be used to order this
* priority queue. If {@code null}, the {@linkplain Comparable
* natural ordering} of the elements will be used.
* @throws IllegalArgumentException if {@code initialCapacity} is
* less than 1
*/
public
PriorityQueue(int
initialCapacity,
Comparator<? super E>
comparator) {
// Note: This restriction of at least one is not actually needed,
// but continues for 1.5 compatibility
if (
initialCapacity < 1)
throw new
IllegalArgumentException();
this.
queue = new
Object[
initialCapacity];
this.
comparator =
comparator;
}
/**
* Creates a {@code PriorityQueue} containing the elements in the
* specified collection. If the specified collection is an instance of
* a {@link SortedSet} or is another {@code PriorityQueue}, this
* priority queue will be ordered according to the same ordering.
* Otherwise, this priority queue will be ordered according to the
* {@linkplain Comparable natural ordering} of its elements.
*
* @param c the collection whose elements are to be placed
* into this priority queue
* @throws ClassCastException if elements of the specified collection
* cannot be compared to one another according to the priority
* queue's ordering
* @throws NullPointerException if the specified collection or any
* of its elements are null
*/
@
SuppressWarnings("unchecked")
public
PriorityQueue(
Collection<? extends E>
c) {
if (
c instanceof
SortedSet<?>) {
SortedSet<? extends E>
ss = (
SortedSet<? extends E>)
c;
this.
comparator = (
Comparator<? super E>)
ss.
comparator();
initElementsFromCollection(
ss);
}
else if (
c instanceof
PriorityQueue<?>) {
PriorityQueue<? extends E>
pq = (
PriorityQueue<? extends E>)
c;
this.
comparator = (
Comparator<? super E>)
pq.
comparator();
initFromPriorityQueue(
pq);
}
else {
this.
comparator = null;
initFromCollection(
c);
}
}
/**
* Creates a {@code PriorityQueue} containing the elements in the
* specified priority queue. This priority queue will be
* ordered according to the same ordering as the given priority
* queue.
*
* @param c the priority queue whose elements are to be placed
* into this priority queue
* @throws ClassCastException if elements of {@code c} cannot be
* compared to one another according to {@code c}'s
* ordering
* @throws NullPointerException if the specified priority queue or any
* of its elements are null
*/
@
SuppressWarnings("unchecked")
public
PriorityQueue(
PriorityQueue<? extends E>
c) {
this.
comparator = (
Comparator<? super E>)
c.
comparator();
initFromPriorityQueue(
c);
}
/**
* Creates a {@code PriorityQueue} containing the elements in the
* specified sorted set. This priority queue will be ordered
* according to the same ordering as the given sorted set.
*
* @param c the sorted set whose elements are to be placed
* into this priority queue
* @throws ClassCastException if elements of the specified sorted
* set cannot be compared to one another according to the
* sorted set's ordering
* @throws NullPointerException if the specified sorted set or any
* of its elements are null
*/
@
SuppressWarnings("unchecked")
public
PriorityQueue(
SortedSet<? extends E>
c) {
this.
comparator = (
Comparator<? super E>)
c.
comparator();
initElementsFromCollection(
c);
}
private void
initFromPriorityQueue(
PriorityQueue<? extends E>
c) {
if (
c.
getClass() ==
PriorityQueue.class) {
this.
queue =
c.
toArray();
this.
size =
c.
size();
} else {
initFromCollection(
c);
}
}
private void
initElementsFromCollection(
Collection<? extends E>
c) {
Object[]
a =
c.
toArray();
// If c.toArray incorrectly doesn't return Object[], copy it.
if (
a.
getClass() !=
Object[].class)
a =
Arrays.
copyOf(
a,
a.length,
Object[].class);
int
len =
a.length;
if (
len == 1 || this.
comparator != null)
for (int
i = 0;
i <
len;
i++)
if (
a[
i] == null)
throw new
NullPointerException();
this.
queue =
a;
this.
size =
a.length;
}
/**
* Initializes queue array with elements from the given Collection.
*
* @param c the collection
*/
private void
initFromCollection(
Collection<? extends E>
c) {
initElementsFromCollection(
c);
heapify();
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int
MAX_ARRAY_SIZE =
Integer.
MAX_VALUE - 8;
/**
* Increases the capacity of the array.
*
* @param minCapacity the desired minimum capacity
*/
private void
grow(int
minCapacity) {
int
oldCapacity =
queue.length;
// Double size if small; else grow by 50%
int
newCapacity =
oldCapacity + ((
oldCapacity < 64) ?
(
oldCapacity + 2) :
(
oldCapacity >> 1));
// overflow-conscious code
if (
newCapacity -
MAX_ARRAY_SIZE > 0)
newCapacity =
hugeCapacity(
minCapacity);
queue =
Arrays.
copyOf(
queue,
newCapacity);
}
private static int
hugeCapacity(int
minCapacity) {
if (
minCapacity < 0) // overflow
throw new
OutOfMemoryError();
return (
minCapacity >
MAX_ARRAY_SIZE) ?
Integer.
MAX_VALUE :
MAX_ARRAY_SIZE;
}
/**
* Inserts the specified element into this priority queue.
*
* @return {@code true} (as specified by {@link Collection#add})
* @throws ClassCastException if the specified element cannot be
* compared with elements currently in this priority queue
* according to the priority queue's ordering
* @throws NullPointerException if the specified element is null
*/
public boolean
add(E
e) {
return
offer(
e);
}
/**
* Inserts the specified element into this priority queue.
*
* @return {@code true} (as specified by {@link Queue#offer})
* @throws ClassCastException if the specified element cannot be
* compared with elements currently in this priority queue
* according to the priority queue's ordering
* @throws NullPointerException if the specified element is null
*/
public boolean
offer(E
e) {
if (
e == null)
throw new
NullPointerException();
modCount++;
int
i =
size;
if (
i >=
queue.length)
grow(
i + 1);
size =
i + 1;
if (
i == 0)
queue[0] =
e;
else
siftUp(
i,
e);
return true;
}
@
SuppressWarnings("unchecked")
public E
peek() {
return (
size == 0) ? null : (E)
queue[0];
}
private int
indexOf(
Object o) {
if (
o != null) {
for (int
i = 0;
i <
size;
i++)
if (
o.
equals(
queue[
i]))
return
i;
}
return -1;
}
/**
* Removes a single instance of the specified element from this queue,
* if it is present. More formally, removes an element {@code e} such
* that {@code o.equals(e)}, if this queue contains one or more such
* elements. Returns {@code true} if and only if this queue contained
* the specified element (or equivalently, if this queue changed as a
* result of the call).
*
* @param o element to be removed from this queue, if present
* @return {@code true} if this queue changed as a result of the call
*/
public boolean
remove(
Object o) {
int
i =
indexOf(
o);
if (
i == -1)
return false;
else {
removeAt(
i);
return true;
}
}
/**
* Version of remove using reference equality, not equals.
* Needed by iterator.remove.
*
* @param o element to be removed from this queue, if present
* @return {@code true} if removed
*/
boolean
removeEq(
Object o) {
for (int
i = 0;
i <
size;
i++) {
if (
o ==
queue[
i]) {
removeAt(
i);
return true;
}
}
return false;
}
/**
* Returns {@code true} if this queue contains the specified element.
* More formally, returns {@code true} if and only if this queue contains
* at least one element {@code e} such that {@code o.equals(e)}.
*
* @param o object to be checked for containment in this queue
* @return {@code true} if this queue contains the specified element
*/
public boolean
contains(
Object o) {
return
indexOf(
o) != -1;
}
/**
* Returns an array containing all of the elements in this queue.
* The elements are in no particular order.
*
* <p>The returned array will be "safe" in that no references to it are
* maintained by this queue. (In other words, this method must allocate
* a new array). The caller is thus free to modify the returned array.
*
* <p>This method acts as bridge between array-based and collection-based
* APIs.
*
* @return an array containing all of the elements in this queue
*/
public
Object[]
toArray() {
return
Arrays.
copyOf(
queue,
size);
}
/**
* Returns an array containing all of the elements in this queue; the
* runtime type of the returned array is that of the specified array.
* The returned array elements are in no particular order.
* If the queue fits in the specified array, it is returned therein.
* Otherwise, a new array is allocated with the runtime type of the
* specified array and the size of this queue.
*
* <p>If the queue fits in the specified array with room to spare
* (i.e., the array has more elements than the queue), the element in
* the array immediately following the end of the collection is set to
* {@code null}.
*
* <p>Like the {@link #toArray()} method, this method acts as bridge between
* array-based and collection-based APIs. Further, this method allows
* precise control over the runtime type of the output array, and may,
* under certain circumstances, be used to save allocation costs.
*
* <p>Suppose {@code x} is a queue known to contain only strings.
* The following code can be used to dump the queue into a newly
* allocated array of {@code String}:
*
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
*
* Note that {@code toArray(new Object[0])} is identical in function to
* {@code toArray()}.
*
* @param a the array into which the elements of the queue are to
* be stored, if it is big enough; otherwise, a new array of the
* same runtime type is allocated for this purpose.
* @return an array containing all of the elements in this queue
* @throws ArrayStoreException if the runtime type of the specified array
* is not a supertype of the runtime type of every element in
* this queue
* @throws NullPointerException if the specified array is null
*/
@
SuppressWarnings("unchecked")
public <T> T[]
toArray(T[]
a) {
final int
size = this.
size;
if (
a.length <
size)
// Make a new array of a's runtime type, but my contents:
return (T[])
Arrays.
copyOf(
queue,
size,
a.
getClass());
System.
arraycopy(
queue, 0,
a, 0,
size);
if (
a.length >
size)
a[
size] = null;
return
a;
}
/**
* Returns an iterator over the elements in this queue. The iterator
* does not return the elements in any particular order.
*
* @return an iterator over the elements in this queue
*/
public
Iterator<E>
iterator() {
return new
Itr();
}
private final class
Itr implements
Iterator<E> {
/**
* Index (into queue array) of element to be returned by
* subsequent call to next.
*/
private int
cursor = 0;
/**
* Index of element returned by most recent call to next,
* unless that element came from the forgetMeNot list.
* Set to -1 if element is deleted by a call to remove.
*/
private int
lastRet = -1;
/**
* A queue of elements that were moved from the unvisited portion of
* the heap into the visited portion as a result of "unlucky" element
* removals during the iteration. (Unlucky element removals are those
* that require a siftup instead of a siftdown.) We must visit all of
* the elements in this list to complete the iteration. We do this
* after we've completed the "normal" iteration.
*
* We expect that most iterations, even those involving removals,
* will not need to store elements in this field.
*/
private
ArrayDeque<E>
forgetMeNot = null;
/**
* Element returned by the most recent call to next iff that
* element was drawn from the forgetMeNot list.
*/
private E
lastRetElt = null;
/**
* The modCount value that the iterator believes that the backing
* Queue should have. If this expectation is violated, the iterator
* has detected concurrent modification.
*/
private int
expectedModCount =
modCount;
public boolean
hasNext() {
return
cursor <
size ||
(
forgetMeNot != null && !
forgetMeNot.
isEmpty());
}
@
SuppressWarnings("unchecked")
public E
next() {
if (
expectedModCount !=
modCount)
throw new
ConcurrentModificationException();
if (
cursor <
size)
return (E)
queue[
lastRet =
cursor++];
if (
forgetMeNot != null) {
lastRet = -1;
lastRetElt =
forgetMeNot.
poll();
if (
lastRetElt != null)
return
lastRetElt;
}
throw new
NoSuchElementException();
}
public void
remove() {
if (
expectedModCount !=
modCount)
throw new
ConcurrentModificationException();
if (
lastRet != -1) {
E
moved =
PriorityQueue.this.
removeAt(
lastRet);
lastRet = -1;
if (
moved == null)
cursor--;
else {
if (
forgetMeNot == null)
forgetMeNot = new
ArrayDeque<>();
forgetMeNot.
add(
moved);
}
} else if (
lastRetElt != null) {
PriorityQueue.this.
removeEq(
lastRetElt);
lastRetElt = null;
} else {
throw new
IllegalStateException();
}
expectedModCount =
modCount;
}
}
public int
size() {
return
size;
}
/**
* Removes all of the elements from this priority queue.
* The queue will be empty after this call returns.
*/
public void
clear() {
modCount++;
for (int
i = 0;
i <
size;
i++)
queue[
i] = null;
size = 0;
}
@
SuppressWarnings("unchecked")
public E
poll() {
if (
size == 0)
return null;
int
s = --
size;
modCount++;
E
result = (E)
queue[0];
E
x = (E)
queue[
s];
queue[
s] = null;
if (
s != 0)
siftDown(0,
x);
return
result;
}
/**
* Removes the ith element from queue.
*
* Normally this method leaves the elements at up to i-1,
* inclusive, untouched. Under these circumstances, it returns
* null. Occasionally, in order to maintain the heap invariant,
* it must swap a later element of the list with one earlier than
* i. Under these circumstances, this method returns the element
* that was previously at the end of the list and is now at some
* position before i. This fact is used by iterator.remove so as to
* avoid missing traversing elements.
*/
@
SuppressWarnings("unchecked")
private E
removeAt(int
i) {
// assert i >= 0 && i < size;
modCount++;
int
s = --
size;
if (
s ==
i) // removed last element
queue[
i] = null;
else {
E
moved = (E)
queue[
s];
queue[
s] = null;
siftDown(
i,
moved);
if (
queue[
i] ==
moved) {
siftUp(
i,
moved);
if (
queue[
i] !=
moved)
return
moved;
}
}
return null;
}
/**
* Inserts item x at position k, maintaining heap invariant by
* promoting x up the tree until it is greater than or equal to
* its parent, or is the root.
*
* To simplify and speed up coercions and comparisons. the
* Comparable and Comparator versions are separated into different
* methods that are otherwise identical. (Similarly for siftDown.)
*
* @param k the position to fill
* @param x the item to insert
*/
private void
siftUp(int
k, E
x) {
if (
comparator != null)
siftUpUsingComparator(
k,
x);
else
siftUpComparable(
k,
x);
}
@
SuppressWarnings("unchecked")
private void
siftUpComparable(int
k, E
x) {
Comparable<? super E>
key = (
Comparable<? super E>)
x;
while (
k > 0) {
int
parent = (
k - 1) >>> 1;
Object e =
queue[
parent];
if (
key.
compareTo((E)
e) >= 0)
break;
queue[
k] =
e;
k =
parent;
}
queue[
k] =
key;
}
@
SuppressWarnings("unchecked")
private void
siftUpUsingComparator(int
k, E
x) {
while (
k > 0) {
int
parent = (
k - 1) >>> 1;
Object e =
queue[
parent];
if (
comparator.
compare(
x, (E)
e) >= 0)
break;
queue[
k] =
e;
k =
parent;
}
queue[
k] =
x;
}
/**
* Inserts item x at position k, maintaining heap invariant by
* demoting x down the tree repeatedly until it is less than or
* equal to its children or is a leaf.
*
* @param k the position to fill
* @param x the item to insert
*/
private void
siftDown(int
k, E
x) {
if (
comparator != null)
siftDownUsingComparator(
k,
x);
else
siftDownComparable(
k,
x);
}
@
SuppressWarnings("unchecked")
private void
siftDownComparable(int
k, E
x) {
Comparable<? super E>
key = (
Comparable<? super E>)
x;
int
half =
size >>> 1; // loop while a non-leaf
while (
k <
half) {
int
child = (
k << 1) + 1; // assume left child is least
Object c =
queue[
child];
int
right =
child + 1;
if (
right <
size &&
((
Comparable<? super E>)
c).
compareTo((E)
queue[
right]) > 0)
c =
queue[
child =
right];
if (
key.
compareTo((E)
c) <= 0)
break;
queue[
k] =
c;
k =
child;
}
queue[
k] =
key;
}
@
SuppressWarnings("unchecked")
private void
siftDownUsingComparator(int
k, E
x) {
int
half =
size >>> 1;
while (
k <
half) {
int
child = (
k << 1) + 1;
Object c =
queue[
child];
int
right =
child + 1;
if (
right <
size &&
comparator.
compare((E)
c, (E)
queue[
right]) > 0)
c =
queue[
child =
right];
if (
comparator.
compare(
x, (E)
c) <= 0)
break;
queue[
k] =
c;
k =
child;
}
queue[
k] =
x;
}
/**
* Establishes the heap invariant (described above) in the entire tree,
* assuming nothing about the order of the elements prior to the call.
*/
@
SuppressWarnings("unchecked")
private void
heapify() {
for (int
i = (
size >>> 1) - 1;
i >= 0;
i--)
siftDown(
i, (E)
queue[
i]);
}
/**
* Returns the comparator used to order the elements in this
* queue, or {@code null} if this queue is sorted according to
* the {@linkplain Comparable natural ordering} of its elements.
*
* @return the comparator used to order this queue, or
* {@code null} if this queue is sorted according to the
* natural ordering of its elements
*/
public
Comparator<? super E>
comparator() {
return
comparator;
}
/**
* Saves this queue to a stream (that is, serializes it).
*
* @serialData The length of the array backing the instance is
* emitted (int), followed by all of its elements
* (each an {@code Object}) in the proper order.
* @param s the stream
*/
private void
writeObject(java.io.
ObjectOutputStream s)
throws java.io.
IOException {
// Write out element count, and any hidden stuff
s.
defaultWriteObject();
// Write out array length, for compatibility with 1.5 version
s.
writeInt(
Math.
max(2,
size + 1));
// Write out all elements in the "proper order".
for (int
i = 0;
i <
size;
i++)
s.
writeObject(
queue[
i]);
}
/**
* Reconstitutes the {@code PriorityQueue} instance from a stream
* (that is, deserializes it).
*
* @param s the stream
*/
private void
readObject(java.io.
ObjectInputStream s)
throws java.io.
IOException,
ClassNotFoundException {
// Read in size, and any hidden stuff
s.
defaultReadObject();
// Read in (and discard) array length
s.
readInt();
SharedSecrets.
getJavaOISAccess().
checkArray(
s,
Object[].class,
size);
queue = new
Object[
size];
// Read in all elements.
for (int
i = 0;
i <
size;
i++)
queue[
i] =
s.
readObject();
// Elements are guaranteed to be in "proper order", but the
// spec has never explained what that might be.
heapify();
}
/**
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
* and <em>fail-fast</em> {@link Spliterator} over the elements in this
* queue.
*
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
* Overriding implementations should document the reporting of additional
* characteristic values.
*
* @return a {@code Spliterator} over the elements in this queue
* @since 1.8
*/
public final
Spliterator<E>
spliterator() {
return new
PriorityQueueSpliterator<E>(this, 0, -1, 0);
}
static final class
PriorityQueueSpliterator<E> implements
Spliterator<E> {
/*
* This is very similar to ArrayList Spliterator, except for
* extra null checks.
*/
private final
PriorityQueue<E>
pq;
private int
index; // current index, modified on advance/split
private int
fence; // -1 until first use
private int
expectedModCount; // initialized when fence set
/** Creates new spliterator covering the given range */
PriorityQueueSpliterator(
PriorityQueue<E>
pq, int
origin, int
fence,
int
expectedModCount) {
this.
pq =
pq;
this.
index =
origin;
this.
fence =
fence;
this.
expectedModCount =
expectedModCount;
}
private int
getFence() { // initialize fence to size on first use
int
hi;
if ((
hi =
fence) < 0) {
expectedModCount =
pq.
modCount;
hi =
fence =
pq.
size;
}
return
hi;
}
public
PriorityQueueSpliterator<E>
trySplit() {
int
hi =
getFence(),
lo =
index,
mid = (
lo +
hi) >>> 1;
return (
lo >=
mid) ? null :
new
PriorityQueueSpliterator<E>(
pq,
lo,
index =
mid,
expectedModCount);
}
@
SuppressWarnings("unchecked")
public void
forEachRemaining(
Consumer<? super E>
action) {
int
i,
hi,
mc; // hoist accesses and checks from loop
PriorityQueue<E>
q;
Object[]
a;
if (
action == null)
throw new
NullPointerException();
if ((
q =
pq) != null && (
a =
q.
queue) != null) {
if ((
hi =
fence) < 0) {
mc =
q.
modCount;
hi =
q.
size;
}
else
mc =
expectedModCount;
if ((
i =
index) >= 0 && (
index =
hi) <=
a.length) {
for (E
e;; ++
i) {
if (
i <
hi) {
if ((
e = (E)
a[
i]) == null) // must be CME
break;
action.
accept(
e);
}
else if (
q.
modCount !=
mc)
break;
else
return;
}
}
}
throw new
ConcurrentModificationException();
}
public boolean
tryAdvance(
Consumer<? super E>
action) {
if (
action == null)
throw new
NullPointerException();
int
hi =
getFence(),
lo =
index;
if (
lo >= 0 &&
lo <
hi) {
index =
lo + 1;
@
SuppressWarnings("unchecked") E
e = (E)
pq.
queue[
lo];
if (
e == null)
throw new
ConcurrentModificationException();
action.
accept(
e);
if (
pq.
modCount !=
expectedModCount)
throw new
ConcurrentModificationException();
return true;
}
return false;
}
public long
estimateSize() {
return (long) (
getFence() -
index);
}
public int
characteristics() {
return
Spliterator.
SIZED |
Spliterator.
SUBSIZED |
Spliterator.
NONNULL;
}
}
}