jaroslav@1890: /*
jaroslav@1890:  * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
jaroslav@1890:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@1890:  *
jaroslav@1890:  * This code is free software; you can redistribute it and/or modify it
jaroslav@1890:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@1890:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@1890:  * particular file as subject to the "Classpath" exception as provided
jaroslav@1890:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@1890:  *
jaroslav@1890:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@1890:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@1890:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@1890:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@1890:  * accompanied this code).
jaroslav@1890:  *
jaroslav@1890:  * You should have received a copy of the GNU General Public License version
jaroslav@1890:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@1890:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@1890:  *
jaroslav@1890:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@1890:  * or visit www.oracle.com if you need additional information or have any
jaroslav@1890:  * questions.
jaroslav@1890:  */
jaroslav@1890: 
jaroslav@1890: /*
jaroslav@1890:  * Written by Doug Lea with assistance from members of JCP JSR-166
jaroslav@1890:  * Expert Group.  Adapted and released, under explicit permission,
jaroslav@1890:  * from JDK ArrayList.java which carries the following copyright:
jaroslav@1890:  *
jaroslav@1890:  * Copyright 1997 by Sun Microsystems, Inc.,
jaroslav@1890:  * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
jaroslav@1890:  * All rights reserved.
jaroslav@1890:  */
jaroslav@1890: 
jaroslav@1890: package java.util.concurrent;
jaroslav@1890: import java.util.*;
jaroslav@1890: import java.util.concurrent.locks.*;
jaroslav@1890: 
jaroslav@1890: /**
jaroslav@1890:  * A thread-safe variant of {@link java.util.ArrayList} in which all mutative
jaroslav@1890:  * operations (<tt>add</tt>, <tt>set</tt>, and so on) are implemented by
jaroslav@1890:  * making a fresh copy of the underlying array.
jaroslav@1890:  *
jaroslav@1890:  * <p> This is ordinarily too costly, but may be <em>more</em> efficient
jaroslav@1890:  * than alternatives when traversal operations vastly outnumber
jaroslav@1890:  * mutations, and is useful when you cannot or don't want to
jaroslav@1890:  * synchronize traversals, yet need to preclude interference among
jaroslav@1890:  * concurrent threads.  The "snapshot" style iterator method uses a
jaroslav@1890:  * reference to the state of the array at the point that the iterator
jaroslav@1890:  * was created. This array never changes during the lifetime of the
jaroslav@1890:  * iterator, so interference is impossible and the iterator is
jaroslav@1890:  * guaranteed not to throw <tt>ConcurrentModificationException</tt>.
jaroslav@1890:  * The iterator will not reflect additions, removals, or changes to
jaroslav@1890:  * the list since the iterator was created.  Element-changing
jaroslav@1890:  * operations on iterators themselves (<tt>remove</tt>, <tt>set</tt>, and
jaroslav@1890:  * <tt>add</tt>) are not supported. These methods throw
jaroslav@1890:  * <tt>UnsupportedOperationException</tt>.
jaroslav@1890:  *
jaroslav@1890:  * <p>All elements are permitted, including <tt>null</tt>.
jaroslav@1890:  *
jaroslav@1890:  * <p>Memory consistency effects: As with other concurrent
jaroslav@1890:  * collections, actions in a thread prior to placing an object into a
jaroslav@1890:  * {@code CopyOnWriteArrayList}
jaroslav@1890:  * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
jaroslav@1890:  * actions subsequent to the access or removal of that element from
jaroslav@1890:  * the {@code CopyOnWriteArrayList} in another thread.
jaroslav@1890:  *
jaroslav@1890:  * <p>This class is a member of the
jaroslav@1890:  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
jaroslav@1890:  * Java Collections Framework</a>.
jaroslav@1890:  *
jaroslav@1890:  * @since 1.5
jaroslav@1890:  * @author Doug Lea
jaroslav@1890:  * @param <E> the type of elements held in this collection
jaroslav@1890:  */
jaroslav@1890: public class CopyOnWriteArrayList<E>
jaroslav@1890:     implements List<E>, RandomAccess, Cloneable, java.io.Serializable {
jaroslav@1890:     private static final long serialVersionUID = 8673264195747942595L;
jaroslav@1890: 
jaroslav@1890:     /** The lock protecting all mutators */
jaroslav@1895:     transient ReentrantLock lock = new ReentrantLock();
jaroslav@1890: 
jaroslav@1890:     /** The array, accessed only via getArray/setArray. */
jaroslav@1890:     private volatile transient Object[] array;
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Gets the array.  Non-private so as to also be accessible
jaroslav@1890:      * from CopyOnWriteArraySet class.
jaroslav@1890:      */
jaroslav@1890:     final Object[] getArray() {
jaroslav@1890:         return array;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Sets the array.
jaroslav@1890:      */
jaroslav@1890:     final void setArray(Object[] a) {
jaroslav@1890:         array = a;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Creates an empty list.
jaroslav@1890:      */
jaroslav@1890:     public CopyOnWriteArrayList() {
jaroslav@1890:         setArray(new Object[0]);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Creates a list containing the elements of the specified
jaroslav@1890:      * collection, in the order they are returned by the collection's
jaroslav@1890:      * iterator.
jaroslav@1890:      *
jaroslav@1890:      * @param c the collection of initially held elements
jaroslav@1890:      * @throws NullPointerException if the specified collection is null
jaroslav@1890:      */
jaroslav@1890:     public CopyOnWriteArrayList(Collection<? extends E> c) {
jaroslav@1890:         Object[] elements = c.toArray();
jaroslav@1890:         // c.toArray might (incorrectly) not return Object[] (see 6260652)
jaroslav@1890:         if (elements.getClass() != Object[].class)
jaroslav@1890:             elements = Arrays.copyOf(elements, elements.length, Object[].class);
jaroslav@1890:         setArray(elements);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Creates a list holding a copy of the given array.
jaroslav@1890:      *
jaroslav@1890:      * @param toCopyIn the array (a copy of this array is used as the
jaroslav@1890:      *        internal array)
jaroslav@1890:      * @throws NullPointerException if the specified array is null
jaroslav@1890:      */
jaroslav@1890:     public CopyOnWriteArrayList(E[] toCopyIn) {
jaroslav@1890:         setArray(Arrays.copyOf(toCopyIn, toCopyIn.length, Object[].class));
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns the number of elements in this list.
jaroslav@1890:      *
jaroslav@1890:      * @return the number of elements in this list
jaroslav@1890:      */
jaroslav@1890:     public int size() {
jaroslav@1890:         return getArray().length;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns <tt>true</tt> if this list contains no elements.
jaroslav@1890:      *
jaroslav@1890:      * @return <tt>true</tt> if this list contains no elements
jaroslav@1890:      */
jaroslav@1890:     public boolean isEmpty() {
jaroslav@1890:         return size() == 0;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Test for equality, coping with nulls.
jaroslav@1890:      */
jaroslav@1890:     private static boolean eq(Object o1, Object o2) {
jaroslav@1890:         return (o1 == null ? o2 == null : o1.equals(o2));
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * static version of indexOf, to allow repeated calls without
jaroslav@1890:      * needing to re-acquire array each time.
jaroslav@1890:      * @param o element to search for
jaroslav@1890:      * @param elements the array
jaroslav@1890:      * @param index first index to search
jaroslav@1890:      * @param fence one past last index to search
jaroslav@1890:      * @return index of element, or -1 if absent
jaroslav@1890:      */
jaroslav@1890:     private static int indexOf(Object o, Object[] elements,
jaroslav@1890:                                int index, int fence) {
jaroslav@1890:         if (o == null) {
jaroslav@1890:             for (int i = index; i < fence; i++)
jaroslav@1890:                 if (elements[i] == null)
jaroslav@1890:                     return i;
jaroslav@1890:         } else {
jaroslav@1890:             for (int i = index; i < fence; i++)
jaroslav@1890:                 if (o.equals(elements[i]))
jaroslav@1890:                     return i;
jaroslav@1890:         }
jaroslav@1890:         return -1;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * static version of lastIndexOf.
jaroslav@1890:      * @param o element to search for
jaroslav@1890:      * @param elements the array
jaroslav@1890:      * @param index first index to search
jaroslav@1890:      * @return index of element, or -1 if absent
jaroslav@1890:      */
jaroslav@1890:     private static int lastIndexOf(Object o, Object[] elements, int index) {
jaroslav@1890:         if (o == null) {
jaroslav@1890:             for (int i = index; i >= 0; i--)
jaroslav@1890:                 if (elements[i] == null)
jaroslav@1890:                     return i;
jaroslav@1890:         } else {
jaroslav@1890:             for (int i = index; i >= 0; i--)
jaroslav@1890:                 if (o.equals(elements[i]))
jaroslav@1890:                     return i;
jaroslav@1890:         }
jaroslav@1890:         return -1;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns <tt>true</tt> if this list contains the specified element.
jaroslav@1890:      * More formally, returns <tt>true</tt> if and only if this list contains
jaroslav@1890:      * at least one element <tt>e</tt> such that
jaroslav@1890:      * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
jaroslav@1890:      *
jaroslav@1890:      * @param o element whose presence in this list is to be tested
jaroslav@1890:      * @return <tt>true</tt> if this list contains the specified element
jaroslav@1890:      */
jaroslav@1890:     public boolean contains(Object o) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         return indexOf(o, elements, 0, elements.length) >= 0;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public int indexOf(Object o) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         return indexOf(o, elements, 0, elements.length);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns the index of the first occurrence of the specified element in
jaroslav@1890:      * this list, searching forwards from <tt>index</tt>, or returns -1 if
jaroslav@1890:      * the element is not found.
jaroslav@1890:      * More formally, returns the lowest index <tt>i</tt> such that
jaroslav@1890:      * <tt>(i&nbsp;&gt;=&nbsp;index&nbsp;&amp;&amp;&nbsp;(e==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;e.equals(get(i))))</tt>,
jaroslav@1890:      * or -1 if there is no such index.
jaroslav@1890:      *
jaroslav@1890:      * @param e element to search for
jaroslav@1890:      * @param index index to start searching from
jaroslav@1890:      * @return the index of the first occurrence of the element in
jaroslav@1890:      *         this list at position <tt>index</tt> or later in the list;
jaroslav@1890:      *         <tt>-1</tt> if the element is not found.
jaroslav@1890:      * @throws IndexOutOfBoundsException if the specified index is negative
jaroslav@1890:      */
jaroslav@1890:     public int indexOf(E e, int index) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         return indexOf(e, elements, index, elements.length);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public int lastIndexOf(Object o) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         return lastIndexOf(o, elements, elements.length - 1);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns the index of the last occurrence of the specified element in
jaroslav@1890:      * this list, searching backwards from <tt>index</tt>, or returns -1 if
jaroslav@1890:      * the element is not found.
jaroslav@1890:      * More formally, returns the highest index <tt>i</tt> such that
jaroslav@1890:      * <tt>(i&nbsp;&lt;=&nbsp;index&nbsp;&amp;&amp;&nbsp;(e==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;e.equals(get(i))))</tt>,
jaroslav@1890:      * or -1 if there is no such index.
jaroslav@1890:      *
jaroslav@1890:      * @param e element to search for
jaroslav@1890:      * @param index index to start searching backwards from
jaroslav@1890:      * @return the index of the last occurrence of the element at position
jaroslav@1890:      *         less than or equal to <tt>index</tt> in this list;
jaroslav@1890:      *         -1 if the element is not found.
jaroslav@1890:      * @throws IndexOutOfBoundsException if the specified index is greater
jaroslav@1890:      *         than or equal to the current size of this list
jaroslav@1890:      */
jaroslav@1890:     public int lastIndexOf(E e, int index) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         return lastIndexOf(e, elements, index);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns a shallow copy of this list.  (The elements themselves
jaroslav@1890:      * are not copied.)
jaroslav@1890:      *
jaroslav@1890:      * @return a clone of this list
jaroslav@1890:      */
jaroslav@1890:     public Object clone() {
jaroslav@1890:         try {
jaroslav@1890:             CopyOnWriteArrayList c = (CopyOnWriteArrayList)(super.clone());
jaroslav@1890:             c.resetLock();
jaroslav@1890:             return c;
jaroslav@1890:         } catch (CloneNotSupportedException e) {
jaroslav@1890:             // this shouldn't happen, since we are Cloneable
jaroslav@1890:             throw new InternalError();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns an array containing all of the elements in this list
jaroslav@1890:      * in proper sequence (from first to last element).
jaroslav@1890:      *
jaroslav@1890:      * <p>The returned array will be "safe" in that no references to it are
jaroslav@1890:      * maintained by this list.  (In other words, this method must allocate
jaroslav@1890:      * a new array).  The caller is thus free to modify the returned array.
jaroslav@1890:      *
jaroslav@1890:      * <p>This method acts as bridge between array-based and collection-based
jaroslav@1890:      * APIs.
jaroslav@1890:      *
jaroslav@1890:      * @return an array containing all the elements in this list
jaroslav@1890:      */
jaroslav@1890:     public Object[] toArray() {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         return Arrays.copyOf(elements, elements.length);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns an array containing all of the elements in this list in
jaroslav@1890:      * proper sequence (from first to last element); the runtime type of
jaroslav@1890:      * the returned array is that of the specified array.  If the list fits
jaroslav@1890:      * in the specified array, it is returned therein.  Otherwise, a new
jaroslav@1890:      * array is allocated with the runtime type of the specified array and
jaroslav@1890:      * the size of this list.
jaroslav@1890:      *
jaroslav@1890:      * <p>If this list fits in the specified array with room to spare
jaroslav@1890:      * (i.e., the array has more elements than this list), the element in
jaroslav@1890:      * the array immediately following the end of the list is set to
jaroslav@1890:      * <tt>null</tt>.  (This is useful in determining the length of this
jaroslav@1890:      * list <i>only</i> if the caller knows that this list does not contain
jaroslav@1890:      * any null elements.)
jaroslav@1890:      *
jaroslav@1890:      * <p>Like the {@link #toArray()} method, this method acts as bridge between
jaroslav@1890:      * array-based and collection-based APIs.  Further, this method allows
jaroslav@1890:      * precise control over the runtime type of the output array, and may,
jaroslav@1890:      * under certain circumstances, be used to save allocation costs.
jaroslav@1890:      *
jaroslav@1890:      * <p>Suppose <tt>x</tt> is a list known to contain only strings.
jaroslav@1890:      * The following code can be used to dump the list into a newly
jaroslav@1890:      * allocated array of <tt>String</tt>:
jaroslav@1890:      *
jaroslav@1890:      * <pre>
jaroslav@1890:      *     String[] y = x.toArray(new String[0]);</pre>
jaroslav@1890:      *
jaroslav@1890:      * Note that <tt>toArray(new Object[0])</tt> is identical in function to
jaroslav@1890:      * <tt>toArray()</tt>.
jaroslav@1890:      *
jaroslav@1890:      * @param a the array into which the elements of the list are to
jaroslav@1890:      *          be stored, if it is big enough; otherwise, a new array of the
jaroslav@1890:      *          same runtime type is allocated for this purpose.
jaroslav@1890:      * @return an array containing all the elements in this list
jaroslav@1890:      * @throws ArrayStoreException if the runtime type of the specified array
jaroslav@1890:      *         is not a supertype of the runtime type of every element in
jaroslav@1890:      *         this list
jaroslav@1890:      * @throws NullPointerException if the specified array is null
jaroslav@1890:      */
jaroslav@1890:     @SuppressWarnings("unchecked")
jaroslav@1890:     public <T> T[] toArray(T a[]) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         int len = elements.length;
jaroslav@1890:         if (a.length < len)
jaroslav@1890:             return (T[]) Arrays.copyOf(elements, len, a.getClass());
jaroslav@1890:         else {
jaroslav@1890:             System.arraycopy(elements, 0, a, 0, len);
jaroslav@1890:             if (a.length > len)
jaroslav@1890:                 a[len] = null;
jaroslav@1890:             return a;
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     // Positional Access Operations
jaroslav@1890: 
jaroslav@1890:     @SuppressWarnings("unchecked")
jaroslav@1890:     private E get(Object[] a, int index) {
jaroslav@1890:         return (E) a[index];
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * {@inheritDoc}
jaroslav@1890:      *
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public E get(int index) {
jaroslav@1890:         return get(getArray(), index);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Replaces the element at the specified position in this list with the
jaroslav@1890:      * specified element.
jaroslav@1890:      *
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public E set(int index, E element) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             E oldValue = get(elements, index);
jaroslav@1890: 
jaroslav@1890:             if (oldValue != element) {
jaroslav@1890:                 int len = elements.length;
jaroslav@1890:                 Object[] newElements = Arrays.copyOf(elements, len);
jaroslav@1890:                 newElements[index] = element;
jaroslav@1890:                 setArray(newElements);
jaroslav@1890:             } else {
jaroslav@1890:                 // Not quite a no-op; ensures volatile write semantics
jaroslav@1890:                 setArray(elements);
jaroslav@1890:             }
jaroslav@1890:             return oldValue;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Appends the specified element to the end of this list.
jaroslav@1890:      *
jaroslav@1890:      * @param e element to be appended to this list
jaroslav@1890:      * @return <tt>true</tt> (as specified by {@link Collection#add})
jaroslav@1890:      */
jaroslav@1890:     public boolean add(E e) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             Object[] newElements = Arrays.copyOf(elements, len + 1);
jaroslav@1890:             newElements[len] = e;
jaroslav@1890:             setArray(newElements);
jaroslav@1890:             return true;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Inserts the specified element at the specified position in this
jaroslav@1890:      * list. Shifts the element currently at that position (if any) and
jaroslav@1890:      * any subsequent elements to the right (adds one to their indices).
jaroslav@1890:      *
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public void add(int index, E element) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             if (index > len || index < 0)
jaroslav@1890:                 throw new IndexOutOfBoundsException("Index: "+index+
jaroslav@1890:                                                     ", Size: "+len);
jaroslav@1890:             Object[] newElements;
jaroslav@1890:             int numMoved = len - index;
jaroslav@1890:             if (numMoved == 0)
jaroslav@1890:                 newElements = Arrays.copyOf(elements, len + 1);
jaroslav@1890:             else {
jaroslav@1890:                 newElements = new Object[len + 1];
jaroslav@1890:                 System.arraycopy(elements, 0, newElements, 0, index);
jaroslav@1890:                 System.arraycopy(elements, index, newElements, index + 1,
jaroslav@1890:                                  numMoved);
jaroslav@1890:             }
jaroslav@1890:             newElements[index] = element;
jaroslav@1890:             setArray(newElements);
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Removes the element at the specified position in this list.
jaroslav@1890:      * Shifts any subsequent elements to the left (subtracts one from their
jaroslav@1890:      * indices).  Returns the element that was removed from the list.
jaroslav@1890:      *
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public E remove(int index) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             E oldValue = get(elements, index);
jaroslav@1890:             int numMoved = len - index - 1;
jaroslav@1890:             if (numMoved == 0)
jaroslav@1890:                 setArray(Arrays.copyOf(elements, len - 1));
jaroslav@1890:             else {
jaroslav@1890:                 Object[] newElements = new Object[len - 1];
jaroslav@1890:                 System.arraycopy(elements, 0, newElements, 0, index);
jaroslav@1890:                 System.arraycopy(elements, index + 1, newElements, index,
jaroslav@1890:                                  numMoved);
jaroslav@1890:                 setArray(newElements);
jaroslav@1890:             }
jaroslav@1890:             return oldValue;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Removes the first occurrence of the specified element from this list,
jaroslav@1890:      * if it is present.  If this list does not contain the element, it is
jaroslav@1890:      * unchanged.  More formally, removes the element with the lowest index
jaroslav@1890:      * <tt>i</tt> such that
jaroslav@1890:      * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>
jaroslav@1890:      * (if such an element exists).  Returns <tt>true</tt> if this list
jaroslav@1890:      * contained the specified element (or equivalently, if this list
jaroslav@1890:      * changed as a result of the call).
jaroslav@1890:      *
jaroslav@1890:      * @param o element to be removed from this list, if present
jaroslav@1890:      * @return <tt>true</tt> if this list contained the specified element
jaroslav@1890:      */
jaroslav@1890:     public boolean remove(Object o) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             if (len != 0) {
jaroslav@1890:                 // Copy while searching for element to remove
jaroslav@1890:                 // This wins in the normal case of element being present
jaroslav@1890:                 int newlen = len - 1;
jaroslav@1890:                 Object[] newElements = new Object[newlen];
jaroslav@1890: 
jaroslav@1890:                 for (int i = 0; i < newlen; ++i) {
jaroslav@1890:                     if (eq(o, elements[i])) {
jaroslav@1890:                         // found one;  copy remaining and exit
jaroslav@1890:                         for (int k = i + 1; k < len; ++k)
jaroslav@1890:                             newElements[k-1] = elements[k];
jaroslav@1890:                         setArray(newElements);
jaroslav@1890:                         return true;
jaroslav@1890:                     } else
jaroslav@1890:                         newElements[i] = elements[i];
jaroslav@1890:                 }
jaroslav@1890: 
jaroslav@1890:                 // special handling for last cell
jaroslav@1890:                 if (eq(o, elements[newlen])) {
jaroslav@1890:                     setArray(newElements);
jaroslav@1890:                     return true;
jaroslav@1890:                 }
jaroslav@1890:             }
jaroslav@1890:             return false;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Removes from this list all of the elements whose index is between
jaroslav@1890:      * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
jaroslav@1890:      * Shifts any succeeding elements to the left (reduces their index).
jaroslav@1890:      * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
jaroslav@1890:      * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
jaroslav@1890:      *
jaroslav@1890:      * @param fromIndex index of first element to be removed
jaroslav@1890:      * @param toIndex index after last element to be removed
jaroslav@1890:      * @throws IndexOutOfBoundsException if fromIndex or toIndex out of range
jaroslav@1890:      *         ({@code{fromIndex < 0 || toIndex > size() || toIndex < fromIndex})
jaroslav@1890:      */
jaroslav@1890:     private void removeRange(int fromIndex, int toIndex) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890: 
jaroslav@1890:             if (fromIndex < 0 || toIndex > len || toIndex < fromIndex)
jaroslav@1890:                 throw new IndexOutOfBoundsException();
jaroslav@1890:             int newlen = len - (toIndex - fromIndex);
jaroslav@1890:             int numMoved = len - toIndex;
jaroslav@1890:             if (numMoved == 0)
jaroslav@1890:                 setArray(Arrays.copyOf(elements, newlen));
jaroslav@1890:             else {
jaroslav@1890:                 Object[] newElements = new Object[newlen];
jaroslav@1890:                 System.arraycopy(elements, 0, newElements, 0, fromIndex);
jaroslav@1890:                 System.arraycopy(elements, toIndex, newElements,
jaroslav@1890:                                  fromIndex, numMoved);
jaroslav@1890:                 setArray(newElements);
jaroslav@1890:             }
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Append the element if not present.
jaroslav@1890:      *
jaroslav@1890:      * @param e element to be added to this list, if absent
jaroslav@1890:      * @return <tt>true</tt> if the element was added
jaroslav@1890:      */
jaroslav@1890:     public boolean addIfAbsent(E e) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             // Copy while checking if already present.
jaroslav@1890:             // This wins in the most common case where it is not present
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             Object[] newElements = new Object[len + 1];
jaroslav@1890:             for (int i = 0; i < len; ++i) {
jaroslav@1890:                 if (eq(e, elements[i]))
jaroslav@1890:                     return false; // exit, throwing away copy
jaroslav@1890:                 else
jaroslav@1890:                     newElements[i] = elements[i];
jaroslav@1890:             }
jaroslav@1890:             newElements[len] = e;
jaroslav@1890:             setArray(newElements);
jaroslav@1890:             return true;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns <tt>true</tt> if this list contains all of the elements of the
jaroslav@1890:      * specified collection.
jaroslav@1890:      *
jaroslav@1890:      * @param c collection to be checked for containment in this list
jaroslav@1890:      * @return <tt>true</tt> if this list contains all of the elements of the
jaroslav@1890:      *         specified collection
jaroslav@1890:      * @throws NullPointerException if the specified collection is null
jaroslav@1890:      * @see #contains(Object)
jaroslav@1890:      */
jaroslav@1890:     public boolean containsAll(Collection<?> c) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         int len = elements.length;
jaroslav@1890:         for (Object e : c) {
jaroslav@1890:             if (indexOf(e, elements, 0, len) < 0)
jaroslav@1890:                 return false;
jaroslav@1890:         }
jaroslav@1890:         return true;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Removes from this list all of its elements that are contained in
jaroslav@1890:      * the specified collection. This is a particularly expensive operation
jaroslav@1890:      * in this class because of the need for an internal temporary array.
jaroslav@1890:      *
jaroslav@1890:      * @param c collection containing elements to be removed from this list
jaroslav@1890:      * @return <tt>true</tt> if this list changed as a result of the call
jaroslav@1890:      * @throws ClassCastException if the class of an element of this list
jaroslav@1890:      *         is incompatible with the specified collection
jaroslav@1890:      *         (<a href="../Collection.html#optional-restrictions">optional</a>)
jaroslav@1890:      * @throws NullPointerException if this list contains a null element and the
jaroslav@1890:      *         specified collection does not permit null elements
jaroslav@1890:      *         (<a href="../Collection.html#optional-restrictions">optional</a>),
jaroslav@1890:      *         or if the specified collection is null
jaroslav@1890:      * @see #remove(Object)
jaroslav@1890:      */
jaroslav@1890:     public boolean removeAll(Collection<?> c) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             if (len != 0) {
jaroslav@1890:                 // temp array holds those elements we know we want to keep
jaroslav@1890:                 int newlen = 0;
jaroslav@1890:                 Object[] temp = new Object[len];
jaroslav@1890:                 for (int i = 0; i < len; ++i) {
jaroslav@1890:                     Object element = elements[i];
jaroslav@1890:                     if (!c.contains(element))
jaroslav@1890:                         temp[newlen++] = element;
jaroslav@1890:                 }
jaroslav@1890:                 if (newlen != len) {
jaroslav@1890:                     setArray(Arrays.copyOf(temp, newlen));
jaroslav@1890:                     return true;
jaroslav@1890:                 }
jaroslav@1890:             }
jaroslav@1890:             return false;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Retains only the elements in this list that are contained in the
jaroslav@1890:      * specified collection.  In other words, removes from this list all of
jaroslav@1890:      * its elements that are not contained in the specified collection.
jaroslav@1890:      *
jaroslav@1890:      * @param c collection containing elements to be retained in this list
jaroslav@1890:      * @return <tt>true</tt> if this list changed as a result of the call
jaroslav@1890:      * @throws ClassCastException if the class of an element of this list
jaroslav@1890:      *         is incompatible with the specified collection
jaroslav@1890:      *         (<a href="../Collection.html#optional-restrictions">optional</a>)
jaroslav@1890:      * @throws NullPointerException if this list contains a null element and the
jaroslav@1890:      *         specified collection does not permit null elements
jaroslav@1890:      *         (<a href="../Collection.html#optional-restrictions">optional</a>),
jaroslav@1890:      *         or if the specified collection is null
jaroslav@1890:      * @see #remove(Object)
jaroslav@1890:      */
jaroslav@1890:     public boolean retainAll(Collection<?> c) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             if (len != 0) {
jaroslav@1890:                 // temp array holds those elements we know we want to keep
jaroslav@1890:                 int newlen = 0;
jaroslav@1890:                 Object[] temp = new Object[len];
jaroslav@1890:                 for (int i = 0; i < len; ++i) {
jaroslav@1890:                     Object element = elements[i];
jaroslav@1890:                     if (c.contains(element))
jaroslav@1890:                         temp[newlen++] = element;
jaroslav@1890:                 }
jaroslav@1890:                 if (newlen != len) {
jaroslav@1890:                     setArray(Arrays.copyOf(temp, newlen));
jaroslav@1890:                     return true;
jaroslav@1890:                 }
jaroslav@1890:             }
jaroslav@1890:             return false;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Appends all of the elements in the specified collection that
jaroslav@1890:      * are not already contained in this list, to the end of
jaroslav@1890:      * this list, in the order that they are returned by the
jaroslav@1890:      * specified collection's iterator.
jaroslav@1890:      *
jaroslav@1890:      * @param c collection containing elements to be added to this list
jaroslav@1890:      * @return the number of elements added
jaroslav@1890:      * @throws NullPointerException if the specified collection is null
jaroslav@1890:      * @see #addIfAbsent(Object)
jaroslav@1890:      */
jaroslav@1890:     public int addAllAbsent(Collection<? extends E> c) {
jaroslav@1890:         Object[] cs = c.toArray();
jaroslav@1890:         if (cs.length == 0)
jaroslav@1890:             return 0;
jaroslav@1890:         Object[] uniq = new Object[cs.length];
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             int added = 0;
jaroslav@1890:             for (int i = 0; i < cs.length; ++i) { // scan for duplicates
jaroslav@1890:                 Object e = cs[i];
jaroslav@1890:                 if (indexOf(e, elements, 0, len) < 0 &&
jaroslav@1890:                     indexOf(e, uniq, 0, added) < 0)
jaroslav@1890:                     uniq[added++] = e;
jaroslav@1890:             }
jaroslav@1890:             if (added > 0) {
jaroslav@1890:                 Object[] newElements = Arrays.copyOf(elements, len + added);
jaroslav@1890:                 System.arraycopy(uniq, 0, newElements, len, added);
jaroslav@1890:                 setArray(newElements);
jaroslav@1890:             }
jaroslav@1890:             return added;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Removes all of the elements from this list.
jaroslav@1890:      * The list will be empty after this call returns.
jaroslav@1890:      */
jaroslav@1890:     public void clear() {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             setArray(new Object[0]);
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Appends all of the elements in the specified collection to the end
jaroslav@1890:      * of this list, in the order that they are returned by the specified
jaroslav@1890:      * collection's iterator.
jaroslav@1890:      *
jaroslav@1890:      * @param c collection containing elements to be added to this list
jaroslav@1890:      * @return <tt>true</tt> if this list changed as a result of the call
jaroslav@1890:      * @throws NullPointerException if the specified collection is null
jaroslav@1890:      * @see #add(Object)
jaroslav@1890:      */
jaroslav@1890:     public boolean addAll(Collection<? extends E> c) {
jaroslav@1890:         Object[] cs = c.toArray();
jaroslav@1890:         if (cs.length == 0)
jaroslav@1890:             return false;
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             Object[] newElements = Arrays.copyOf(elements, len + cs.length);
jaroslav@1890:             System.arraycopy(cs, 0, newElements, len, cs.length);
jaroslav@1890:             setArray(newElements);
jaroslav@1890:             return true;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Inserts all of the elements in the specified collection into this
jaroslav@1890:      * list, starting at the specified position.  Shifts the element
jaroslav@1890:      * currently at that position (if any) and any subsequent elements to
jaroslav@1890:      * the right (increases their indices).  The new elements will appear
jaroslav@1890:      * in this list in the order that they are returned by the
jaroslav@1890:      * specified collection's iterator.
jaroslav@1890:      *
jaroslav@1890:      * @param index index at which to insert the first element
jaroslav@1890:      *        from the specified collection
jaroslav@1890:      * @param c collection containing elements to be added to this list
jaroslav@1890:      * @return <tt>true</tt> if this list changed as a result of the call
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      * @throws NullPointerException if the specified collection is null
jaroslav@1890:      * @see #add(int,Object)
jaroslav@1890:      */
jaroslav@1890:     public boolean addAll(int index, Collection<? extends E> c) {
jaroslav@1890:         Object[] cs = c.toArray();
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             if (index > len || index < 0)
jaroslav@1890:                 throw new IndexOutOfBoundsException("Index: "+index+
jaroslav@1890:                                                     ", Size: "+len);
jaroslav@1890:             if (cs.length == 0)
jaroslav@1890:                 return false;
jaroslav@1890:             int numMoved = len - index;
jaroslav@1890:             Object[] newElements;
jaroslav@1890:             if (numMoved == 0)
jaroslav@1890:                 newElements = Arrays.copyOf(elements, len + cs.length);
jaroslav@1890:             else {
jaroslav@1890:                 newElements = new Object[len + cs.length];
jaroslav@1890:                 System.arraycopy(elements, 0, newElements, 0, index);
jaroslav@1890:                 System.arraycopy(elements, index,
jaroslav@1890:                                  newElements, index + cs.length,
jaroslav@1890:                                  numMoved);
jaroslav@1890:             }
jaroslav@1890:             System.arraycopy(cs, 0, newElements, index, cs.length);
jaroslav@1890:             setArray(newElements);
jaroslav@1890:             return true;
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Saves the state of the list to a stream (that is, serializes it).
jaroslav@1890:      *
jaroslav@1890:      * @serialData The length of the array backing the list is emitted
jaroslav@1890:      *               (int), followed by all of its elements (each an Object)
jaroslav@1890:      *               in the proper order.
jaroslav@1890:      * @param s the stream
jaroslav@1890:      */
jaroslav@1890:     private void writeObject(java.io.ObjectOutputStream s)
jaroslav@1890:         throws java.io.IOException{
jaroslav@1890: 
jaroslav@1890:         s.defaultWriteObject();
jaroslav@1890: 
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         // Write out array length
jaroslav@1890:         s.writeInt(elements.length);
jaroslav@1890: 
jaroslav@1890:         // Write out all elements in the proper order.
jaroslav@1890:         for (Object element : elements)
jaroslav@1890:             s.writeObject(element);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Reconstitutes the list from a stream (that is, deserializes it).
jaroslav@1890:      *
jaroslav@1890:      * @param s the stream
jaroslav@1890:      */
jaroslav@1890:     private void readObject(java.io.ObjectInputStream s)
jaroslav@1890:         throws java.io.IOException, ClassNotFoundException {
jaroslav@1890: 
jaroslav@1890:         s.defaultReadObject();
jaroslav@1890: 
jaroslav@1890:         // bind to new lock
jaroslav@1890:         resetLock();
jaroslav@1890: 
jaroslav@1890:         // Read in array length and allocate array
jaroslav@1890:         int len = s.readInt();
jaroslav@1890:         Object[] elements = new Object[len];
jaroslav@1890: 
jaroslav@1890:         // Read in all elements in the proper order.
jaroslav@1890:         for (int i = 0; i < len; i++)
jaroslav@1890:             elements[i] = s.readObject();
jaroslav@1890:         setArray(elements);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns a string representation of this list.  The string
jaroslav@1890:      * representation consists of the string representations of the list's
jaroslav@1890:      * elements in the order they are returned by its iterator, enclosed in
jaroslav@1890:      * square brackets (<tt>"[]"</tt>).  Adjacent elements are separated by
jaroslav@1890:      * the characters <tt>", "</tt> (comma and space).  Elements are
jaroslav@1890:      * converted to strings as by {@link String#valueOf(Object)}.
jaroslav@1890:      *
jaroslav@1890:      * @return a string representation of this list
jaroslav@1890:      */
jaroslav@1890:     public String toString() {
jaroslav@1890:         return Arrays.toString(getArray());
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Compares the specified object with this list for equality.
jaroslav@1890:      * Returns {@code true} if the specified object is the same object
jaroslav@1890:      * as this object, or if it is also a {@link List} and the sequence
jaroslav@1890:      * of elements returned by an {@linkplain List#iterator() iterator}
jaroslav@1890:      * over the specified list is the same as the sequence returned by
jaroslav@1890:      * an iterator over this list.  The two sequences are considered to
jaroslav@1890:      * be the same if they have the same length and corresponding
jaroslav@1890:      * elements at the same position in the sequence are <em>equal</em>.
jaroslav@1890:      * Two elements {@code e1} and {@code e2} are considered
jaroslav@1890:      * <em>equal</em> if {@code (e1==null ? e2==null : e1.equals(e2))}.
jaroslav@1890:      *
jaroslav@1890:      * @param o the object to be compared for equality with this list
jaroslav@1890:      * @return {@code true} if the specified object is equal to this list
jaroslav@1890:      */
jaroslav@1890:     public boolean equals(Object o) {
jaroslav@1890:         if (o == this)
jaroslav@1890:             return true;
jaroslav@1890:         if (!(o instanceof List))
jaroslav@1890:             return false;
jaroslav@1890: 
jaroslav@1890:         List<?> list = (List<?>)(o);
jaroslav@1890:         Iterator<?> it = list.iterator();
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         int len = elements.length;
jaroslav@1890:         for (int i = 0; i < len; ++i)
jaroslav@1890:             if (!it.hasNext() || !eq(elements[i], it.next()))
jaroslav@1890:                 return false;
jaroslav@1890:         if (it.hasNext())
jaroslav@1890:             return false;
jaroslav@1890:         return true;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns the hash code value for this list.
jaroslav@1890:      *
jaroslav@1890:      * <p>This implementation uses the definition in {@link List#hashCode}.
jaroslav@1890:      *
jaroslav@1890:      * @return the hash code value for this list
jaroslav@1890:      */
jaroslav@1890:     public int hashCode() {
jaroslav@1890:         int hashCode = 1;
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         int len = elements.length;
jaroslav@1890:         for (int i = 0; i < len; ++i) {
jaroslav@1890:             Object obj = elements[i];
jaroslav@1890:             hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());
jaroslav@1890:         }
jaroslav@1890:         return hashCode;
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns an iterator over the elements in this list in proper sequence.
jaroslav@1890:      *
jaroslav@1890:      * <p>The returned iterator provides a snapshot of the state of the list
jaroslav@1890:      * when the iterator was constructed. No synchronization is needed while
jaroslav@1890:      * traversing the iterator. The iterator does <em>NOT</em> support the
jaroslav@1890:      * <tt>remove</tt> method.
jaroslav@1890:      *
jaroslav@1890:      * @return an iterator over the elements in this list in proper sequence
jaroslav@1890:      */
jaroslav@1890:     public Iterator<E> iterator() {
jaroslav@1890:         return new COWIterator<E>(getArray(), 0);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * {@inheritDoc}
jaroslav@1890:      *
jaroslav@1890:      * <p>The returned iterator provides a snapshot of the state of the list
jaroslav@1890:      * when the iterator was constructed. No synchronization is needed while
jaroslav@1890:      * traversing the iterator. The iterator does <em>NOT</em> support the
jaroslav@1890:      * <tt>remove</tt>, <tt>set</tt> or <tt>add</tt> methods.
jaroslav@1890:      */
jaroslav@1890:     public ListIterator<E> listIterator() {
jaroslav@1890:         return new COWIterator<E>(getArray(), 0);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * {@inheritDoc}
jaroslav@1890:      *
jaroslav@1890:      * <p>The returned iterator provides a snapshot of the state of the list
jaroslav@1890:      * when the iterator was constructed. No synchronization is needed while
jaroslav@1890:      * traversing the iterator. The iterator does <em>NOT</em> support the
jaroslav@1890:      * <tt>remove</tt>, <tt>set</tt> or <tt>add</tt> methods.
jaroslav@1890:      *
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public ListIterator<E> listIterator(final int index) {
jaroslav@1890:         Object[] elements = getArray();
jaroslav@1890:         int len = elements.length;
jaroslav@1890:         if (index<0 || index>len)
jaroslav@1890:             throw new IndexOutOfBoundsException("Index: "+index);
jaroslav@1890: 
jaroslav@1890:         return new COWIterator<E>(elements, index);
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     private static class COWIterator<E> implements ListIterator<E> {
jaroslav@1890:         /** Snapshot of the array */
jaroslav@1890:         private final Object[] snapshot;
jaroslav@1890:         /** Index of element to be returned by subsequent call to next.  */
jaroslav@1890:         private int cursor;
jaroslav@1890: 
jaroslav@1890:         private COWIterator(Object[] elements, int initialCursor) {
jaroslav@1890:             cursor = initialCursor;
jaroslav@1890:             snapshot = elements;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public boolean hasNext() {
jaroslav@1890:             return cursor < snapshot.length;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public boolean hasPrevious() {
jaroslav@1890:             return cursor > 0;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         @SuppressWarnings("unchecked")
jaroslav@1890:         public E next() {
jaroslav@1890:             if (! hasNext())
jaroslav@1890:                 throw new NoSuchElementException();
jaroslav@1890:             return (E) snapshot[cursor++];
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         @SuppressWarnings("unchecked")
jaroslav@1890:         public E previous() {
jaroslav@1890:             if (! hasPrevious())
jaroslav@1890:                 throw new NoSuchElementException();
jaroslav@1890:             return (E) snapshot[--cursor];
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public int nextIndex() {
jaroslav@1890:             return cursor;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public int previousIndex() {
jaroslav@1890:             return cursor-1;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         /**
jaroslav@1890:          * Not supported. Always throws UnsupportedOperationException.
jaroslav@1890:          * @throws UnsupportedOperationException always; <tt>remove</tt>
jaroslav@1890:          *         is not supported by this iterator.
jaroslav@1890:          */
jaroslav@1890:         public void remove() {
jaroslav@1890:             throw new UnsupportedOperationException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         /**
jaroslav@1890:          * Not supported. Always throws UnsupportedOperationException.
jaroslav@1890:          * @throws UnsupportedOperationException always; <tt>set</tt>
jaroslav@1890:          *         is not supported by this iterator.
jaroslav@1890:          */
jaroslav@1890:         public void set(E e) {
jaroslav@1890:             throw new UnsupportedOperationException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         /**
jaroslav@1890:          * Not supported. Always throws UnsupportedOperationException.
jaroslav@1890:          * @throws UnsupportedOperationException always; <tt>add</tt>
jaroslav@1890:          *         is not supported by this iterator.
jaroslav@1890:          */
jaroslav@1890:         public void add(E e) {
jaroslav@1890:             throw new UnsupportedOperationException();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Returns a view of the portion of this list between
jaroslav@1890:      * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
jaroslav@1890:      * The returned list is backed by this list, so changes in the
jaroslav@1890:      * returned list are reflected in this list.
jaroslav@1890:      *
jaroslav@1890:      * <p>The semantics of the list returned by this method become
jaroslav@1890:      * undefined if the backing list (i.e., this list) is modified in
jaroslav@1890:      * any way other than via the returned list.
jaroslav@1890:      *
jaroslav@1890:      * @param fromIndex low endpoint (inclusive) of the subList
jaroslav@1890:      * @param toIndex high endpoint (exclusive) of the subList
jaroslav@1890:      * @return a view of the specified range within this list
jaroslav@1890:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@1890:      */
jaroslav@1890:     public List<E> subList(int fromIndex, int toIndex) {
jaroslav@1890:         final ReentrantLock lock = this.lock;
jaroslav@1890:         lock.lock();
jaroslav@1890:         try {
jaroslav@1890:             Object[] elements = getArray();
jaroslav@1890:             int len = elements.length;
jaroslav@1890:             if (fromIndex < 0 || toIndex > len || fromIndex > toIndex)
jaroslav@1890:                 throw new IndexOutOfBoundsException();
jaroslav@1890:             return new COWSubList<E>(this, fromIndex, toIndex);
jaroslav@1890:         } finally {
jaroslav@1890:             lock.unlock();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     /**
jaroslav@1890:      * Sublist for CopyOnWriteArrayList.
jaroslav@1890:      * This class extends AbstractList merely for convenience, to
jaroslav@1890:      * avoid having to define addAll, etc. This doesn't hurt, but
jaroslav@1890:      * is wasteful.  This class does not need or use modCount
jaroslav@1890:      * mechanics in AbstractList, but does need to check for
jaroslav@1890:      * concurrent modification using similar mechanics.  On each
jaroslav@1890:      * operation, the array that we expect the backing list to use
jaroslav@1890:      * is checked and updated.  Since we do this for all of the
jaroslav@1890:      * base operations invoked by those defined in AbstractList,
jaroslav@1890:      * all is well.  While inefficient, this is not worth
jaroslav@1890:      * improving.  The kinds of list operations inherited from
jaroslav@1890:      * AbstractList are already so slow on COW sublists that
jaroslav@1890:      * adding a bit more space/time doesn't seem even noticeable.
jaroslav@1890:      */
jaroslav@1890:     private static class COWSubList<E>
jaroslav@1890:         extends AbstractList<E>
jaroslav@1890:         implements RandomAccess
jaroslav@1890:     {
jaroslav@1890:         private final CopyOnWriteArrayList<E> l;
jaroslav@1890:         private final int offset;
jaroslav@1890:         private int size;
jaroslav@1890:         private Object[] expectedArray;
jaroslav@1890: 
jaroslav@1890:         // only call this holding l's lock
jaroslav@1890:         COWSubList(CopyOnWriteArrayList<E> list,
jaroslav@1890:                    int fromIndex, int toIndex) {
jaroslav@1890:             l = list;
jaroslav@1890:             expectedArray = l.getArray();
jaroslav@1890:             offset = fromIndex;
jaroslav@1890:             size = toIndex - fromIndex;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         // only call this holding l's lock
jaroslav@1890:         private void checkForComodification() {
jaroslav@1890:             if (l.getArray() != expectedArray)
jaroslav@1890:                 throw new ConcurrentModificationException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         // only call this holding l's lock
jaroslav@1890:         private void rangeCheck(int index) {
jaroslav@1890:             if (index<0 || index>=size)
jaroslav@1890:                 throw new IndexOutOfBoundsException("Index: "+index+
jaroslav@1890:                                                     ",Size: "+size);
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public E set(int index, E element) {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 rangeCheck(index);
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 E x = l.set(index+offset, element);
jaroslav@1890:                 expectedArray = l.getArray();
jaroslav@1890:                 return x;
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public E get(int index) {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 rangeCheck(index);
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 return l.get(index+offset);
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public int size() {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 return size;
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public void add(int index, E element) {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 if (index<0 || index>size)
jaroslav@1890:                     throw new IndexOutOfBoundsException();
jaroslav@1890:                 l.add(index+offset, element);
jaroslav@1890:                 expectedArray = l.getArray();
jaroslav@1890:                 size++;
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public void clear() {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 l.removeRange(offset, offset+size);
jaroslav@1890:                 expectedArray = l.getArray();
jaroslav@1890:                 size = 0;
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public E remove(int index) {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 rangeCheck(index);
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 E result = l.remove(index+offset);
jaroslav@1890:                 expectedArray = l.getArray();
jaroslav@1890:                 size--;
jaroslav@1890:                 return result;
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public boolean remove(Object o) {
jaroslav@1890:             int index = indexOf(o);
jaroslav@1890:             if (index == -1)
jaroslav@1890:                 return false;
jaroslav@1890:             remove(index);
jaroslav@1890:             return true;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public Iterator<E> iterator() {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 return new COWSubListIterator<E>(l, 0, offset, size);
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public ListIterator<E> listIterator(final int index) {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 if (index<0 || index>size)
jaroslav@1890:                     throw new IndexOutOfBoundsException("Index: "+index+
jaroslav@1890:                                                         ", Size: "+size);
jaroslav@1890:                 return new COWSubListIterator<E>(l, index, offset, size);
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public List<E> subList(int fromIndex, int toIndex) {
jaroslav@1890:             final ReentrantLock lock = l.lock;
jaroslav@1890:             lock.lock();
jaroslav@1890:             try {
jaroslav@1890:                 checkForComodification();
jaroslav@1890:                 if (fromIndex<0 || toIndex>size)
jaroslav@1890:                     throw new IndexOutOfBoundsException();
jaroslav@1890:                 return new COWSubList<E>(l, fromIndex + offset,
jaroslav@1890:                                          toIndex + offset);
jaroslav@1890:             } finally {
jaroslav@1890:                 lock.unlock();
jaroslav@1890:             }
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890: 
jaroslav@1890:     private static class COWSubListIterator<E> implements ListIterator<E> {
jaroslav@1890:         private final ListIterator<E> i;
jaroslav@1890:         private final int index;
jaroslav@1890:         private final int offset;
jaroslav@1890:         private final int size;
jaroslav@1890: 
jaroslav@1890:         COWSubListIterator(List<E> l, int index, int offset,
jaroslav@1890:                            int size) {
jaroslav@1890:             this.index = index;
jaroslav@1890:             this.offset = offset;
jaroslav@1890:             this.size = size;
jaroslav@1890:             i = l.listIterator(index+offset);
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public boolean hasNext() {
jaroslav@1890:             return nextIndex() < size;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public E next() {
jaroslav@1890:             if (hasNext())
jaroslav@1890:                 return i.next();
jaroslav@1890:             else
jaroslav@1890:                 throw new NoSuchElementException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public boolean hasPrevious() {
jaroslav@1890:             return previousIndex() >= 0;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public E previous() {
jaroslav@1890:             if (hasPrevious())
jaroslav@1890:                 return i.previous();
jaroslav@1890:             else
jaroslav@1890:                 throw new NoSuchElementException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public int nextIndex() {
jaroslav@1890:             return i.nextIndex() - offset;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public int previousIndex() {
jaroslav@1890:             return i.previousIndex() - offset;
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public void remove() {
jaroslav@1890:             throw new UnsupportedOperationException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public void set(E e) {
jaroslav@1890:             throw new UnsupportedOperationException();
jaroslav@1890:         }
jaroslav@1890: 
jaroslav@1890:         public void add(E e) {
jaroslav@1890:             throw new UnsupportedOperationException();
jaroslav@1890:         }
jaroslav@1890:     }
jaroslav@1890: 
jaroslav@1890:     // Support for resetting lock while deserializing
jaroslav@1890:     private void resetLock() {
jaroslav@1895:         this.lock = new ReentrantLock();
jaroslav@1890:     }
jaroslav@1890: }