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root/jsr166/jsr166/src/main/java/util/ArrayDeque.java

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.40 by jsr166, Sun Feb 26 22:43:03 2012 UTC vs.
Revision 1.50 by jsr166, Wed Feb 20 12:32:01 2013 UTC

#	Line 4 | Line 4
4		*/
5
6		package java.util;
7	+	import java.io.Serializable;
8	+	import java.util.function.Consumer;
9	+	import java.util.stream.Stream;
10	+	import java.util.stream.Streams;
11
12		/**
13		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 15 | Line 19 | package java.util;
19		* when used as a queue.
20		*
21		* <p>Most {@code ArrayDeque} operations run in amortized constant time.
22	<	* Exceptions include
23	<	* {@link #remove(Object) remove},
24	<	* {@link #removeFirstOccurrence removeFirstOccurrence},
25	<	* {@link #removeLastOccurrence removeLastOccurrence},
26	<	* {@link #contains contains},
23	<	* {@link #iterator iterator.remove()},
24	<	* and the bulk operations, all of which run in linear time.
22	>	* Exceptions include {@link #remove(Object) remove}, {@link
23	>	* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
24	>	* removeLastOccurrence}, {@link #contains contains}, {@link #iterator
25	>	* iterator.remove()}, and the bulk operations, all of which run in linear
26	>	* time.
27		*
28	<	* <p>The iterators returned by this class's {@link #iterator() iterator}
29	<	* method are <em>fail-fast</em>: If the deque is modified at any time after
30	<	* the iterator is created, in any way except through the iterator's own
31	<	* {@code remove} method, the iterator will generally throw a {@link
28	>	* <p>The iterators returned by this class's {@code iterator} method are
29	>	* <i>fail-fast</i>: If the deque is modified at any time after the iterator
30	>	* is created, in any way except through the iterator's own {@code remove}
31	>	* method, the iterator will generally throw a {@link
32		* ConcurrentModificationException}.  Thus, in the face of concurrent
33		* modification, the iterator fails quickly and cleanly, rather than risking
34		* arbitrary, non-deterministic behavior at an undetermined time in the
#	Line 53 | Line 55 | package java.util;
55		* @param <E> the type of elements held in this collection
56		*/
57		public class ArrayDeque<E> extends AbstractCollection<E>
58	<	implements Deque<E>, Cloneable, java.io.Serializable
58	>	implements Deque<E>, Cloneable, Serializable
59		{
60		/**
61		* The array in which the elements of the deque are stored.
#	Line 65 | Line 67 | public class ArrayDeque<E> extends Abstr
67		* other.  We also guarantee that all array cells not holding
68		* deque elements are always null.
69		*/
70	<	private transient Object[] elements;
70	>	transient Object[] elements; // non-private to simplify nested class access
71
72		/**
73		* The index of the element at the head of the deque (which is the
74		* element that would be removed by remove() or pop()); or an
75		* arbitrary number equal to tail if the deque is empty.
76		*/
77	<	private transient int head;
77	>	transient int head;
78
79		/**
80		* The index at which the next element would be added to the tail
81		* of the deque (via addLast(E), add(E), or push(E)).
82		*/
83	<	private transient int tail;
83	>	transient int tail;
84
85		/**
86		* The minimum capacity that we'll use for a newly created deque.
#	Line 133 | Line 135 | public class ArrayDeque<E> extends Abstr
135		}
136
137		/**
136	–	* Copies the elements from our element array into the specified array,
137	–	* in order (from first to last element in the deque).  It is assumed
138	–	* that the array is large enough to hold all elements in the deque.
139	–	*
140	–	* @return its argument
141	–	*/
142	–	private <T> T[] copyElements(T[] a) {
143	–	if (head < tail) {
144	–	System.arraycopy(elements, head, a, 0, size());
145	–	} else if (head > tail) {
146	–	int headPortionLen = elements.length - head;
147	–	System.arraycopy(elements, head, a, 0, headPortionLen);
148	–	System.arraycopy(elements, 0, a, headPortionLen, tail);
149	–	}
150	–	return a;
151	–	}
152	–
153	–	/**
138		* Constructs an empty array deque with an initial capacity
139		* sufficient to hold 16 elements.
140		*/
#	Line 694 | Line 678 | public class ArrayDeque<E> extends Abstr
678		* Returns {@code true} if this deque contained the specified element
679		* (or equivalently, if this deque changed as a result of the call).
680		*
681	<	* <p>This method is equivalent to {@link #removeFirstOccurrence}.
681	>	* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
682		*
683		* @param o element to be removed from this deque, if present
684		* @return {@code true} if this deque contained the specified element
#	Line 735 | Line 719 | public class ArrayDeque<E> extends Abstr
719		* @return an array containing all of the elements in this deque
720		*/
721		public Object[] toArray() {
722	<	return copyElements(new Object[size()]);
722	>	final int head = this.head;
723	>	final int tail = this.tail;
724	>	boolean wrap = (tail < head);
725	>	int end = wrap ? tail + elements.length : tail;
726	>	Object[] a = Arrays.copyOfRange(elements, head, end);
727	>	if (wrap)
728	>	System.arraycopy(elements, 0, a, elements.length - head, tail);
729	>	return a;
730		}
731
732		/**
#	Line 776 | Line 767 | public class ArrayDeque<E> extends Abstr
767		*/
768		@SuppressWarnings("unchecked")
769		public <T> T[] toArray(T[] a) {
770	<	int size = size();
771	<	if (a.length < size)
772	<	a = (T[])java.lang.reflect.Array.newInstance(
773	<	a.getClass().getComponentType(), size);
774	<	copyElements(a);
775	<	if (a.length > size)
776	<	a[size] = null;
770	>	final int head = this.head;
771	>	final int tail = this.tail;
772	>	boolean wrap = (tail < head);
773	>	int size = (tail - head) + (wrap ? elements.length : 0);
774	>	int firstLeg = size - (wrap ? tail : 0);
775	>	int len = a.length;
776	>	if (size > len) {
777	>	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
778	>	a.getClass());
779	>	} else {
780	>	System.arraycopy(elements, head, a, 0, firstLeg);
781	>	if (size < len)
782	>	a[size] = null;
783	>	}
784	>	if (wrap)
785	>	System.arraycopy(elements, 0, a, firstLeg, tail);
786		return a;
787		}
788
#	Line 843 | Line 843 | public class ArrayDeque<E> extends Abstr
843		for (int i = 0; i < size; i++)
844		elements[i] = s.readObject();
845		}
846	+
847	+	Spliterator<E> spliterator() {
848	+	return new DeqSpliterator<E>(this, -1, -1);
849	+	}
850	+
851	+	public Stream<E> stream() {
852	+	return Streams.stream(spliterator());
853	+	}
854	+
855	+	public Stream<E> parallelStream() {
856	+	return Streams.parallelStream(spliterator());
857	+	}
858	+
859	+	static final class DeqSpliterator<E> implements Spliterator<E> {
860	+	private final ArrayDeque<E> deq;
861	+	private int fence;  // -1 until first use
862	+	private int index;  // current index, modified on traverse/split
863	+
864	+	/** Creates new spliterator covering the given array and range */
865	+	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
866	+	this.deq = deq;
867	+	this.index = origin;
868	+	this.fence = fence;
869	+	}
870	+
871	+	private int getFence() { // force initialization
872	+	int t;
873	+	if ((t = fence) < 0) {
874	+	t = fence = deq.tail;
875	+	index = deq.head;
876	+	}
877	+	return t;
878	+	}
879	+
880	+	public DeqSpliterator<E> trySplit() {
881	+	int t = getFence(), h = index, n = deq.elements.length;
882	+	if (h != t && ((h + 1) & (n - 1)) != t) {
883	+	if (h > t)
884	+	t += n;
885	+	int m = ((h + t) >>> 1) & (n - 1);
886	+	return new DeqSpliterator<>(deq, h, index = m);
887	+	}
888	+	return null;
889	+	}
890	+
891	+	public void forEach(Consumer<? super E> consumer) {
892	+	if (consumer == null)
893	+	throw new NullPointerException();
894	+	Object[] a = deq.elements;
895	+	int m = a.length - 1, f = getFence(), i = index;
896	+	index = f;
897	+	while (i != f) {
898	+	@SuppressWarnings("unchecked") E e = (E)a[i];
899	+	i = (i + 1) & m;
900	+	if (e == null)
901	+	throw new ConcurrentModificationException();
902	+	consumer.accept(e);
903	+	}
904	+	}
905	+
906	+	public boolean tryAdvance(Consumer<? super E> consumer) {
907	+	if (consumer == null)
908	+	throw new NullPointerException();
909	+	Object[] a = deq.elements;
910	+	int m = a.length - 1, f = getFence(), i = index;
911	+	if (i != fence) {
912	+	@SuppressWarnings("unchecked") E e = (E)a[i];
913	+	index = (i + 1) & m;
914	+	if (e == null)
915	+	throw new ConcurrentModificationException();
916	+	consumer.accept(e);
917	+	return true;
918	+	}
919	+	return false;
920	+	}
921	+
922	+	public long estimateSize() {
923	+	int n = getFence() - index;
924	+	if (n < 0)
925	+	n += deq.elements.length;
926	+	return (long) n;
927	+	}
928	+
929	+	@Override
930	+	public int characteristics() {
931	+	return Spliterator.ORDERED | Spliterator.SIZED |
932	+	Spliterator.NONNULL | Spliterator.SUBSIZED;
933	+	}
934	+	}
935	+
936		}

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