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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 1.73 by jsr166, Sun Oct 11 00:50:06 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 109 | Line 109 | public class ArrayDeque<E> extends Abstr
109		initialCapacity |= (initialCapacity >>> 16);
110		initialCapacity++;
111
112	<	if (initialCapacity < 0)   // Too many elements, must back off
113	<	initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
112	>	if (initialCapacity < 0)    // Too many elements, must back off
113	>	initialCapacity >>>= 1; // Good luck allocating 2^30 elements
114		}
115		elements = new Object[initialCapacity];
116		}
#	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 508 | Line 488 | public class ArrayDeque<E> extends Abstr
488		*
489		* @return true if elements moved backwards
490		*/
491	<	private boolean delete(int i) {
491	>	boolean delete(int i) {
492		checkInvariants();
493		final Object[] elements = this.elements;
494		final int mask = elements.length - 1;
#	Line 628 | Line 608 | public class ArrayDeque<E> extends Abstr
608		}
609		lastRet = -1;
610		}
611	+
612	+	public void forEachRemaining(Consumer<? super E> action) {
613	+	Objects.requireNonNull(action);
614	+	Object[] a = elements;
615	+	int m = a.length - 1, f = fence, i = cursor;
616	+	cursor = f;
617	+	while (i != f) {
618	+	@SuppressWarnings("unchecked") E e = (E)a[i];
619	+	i = (i + 1) & m;
620	+	if (e == null)
621	+	throw new ConcurrentModificationException();
622	+	action.accept(e);
623	+	}
624	+	}
625		}
626
627	+	/**
628	+	* This class is nearly a mirror-image of DeqIterator, using tail
629	+	* instead of head for initial cursor, and head instead of tail
630	+	* for fence.
631	+	*/
632		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	–	*/
633		private int cursor = tail;
634		private int fence = head;
635		private int lastRet = -1;
#	Line 676 | Line 670 | public class ArrayDeque<E> extends Abstr
670		* @return {@code true} if this deque contains the specified element
671		*/
672		public boolean contains(Object o) {
673	<	if (o == null)
674	<	return false;
675	<	int mask = elements.length - 1;
676	<	int i = head;
677	<	Object x;
678	<	while ( (x = elements[i]) != null) {
679	<	if (o.equals(x))
686	<	return true;
687	<	i = (i + 1) & mask;
673	>	if (o != null) {
674	>	int mask = elements.length - 1;
675	>	int i = head;
676	>	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
677	>	if (o.equals(x))
678	>	return true;
679	>	}
680		}
681		return false;
682		}
#	Line 738 | Line 730 | public class ArrayDeque<E> extends Abstr
730		* @return an array containing all of the elements in this deque
731		*/
732		public Object[] toArray() {
733	<	return copyElements(new Object[size()]);
733	>	final int head = this.head;
734	>	final int tail = this.tail;
735	>	boolean wrap = (tail < head);
736	>	int end = wrap ? tail + elements.length : tail;
737	>	Object[] a = Arrays.copyOfRange(elements, head, end);
738	>	if (wrap)
739	>	System.arraycopy(elements, 0, a, elements.length - head, tail);
740	>	return a;
741		}
742
743		/**
#	Line 763 | Line 762 | public class ArrayDeque<E> extends Abstr
762		* The following code can be used to dump the deque into a newly
763		* allocated array of {@code String}:
764		*
765	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
765	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
766		*
767		* Note that {@code toArray(new Object[0])} is identical in function to
768		* {@code toArray()}.
#	Line 779 | Line 778 | public class ArrayDeque<E> extends Abstr
778		*/
779		@SuppressWarnings("unchecked")
780		public <T> T[] toArray(T[] a) {
781	<	int size = size();
782	<	if (a.length < size)
783	<	a = (T[])java.lang.reflect.Array.newInstance(
784	<	a.getClass().getComponentType(), size);
785	<	copyElements(a);
786	<	if (a.length > size)
787	<	a[size] = null;
781	>	final int head = this.head;
782	>	final int tail = this.tail;
783	>	boolean wrap = (tail < head);
784	>	int size = (tail - head) + (wrap ? elements.length : 0);
785	>	int firstLeg = size - (wrap ? tail : 0);
786	>	int len = a.length;
787	>	if (size > len) {
788	>	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
789	>	a.getClass());
790	>	} else {
791	>	System.arraycopy(elements, head, a, 0, firstLeg);
792	>	if (size < len)
793	>	a[size] = null;
794	>	}
795	>	if (wrap)
796	>	System.arraycopy(elements, 0, a, firstLeg, tail);
797		return a;
798		}
799
#	Line 812 | Line 820 | public class ArrayDeque<E> extends Abstr
820		/**
821		* Saves this deque to a stream (that is, serializes it).
822		*
823	+	* @param s the stream
824	+	* @throws java.io.IOException if an I/O error occurs
825		* @serialData The current size ({@code int}) of the deque,
826		* followed by all of its elements (each an object reference) in
827		* first-to-last order.
#	Line 831 | Line 841 | public class ArrayDeque<E> extends Abstr
841
842		/**
843		* Reconstitutes this deque from a stream (that is, deserializes it).
844	+	* @param s the stream
845	+	* @throws ClassNotFoundException if the class of a serialized object
846	+	*         could not be found
847	+	* @throws java.io.IOException if an I/O error occurs
848		*/
849		private void readObject(java.io.ObjectInputStream s)
850		throws java.io.IOException, ClassNotFoundException {
#	Line 847 | Line 861 | public class ArrayDeque<E> extends Abstr
861		elements[i] = s.readObject();
862		}
863
864	<	public Stream<E> stream() {
865	<	int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED;
866	<	return Streams.stream
867	<	(() -> new DeqSpliterator<E>(this, head, tail), flags);
868	<	}
869	<	public Stream<E> parallelStream() {
870	<	int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED;
871	<	return Streams.parallelStream
872	<	(() -> new DeqSpliterator<E>(this, head, tail), flags);
864	>	/**
865	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
866	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
867	>	* deque.
868	>	*
869	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
870	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
871	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
872	>	* the reporting of additional characteristic values.
873	>	*
874	>	* @return a {@code Spliterator} over the elements in this deque
875	>	* @since 1.8
876	>	*/
877	>	public Spliterator<E> spliterator() {
878	>	return new DeqSpliterator<>(this, -1, -1);
879		}
880
861	–
881		static final class DeqSpliterator<E> implements Spliterator<E> {
882		private final ArrayDeque<E> deq;
883	<	private final int fence;  // initially tail
884	<	private int index;        // current index, modified on traverse/split
883	>	private int fence;  // -1 until first use
884	>	private int index;  // current index, modified on traverse/split
885
886	<	/** Create new spliterator covering the given array and range */
886	>	/** Creates new spliterator covering the given array and range. */
887		DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
888	<	this.deq = deq; this.index = origin; this.fence = fence;
888	>	this.deq = deq;
889	>	this.index = origin;
890	>	this.fence = fence;
891	>	}
892	>
893	>	private int getFence() { // force initialization
894	>	int t;
895	>	if ((t = fence) < 0) {
896	>	t = fence = deq.tail;
897	>	index = deq.head;
898	>	}
899	>	return t;
900		}
901
902		public DeqSpliterator<E> trySplit() {
903	<	int n = deq.elements.length;
874	<	int h = index, t = fence;
903	>	int t = getFence(), h = index, n = deq.elements.length;
904		if (h != t && ((h + 1) & (n - 1)) != t) {
905		if (h > t)
906		t += n;
#	Line 881 | Line 910 | public class ArrayDeque<E> extends Abstr
910		return null;
911		}
912
913	<	public void forEach(Consumer<? super E> block) {
914	<	if (block == null)
913	>	public void forEachRemaining(Consumer<? super E> consumer) {
914	>	if (consumer == null)
915		throw new NullPointerException();
916		Object[] a = deq.elements;
917	<	int m = a.length - 1, f = fence, i = index;
917	>	int m = a.length - 1, f = getFence(), i = index;
918		index = f;
919		while (i != f) {
920		@SuppressWarnings("unchecked") E e = (E)a[i];
921		i = (i + 1) & m;
922		if (e == null)
923		throw new ConcurrentModificationException();
924	<	block.accept(e);
924	>	consumer.accept(e);
925		}
926		}
927
928	<	public boolean tryAdvance(Consumer<? super E> block) {
929	<	if (block == null)
928	>	public boolean tryAdvance(Consumer<? super E> consumer) {
929	>	if (consumer == null)
930		throw new NullPointerException();
931		Object[] a = deq.elements;
932	<	int m = a.length - 1, i = index;
933	<	if (i != fence) {
932	>	int m = a.length - 1, f = getFence(), i = index;
933	>	if (i != f) {
934		@SuppressWarnings("unchecked") E e = (E)a[i];
935		index = (i + 1) & m;
936		if (e == null)
937		throw new ConcurrentModificationException();
938	<	block.accept(e);
938	>	consumer.accept(e);
939		return true;
940		}
941		return false;
942		}
943
915	–	// Other spliterator methods
944		public long estimateSize() {
945	<	int n = fence - index;
945	>	int n = getFence() - index;
946		if (n < 0)
947		n += deq.elements.length;
948	<	return (long)n;
948	>	return (long) n;
949	>	}
950	>
951	>	@Override
952	>	public int characteristics() {
953	>	return Spliterator.ORDERED | Spliterator.SIZED |
954	>	Spliterator.NONNULL | Spliterator.SUBSIZED;
955		}
922	–	public boolean hasExactSize() { return true; }
923	–	public boolean hasExactSplits() { return true; }
956		}
957
958		}

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