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

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.46 by jsr166, Mon Feb 11 07:42:43 2013 UTC vs.
Revision 1.66 by jsr166, Sat Feb 28 22:16:45 2015 UTC

#	Line 1 | Line 1
1		/*
2	<	* Written by Doug Lea with assistance from members of JCP JSR-166
3	<	* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/publicdomain/zero/1.0/
2	>	* Written by Josh Bloch of Google Inc. and released to the public domain,
3	>	* as explained at http://creativecommons.org/publicdomain/zero/1.0/.
4		*/
5
6		package java.util;
7	<	import java.util.Spliterator;
8	<	import java.util.stream.Stream;
10	<	import java.util.stream.Streams;
7	>
8	>	import java.io.Serializable;
9		import java.util.function.Consumer;
10
11		/**
#	Line 20 | Line 18 | import java.util.function.Consumer;
18		* when used as a queue.
19		*
20		* <p>Most {@code ArrayDeque} operations run in amortized constant time.
21	<	* Exceptions include {@link #remove(Object) remove}, {@link
22	<	* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
23	<	* removeLastOccurrence}, {@link #contains contains}, {@link #iterator
24	<	* iterator.remove()}, and the bulk operations, all of which run in linear
25	<	* time.
21	>	* Exceptions include
22	>	* {@link #remove(Object) remove},
23	>	* {@link #removeFirstOccurrence removeFirstOccurrence},
24	>	* {@link #removeLastOccurrence removeLastOccurrence},
25	>	* {@link #contains contains},
26	>	* {@link #iterator iterator.remove()},
27	>	* and the bulk operations, all of which run in linear time.
28		*
29	<	* <p>The iterators returned by this class's {@code iterator} method are
30	<	* <i>fail-fast</i>: If the deque is modified at any time after the iterator
31	<	* is created, in any way except through the iterator's own {@code remove}
32	<	* method, the iterator will generally throw a {@link
29	>	* <p>The iterators returned by this class's {@link #iterator() iterator}
30	>	* method are <em>fail-fast</em>: If the deque is modified at any time after
31	>	* the iterator is created, in any way except through the iterator's own
32	>	* {@code remove} method, the iterator will generally throw a {@link
33		* ConcurrentModificationException}.  Thus, in the face of concurrent
34		* modification, the iterator fails quickly and cleanly, rather than risking
35		* arbitrary, non-deterministic behavior at an undetermined time in the
#	Line 53 | Line 53 | import java.util.function.Consumer;
53		*
54		* @author  Josh Bloch and Doug Lea
55		* @since   1.6
56	<	* @param <E> the type of elements held in this collection
56	>	* @param <E> the type of elements held in this deque
57		*/
58		public class ArrayDeque<E> extends AbstractCollection<E>
59	<	implements Deque<E>, Cloneable, java.io.Serializable
59	>	implements Deque<E>, Cloneable, Serializable
60		{
61		/**
62		* The array in which the elements of the deque are stored.
#	Line 136 | Line 136 | public class ArrayDeque<E> extends Abstr
136		}
137
138		/**
139	–	* Copies the elements from our element array into the specified array,
140	–	* in order (from first to last element in the deque).  It is assumed
141	–	* that the array is large enough to hold all elements in the deque.
142	–	*
143	–	* @return its argument
144	–	*/
145	–	private <T> T[] copyElements(T[] a) {
146	–	if (head < tail) {
147	–	System.arraycopy(elements, head, a, 0, size());
148	–	} else if (head > tail) {
149	–	int headPortionLen = elements.length - head;
150	–	System.arraycopy(elements, head, a, 0, headPortionLen);
151	–	System.arraycopy(elements, 0, a, headPortionLen, tail);
152	–	}
153	–	return a;
154	–	}
155	–
156	–	/**
139		* Constructs an empty array deque with an initial capacity
140		* sufficient to hold 16 elements.
141		*/
#	Line 265 | Line 247 | public class ArrayDeque<E> extends Abstr
247		}
248
249		public E pollFirst() {
250	<	int h = head;
250	>	final Object[] elements = this.elements;
251	>	final int h = head;
252		@SuppressWarnings("unchecked")
253		E result = (E) elements[h];
254		// Element is null if deque empty
255	<	if (result == null)
256	<	return null;
257	<	elements[h] = null;     // Must null out slot
258	<	head = (h + 1) & (elements.length - 1);
255	>	if (result != null) {
256	>	elements[h] = null; // Must null out slot
257	>	head = (h + 1) & (elements.length - 1);
258	>	}
259		return result;
260		}
261
262		public E pollLast() {
263	<	int t = (tail - 1) & (elements.length - 1);
263	>	final Object[] elements = this.elements;
264	>	final int t = (tail - 1) & (elements.length - 1);
265		@SuppressWarnings("unchecked")
266		E result = (E) elements[t];
267	<	if (result == null)
268	<	return null;
269	<	elements[t] = null;
270	<	tail = t;
267	>	if (result != null) {
268	>	elements[t] = null;
269	>	tail = t;
270	>	}
271		return result;
272		}
273
#	Line 333 | Line 317 | public class ArrayDeque<E> extends Abstr
317		* @return {@code true} if the deque contained the specified element
318		*/
319		public boolean removeFirstOccurrence(Object o) {
320	<	if (o == null)
321	<	return false;
322	<	int mask = elements.length - 1;
323	<	int i = head;
324	<	Object x;
325	<	while ( (x = elements[i]) != null) {
326	<	if (o.equals(x)) {
327	<	delete(i);
344	<	return true;
320	>	if (o != null) {
321	>	int mask = elements.length - 1;
322	>	int i = head;
323	>	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
324	>	if (o.equals(x)) {
325	>	delete(i);
326	>	return true;
327	>	}
328		}
346	–	i = (i + 1) & mask;
329		}
330		return false;
331		}
#	Line 361 | Line 343 | public class ArrayDeque<E> extends Abstr
343		* @return {@code true} if the deque contained the specified element
344		*/
345		public boolean removeLastOccurrence(Object o) {
346	<	if (o == null)
347	<	return false;
348	<	int mask = elements.length - 1;
349	<	int i = (tail - 1) & mask;
350	<	Object x;
351	<	while ( (x = elements[i]) != null) {
352	<	if (o.equals(x)) {
353	<	delete(i);
372	<	return true;
346	>	if (o != null) {
347	>	int mask = elements.length - 1;
348	>	int i = (tail - 1) & mask;
349	>	for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) {
350	>	if (o.equals(x)) {
351	>	delete(i);
352	>	return true;
353	>	}
354		}
374	–	i = (i - 1) & mask;
355		}
356		return false;
357		}
#	Line 630 | Line 610 | public class ArrayDeque<E> extends Abstr
610		}
611		}
612
613	+	/**
614	+	* This class is nearly a mirror-image of DeqIterator, using tail
615	+	* instead of head for initial cursor, and head instead of tail
616	+	* for fence.
617	+	*/
618		private class DescendingIterator implements Iterator<E> {
634	–	/*
635	–	* This class is nearly a mirror-image of DeqIterator, using
636	–	* tail instead of head for initial cursor, and head instead of
637	–	* tail for fence.
638	–	*/
619		private int cursor = tail;
620		private int fence = head;
621		private int lastRet = -1;
#	Line 676 | Line 656 | public class ArrayDeque<E> extends Abstr
656		* @return {@code true} if this deque contains the specified element
657		*/
658		public boolean contains(Object o) {
659	<	if (o == null)
660	<	return false;
661	<	int mask = elements.length - 1;
662	<	int i = head;
663	<	Object x;
664	<	while ( (x = elements[i]) != null) {
665	<	if (o.equals(x))
686	<	return true;
687	<	i = (i + 1) & mask;
659	>	if (o != null) {
660	>	int mask = elements.length - 1;
661	>	int i = head;
662	>	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
663	>	if (o.equals(x))
664	>	return true;
665	>	}
666		}
667		return false;
668		}
#	Line 738 | Line 716 | public class ArrayDeque<E> extends Abstr
716		* @return an array containing all of the elements in this deque
717		*/
718		public Object[] toArray() {
719	<	return copyElements(new Object[size()]);
719	>	final int head = this.head;
720	>	final int tail = this.tail;
721	>	boolean wrap = (tail < head);
722	>	int end = wrap ? tail + elements.length : tail;
723	>	Object[] a = Arrays.copyOfRange(elements, head, end);
724	>	if (wrap)
725	>	System.arraycopy(elements, 0, a, elements.length - head, tail);
726	>	return a;
727		}
728
729		/**
#	Line 763 | Line 748 | public class ArrayDeque<E> extends Abstr
748		* The following code can be used to dump the deque into a newly
749		* allocated array of {@code String}:
750		*
751	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
751	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
752		*
753		* Note that {@code toArray(new Object[0])} is identical in function to
754		* {@code toArray()}.
#	Line 779 | Line 764 | public class ArrayDeque<E> extends Abstr
764		*/
765		@SuppressWarnings("unchecked")
766		public <T> T[] toArray(T[] a) {
767	<	int size = size();
768	<	if (a.length < size)
769	<	a = (T[])java.lang.reflect.Array.newInstance(
770	<	a.getClass().getComponentType(), size);
771	<	copyElements(a);
772	<	if (a.length > size)
773	<	a[size] = null;
767	>	final int head = this.head;
768	>	final int tail = this.tail;
769	>	boolean wrap = (tail < head);
770	>	int size = (tail - head) + (wrap ? elements.length : 0);
771	>	int firstLeg = size - (wrap ? tail : 0);
772	>	int len = a.length;
773	>	if (size > len) {
774	>	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
775	>	a.getClass());
776	>	} else {
777	>	System.arraycopy(elements, head, a, 0, firstLeg);
778	>	if (size < len)
779	>	a[size] = null;
780	>	}
781	>	if (wrap)
782	>	System.arraycopy(elements, 0, a, firstLeg, tail);
783		return a;
784		}
785
#	Line 812 | Line 806 | public class ArrayDeque<E> extends Abstr
806		/**
807		* Saves this deque to a stream (that is, serializes it).
808		*
809	+	* @param s the stream
810	+	* @throws java.io.IOException if an I/O error occurs
811		* @serialData The current size ({@code int}) of the deque,
812		* followed by all of its elements (each an object reference) in
813		* first-to-last order.
#	Line 831 | Line 827 | public class ArrayDeque<E> extends Abstr
827
828		/**
829		* Reconstitutes this deque from a stream (that is, deserializes it).
830	+	* @param s the stream
831	+	* @throws ClassNotFoundException if the class of a serialized object
832	+	*         could not be found
833	+	* @throws java.io.IOException if an I/O error occurs
834		*/
835		private void readObject(java.io.ObjectInputStream s)
836		throws java.io.IOException, ClassNotFoundException {
#	Line 847 | Line 847 | public class ArrayDeque<E> extends Abstr
847		elements[i] = s.readObject();
848		}
849
850	<	public Stream<E> stream() {
851	<	int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED;
852	<	return Streams.stream
853	<	(() -> new DeqSpliterator<E>(this, head, tail), flags);
854	<	}
855	<	public Stream<E> parallelStream() {
856	<	int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED;
857	<	return Streams.parallelStream
858	<	(() -> new DeqSpliterator<E>(this, head, tail), flags);
850	>	public Spliterator<E> spliterator() {
851	>	return new DeqSpliterator<E>(this, -1, -1);
852		}
853
861	–
854		static final class DeqSpliterator<E> implements Spliterator<E> {
855		private final ArrayDeque<E> deq;
856	<	private final int fence;  // initially tail
857	<	private int index;        // current index, modified on traverse/split
856	>	private int fence;  // -1 until first use
857	>	private int index;  // current index, modified on traverse/split
858
859	<	/** Create new spliterator covering the given array and range */
859	>	/** Creates new spliterator covering the given array and range */
860		DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
861	<	this.deq = deq; this.index = origin; this.fence = fence;
861	>	this.deq = deq;
862	>	this.index = origin;
863	>	this.fence = fence;
864		}
865
866	<	public DeqSpliterator<E> trySplit() {
867	<	int n = deq.elements.length;
868	<	int h = index, t = fence;
866	>	private int getFence() { // force initialization
867	>	int t;
868	>	if ((t = fence) < 0) {
869	>	t = fence = deq.tail;
870	>	index = deq.head;
871	>	}
872	>	return t;
873	>	}
874	>
875	>	public Spliterator<E> trySplit() {
876	>	int t = getFence(), h = index, n = deq.elements.length;
877		if (h != t && ((h + 1) & (n - 1)) != t) {
878		if (h > t)
879		t += n;
880		int m = ((h + t) >>> 1) & (n - 1);
881	<	return new DeqSpliterator<E>(deq, h, index = m);
881	>	return new DeqSpliterator<>(deq, h, index = m);
882		}
883		return null;
884		}
885
886	<	public void forEach(Consumer<? super E> block) {
887	<	if (block == null)
886	>	public void forEachRemaining(Consumer<? super E> consumer) {
887	>	if (consumer == null)
888		throw new NullPointerException();
889		Object[] a = deq.elements;
890	<	int m = a.length - 1, f = fence, i = index;
890	>	int m = a.length - 1, f = getFence(), i = index;
891		index = f;
892		while (i != f) {
893		@SuppressWarnings("unchecked") E e = (E)a[i];
894		i = (i + 1) & m;
895		if (e == null)
896		throw new ConcurrentModificationException();
897	<	block.accept(e);
897	>	consumer.accept(e);
898		}
899		}
900
901	<	public boolean tryAdvance(Consumer<? super E> block) {
902	<	if (block == null)
901	>	public boolean tryAdvance(Consumer<? super E> consumer) {
902	>	if (consumer == null)
903		throw new NullPointerException();
904		Object[] a = deq.elements;
905	<	int m = a.length - 1, i = index;
906	<	if (i != fence) {
905	>	int m = a.length - 1, f = getFence(), i = index;
906	>	if (i != f) {
907		@SuppressWarnings("unchecked") E e = (E)a[i];
908		index = (i + 1) & m;
909		if (e == null)
910		throw new ConcurrentModificationException();
911	<	block.accept(e);
911	>	consumer.accept(e);
912		return true;
913		}
914		return false;
915		}
916
915	–	// Other spliterator methods
917		public long estimateSize() {
918	<	int n = fence - index;
918	>	int n = getFence() - index;
919		if (n < 0)
920		n += deq.elements.length;
921	<	return (long)n;
921	>	return (long) n;
922	>	}
923	>
924	>	@Override
925	>	public int characteristics() {
926	>	return Spliterator.ORDERED | Spliterator.SIZED |
927	>	Spliterator.NONNULL | Spliterator.SUBSIZED;
928		}
922	–	public boolean hasExactSize() { return true; }
923	–	public boolean hasExactSplits() { return true; }
929		}
930
931		}

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