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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.38 by jsr166, Mon Dec 12 20:53:11 2011 UTC vs.
Revision 1.62 by jsr166, Wed Dec 31 09:37:19 2014 UTC

#	Line 5 | Line 5
5
6		package java.util;
7
8	+	import java.io.Serializable;
9	+	import java.util.function.Consumer;
10	+
11		/**
12		* Resizable-array implementation of the {@link Deque} interface.  Array
13		* deques have no capacity restrictions; they grow as necessary to support
#	Line 14 | Line 17 | package java.util;
17		* {@link Stack} when used as a stack, and faster than {@link LinkedList}
18		* when used as a queue.
19		*
20	<	* <p>Most <tt>ArrayDeque</tt> 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.
20	>	* <p>Most {@code ArrayDeque} operations run in amortized constant 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 <tt>iterator</tt> 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 <tt>remove</tt>
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 33 | Line 38 | package java.util;
38		* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
39		* as it is, generally speaking, impossible to make any hard guarantees in the
40		* presence of unsynchronized concurrent modification.  Fail-fast iterators
41	<	* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
41	>	* throw {@code ConcurrentModificationException} on a best-effort basis.
42		* Therefore, it would be wrong to write a program that depended on this
43		* exception for its correctness: <i>the fail-fast behavior of iterators
44		* should be used only to detect bugs.</i>
#	Line 48 | Line 53 | package java.util;
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 63 | Line 68 | public class ArrayDeque<E> extends Abstr
68		* other.  We also guarantee that all array cells not holding
69		* deque elements are always null.
70		*/
71	<	private transient Object[] elements;
71	>	transient Object[] elements; // non-private to simplify nested class access
72
73		/**
74		* The index of the element at the head of the deque (which is the
75		* element that would be removed by remove() or pop()); or an
76		* arbitrary number equal to tail if the deque is empty.
77		*/
78	<	private transient int head;
78	>	transient int head;
79
80		/**
81		* The index at which the next element would be added to the tail
82		* of the deque (via addLast(E), add(E), or push(E)).
83		*/
84	<	private transient int tail;
84	>	transient int tail;
85
86		/**
87		* The minimum capacity that we'll use for a newly created deque.
#	Line 87 | Line 92 | public class ArrayDeque<E> extends Abstr
92		// ******  Array allocation and resizing utilities ******
93
94		/**
95	<	* Allocate empty array to hold the given number of elements.
95	>	* Allocates empty array to hold the given number of elements.
96		*
97		* @param numElements  the number of elements to hold
98		*/
#	Line 111 | Line 116 | public class ArrayDeque<E> extends Abstr
116		}
117
118		/**
119	<	* Double the capacity of this deque.  Call only when full, i.e.,
119	>	* Doubles the capacity of this deque.  Call only when full, i.e.,
120		* when head and tail have wrapped around to become equal.
121		*/
122		private void doubleCapacity() {
#	Line 131 | Line 136 | public class ArrayDeque<E> extends Abstr
136		}
137
138		/**
134	–	* Copies the elements from our element array into the specified array,
135	–	* in order (from first to last element in the deque).  It is assumed
136	–	* that the array is large enough to hold all elements in the deque.
137	–	*
138	–	* @return its argument
139	–	*/
140	–	private <T> T[] copyElements(T[] a) {
141	–	if (head < tail) {
142	–	System.arraycopy(elements, head, a, 0, size());
143	–	} else if (head > tail) {
144	–	int headPortionLen = elements.length - head;
145	–	System.arraycopy(elements, head, a, 0, headPortionLen);
146	–	System.arraycopy(elements, 0, a, headPortionLen, tail);
147	–	}
148	–	return a;
149	–	}
150	–
151	–	/**
139		* Constructs an empty array deque with an initial capacity
140		* sufficient to hold 16 elements.
141		*/
#	Line 219 | Line 206 | public class ArrayDeque<E> extends Abstr
206		* Inserts the specified element at the front of this deque.
207		*
208		* @param e the element to add
209	<	* @return <tt>true</tt> (as specified by {@link Deque#offerFirst})
209	>	* @return {@code true} (as specified by {@link Deque#offerFirst})
210		* @throws NullPointerException if the specified element is null
211		*/
212		public boolean offerFirst(E e) {
#	Line 231 | Line 218 | public class ArrayDeque<E> extends Abstr
218		* Inserts the specified element at the end of this deque.
219		*
220		* @param e the element to add
221	<	* @return <tt>true</tt> (as specified by {@link Deque#offerLast})
221	>	* @return {@code true} (as specified by {@link Deque#offerLast})
222		* @throws NullPointerException if the specified element is null
223		*/
224		public boolean offerLast(E e) {
#	Line 319 | Line 306 | public class ArrayDeque<E> extends Abstr
306		* Removes the first occurrence of the specified element in this
307		* deque (when traversing the deque from head to tail).
308		* If the deque does not contain the element, it is unchanged.
309	<	* More formally, removes the first element <tt>e</tt> such that
310	<	* <tt>o.equals(e)</tt> (if such an element exists).
311	<	* Returns <tt>true</tt> if this deque contained the specified element
309	>	* More formally, removes the first element {@code e} such that
310	>	* {@code o.equals(e)} (if such an element exists).
311	>	* Returns {@code true} if this deque contained the specified element
312		* (or equivalently, if this deque changed as a result of the call).
313		*
314		* @param o element to be removed from this deque, if present
315	<	* @return <tt>true</tt> if the deque contained the specified element
315	>	* @return {@code true} if the deque contained the specified element
316		*/
317		public boolean removeFirstOccurrence(Object o) {
318	<	if (o == null)
319	<	return false;
320	<	int mask = elements.length - 1;
321	<	int i = head;
322	<	Object x;
323	<	while ( (x = elements[i]) != null) {
324	<	if (o.equals(x)) {
325	<	delete(i);
339	<	return true;
318	>	if (o != null) {
319	>	int mask = elements.length - 1;
320	>	int i = head;
321	>	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
322	>	if (o.equals(x)) {
323	>	delete(i);
324	>	return true;
325	>	}
326		}
341	–	i = (i + 1) & mask;
327		}
328		return false;
329		}
#	Line 347 | Line 332 | public class ArrayDeque<E> extends Abstr
332		* Removes the last occurrence of the specified element in this
333		* deque (when traversing the deque from head to tail).
334		* If the deque does not contain the element, it is unchanged.
335	<	* More formally, removes the last element <tt>e</tt> such that
336	<	* <tt>o.equals(e)</tt> (if such an element exists).
337	<	* Returns <tt>true</tt> if this deque contained the specified element
335	>	* More formally, removes the last element {@code e} such that
336	>	* {@code o.equals(e)} (if such an element exists).
337	>	* Returns {@code true} if this deque contained the specified element
338		* (or equivalently, if this deque changed as a result of the call).
339		*
340		* @param o element to be removed from this deque, if present
341	<	* @return <tt>true</tt> if the deque contained the specified element
341	>	* @return {@code true} if the deque contained the specified element
342		*/
343		public boolean removeLastOccurrence(Object o) {
344	<	if (o == null)
345	<	return false;
346	<	int mask = elements.length - 1;
347	<	int i = (tail - 1) & mask;
348	<	Object x;
349	<	while ( (x = elements[i]) != null) {
350	<	if (o.equals(x)) {
351	<	delete(i);
367	<	return true;
344	>	if (o != null) {
345	>	int mask = elements.length - 1;
346	>	int i = (tail - 1) & mask;
347	>	for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) {
348	>	if (o.equals(x)) {
349	>	delete(i);
350	>	return true;
351	>	}
352		}
369	–	i = (i - 1) & mask;
353		}
354		return false;
355		}
#	Line 379 | Line 362 | public class ArrayDeque<E> extends Abstr
362		* <p>This method is equivalent to {@link #addLast}.
363		*
364		* @param e the element to add
365	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
365	>	* @return {@code true} (as specified by {@link Collection#add})
366		* @throws NullPointerException if the specified element is null
367		*/
368		public boolean add(E e) {
#	Line 393 | Line 376 | public class ArrayDeque<E> extends Abstr
376		* <p>This method is equivalent to {@link #offerLast}.
377		*
378		* @param e the element to add
379	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
379	>	* @return {@code true} (as specified by {@link Queue#offer})
380		* @throws NullPointerException if the specified element is null
381		*/
382		public boolean offer(E e) {
#	Line 418 | Line 401 | public class ArrayDeque<E> extends Abstr
401		/**
402		* Retrieves and removes the head of the queue represented by this deque
403		* (in other words, the first element of this deque), or returns
404	<	* <tt>null</tt> if this deque is empty.
404	>	* {@code null} if this deque is empty.
405		*
406		* <p>This method is equivalent to {@link #pollFirst}.
407		*
408		* @return the head of the queue represented by this deque, or
409	<	*         <tt>null</tt> if this deque is empty
409	>	*         {@code null} if this deque is empty
410		*/
411		public E poll() {
412		return pollFirst();
#	Line 445 | Line 428 | public class ArrayDeque<E> extends Abstr
428
429		/**
430		* Retrieves, but does not remove, the head of the queue represented by
431	<	* this deque, or returns <tt>null</tt> if this deque is empty.
431	>	* this deque, or returns {@code null} if this deque is empty.
432		*
433		* <p>This method is equivalent to {@link #peekFirst}.
434		*
435		* @return the head of the queue represented by this deque, or
436	<	*         <tt>null</tt> if this deque is empty
436	>	*         {@code null} if this deque is empty
437		*/
438		public E peek() {
439		return peekFirst();
#	Line 554 | Line 537 | public class ArrayDeque<E> extends Abstr
537		}
538
539		/**
540	<	* Returns <tt>true</tt> if this deque contains no elements.
540	>	* Returns {@code true} if this deque contains no elements.
541		*
542	<	* @return <tt>true</tt> if this deque contains no elements
542	>	* @return {@code true} if this deque contains no elements
543		*/
544		public boolean isEmpty() {
545		return head == tail;
#	Line 625 | Line 608 | public class ArrayDeque<E> extends Abstr
608		}
609		}
610
611	+	/**
612	+	* This class is nearly a mirror-image of DeqIterator, using tail
613	+	* instead of head for initial cursor, and head instead of tail
614	+	* for fence.
615	+	*/
616		private class DescendingIterator implements Iterator<E> {
629	–	/*
630	–	* This class is nearly a mirror-image of DeqIterator, using
631	–	* tail instead of head for initial cursor, and head instead of
632	–	* tail for fence.
633	–	*/
617		private int cursor = tail;
618		private int fence = head;
619		private int lastRet = -1;
#	Line 663 | Line 646 | public class ArrayDeque<E> extends Abstr
646		}
647
648		/**
649	<	* Returns <tt>true</tt> if this deque contains the specified element.
650	<	* More formally, returns <tt>true</tt> if and only if this deque contains
651	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
649	>	* Returns {@code true} if this deque contains the specified element.
650	>	* More formally, returns {@code true} if and only if this deque contains
651	>	* at least one element {@code e} such that {@code o.equals(e)}.
652		*
653		* @param o object to be checked for containment in this deque
654	<	* @return <tt>true</tt> if this deque contains the specified element
654	>	* @return {@code true} if this deque contains the specified element
655		*/
656		public boolean contains(Object o) {
657	<	if (o == null)
658	<	return false;
659	<	int mask = elements.length - 1;
660	<	int i = head;
661	<	Object x;
662	<	while ( (x = elements[i]) != null) {
663	<	if (o.equals(x))
681	<	return true;
682	<	i = (i + 1) & mask;
657	>	if (o != null) {
658	>	int mask = elements.length - 1;
659	>	int i = head;
660	>	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
661	>	if (o.equals(x))
662	>	return true;
663	>	}
664		}
665		return false;
666		}
#	Line 687 | Line 668 | public class ArrayDeque<E> extends Abstr
668		/**
669		* Removes a single instance of the specified element from this deque.
670		* If the deque does not contain the element, it is unchanged.
671	<	* More formally, removes the first element <tt>e</tt> such that
672	<	* <tt>o.equals(e)</tt> (if such an element exists).
673	<	* Returns <tt>true</tt> if this deque contained the specified element
671	>	* More formally, removes the first element {@code e} such that
672	>	* {@code o.equals(e)} (if such an element exists).
673	>	* Returns {@code true} if this deque contained the specified element
674		* (or equivalently, if this deque changed as a result of the call).
675		*
676	<	* <p>This method is equivalent to {@link #removeFirstOccurrence}.
676	>	* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
677		*
678		* @param o element to be removed from this deque, if present
679	<	* @return <tt>true</tt> if this deque contained the specified element
679	>	* @return {@code true} if this deque contained the specified element
680		*/
681		public boolean remove(Object o) {
682		return removeFirstOccurrence(o);
#	Line 733 | Line 714 | public class ArrayDeque<E> extends Abstr
714		* @return an array containing all of the elements in this deque
715		*/
716		public Object[] toArray() {
717	<	return copyElements(new Object[size()]);
717	>	final int head = this.head;
718	>	final int tail = this.tail;
719	>	boolean wrap = (tail < head);
720	>	int end = wrap ? tail + elements.length : tail;
721	>	Object[] a = Arrays.copyOfRange(elements, head, end);
722	>	if (wrap)
723	>	System.arraycopy(elements, 0, a, elements.length - head, tail);
724	>	return a;
725		}
726
727		/**
#	Line 747 | Line 735 | public class ArrayDeque<E> extends Abstr
735		* <p>If this deque fits in the specified array with room to spare
736		* (i.e., the array has more elements than this deque), the element in
737		* the array immediately following the end of the deque is set to
738	<	* <tt>null</tt>.
738	>	* {@code null}.
739		*
740		* <p>Like the {@link #toArray()} method, this method acts as bridge between
741		* array-based and collection-based APIs.  Further, this method allows
742		* precise control over the runtime type of the output array, and may,
743		* under certain circumstances, be used to save allocation costs.
744		*
745	<	* <p>Suppose <tt>x</tt> is a deque known to contain only strings.
745	>	* <p>Suppose {@code x} is a deque known to contain only strings.
746		* The following code can be used to dump the deque into a newly
747	<	* allocated array of <tt>String</tt>:
747	>	* allocated array of {@code String}:
748		*
749		*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
750		*
751	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
752	<	* <tt>toArray()</tt>.
751	>	* Note that {@code toArray(new Object[0])} is identical in function to
752	>	* {@code toArray()}.
753		*
754		* @param a the array into which the elements of the deque are to
755		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 774 | Line 762 | public class ArrayDeque<E> extends Abstr
762		*/
763		@SuppressWarnings("unchecked")
764		public <T> T[] toArray(T[] a) {
765	<	int size = size();
766	<	if (a.length < size)
767	<	a = (T[])java.lang.reflect.Array.newInstance(
768	<	a.getClass().getComponentType(), size);
769	<	copyElements(a);
770	<	if (a.length > size)
771	<	a[size] = null;
765	>	final int head = this.head;
766	>	final int tail = this.tail;
767	>	boolean wrap = (tail < head);
768	>	int size = (tail - head) + (wrap ? elements.length : 0);
769	>	int firstLeg = size - (wrap ? tail : 0);
770	>	int len = a.length;
771	>	if (size > len) {
772	>	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
773	>	a.getClass());
774	>	} else {
775	>	System.arraycopy(elements, head, a, 0, firstLeg);
776	>	if (size < len)
777	>	a[size] = null;
778	>	}
779	>	if (wrap)
780	>	System.arraycopy(elements, 0, a, firstLeg, tail);
781		return a;
782		}
783
#	Line 807 | Line 804 | public class ArrayDeque<E> extends Abstr
804		/**
805		* Saves this deque to a stream (that is, serializes it).
806		*
807	<	* @serialData The current size (<tt>int</tt>) of the deque,
807	>	* @param s the stream
808	>	* @throws java.io.IOException if an I/O error occurs
809	>	* @serialData The current size ({@code int}) of the deque,
810		* followed by all of its elements (each an object reference) in
811		* first-to-last order.
812		*/
#	Line 826 | Line 825 | public class ArrayDeque<E> extends Abstr
825
826		/**
827		* Reconstitutes this deque from a stream (that is, deserializes it).
828	+	* @param s the stream
829	+	* @throws ClassNotFoundException if the class of a serialized object
830	+	*         could not be found
831	+	* @throws java.io.IOException if an I/O error occurs
832		*/
833		private void readObject(java.io.ObjectInputStream s)
834		throws java.io.IOException, ClassNotFoundException {
#	Line 841 | Line 844 | public class ArrayDeque<E> extends Abstr
844		for (int i = 0; i < size; i++)
845		elements[i] = s.readObject();
846		}
847	+
848	+	public Spliterator<E> spliterator() {
849	+	return new DeqSpliterator<E>(this, -1, -1);
850	+	}
851	+
852	+	static final class DeqSpliterator<E> implements Spliterator<E> {
853	+	private final ArrayDeque<E> deq;
854	+	private int fence;  // -1 until first use
855	+	private int index;  // current index, modified on traverse/split
856	+
857	+	/** Creates new spliterator covering the given array and range */
858	+	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
859	+	this.deq = deq;
860	+	this.index = origin;
861	+	this.fence = fence;
862	+	}
863	+
864	+	private int getFence() { // force initialization
865	+	int t;
866	+	if ((t = fence) < 0) {
867	+	t = fence = deq.tail;
868	+	index = deq.head;
869	+	}
870	+	return t;
871	+	}
872	+
873	+	public Spliterator<E> trySplit() {
874	+	int t = getFence(), h = index, n = deq.elements.length;
875	+	if (h != t && ((h + 1) & (n - 1)) != t) {
876	+	if (h > t)
877	+	t += n;
878	+	int m = ((h + t) >>> 1) & (n - 1);
879	+	return new DeqSpliterator<>(deq, h, index = m);
880	+	}
881	+	return null;
882	+	}
883	+
884	+	public void forEachRemaining(Consumer<? super E> consumer) {
885	+	if (consumer == null)
886	+	throw new NullPointerException();
887	+	Object[] a = deq.elements;
888	+	int m = a.length - 1, f = getFence(), i = index;
889	+	index = f;
890	+	while (i != f) {
891	+	@SuppressWarnings("unchecked") E e = (E)a[i];
892	+	i = (i + 1) & m;
893	+	if (e == null)
894	+	throw new ConcurrentModificationException();
895	+	consumer.accept(e);
896	+	}
897	+	}
898	+
899	+	public boolean tryAdvance(Consumer<? super E> consumer) {
900	+	if (consumer == null)
901	+	throw new NullPointerException();
902	+	Object[] a = deq.elements;
903	+	int m = a.length - 1, f = getFence(), i = index;
904	+	if (i != fence) {
905	+	@SuppressWarnings("unchecked") E e = (E)a[i];
906	+	index = (i + 1) & m;
907	+	if (e == null)
908	+	throw new ConcurrentModificationException();
909	+	consumer.accept(e);
910	+	return true;
911	+	}
912	+	return false;
913	+	}
914	+
915	+	public long estimateSize() {
916	+	int n = getFence() - index;
917	+	if (n < 0)
918	+	n += deq.elements.length;
919	+	return (long) n;
920	+	}
921	+
922	+	@Override
923	+	public int characteristics() {
924	+	return Spliterator.ORDERED | Spliterator.SIZED |
925	+	Spliterator.NONNULL | Spliterator.SUBSIZED;
926	+	}
927	+	}
928	+
929		}

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