--- a/jdk/src/share/classes/java/util/ArrayDeque.java Wed Apr 17 14:39:04 2013 -0400
+++ b/jdk/src/share/classes/java/util/ArrayDeque.java Wed Apr 17 11:34:31 2013 +0200
@@ -33,7 +33,9 @@
*/
package java.util;
-import java.io.*;
+
+import java.io.Serializable;
+import java.util.function.Consumer;
/**
* Resizable-array implementation of the {@link Deque} interface. Array
@@ -44,16 +46,16 @@
* {@link Stack} when used as a stack, and faster than {@link LinkedList}
* when used as a queue.
*
- * <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time.
+ * <p>Most {@code ArrayDeque} operations run in amortized constant time.
* Exceptions include {@link #remove(Object) remove}, {@link
* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
* removeLastOccurrence}, {@link #contains contains}, {@link #iterator
* iterator.remove()}, and the bulk operations, all of which run in linear
* time.
*
- * <p>The iterators returned by this class's <tt>iterator</tt> method are
+ * <p>The iterators returned by this class's {@code iterator} method are
* <i>fail-fast</i>: If the deque is modified at any time after the iterator
- * is created, in any way except through the iterator's own <tt>remove</tt>
+ * is created, in any way except through the iterator's own {@code remove}
* method, the iterator will generally throw a {@link
* ConcurrentModificationException}. Thus, in the face of concurrent
* modification, the iterator fails quickly and cleanly, rather than risking
@@ -63,7 +65,7 @@
* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
* as it is, generally speaking, impossible to make any hard guarantees in the
* presence of unsynchronized concurrent modification. Fail-fast iterators
- * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
+ * throw {@code ConcurrentModificationException} on a best-effort basis.
* Therefore, it would be wrong to write a program that depended on this
* exception for its correctness: <i>the fail-fast behavior of iterators
* should be used only to detect bugs.</i>
@@ -93,20 +95,20 @@
* other. We also guarantee that all array cells not holding
* deque elements are always null.
*/
- private transient E[] elements;
+ transient Object[] elements; // non-private to simplify nested class access
/**
* The index of the element at the head of the deque (which is the
* element that would be removed by remove() or pop()); or an
* arbitrary number equal to tail if the deque is empty.
*/
- private transient int head;
+ transient int head;
/**
* The index at which the next element would be added to the tail
* of the deque (via addLast(E), add(E), or push(E)).
*/
- private transient int tail;
+ transient int tail;
/**
* The minimum capacity that we'll use for a newly created deque.
@@ -117,11 +119,10 @@
// ****** Array allocation and resizing utilities ******
/**
- * Allocate empty array to hold the given number of elements.
+ * Allocates empty array to hold the given number of elements.
*
* @param numElements the number of elements to hold
*/
- @SuppressWarnings("unchecked")
private void allocateElements(int numElements) {
int initialCapacity = MIN_INITIAL_CAPACITY;
// Find the best power of two to hold elements.
@@ -138,11 +139,11 @@
if (initialCapacity < 0) // Too many elements, must back off
initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
}
- elements = (E[]) new Object[initialCapacity];
+ elements = new Object[initialCapacity];
}
/**
- * Double the capacity of this deque. Call only when full, i.e.,
+ * Doubles the capacity of this deque. Call only when full, i.e.,
* when head and tail have wrapped around to become equal.
*/
private void doubleCapacity() {
@@ -153,8 +154,7 @@
int newCapacity = n << 1;
if (newCapacity < 0)
throw new IllegalStateException("Sorry, deque too big");
- @SuppressWarnings("unchecked")
- E[] a = (E[]) new Object[newCapacity];
+ Object[] a = new Object[newCapacity];
System.arraycopy(elements, p, a, 0, r);
System.arraycopy(elements, 0, a, r, p);
elements = a;
@@ -184,9 +184,8 @@
* Constructs an empty array deque with an initial capacity
* sufficient to hold 16 elements.
*/
- @SuppressWarnings("unchecked")
public ArrayDeque() {
- elements = (E[]) new Object[16];
+ elements = new Object[16];
}
/**
@@ -252,7 +251,7 @@
* Inserts the specified element at the front of this deque.
*
* @param e the element to add
- * @return <tt>true</tt> (as specified by {@link Deque#offerFirst})
+ * @return {@code true} (as specified by {@link Deque#offerFirst})
* @throws NullPointerException if the specified element is null
*/
public boolean offerFirst(E e) {
@@ -264,7 +263,7 @@
* Inserts the specified element at the end of this deque.
*
* @param e the element to add
- * @return <tt>true</tt> (as specified by {@link Deque#offerLast})
+ * @return {@code true} (as specified by {@link Deque#offerLast})
* @throws NullPointerException if the specified element is null
*/
public boolean offerLast(E e) {
@@ -294,7 +293,9 @@
public E pollFirst() {
int h = head;
- E result = elements[h]; // Element is null if deque empty
+ @SuppressWarnings("unchecked")
+ E result = (E) elements[h];
+ // Element is null if deque empty
if (result == null)
return null;
elements[h] = null; // Must null out slot
@@ -304,7 +305,8 @@
public E pollLast() {
int t = (tail - 1) & (elements.length - 1);
- E result = elements[t];
+ @SuppressWarnings("unchecked")
+ E result = (E) elements[t];
if (result == null)
return null;
elements[t] = null;
@@ -316,48 +318,53 @@
* @throws NoSuchElementException {@inheritDoc}
*/
public E getFirst() {
- E x = elements[head];
- if (x == null)
+ @SuppressWarnings("unchecked")
+ E result = (E) elements[head];
+ if (result == null)
throw new NoSuchElementException();
- return x;
+ return result;
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
public E getLast() {
- E x = elements[(tail - 1) & (elements.length - 1)];
- if (x == null)
+ @SuppressWarnings("unchecked")
+ E result = (E) elements[(tail - 1) & (elements.length - 1)];
+ if (result == null)
throw new NoSuchElementException();
- return x;
+ return result;
}
+ @SuppressWarnings("unchecked")
public E peekFirst() {
- return elements[head]; // elements[head] is null if deque empty
+ // elements[head] is null if deque empty
+ return (E) elements[head];
}
+ @SuppressWarnings("unchecked")
public E peekLast() {
- return elements[(tail - 1) & (elements.length - 1)];
+ return (E) elements[(tail - 1) & (elements.length - 1)];
}
/**
* Removes the first occurrence of the specified element in this
* deque (when traversing the deque from head to tail).
* If the deque does not contain the element, it is unchanged.
- * More formally, removes the first element <tt>e</tt> such that
- * <tt>o.equals(e)</tt> (if such an element exists).
- * Returns <tt>true</tt> if this deque contained the specified element
+ * More formally, removes the first element {@code e} such that
+ * {@code o.equals(e)} (if such an element exists).
+ * Returns {@code true} if this deque contained the specified element
* (or equivalently, if this deque changed as a result of the call).
*
* @param o element to be removed from this deque, if present
- * @return <tt>true</tt> if the deque contained the specified element
+ * @return {@code true} if the deque contained the specified element
*/
public boolean removeFirstOccurrence(Object o) {
if (o == null)
return false;
int mask = elements.length - 1;
int i = head;
- E x;
+ Object x;
while ( (x = elements[i]) != null) {
if (o.equals(x)) {
delete(i);
@@ -372,20 +379,20 @@
* Removes the last occurrence of the specified element in this
* deque (when traversing the deque from head to tail).
* If the deque does not contain the element, it is unchanged.
- * More formally, removes the last element <tt>e</tt> such that
- * <tt>o.equals(e)</tt> (if such an element exists).
- * Returns <tt>true</tt> if this deque contained the specified element
+ * More formally, removes the last element {@code e} such that
+ * {@code o.equals(e)} (if such an element exists).
+ * Returns {@code true} if this deque contained the specified element
* (or equivalently, if this deque changed as a result of the call).
*
* @param o element to be removed from this deque, if present
- * @return <tt>true</tt> if the deque contained the specified element
+ * @return {@code true} if the deque contained the specified element
*/
public boolean removeLastOccurrence(Object o) {
if (o == null)
return false;
int mask = elements.length - 1;
int i = (tail - 1) & mask;
- E x;
+ Object x;
while ( (x = elements[i]) != null) {
if (o.equals(x)) {
delete(i);
@@ -404,7 +411,7 @@
* <p>This method is equivalent to {@link #addLast}.
*
* @param e the element to add
- * @return <tt>true</tt> (as specified by {@link Collection#add})
+ * @return {@code true} (as specified by {@link Collection#add})
* @throws NullPointerException if the specified element is null
*/
public boolean add(E e) {
@@ -418,7 +425,7 @@
* <p>This method is equivalent to {@link #offerLast}.
*
* @param e the element to add
- * @return <tt>true</tt> (as specified by {@link Queue#offer})
+ * @return {@code true} (as specified by {@link Queue#offer})
* @throws NullPointerException if the specified element is null
*/
public boolean offer(E e) {
@@ -443,12 +450,12 @@
/**
* Retrieves and removes the head of the queue represented by this deque
* (in other words, the first element of this deque), or returns
- * <tt>null</tt> if this deque is empty.
+ * {@code null} if this deque is empty.
*
* <p>This method is equivalent to {@link #pollFirst}.
*
* @return the head of the queue represented by this deque, or
- * <tt>null</tt> if this deque is empty
+ * {@code null} if this deque is empty
*/
public E poll() {
return pollFirst();
@@ -470,12 +477,12 @@
/**
* Retrieves, but does not remove, the head of the queue represented by
- * this deque, or returns <tt>null</tt> if this deque is empty.
+ * this deque, or returns {@code null} if this deque is empty.
*
* <p>This method is equivalent to {@link #peekFirst}.
*
* @return the head of the queue represented by this deque, or
- * <tt>null</tt> if this deque is empty
+ * {@code null} if this deque is empty
*/
public E peek() {
return peekFirst();
@@ -530,7 +537,7 @@
*/
private boolean delete(int i) {
checkInvariants();
- final E[] elements = this.elements;
+ final Object[] elements = this.elements;
final int mask = elements.length - 1;
final int h = head;
final int t = tail;
@@ -579,9 +586,9 @@
}
/**
- * Returns <tt>true</tt> if this deque contains no elements.
+ * Returns {@code true} if this deque contains no elements.
*
- * @return <tt>true</tt> if this deque contains no elements
+ * @return {@code true} if this deque contains no elements
*/
public boolean isEmpty() {
return head == tail;
@@ -628,7 +635,8 @@
public E next() {
if (cursor == fence)
throw new NoSuchElementException();
- E result = elements[cursor];
+ @SuppressWarnings("unchecked")
+ E result = (E) elements[cursor];
// This check doesn't catch all possible comodifications,
// but does catch the ones that corrupt traversal
if (tail != fence || result == null)
@@ -647,6 +655,20 @@
}
lastRet = -1;
}
+
+ public void forEachRemaining(Consumer<? super E> action) {
+ Objects.requireNonNull(action);
+ Object[] a = elements;
+ int m = a.length - 1, f = fence, i = cursor;
+ cursor = f;
+ while (i != f) {
+ @SuppressWarnings("unchecked") E e = (E)a[i];
+ i = (i + 1) & m;
+ if (e == null)
+ throw new ConcurrentModificationException();
+ action.accept(e);
+ }
+ }
}
private class DescendingIterator implements Iterator<E> {
@@ -667,7 +689,8 @@
if (cursor == fence)
throw new NoSuchElementException();
cursor = (cursor - 1) & (elements.length - 1);
- E result = elements[cursor];
+ @SuppressWarnings("unchecked")
+ E result = (E) elements[cursor];
if (head != fence || result == null)
throw new ConcurrentModificationException();
lastRet = cursor;
@@ -686,19 +709,19 @@
}
/**
- * Returns <tt>true</tt> if this deque contains the specified element.
- * More formally, returns <tt>true</tt> if and only if this deque contains
- * at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
+ * Returns {@code true} if this deque contains the specified element.
+ * More formally, returns {@code true} if and only if this deque contains
+ * at least one element {@code e} such that {@code o.equals(e)}.
*
* @param o object to be checked for containment in this deque
- * @return <tt>true</tt> if this deque contains the specified element
+ * @return {@code true} if this deque contains the specified element
*/
public boolean contains(Object o) {
if (o == null)
return false;
int mask = elements.length - 1;
int i = head;
- E x;
+ Object x;
while ( (x = elements[i]) != null) {
if (o.equals(x))
return true;
@@ -710,15 +733,15 @@
/**
* Removes a single instance of the specified element from this deque.
* If the deque does not contain the element, it is unchanged.
- * More formally, removes the first element <tt>e</tt> such that
- * <tt>o.equals(e)</tt> (if such an element exists).
- * Returns <tt>true</tt> if this deque contained the specified element
+ * More formally, removes the first element {@code e} such that
+ * {@code o.equals(e)} (if such an element exists).
+ * Returns {@code true} if this deque contained the specified element
* (or equivalently, if this deque changed as a result of the call).
*
- * <p>This method is equivalent to {@link #removeFirstOccurrence}.
+ * <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
*
* @param o element to be removed from this deque, if present
- * @return <tt>true</tt> if this deque contained the specified element
+ * @return {@code true} if this deque contained the specified element
*/
public boolean remove(Object o) {
return removeFirstOccurrence(o);
@@ -770,22 +793,21 @@
* <p>If this deque fits in the specified array with room to spare
* (i.e., the array has more elements than this deque), the element in
* the array immediately following the end of the deque is set to
- * <tt>null</tt>.
+ * {@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 <tt>x</tt> is a deque known to contain only strings.
+ * <p>Suppose {@code x} is a deque known to contain only strings.
* The following code can be used to dump the deque into a newly
- * allocated array of <tt>String</tt>:
+ * allocated array of {@code String}:
*
- * <pre>
- * String[] y = x.toArray(new String[0]);</pre>
+ * <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
*
- * Note that <tt>toArray(new Object[0])</tt> is identical in function to
- * <tt>toArray()</tt>.
+ * Note that {@code toArray(new Object[0])} is identical in function to
+ * {@code toArray()}.
*
* @param a the array into which the elements of the deque are to
* be stored, if it is big enough; otherwise, a new array of the
@@ -818,28 +840,25 @@
public ArrayDeque<E> clone() {
try {
@SuppressWarnings("unchecked")
- ArrayDeque<E> result = (ArrayDeque<E>) super.clone();
+ ArrayDeque<E> result = (ArrayDeque<E>) super.clone();
result.elements = Arrays.copyOf(elements, elements.length);
return result;
-
} catch (CloneNotSupportedException e) {
throw new AssertionError();
}
}
- /**
- * Appease the serialization gods.
- */
private static final long serialVersionUID = 2340985798034038923L;
/**
- * Serialize this deque.
+ * Saves this deque to a stream (that is, serializes it).
*
- * @serialData The current size (<tt>int</tt>) of the deque,
+ * @serialData The current size ({@code int}) of the deque,
* followed by all of its elements (each an object reference) in
* first-to-last order.
*/
- private void writeObject(ObjectOutputStream s) throws IOException {
+ private void writeObject(java.io.ObjectOutputStream s)
+ throws java.io.IOException {
s.defaultWriteObject();
// Write out size
@@ -852,11 +871,10 @@
}
/**
- * Deserialize this deque.
+ * Reconstitutes this deque from a stream (that is, deserializes it).
*/
- @SuppressWarnings("unchecked")
- private void readObject(ObjectInputStream s)
- throws IOException, ClassNotFoundException {
+ private void readObject(java.io.ObjectInputStream s)
+ throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
// Read in size and allocate array
@@ -867,6 +885,88 @@
// Read in all elements in the proper order.
for (int i = 0; i < size; i++)
- elements[i] = (E)s.readObject();
+ elements[i] = s.readObject();
+ }
+
+ public Spliterator<E> spliterator() {
+ return new DeqSpliterator<E>(this, -1, -1);
}
+
+ static final class DeqSpliterator<E> implements Spliterator<E> {
+ private final ArrayDeque<E> deq;
+ private int fence; // -1 until first use
+ private int index; // current index, modified on traverse/split
+
+ /** Creates new spliterator covering the given array and range */
+ DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
+ this.deq = deq;
+ this.index = origin;
+ this.fence = fence;
+ }
+
+ private int getFence() { // force initialization
+ int t;
+ if ((t = fence) < 0) {
+ t = fence = deq.tail;
+ index = deq.head;
+ }
+ return t;
+ }
+
+ public DeqSpliterator<E> trySplit() {
+ int t = getFence(), h = index, n = deq.elements.length;
+ if (h != t && ((h + 1) & (n - 1)) != t) {
+ if (h > t)
+ t += n;
+ int m = ((h + t) >>> 1) & (n - 1);
+ return new DeqSpliterator<>(deq, h, index = m);
+ }
+ return null;
+ }
+
+ public void forEachRemaining(Consumer<? super E> consumer) {
+ if (consumer == null)
+ throw new NullPointerException();
+ Object[] a = deq.elements;
+ int m = a.length - 1, f = getFence(), i = index;
+ index = f;
+ while (i != f) {
+ @SuppressWarnings("unchecked") E e = (E)a[i];
+ i = (i + 1) & m;
+ if (e == null)
+ throw new ConcurrentModificationException();
+ consumer.accept(e);
+ }
+ }
+
+ public boolean tryAdvance(Consumer<? super E> consumer) {
+ if (consumer == null)
+ throw new NullPointerException();
+ Object[] a = deq.elements;
+ int m = a.length - 1, f = getFence(), i = index;
+ if (i != fence) {
+ @SuppressWarnings("unchecked") E e = (E)a[i];
+ index = (i + 1) & m;
+ if (e == null)
+ throw new ConcurrentModificationException();
+ consumer.accept(e);
+ return true;
+ }
+ return false;
+ }
+
+ public long estimateSize() {
+ int n = getFence() - index;
+ if (n < 0)
+ n += deq.elements.length;
+ return (long) n;
+ }
+
+ @Override
+ public int characteristics() {
+ return Spliterator.ORDERED | Spliterator.SIZED |
+ Spliterator.NONNULL | Spliterator.SUBSIZED;
+ }
+ }
+
}