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Comparing jsr166/src/main/java/util/AbstractList.java (file contents):
Revision 1.12 by jsr166, Mon Jun 26 00:46:50 2006 UTC vs.
Revision 1.19 by jsr166, Sun May 18 23:47:55 2008 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
3	>	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5	<	* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5	>	* This code is free software; you can redistribute it and/or modify it
6	>	* under the terms of the GNU General Public License version 2 only, as
7	>	* published by the Free Software Foundation.  Sun designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Sun in the LICENSE file that accompanied this code.
10	>	*
11	>	* This code is distributed in the hope that it will be useful, but WITHOUT
12	>	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13	>	* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14	>	* version 2 for more details (a copy is included in the LICENSE file that
15	>	* accompanied this code).
16	>	*
17	>	* You should have received a copy of the GNU General Public License version
18	>	* 2 along with this work; if not, write to the Free Software Foundation,
19	>	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20	>	*
21	>	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22	>	* CA 95054 USA or visit www.sun.com if you need additional information or
23	>	* have any questions.
24		*/
25
26		package java.util;
27
28		/**
29	<	* This class provides a skeletal implementation of the {@code List}
29	>	* This class provides a skeletal implementation of the {@link List}
30		* interface to minimize the effort required to implement this interface
31		* backed by a "random access" data store (such as an array).  For sequential
32	<	* access data (such as a linked list), {@code AbstractSequentialList} should
32	>	* access data (such as a linked list), {@link AbstractSequentialList} should
33		* be used in preference to this class.
34		*
35	<	* <p>To implement an unmodifiable list, the programmer needs only to extend this
36	<	* class and provide implementations for the {@code get(int index)} and
37	<	* {@code size()} methods.
38	<	*
39	<	* <p>To implement a modifiable list, the programmer must additionally override
40	<	* the {@code set(int index, Object element)} method (which otherwise throws
41	<	* an {@code UnsupportedOperationException}.  If the list is variable-size
42	<	* the programmer must additionally override the {@code add(int index, Object
43	<	* element)} and {@code remove(int index)} methods.
35	>	* <p>To implement an unmodifiable list, the programmer needs only to extend
36	>	* this class and provide implementations for the {@link #get(int)} and
37	>	* {@link List#size() size()} methods.
38	>	*
39	>	* <p>To implement a modifiable list, the programmer must additionally
40	>	* override the {@link #set(int, Object) set(int, E)} method (which otherwise
41	>	* throws an {@code UnsupportedOperationException}).  If the list is
42	>	* variable-size the programmer must additionally override the
43	>	* {@link #add(int, Object) add(int, E)} and {@link #remove(int)} methods.
44		*
45		* <p>The programmer should generally provide a void (no argument) and collection
46	<	* constructor, as per the recommendation in the {@code Collection} interface
46	>	* constructor, as per the recommendation in the {@link Collection} interface
47		* specification.
48		*
49		* <p>Unlike the other abstract collection implementations, the programmer does
50		* <i>not</i> have to provide an iterator implementation; the iterator and
51		* list iterator are implemented by this class, on top of the "random access"
52	<	* methods: {@code get(int index)}, {@code set(int index, E element)},
53	<	* {@code add(int index, E element)} and {@code remove(int index)}.
52	>	* methods:
53	>	* {@link #get(int)},
54	>	* {@link #set(int, Object) set(int, E)},
55	>	* {@link #add(int, Object) add(int, E)} and
56	>	* {@link #remove(int)}.
57		*
58	<	* <p>The documentation for each non-abstract methods in this class describes its
58	>	* <p>The documentation for each non-abstract method in this class describes its
59		* implementation in detail.  Each of these methods may be overridden if the
60		* collection being implemented admits a more efficient implementation.
61		*
#	Line 45 | Line 66 | package java.util;
66		* @author  Josh Bloch
67		* @author  Neal Gafter
68		* @version %I%, %G%
48	–	* @see Collection
49	–	* @see List
50	–	* @see AbstractSequentialList
51	–	* @see AbstractCollection
69		* @since 1.2
70		*/
71
#	Line 74 | Line 91 | public abstract class AbstractList<E> ex
91		* <p>This implementation calls {@code add(size(), e)}.
92		*
93		* <p>Note that this implementation throws an
94	<	* {@code UnsupportedOperationException} unless {@code add(int, Object)}
95	<	* is overridden.
94	>	* {@code UnsupportedOperationException} unless
95	>	* {@link #add(int, Object) add(int, E)} is overridden.
96		*
97		* @param e element to be appended to this list
98		* @return {@code true} (as specified by {@link Collection#add})
#	Line 89 | Line 106 | public abstract class AbstractList<E> ex
106		*         prevents it from being added to this list
107		*/
108		public boolean add(E e) {
109	<	add(size(), e);
110	<	return true;
109	>	add(size(), e);
110	>	return true;
111		}
112
113		/**
#	Line 113 | Line 130 | public abstract class AbstractList<E> ex
130		* @throws IndexOutOfBoundsException     {@inheritDoc}
131		*/
132		public E set(int index, E element) {
133	<	throw new UnsupportedOperationException();
133	>	throw new UnsupportedOperationException();
134		}
135
136		/**
#	Line 129 | Line 146 | public abstract class AbstractList<E> ex
146		* @throws IndexOutOfBoundsException     {@inheritDoc}
147		*/
148		public void add(int index, E element) {
149	<	throw new UnsupportedOperationException();
149	>	throw new UnsupportedOperationException();
150		}
151
152		/**
#	Line 142 | Line 159 | public abstract class AbstractList<E> ex
159		* @throws IndexOutOfBoundsException     {@inheritDoc}
160		*/
161		public E remove(int index) {
162	<	throw new UnsupportedOperationException();
162	>	throw new UnsupportedOperationException();
163		}
164
165
#	Line 159 | Line 176 | public abstract class AbstractList<E> ex
176		* @throws NullPointerException {@inheritDoc}
177		*/
178		public int indexOf(Object o) {
179	<	ListIterator<E> e = listIterator();
180	<	if (o==null) {
181	<	while (e.hasNext())
182	<	if (e.next()==null)
183	<	return e.previousIndex();
184	<	} else {
185	<	while (e.hasNext())
186	<	if (o.equals(e.next()))
187	<	return e.previousIndex();
188	<	}
189	<	return -1;
179	>	ListIterator<E> e = listIterator();
180	>	if (o==null) {
181	>	while (e.hasNext())
182	>	if (e.next()==null)
183	>	return e.previousIndex();
184	>	} else {
185	>	while (e.hasNext())
186	>	if (o.equals(e.next()))
187	>	return e.previousIndex();
188	>	}
189	>	return -1;
190		}
191
192		/**
#	Line 184 | Line 201 | public abstract class AbstractList<E> ex
201		* @throws NullPointerException {@inheritDoc}
202		*/
203		public int lastIndexOf(Object o) {
204	<	ListIterator<E> e = listIterator(size());
205	<	if (o==null) {
206	<	while (e.hasPrevious())
207	<	if (e.previous()==null)
208	<	return e.nextIndex();
209	<	} else {
210	<	while (e.hasPrevious())
211	<	if (o.equals(e.previous()))
212	<	return e.nextIndex();
213	<	}
214	<	return -1;
204	>	ListIterator<E> e = listIterator(size());
205	>	if (o==null) {
206	>	while (e.hasPrevious())
207	>	if (e.previous()==null)
208	>	return e.nextIndex();
209	>	} else {
210	>	while (e.hasPrevious())
211	>	if (o.equals(e.previous()))
212	>	return e.nextIndex();
213	>	}
214	>	return -1;
215		}
216
217
#	Line 221 | Line 238 | public abstract class AbstractList<E> ex
238		/**
239		* {@inheritDoc}
240		*
241	<	* <p>This implementation gets an iterator over the specified collection and
242	<	* iterates over it, inserting the elements obtained from the iterator
243	<	* into this list at the appropriate position, one at a time, using
244	<	* {@code add(int, Object)}.  Many implementations will override this
245	<	* method for efficiency.
241	>	* <p>This implementation gets an iterator over the specified collection
242	>	* and iterates over it, inserting the elements obtained from the
243	>	* iterator into this list at the appropriate position, one at a time,
244	>	* using {@code add(int, E)}.
245	>	* Many implementations will override this method for efficiency.
246		*
247		* <p>Note that this implementation throws an
248	<	* {@code UnsupportedOperationException} unless {@code add(int, Object)}
249	<	* is overridden.
248	>	* {@code UnsupportedOperationException} unless
249	>	* {@link #add(int, Object) add(int, E)} is overridden.
250		*
251		* @throws UnsupportedOperationException {@inheritDoc}
252		* @throws ClassCastException            {@inheritDoc}
#	Line 238 | Line 255 | public abstract class AbstractList<E> ex
255		* @throws IndexOutOfBoundsException     {@inheritDoc}
256		*/
257		public boolean addAll(int index, Collection<? extends E> c) {
258	<	boolean modified = false;
259	<	Iterator<? extends E> e = c.iterator();
260	<	while (e.hasNext()) {
261	<	add(index++, e.next());
262	<	modified = true;
263	<	}
264	<	return modified;
258	>	rangeCheckForAdd(index);
259	>	boolean modified = false;
260	>	Iterator<? extends E> e = c.iterator();
261	>	while (e.hasNext()) {
262	>	add(index++, e.next());
263	>	modified = true;
264	>	}
265	>	return modified;
266		}
267
268
269		// Iterators
270
271		/**
272	<	* Returns an iterator over the elements in this list in proper
255	<	* sequence. <p>
272	>	* Returns an iterator over the elements in this list in proper sequence.
273		*
274	<	* This implementation returns a straightforward implementation of the
274	>	* <p>This implementation returns a straightforward implementation of the
275		* iterator interface, relying on the backing list's {@code size()},
276	<	* {@code get(int)}, and {@code remove(int)} methods.<p>
276	>	* {@code get(int)}, and {@code remove(int)} methods.
277		*
278	<	* Note that the iterator returned by this method will throw an
279	<	* {@code UnsupportedOperationException} in response to its
278	>	* <p>Note that the iterator returned by this method will throw an
279	>	* {@link UnsupportedOperationException} in response to its
280		* {@code remove} method unless the list's {@code remove(int)} method is
281	<	* overridden.<p>
281	>	* overridden.
282		*
283	<	* This implementation can be made to throw runtime exceptions in the face
284	<	* of concurrent modification, as described in the specification for the
285	<	* (protected) {@code modCount} field.
283	>	* <p>This implementation can be made to throw runtime exceptions in the
284	>	* face of concurrent modification, as described in the specification
285	>	* for the (protected) {@link #modCount} field.
286		*
287		* @return an iterator over the elements in this list in proper sequence
271	–	*
272	–	* @see #modCount
288		*/
289		public Iterator<E> iterator() {
290	<	return new Itr();
290	>	return new Itr();
291		}
292
293		/**
#	Line 283 | Line 298 | public abstract class AbstractList<E> ex
298		* @see #listIterator(int)
299		*/
300		public ListIterator<E> listIterator() {
301	<	return listIterator(0);
301	>	return listIterator(0);
302		}
303
304		/**
#	Line 293 | Line 308 | public abstract class AbstractList<E> ex
308		* {@code ListIterator} interface that extends the implementation of the
309		* {@code Iterator} interface returned by the {@code iterator()} method.
310		* The {@code ListIterator} implementation relies on the backing list's
311	<	* {@code get(int)}, {@code set(int, Object)}, {@code add(int, Object)}
311	>	* {@code get(int)}, {@code set(int, E)}, {@code add(int, E)}
312		* and {@code remove(int)} methods.
313		*
314		* <p>Note that the list iterator returned by this implementation will
315	<	* throw an {@code UnsupportedOperationException} in response to its
315	>	* throw an {@link UnsupportedOperationException} in response to its
316		* {@code remove}, {@code set} and {@code add} methods unless the
317	<	* list's {@code remove(int)}, {@code set(int, Object)}, and
318	<	* {@code add(int, Object)} methods are overridden.
317	>	* list's {@code remove(int)}, {@code set(int, E)}, and
318	>	* {@code add(int, E)} methods are overridden.
319		*
320		* <p>This implementation can be made to throw runtime exceptions in the
321		* face of concurrent modification, as described in the specification for
322	<	* the (protected) {@code modCount} field.
322	>	* the (protected) {@link #modCount} field.
323		*
324		* @throws IndexOutOfBoundsException {@inheritDoc}
310	–	*
311	–	* @see #modCount
325		*/
326		public ListIterator<E> listIterator(final int index) {
327	<	if (index<0 || index>size())
315	<	throw new IndexOutOfBoundsException("Index: "+index);
327	>	rangeCheckForAdd(index);
328
329	<	return new ListItr(index);
329	>	return new ListItr(index);
330		}
331
332		private class Itr implements Iterator<E> {
333	<	/**
334	<	* Index of element to be returned by subsequent call to next.
335	<	*/
336	<	int cursor = 0;
337	<
338	<	/**
339	<	* Index of element returned by most recent call to next or
340	<	* previous.  Reset to -1 if this element is deleted by a call
341	<	* to remove.
342	<	*/
343	<	int lastRet = -1;
344	<
345	<	/**
346	<	* The modCount value that the iterator believes that the backing
347	<	* List should have.  If this expectation is violated, the iterator
348	<	* has detected concurrent modification.
349	<	*/
350	<	int expectedModCount = modCount;
333	>	/**
334	>	* Index of element to be returned by subsequent call to next.
335	>	*/
336	>	int cursor = 0;
337	>
338	>	/**
339	>	* Index of element returned by most recent call to next or
340	>	* previous.  Reset to -1 if this element is deleted by a call
341	>	* to remove.
342	>	*/
343	>	int lastRet = -1;
344	>
345	>	/**
346	>	* The modCount value that the iterator believes that the backing
347	>	* List should have.  If this expectation is violated, the iterator
348	>	* has detected concurrent modification.
349	>	*/
350	>	int expectedModCount = modCount;
351
352	<	public boolean hasNext() {
352	>	public boolean hasNext() {
353		return cursor != size();
354	<	}
354	>	}
355
356	<	public E next() {
356	>	public E next() {
357		checkForComodification();
358	<	try {
359	<	E next = get(cursor);
360	<	lastRet = cursor++;
361	<	return next;
362	<	} catch (IndexOutOfBoundsException e) {
363	<	checkForComodification();
364	<	throw new NoSuchElementException();
365	<	}
366	<	}
367	<
368	<	public void remove() {
369	<	if (lastRet == -1)
370	<	throw new IllegalStateException();
358	>	try {
359	>	int i = cursor;
360	>	E next = get(i);
361	>	lastRet = i;
362	>	cursor = i + 1;
363	>	return next;
364	>	} catch (IndexOutOfBoundsException e) {
365	>	checkForComodification();
366	>	throw new NoSuchElementException();
367	>	}
368	>	}
369	>
370	>	public void remove() {
371	>	if (lastRet < 0)
372	>	throw new IllegalStateException();
373		checkForComodification();
374
375	<	try {
376	<	AbstractList.this.remove(lastRet);
377	<	if (lastRet < cursor)
378	<	cursor--;
379	<	lastRet = -1;
380	<	expectedModCount = modCount;
381	<	} catch (IndexOutOfBoundsException e) {
382	<	throw new ConcurrentModificationException();
383	<	}
384	<	}
385	<
386	<	final void checkForComodification() {
387	<	if (modCount != expectedModCount)
388	<	throw new ConcurrentModificationException();
389	<	}
375	>	try {
376	>	AbstractList.this.remove(lastRet);
377	>	if (lastRet < cursor)
378	>	cursor--;
379	>	lastRet = -1;
380	>	expectedModCount = modCount;
381	>	} catch (IndexOutOfBoundsException e) {
382	>	throw new ConcurrentModificationException();
383	>	}
384	>	}
385	>
386	>	final void checkForComodification() {
387	>	if (modCount != expectedModCount)
388	>	throw new ConcurrentModificationException();
389	>	}
390		}
391
392		private class ListItr extends Itr implements ListIterator<E> {
393	<	ListItr(int index) {
394	<	cursor = index;
395	<	}
396	<
397	<	public boolean hasPrevious() {
398	<	return cursor != 0;
399	<	}
393	>	ListItr(int index) {
394	>	cursor = index;
395	>	}
396	>
397	>	public boolean hasPrevious() {
398	>	return cursor != 0;
399	>	}
400
401		public E previous() {
402		checkForComodification();
#	Line 397 | Line 411 | public abstract class AbstractList<E> ex
411		}
412		}
413
414	<	public int nextIndex() {
415	<	return cursor;
416	<	}
417	<
418	<	public int previousIndex() {
419	<	return cursor-1;
420	<	}
421	<
422	<	public void set(E e) {
423	<	if (lastRet == -1)
424	<	throw new IllegalStateException();
414	>	public int nextIndex() {
415	>	return cursor;
416	>	}
417	>
418	>	public int previousIndex() {
419	>	return cursor-1;
420	>	}
421	>
422	>	public void set(E e) {
423	>	if (lastRet < 0)
424	>	throw new IllegalStateException();
425		checkForComodification();
426
427	<	try {
428	<	AbstractList.this.set(lastRet, e);
429	<	expectedModCount = modCount;
430	<	} catch (IndexOutOfBoundsException ex) {
431	<	throw new ConcurrentModificationException();
432	<	}
433	<	}
427	>	try {
428	>	AbstractList.this.set(lastRet, e);
429	>	expectedModCount = modCount;
430	>	} catch (IndexOutOfBoundsException ex) {
431	>	throw new ConcurrentModificationException();
432	>	}
433	>	}
434
435	<	public void add(E e) {
435	>	public void add(E e) {
436		checkForComodification();
437
438	<	try {
438	>	try {
439		int i = cursor;
440	<	AbstractList.this.add(i, e);
440	>	AbstractList.this.add(i, e);
441	>	lastRet = -1;
442		cursor = i + 1;
443	<	lastRet = -1;
444	<	expectedModCount = modCount;
445	<	} catch (IndexOutOfBoundsException ex) {
446	<	throw new ConcurrentModificationException();
447	<	}
433	<	}
443	>	expectedModCount = modCount;
444	>	} catch (IndexOutOfBoundsException ex) {
445	>	throw new ConcurrentModificationException();
446	>	}
447	>	}
448		}
449
450		/**
#	Line 445 | Line 459 | public abstract class AbstractList<E> ex
459		* If this list implements {@code RandomAccess} the returned list will
460		* be an instance of the subclass that implements {@code RandomAccess}.
461		*
462	<	* <p>The subclass's {@code set(int, Object)}, {@code get(int)},
463	<	* {@code add(int, Object)}, {@code remove(int)}, {@code addAll(int,
462	>	* <p>The subclass's {@code set(int, E)}, {@code get(int)},
463	>	* {@code add(int, E)}, {@code remove(int)}, {@code addAll(int,
464		* Collection)} and {@code removeRange(int, int)} methods all
465		* delegate to the corresponding methods on the backing abstract list,
466		* after bounds-checking the index and adjusting for the offset.  The
#	Line 463 | Line 477 | public abstract class AbstractList<E> ex
477		* the backing list is equal to its expected value, and throw a
478		* {@code ConcurrentModificationException} if it is not.
479		*
480	<	* @throws IndexOutOfBoundsException endpoint index value out of range
481	<	*         {@code (fromIndex &lt; 0 || toIndex &gt; size)}
480	>	* @throws IndexOutOfBoundsException if an endpoint index value is out of range
481	>	*         {@code (fromIndex < 0 || toIndex > size)}
482		* @throws IllegalArgumentException if the endpoint indices are out of order
483	<	*         {@code (fromIndex &gt; toIndex)}
483	>	*         {@code (fromIndex > toIndex)}
484		*/
485		public List<E> subList(int fromIndex, int toIndex) {
486		return (this instanceof RandomAccess ?
487	<	new RandomAccessSubList(this, this, fromIndex, fromIndex, toIndex) :
488	<	new SubList(this, this, fromIndex, fromIndex, toIndex));
487	>	new RandomAccessSubList<E>(this, fromIndex, toIndex) :
488	>	new SubList<E>(this, fromIndex, toIndex));
489		}
490
491		// Comparison and hashing
#	Line 498 | Line 512 | public abstract class AbstractList<E> ex
512		* @return {@code true} if the specified object is equal to this list
513		*/
514		public boolean equals(Object o) {
515	<	if (o == this)
516	<	return true;
517	<	if (!(o instanceof List))
518	<	return false;
519	<
520	<	ListIterator<E> e1 = listIterator();
521	<	ListIterator e2 = ((List) o).listIterator();
522	<	while(e1.hasNext() && e2.hasNext()) {
523	<	E o1 = e1.next();
524	<	Object o2 = e2.next();
525	<	if (!(o1==null ? o2==null : o1.equals(o2)))
526	<	return false;
527	<	}
528	<	return !(e1.hasNext() || e2.hasNext());
515	>	if (o == this)
516	>	return true;
517	>	if (!(o instanceof List))
518	>	return false;
519	>
520	>	ListIterator<E> e1 = listIterator();
521	>	ListIterator e2 = ((List) o).listIterator();
522	>	while(e1.hasNext() && e2.hasNext()) {
523	>	E o1 = e1.next();
524	>	Object o2 = e2.next();
525	>	if (!(o1==null ? o2==null : o1.equals(o2)))
526	>	return false;
527	>	}
528	>	return !(e1.hasNext() || e2.hasNext());
529		}
530
531		/**
532	<	* Returns the hash code value for this list. <p>
532	>	* Returns the hash code value for this list.
533		*
534	<	* This implementation uses exactly the code that is used to define the
534	>	* <p>This implementation uses exactly the code that is used to define the
535		* list hash function in the documentation for the {@link List#hashCode}
536		* method.
537		*
538		* @return the hash code value for this list
539		*/
540		public int hashCode() {
541	<	int hashCode = 1;
542	<	Iterator<E> i = iterator();
543	<	while (i.hasNext()) {
544	<	E obj = i.next();
531	<	hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());
532	<	}
533	<	return hashCode;
541	>	int hashCode = 1;
542	>	for (E e : this)
543	>	hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
544	>	return hashCode;
545		}
546
547		/**
548		* Removes from this list all of the elements whose index is between
549		* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
550		* Shifts any succeeding elements to the left (reduces their index).
551	<	* This call shortens the ArrayList by {@code (toIndex - fromIndex)}
552	<	* elements.  (If {@code toIndex==fromIndex}, this operation has no
542	<	* effect.)<p>
551	>	* This call shortens the list by {@code (toIndex - fromIndex)} elements.
552	>	* (If {@code toIndex==fromIndex}, this operation has no effect.)
553		*
554	<	* This method is called by the {@code clear} operation on this list
554	>	* <p>This method is called by the {@code clear} operation on this list
555		* and its subLists.  Overriding this method to take advantage of
556		* the internals of the list implementation can <i>substantially</i>
557		* improve the performance of the {@code clear} operation on this list
558	<	* and its subLists.<p>
558	>	* and its subLists.
559		*
560	<	* This implementation gets a list iterator positioned before
560	>	* <p>This implementation gets a list iterator positioned before
561		* {@code fromIndex}, and repeatedly calls {@code ListIterator.next}
562		* followed by {@code ListIterator.remove} until the entire range has
563		* been removed.  <b>Note: if {@code ListIterator.remove} requires linear
#	Line 568 | Line 578 | public abstract class AbstractList<E> ex
578		* The number of times this list has been <i>structurally modified</i>.
579		* Structural modifications are those that change the size of the
580		* list, or otherwise perturb it in such a fashion that iterations in
581	<	* progress may yield incorrect results.<p>
581	>	* progress may yield incorrect results.
582		*
583	<	* This field is used by the iterator and list iterator implementation
583	>	* <p>This field is used by the iterator and list iterator implementation
584		* returned by the {@code iterator} and {@code listIterator} methods.
585		* If the value of this field changes unexpectedly, the iterator (or list
586		* iterator) will throw a {@code ConcurrentModificationException} in
587		* response to the {@code next}, {@code remove}, {@code previous},
588		* {@code set} or {@code add} operations.  This provides
589		* <i>fail-fast</i> behavior, rather than non-deterministic behavior in
590	<	* the face of concurrent modification during iteration.<p>
590	>	* the face of concurrent modification during iteration.
591		*
592	<	* <b>Use of this field by subclasses is optional.</b> If a subclass
592	>	* <p><b>Use of this field by subclasses is optional.</b> If a subclass
593		* wishes to provide fail-fast iterators (and list iterators), then it
594	<	* merely has to increment this field in its {@code add(int, Object)} and
594	>	* merely has to increment this field in its {@code add(int, E)} and
595		* {@code remove(int)} methods (and any other methods that it overrides
596		* that result in structural modifications to the list).  A single call to
597	<	* {@code add(int, Object)} or {@code remove(int)} must add no more than
597	>	* {@code add(int, E)} or {@code remove(int)} must add no more than
598		* one to this field, or the iterators (and list iterators) will throw
599		* bogus {@code ConcurrentModificationExceptions}.  If an implementation
600		* does not wish to provide fail-fast iterators, this field may be
601		* ignored.
602		*/
603		protected transient int modCount = 0;
604	+
605	+	private void rangeCheckForAdd(int index) {
606	+	if (index < 0 || index > size())
607	+	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
608	+	}
609	+
610	+	private String outOfBoundsMsg(int index) {
611	+	return "Index: "+index+", Size: "+size();
612	+	}
613		}
614
596	–	/**
597	–	* Generic sublists. Non-nested to enable construction by other
598	–	* classes in this package.
599	–	*/
615		class SubList<E> extends AbstractList<E> {
616	<	/*
617	<	* A SubList has both a "base", the ultimate backing list, as well
618	<	* as a "parent", which is the list or sublist creating this
619	<	* sublist. All methods that may cause structural modifications
620	<	* must propagate through the parent link, with O(k) performance
606	<	* where k is sublist depth. For example in the case of a
607	<	* sub-sub-list, invoking remove(x) will result in a chain of
608	<	* three remove calls. However, all other non-structurally
609	<	* modifying methods can bypass this chain, and relay directly to
610	<	* the base list. In particular, doing so signficantly speeds up
611	<	* the performance of iterators for deeply-nested sublists.
612	<	*/
613	<	final AbstractList<E> base;   // Backing list
614	<	final AbstractList<E> parent; // Parent list
615	<	final int baseOffset;         // index wrt base
616	<	final int parentOffset;       // index wrt parent
617	<	int length;                   // Number of elements in this sublist
618	<
619	<	SubList(AbstractList<E> base,
620	<	AbstractList<E> parent,
621	<	int baseIndex,
622	<	int fromIndex,
623	<	int toIndex) {
616	>	private final AbstractList<E> l;
617	>	private final int offset;
618	>	private int size;
619	>
620	>	SubList(AbstractList<E> list, int fromIndex, int toIndex) {
621		if (fromIndex < 0)
622		throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
623	<	if (toIndex > parent.size())
623	>	if (toIndex > list.size())
624		throw new IndexOutOfBoundsException("toIndex = " + toIndex);
625		if (fromIndex > toIndex)
626		throw new IllegalArgumentException("fromIndex(" + fromIndex +
627		") > toIndex(" + toIndex + ")");
628	<	this.base = base;
629	<	this.parent = parent;
630	<	this.baseOffset = baseIndex;
631	<	this.parentOffset = fromIndex;
635	<	this.length = toIndex - fromIndex;
636	<	this.modCount = base.modCount;
637	<	}
638	<
639	<	/**
640	<	* Returns an IndexOutOfBoundsException with nicer message
641	<	*/
642	<	private IndexOutOfBoundsException indexError(int index) {
643	<	return new IndexOutOfBoundsException("Index: " + index +
644	<	", Size: " + length);
628	>	l = list;
629	>	offset = fromIndex;
630	>	size = toIndex - fromIndex;
631	>	this.modCount = l.modCount;
632		}
633
634		public E set(int index, E element) {
635	<	if (index < 0 || index >= length)
636	<	throw indexError(index);
637	<	if (base.modCount != modCount)
651	<	throw new ConcurrentModificationException();
652	<	return base.set(index + baseOffset, element);
635	>	rangeCheck(index);
636	>	checkForComodification();
637	>	return l.set(index+offset, element);
638		}
639
640		public E get(int index) {
641	<	if (index < 0 || index >= length)
642	<	throw indexError(index);
643	<	if (base.modCount != modCount)
659	<	throw new ConcurrentModificationException();
660	<	return base.get(index + baseOffset);
641	>	rangeCheck(index);
642	>	checkForComodification();
643	>	return l.get(index+offset);
644		}
645
646		public int size() {
647	<	if (base.modCount != modCount)
648	<	throw new ConcurrentModificationException();
666	<	return length;
647	>	checkForComodification();
648	>	return size;
649		}
650
651		public void add(int index, E element) {
652	<	if (index < 0 || index>length)
653	<	throw indexError(index);
654	<	if (base.modCount != modCount)
655	<	throw new ConcurrentModificationException();
656	<	parent.add(index + parentOffset, element);
675	<	length++;
676	<	modCount = base.modCount;
652	>	rangeCheckForAdd(index);
653	>	checkForComodification();
654	>	l.add(index+offset, element);
655	>	this.modCount = l.modCount;
656	>	size++;
657		}
658
659		public E remove(int index) {
660	<	if (index < 0 || index >= length)
661	<	throw indexError(index);
662	<	if (base.modCount != modCount)
663	<	throw new ConcurrentModificationException();
664	<	E result = parent.remove(index + parentOffset);
685	<	length--;
686	<	modCount = base.modCount;
660	>	rangeCheck(index);
661	>	checkForComodification();
662	>	E result = l.remove(index+offset);
663	>	this.modCount = l.modCount;
664	>	size--;
665		return result;
666		}
667
668		protected void removeRange(int fromIndex, int toIndex) {
669	<	if (base.modCount != modCount)
670	<	throw new ConcurrentModificationException();
671	<	parent.removeRange(fromIndex + parentOffset, toIndex + parentOffset);
672	<	length -= (toIndex-fromIndex);
695	<	modCount = base.modCount;
669	>	checkForComodification();
670	>	l.removeRange(fromIndex+offset, toIndex+offset);
671	>	this.modCount = l.modCount;
672	>	size -= (toIndex-fromIndex);
673		}
674
675		public boolean addAll(Collection<? extends E> c) {
676	<	return addAll(length, c);
676	>	return addAll(size, c);
677		}
678
679		public boolean addAll(int index, Collection<? extends E> c) {
680	<	if (index < 0 || index > length)
704	<	throw indexError(index);
680	>	rangeCheckForAdd(index);
681		int cSize = c.size();
682		if (cSize==0)
683		return false;
684
685	<	if (base.modCount != modCount)
686	<	throw new ConcurrentModificationException();
687	<	parent.addAll(parentOffset + index, c);
688	<	length += cSize;
713	<	modCount = base.modCount;
685	>	checkForComodification();
686	>	l.addAll(offset+index, c);
687	>	this.modCount = l.modCount;
688	>	size += cSize;
689		return true;
690		}
691
717	–	public List<E> subList(int fromIndex, int toIndex) {
718	–	return new SubList(base, this, fromIndex + baseOffset,
719	–	fromIndex, toIndex);
720	–	}
721	–
692		public Iterator<E> iterator() {
693	<	return new SubListIterator(this, 0);
693	>	return listIterator();
694		}
695
696	<	public ListIterator<E> listIterator() {
697	<	return new SubListIterator(this, 0);
698	<	}
729	<
730	<	public ListIterator<E> listIterator(int index) {
731	<	if (index < 0 || index>length)
732	<	throw indexError(index);
733	<	return new SubListIterator(this, index);
734	<	}
696	>	public ListIterator<E> listIterator(final int index) {
697	>	checkForComodification();
698	>	rangeCheckForAdd(index);
699
700	<	/**
701	<	* Generic sublist iterator obeying fastfail semantics via
738	<	* modCount.  The hasNext and next methods locally check for
739	<	* in-range indices before relaying to backing list to get
740	<	* element. If this either encounters an unexpected modCount or
741	<	* fails, the backing list must have been concurrently modified,
742	<	* and is so reported.  The add and remove methods performing
743	<	* structural modifications instead relay them through the
744	<	* sublist.
745	<	*/
746	<	private static final class SubListIterator<E> implements ListIterator<E> {
747	<	final SubList<E> outer;       // Sublist creating this iteraor
748	<	final AbstractList<E> base;   // base list
749	<	final int offset;             // Cursor offset wrt base
750	<	int cursor;                   // Current index
751	<	int fence;                    // Upper bound on cursor
752	<	int lastRet;                  // Index of returned element, or -1
753	<	int expectedModCount;         // Expected modCount of base
754	<
755	<	SubListIterator(SubList<E> list, int index) {
756	<	this.lastRet = -1;
757	<	this.cursor = index;
758	<	this.outer = list;
759	<	this.offset = list.baseOffset;
760	<	this.fence = list.length;
761	<	this.base = list.base;
762	<	this.expectedModCount = base.modCount;
763	<	}
700	>	return new ListIterator<E>() {
701	>	private final ListIterator<E> i = l.listIterator(index+offset);
702
703	<	public boolean hasNext() {
704	<	return cursor < fence;
705	<	}
703	>	public boolean hasNext() {
704	>	return nextIndex() < size;
705	>	}
706
707	<	public boolean hasPrevious() {
708	<	return cursor > 0;
709	<	}
707	>	public E next() {
708	>	if (hasNext())
709	>	return i.next();
710	>	else
711	>	throw new NoSuchElementException();
712	>	}
713
714	<	public int nextIndex() {
715	<	return cursor;
716	<	}
714	>	public boolean hasPrevious() {
715	>	return previousIndex() >= 0;
716	>	}
717
718	<	public int previousIndex() {
719	<	return cursor - 1;
720	<	}
718	>	public E previous() {
719	>	if (hasPrevious())
720	>	return i.previous();
721	>	else
722	>	throw new NoSuchElementException();
723	>	}
724
725	<	public E next() {
726	<	int i = cursor;
783	<	if (cursor >= fence)
784	<	throw new NoSuchElementException();
785	<	if (expectedModCount == base.modCount) {
786	<	try {
787	<	Object next = base.get(i + offset);
788	<	lastRet = i;
789	<	cursor = i + 1;
790	<	return (E)next;
791	<	} catch (IndexOutOfBoundsException fallThrough) {
792	<	}
725	>	public int nextIndex() {
726	>	return i.nextIndex() - offset;
727		}
794	–	throw new ConcurrentModificationException();
795	–	}
728
729	<	public E previous() {
730	<	int i = cursor - 1;
799	<	if (i < 0)
800	<	throw new NoSuchElementException();
801	<	if (expectedModCount == base.modCount) {
802	<	try {
803	<	Object prev = base.get(i + offset);
804	<	lastRet = i;
805	<	cursor = i;
806	<	return (E)prev;
807	<	} catch (IndexOutOfBoundsException fallThrough) {
808	<	}
729	>	public int previousIndex() {
730	>	return i.previousIndex() - offset;
731		}
810	–	throw new ConcurrentModificationException();
811	–	}
732
733	<	public void set(E e) {
734	<	if (lastRet < 0)
735	<	throw new IllegalStateException();
736	<	if (expectedModCount != base.modCount)
817	<	throw new ConcurrentModificationException();
818	<	try {
819	<	outer.set(lastRet, e);
820	<	expectedModCount = base.modCount;
821	<	} catch (IndexOutOfBoundsException ex) {
822	<	throw new ConcurrentModificationException();
733	>	public void remove() {
734	>	i.remove();
735	>	SubList.this.modCount = l.modCount;
736	>	size--;
737		}
824	–	}
738
739	<	public void remove() {
740	<	int i = lastRet;
828	<	if (i < 0)
829	<	throw new IllegalStateException();
830	<	if (expectedModCount != base.modCount)
831	<	throw new ConcurrentModificationException();
832	<	try {
833	<	outer.remove(i);
834	<	if (i < cursor)
835	<	cursor--;
836	<	lastRet = -1;
837	<	fence = outer.length;
838	<	expectedModCount = base.modCount;
839	<	} catch (IndexOutOfBoundsException ex) {
840	<	throw new ConcurrentModificationException();
739	>	public void set(E e) {
740	>	i.set(e);
741		}
842	–	}
742
743	<	public void add(E e) {
744	<	if (expectedModCount != base.modCount)
745	<	throw new ConcurrentModificationException();
746	<	try {
848	<	int i = cursor;
849	<	outer.add(i, e);
850	<	cursor = i + 1;
851	<	lastRet = -1;
852	<	fence = outer.length;
853	<	expectedModCount = base.modCount;
854	<	} catch (IndexOutOfBoundsException ex) {
855	<	throw new ConcurrentModificationException();
743	>	public void add(E e) {
744	>	i.add(e);
745	>	SubList.this.modCount = l.modCount;
746	>	size++;
747		}
748	<	}
748	>	};
749	>	}
750	>
751	>	public List<E> subList(int fromIndex, int toIndex) {
752	>	return new SubList<E>(this, fromIndex, toIndex);
753		}
754
755	+	private void rangeCheck(int index) {
756	+	if (index < 0 || index >= size)
757	+	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
758	+	}
759	+
760	+	private void rangeCheckForAdd(int index) {
761	+	if (index < 0 || index > size)
762	+	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
763	+	}
764	+
765	+	private String outOfBoundsMsg(int index) {
766	+	return "Index: "+index+", Size: "+size;
767	+	}
768	+
769	+	private void checkForComodification() {
770	+	if (this.modCount != l.modCount)
771	+	throw new ConcurrentModificationException();
772	+	}
773		}
774
775		class RandomAccessSubList<E> extends SubList<E> implements RandomAccess {
776	<	RandomAccessSubList(AbstractList<E> base,
777	<	AbstractList<E> parent, int baseIndex,
865	<	int fromIndex, int toIndex) {
866	<	super(base, parent, baseIndex, fromIndex, toIndex);
776	>	RandomAccessSubList(AbstractList<E> list, int fromIndex, int toIndex) {
777	>	super(list, fromIndex, toIndex);
778		}
779
780		public List<E> subList(int fromIndex, int toIndex) {
781	<	return new RandomAccessSubList(base, this, fromIndex + baseOffset,
871	<	fromIndex, toIndex);
781	>	return new RandomAccessSubList<E>(this, fromIndex, toIndex);
782		}
783		}
874	–

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