jdk/src/java.desktop/share/classes/sun/awt/util/IdentityArrayList.java
changeset 25859 3317bb8137f4
parent 24538 25bf8153fbfe
child 30948 0a0972d3b58d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.desktop/share/classes/sun/awt/util/IdentityArrayList.java	Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,546 @@
+/*
+ * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package sun.awt.util;
+
+import java.util.AbstractList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.ConcurrentModificationException;
+import java.util.List;
+import java.util.RandomAccess;
+
+/**
+ * Resizable-array implementation of the <tt>List</tt> interface.  Implements
+ * all optional list operations, and permits all elements, including
+ * <tt>null</tt>.  In addition to implementing the <tt>List</tt> interface,
+ * this class provides methods to manipulate the size of the array that is
+ * used internally to store the list.  (This class is roughly equivalent to
+ * <tt>Vector</tt>, except that it is unsynchronized.)<p>
+ *
+ * The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>,
+ * <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant
+ * time.  The <tt>add</tt> operation runs in <i>amortized constant time</i>,
+ * that is, adding n elements requires O(n) time.  All of the other operations
+ * run in linear time (roughly speaking).  The constant factor is low compared
+ * to that for the <tt>LinkedList</tt> implementation.<p>
+ *
+ * Each <tt>IdentityArrayList</tt> instance has a <i>capacity</i>.  The capacity is
+ * the size of the array used to store the elements in the list.  It is always
+ * at least as large as the list size.  As elements are added to an IdentityArrayList,
+ * its capacity grows automatically.  The details of the growth policy are not
+ * specified beyond the fact that adding an element has constant amortized
+ * time cost.<p>
+ *
+ * An application can increase the capacity of an <tt>IdentityArrayList</tt> instance
+ * before adding a large number of elements using the <tt>ensureCapacity</tt>
+ * operation.  This may reduce the amount of incremental reallocation.
+ *
+ * <p><strong>Note that this implementation is not synchronized.</strong>
+ * If multiple threads access an <tt>IdentityArrayList</tt> instance concurrently,
+ * and at least one of the threads modifies the list structurally, it
+ * <i>must</i> be synchronized externally.  (A structural modification is
+ * any operation that adds or deletes one or more elements, or explicitly
+ * resizes the backing array; merely setting the value of an element is not
+ * a structural modification.)  This is typically accomplished by
+ * synchronizing on some object that naturally encapsulates the list.
+ *
+ * If no such object exists, the list should be "wrapped" using the
+ * {@link Collections#synchronizedList Collections.synchronizedList}
+ * method.  This is best done at creation time, to prevent accidental
+ * unsynchronized access to the list:<pre>
+ *   List list = Collections.synchronizedList(new IdentityArrayList(...));</pre>
+ *
+ * <p>The iterators returned by this class's <tt>iterator</tt> and
+ * <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
+ * structurally modified at any time after the iterator is created, in any way
+ * except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods,
+ * the iterator will throw a {@link ConcurrentModificationException}.  Thus, in
+ * the face of concurrent modification, the iterator fails quickly and cleanly,
+ * rather than risking arbitrary, non-deterministic behavior at an undetermined
+ * time in the future.<p>
+ *
+ * Note that the fail-fast behavior of an iterator cannot be guaranteed
+ * as it is, generally speaking, impossible to make any hard guarantees in the
+ * presence of unsynchronized concurrent modification.  Fail-fast iterators
+ * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
+ * Therefore, it would be wrong to write a program that depended on this
+ * exception for its correctness: <i>the fail-fast behavior of iterators
+ * should be used only to detect bugs.</i><p>
+ *
+ */
+
+public class IdentityArrayList<E> extends AbstractList<E>
+        implements List<E>, RandomAccess
+{
+
+    /**
+     * The array buffer into which the elements of the IdentityArrayList are stored.
+     * The capacity of the IdentityArrayList is the length of this array buffer.
+     */
+    private transient Object[] elementData;
+
+    /**
+     * The size of the IdentityArrayList (the number of elements it contains).
+     *
+     * @serial
+     */
+    private int size;
+
+    /**
+     * Constructs an empty list with the specified initial capacity.
+     *
+     * @param   initialCapacity   the initial capacity of the list
+     * @exception IllegalArgumentException if the specified initial capacity
+     *            is negative
+     */
+    public IdentityArrayList(int initialCapacity) {
+        super();
+        if (initialCapacity < 0)
+            throw new IllegalArgumentException("Illegal Capacity: "+
+                    initialCapacity);
+        this.elementData = new Object[initialCapacity];
+    }
+
+    /**
+     * Constructs an empty list with an initial capacity of ten.
+     */
+    public IdentityArrayList() {
+        this(10);
+    }
+
+    /**
+     * Constructs a list containing the elements of the specified
+     * collection, in the order they are returned by the collection's
+     * iterator.
+     *
+     * @param c the collection whose elements are to be placed into this list
+     * @throws NullPointerException if the specified collection is null
+     */
+    public IdentityArrayList(Collection<? extends E> c) {
+        elementData = c.toArray();
+        size = elementData.length;
+        // c.toArray might (incorrectly) not return Object[] (see 6260652)
+        if (elementData.getClass() != Object[].class)
+            elementData = Arrays.copyOf(elementData, size, Object[].class);
+    }
+
+    /**
+     * Trims the capacity of this <tt>IdentityArrayList</tt> instance to be the
+     * list's current size.  An application can use this operation to minimize
+     * the storage of an <tt>IdentityArrayList</tt> instance.
+     */
+    public void trimToSize() {
+        modCount++;
+        int oldCapacity = elementData.length;
+        if (size < oldCapacity) {
+            elementData = Arrays.copyOf(elementData, size);
+        }
+    }
+
+    /**
+     * Increases the capacity of this <tt>IdentityArrayList</tt> instance, if
+     * necessary, to ensure that it can hold at least the number of elements
+     * specified by the minimum capacity argument.
+     *
+     * @param   minCapacity   the desired minimum capacity
+     */
+    public void ensureCapacity(int minCapacity) {
+        modCount++;
+        int oldCapacity = elementData.length;
+        if (minCapacity > oldCapacity) {
+            Object oldData[] = elementData;
+            int newCapacity = (oldCapacity * 3)/2 + 1;
+            if (newCapacity < minCapacity)
+                newCapacity = minCapacity;
+            // minCapacity is usually close to size, so this is a win:
+            elementData = Arrays.copyOf(elementData, newCapacity);
+        }
+    }
+
+    /**
+     * Returns the number of elements in this list.
+     *
+     * @return the number of elements in this list
+     */
+    public int size() {
+        return size;
+    }
+
+    /**
+     * Returns <tt>true</tt> if this list contains no elements.
+     *
+     * @return <tt>true</tt> if this list contains no elements
+     */
+    public boolean isEmpty() {
+        return size == 0;
+    }
+
+    /**
+     * Returns <tt>true</tt> if this list contains the specified element.
+     * More formally, returns <tt>true</tt> if and only if this list contains
+     * at least one element <tt>e</tt> such that
+     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o == e)</tt>.
+     *
+     * @param o element whose presence in this list is to be tested
+     * @return <tt>true</tt> if this list contains the specified element
+     */
+    public boolean contains(Object o) {
+        return indexOf(o) >= 0;
+    }
+
+    /**
+     * Returns the index of the first occurrence of the specified element
+     * in this list, or -1 if this list does not contain the element.
+     * More formally, returns the lowest index <tt>i</tt> such that
+     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o == get(i))</tt>,
+     * or -1 if there is no such index.
+     */
+    public int indexOf(Object o) {
+        for (int i = 0; i < size; i++) {
+            if (o == elementData[i]) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
+     * Returns the index of the last occurrence of the specified element
+     * in this list, or -1 if this list does not contain the element.
+     * More formally, returns the highest index <tt>i</tt> such that
+     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o == get(i))</tt>,
+     * or -1 if there is no such index.
+     */
+    public int lastIndexOf(Object o) {
+        for (int i = size-1; i >= 0; i--) {
+            if (o == elementData[i]) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
+     * Returns an array containing all of the elements in this list
+     * in proper sequence (from first to last element).
+     *
+     * <p>The returned array will be "safe" in that no references to it are
+     * maintained by this list.  (In other words, this method must allocate
+     * a new array).  The caller is thus free to modify the returned array.
+     *
+     * <p>This method acts as bridge between array-based and collection-based
+     * APIs.
+     *
+     * @return an array containing all of the elements in this list in
+     *         proper sequence
+     */
+    public Object[] toArray() {
+        return Arrays.copyOf(elementData, size);
+    }
+
+    /**
+     * Returns an array containing all of the elements in this list in proper
+     * sequence (from first to last element); the runtime type of the returned
+     * array is that of the specified array.  If the list fits in the
+     * specified array, it is returned therein.  Otherwise, a new array is
+     * allocated with the runtime type of the specified array and the size of
+     * this list.
+     *
+     * <p>If the list fits in the specified array with room to spare
+     * (i.e., the array has more elements than the list), the element in
+     * the array immediately following the end of the collection is set to
+     * <tt>null</tt>.  (This is useful in determining the length of the
+     * list <i>only</i> if the caller knows that the list does not contain
+     * any null elements.)
+     *
+     * @param a the array into which the elements of the list are to
+     *          be stored, if it is big enough; otherwise, a new array of the
+     *          same runtime type is allocated for this purpose.
+     * @return an array containing the elements of the list
+     * @throws ArrayStoreException if the runtime type of the specified array
+     *         is not a supertype of the runtime type of every element in
+     *         this list
+     * @throws NullPointerException if the specified array is null
+     */
+    @SuppressWarnings("unchecked")
+    public <T> T[] toArray(T[] a) {
+        if (a.length < size)
+            // Make a new array of a's runtime type, but my contents:
+            return (T[]) Arrays.copyOf(elementData, size, a.getClass());
+        System.arraycopy(elementData, 0, a, 0, size);
+        if (a.length > size)
+            a[size] = null;
+        return a;
+    }
+
+    // Positional Access Operations
+
+    /**
+     * Returns the element at the specified position in this list.
+     *
+     * @param  index index of the element to return
+     * @return the element at the specified position in this list
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     */
+    public E get(int index) {
+        rangeCheck(index);
+
+        @SuppressWarnings("unchecked")
+        E rv = (E) elementData[index];
+        return rv;
+    }
+
+    /**
+     * Replaces the element at the specified position in this list with
+     * the specified element.
+     *
+     * @param index index of the element to replace
+     * @param element element to be stored at the specified position
+     * @return the element previously at the specified position
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     */
+    public E set(int index, E element) {
+        rangeCheck(index);
+
+        @SuppressWarnings("unchecked")
+        E oldValue = (E) elementData[index];
+        elementData[index] = element;
+        return oldValue;
+    }
+
+    /**
+     * Appends the specified element to the end of this list.
+     *
+     * @param e element to be appended to this list
+     * @return <tt>true</tt> (as specified by {@link Collection#add})
+     */
+    public boolean add(E e) {
+        ensureCapacity(size + 1);  // Increments modCount!!
+        elementData[size++] = e;
+        return true;
+    }
+
+    /**
+     * Inserts the specified element at the specified position in this
+     * list. Shifts the element currently at that position (if any) and
+     * any subsequent elements to the right (adds one to their indices).
+     *
+     * @param index index at which the specified element is to be inserted
+     * @param element element to be inserted
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     */
+    public void add(int index, E element) {
+        rangeCheckForAdd(index);
+
+        ensureCapacity(size+1);  // Increments modCount!!
+        System.arraycopy(elementData, index, elementData, index + 1,
+                size - index);
+        elementData[index] = element;
+        size++;
+    }
+
+    /**
+     * Removes the element at the specified position in this list.
+     * Shifts any subsequent elements to the left (subtracts one from their
+     * indices).
+     *
+     * @param index the index of the element to be removed
+     * @return the element that was removed from the list
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     */
+    public E remove(int index) {
+        rangeCheck(index);
+
+        modCount++;
+        @SuppressWarnings("unchecked")
+        E oldValue = (E) elementData[index];
+
+        int numMoved = size - index - 1;
+        if (numMoved > 0)
+            System.arraycopy(elementData, index+1, elementData, index,
+                    numMoved);
+        elementData[--size] = null; // Let gc do its work
+
+        return oldValue;
+    }
+
+    /**
+     * Removes the first occurrence of the specified element from this list,
+     * if it is present.  If the list does not contain the element, it is
+     * unchanged.  More formally, removes the element with the lowest index
+     * <tt>i</tt> such that
+     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o == get(i))</tt>
+     * (if such an element exists).  Returns <tt>true</tt> if this list
+     * contained the specified element (or equivalently, if this list
+     * changed as a result of the call).
+     *
+     * @param o element to be removed from this list, if present
+     * @return <tt>true</tt> if this list contained the specified element
+     */
+    public boolean remove(Object o) {
+        for (int index = 0; index < size; index++) {
+            if (o == elementData[index]) {
+                fastRemove(index);
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /*
+     * Private remove method that skips bounds checking and does not
+     * return the value removed.
+     */
+    private void fastRemove(int index) {
+        modCount++;
+        int numMoved = size - index - 1;
+        if (numMoved > 0)
+            System.arraycopy(elementData, index+1, elementData, index,
+                    numMoved);
+        elementData[--size] = null; // Let gc do its work
+    }
+
+    /**
+     * Removes all of the elements from this list.  The list will
+     * be empty after this call returns.
+     */
+    public void clear() {
+        modCount++;
+
+        // Let gc do its work
+        for (int i = 0; i < size; i++)
+            elementData[i] = null;
+
+        size = 0;
+    }
+
+    /**
+     * Appends all of the elements in the specified collection to the end of
+     * this list, in the order that they are returned by the
+     * specified collection's Iterator.  The behavior of this operation is
+     * undefined if the specified collection is modified while the operation
+     * is in progress.  (This implies that the behavior of this call is
+     * undefined if the specified collection is this list, and this
+     * list is nonempty.)
+     *
+     * @param c collection containing elements to be added to this list
+     * @return <tt>true</tt> if this list changed as a result of the call
+     * @throws NullPointerException if the specified collection is null
+     */
+    public boolean addAll(Collection<? extends E> c) {
+        Object[] a = c.toArray();
+        int numNew = a.length;
+        ensureCapacity(size + numNew);  // Increments modCount
+        System.arraycopy(a, 0, elementData, size, numNew);
+        size += numNew;
+        return numNew != 0;
+    }
+
+    /**
+     * Inserts all of the elements in the specified collection into this
+     * list, starting at the specified position.  Shifts the element
+     * currently at that position (if any) and any subsequent elements to
+     * the right (increases their indices).  The new elements will appear
+     * in the list in the order that they are returned by the
+     * specified collection's iterator.
+     *
+     * @param index index at which to insert the first element from the
+     *              specified collection
+     * @param c collection containing elements to be added to this list
+     * @return <tt>true</tt> if this list changed as a result of the call
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     * @throws NullPointerException if the specified collection is null
+     */
+    public boolean addAll(int index, Collection<? extends E> c) {
+        rangeCheckForAdd(index);
+
+        Object[] a = c.toArray();
+        int numNew = a.length;
+        ensureCapacity(size + numNew);  // Increments modCount
+
+        int numMoved = size - index;
+        if (numMoved > 0) {
+            System.arraycopy(elementData, index, elementData, index + numNew, numMoved);
+        }
+
+        System.arraycopy(a, 0, elementData, index, numNew);
+        size += numNew;
+        return numNew != 0;
+    }
+
+    /**
+     * Removes from this list all of the elements whose index is between
+     * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
+     * Shifts any succeeding elements to the left (reduces their index).
+     * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
+     * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
+     *
+     * @param fromIndex index of first element to be removed
+     * @param toIndex index after last element to be removed
+     * @throws IndexOutOfBoundsException if fromIndex or toIndex out of
+     *              range (fromIndex &lt; 0 || fromIndex &gt;= size() || toIndex
+     *              &gt; size() || toIndex &lt; fromIndex)
+     */
+    protected void removeRange(int fromIndex, int toIndex) {
+        modCount++;
+        int numMoved = size - toIndex;
+        System.arraycopy(elementData, toIndex, elementData, fromIndex,
+                numMoved);
+
+        // Let gc do its work
+        int newSize = size - (toIndex-fromIndex);
+        while (size != newSize)
+            elementData[--size] = null;
+    }
+
+    /**
+     * Checks if the given index is in range.  If not, throws an appropriate
+     * runtime exception.  This method does *not* check if the index is
+     * negative: It is always used immediately prior to an array access,
+     * which throws an ArrayIndexOutOfBoundsException if index is negative.
+     */
+    private void rangeCheck(int index) {
+        if (index >= size)
+            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+    }
+
+    /**
+     * A version of rangeCheck used by add and addAll.
+     */
+    private void rangeCheckForAdd(int index) {
+        if (index > size || index < 0)
+            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+    }
+
+    /**
+     * Constructs an IndexOutOfBoundsException detail message.
+     * Of the many possible refactorings of the error handling code,
+     * this "outlining" performs best with both server and client VMs.
+     */
+    private String outOfBoundsMsg(int index) {
+        return "Index: "+index+", Size: "+size;
+    }
+}