/*
* Copyright (C) 2002-2014 Sebastiano Vigna
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
/*
* This is a modified version of the fastutil ObjectArrayList. It is modified to use identity checks
* rather than equality checks for higher performance.
*/
package org.apache.geode.internal.cache;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.RandomAccess;
import java.util.NoSuchElementException;
import it.unimi.dsi.fastutil.objects.AbstractObjectList;
import it.unimi.dsi.fastutil.objects.AbstractObjectListIterator;
import it.unimi.dsi.fastutil.objects.ObjectArrays;
import it.unimi.dsi.fastutil.objects.ObjectCollection;
import it.unimi.dsi.fastutil.objects.ObjectIterator;
import it.unimi.dsi.fastutil.objects.ObjectIterators;
import it.unimi.dsi.fastutil.objects.ObjectList;
import it.unimi.dsi.fastutil.objects.ObjectListIterator;
/**
*
*
* A type-specific array-based list; provides some additional methods that use polymorphism to avoid
* (un)boxing.
*
* <P>
* This class implements a lightweight, fast, open, optimized, reuse-oriented version of array-based
* lists. Instances of this class represent a list with an array that is enlarged as needed when new
* entries are created (by doubling the current length), but is <em>never</em> made smaller (even on
* a {@link #clear()}). A family of {@linkplain #trim() trimming methods} lets you control the size
* of the backing array; this is particularly useful if you reuse instances of this class. Range
* checks are equivalent to those of <code>java.util</code>'s classes, but they are delayed as much
* as possible.
*
* <p>
* The backing array is exposed by the {@link #elements()} method. If an instance of this class was
* created {@linkplain #wrap(Object[],int) by wrapping}, backing-array reallocations will be
* performed using reflection, so that {@link #elements()} can return an array of the same type of
* the original array; the comments about efficiency made in
* {@link it.unimi.dsi.fastutil.objects.ObjectArrays} apply here.
*
* <p>
* This class implements the bulk methods <code>removeElements()</code>, <code>addElements()</code>
* and <code>getElements()</code> using high-performance system calls (e.g.,
* {@link System#arraycopy(Object,int,Object,int,int) System.arraycopy()} instead of expensive
* loops.
*
* @see java.util.ArrayList
*/
public class IdentityArrayList<K> extends AbstractObjectList<K>
implements RandomAccess, Cloneable, java.io.Serializable {
private static final long serialVersionUID = 449125332499184497L;
/** The initial default capacity of an array list. */
public final static int DEFAULT_INITIAL_CAPACITY = 16;
/**
* Whether the backing array was passed to <code>wrap()</code>. In this case, we must reallocate
* with the same type of array.
*/
protected final boolean wrapped;
/** The backing array. */
protected transient K a[];
/** The current actual size of the list (never greater than the backing-array length). */
protected int size;
private static final boolean ASSERTS = false;
/**
* Creates a new array list using a given array.
*
* <P>
* This constructor is only meant to be used by the wrapping methods.
*
* @param a the array that will be used to back this array list.
*/
@SuppressWarnings("unused")
protected IdentityArrayList(final K a[], boolean dummy) {
this.a = a;
this.wrapped = true;
}
/**
* Creates a new array list with given capacity.
*
* @param capacity the initial capacity of the array list (may be 0).
*/
@SuppressWarnings("unchecked")
public IdentityArrayList(final int capacity) {
if (capacity < 0)
throw new IllegalArgumentException("Initial capacity (" + capacity + ") is negative");
a = (K[]) new Object[capacity];
wrapped = false;
}
/**
* Creates a new array list with {@link #DEFAULT_INITIAL_CAPACITY} capacity.
*/
public IdentityArrayList() {
this(DEFAULT_INITIAL_CAPACITY);
}
/**
* Creates a new array list and fills it with a given collection.
*
* @param c a collection that will be used to fill the array list.
*/
public IdentityArrayList(final Collection<? extends K> c) {
this(c.size());
size = ObjectIterators.unwrap(c.iterator(), a);
}
/**
* Creates a new array list and fills it with a given type-specific collection.
*
* @param c a type-specific collection that will be used to fill the array list.
*/
public IdentityArrayList(final ObjectCollection<? extends K> c) {
this(c.size());
size = ObjectIterators.unwrap(c.iterator(), a);
}
/**
* Creates a new array list and fills it with a given type-specific list.
*
* @param l a type-specific list that will be used to fill the array list.
*/
public IdentityArrayList(final ObjectList<? extends K> l) {
this(l.size());
l.getElements(0, a, 0, size = l.size());
}
/**
* Creates a new array list and fills it with the elements of a given array.
*
* @param a an array whose elements will be used to fill the array list.
*/
public IdentityArrayList(final K a[]) {
this(a, 0, a.length);
}
/**
* Creates a new array list and fills it with the elements of a given array.
*
* @param a an array whose elements will be used to fill the array list.
* @param offset the first element to use.
* @param length the number of elements to use.
*/
public IdentityArrayList(final K a[], final int offset, final int length) {
this(length);
System.arraycopy(a, offset, this.a, 0, length);
size = length;
}
/**
* Creates a new array list and fills it with the elements returned by an iterator..
*
* @param i an iterator whose returned elements will fill the array list.
*/
public IdentityArrayList(final Iterator<? extends K> i) {
this();
while (i.hasNext())
this.add(i.next());
}
/**
* Creates a new array list and fills it with the elements returned by a type-specific iterator..
*
* @param i a type-specific iterator whose returned elements will fill the array list.
*/
public IdentityArrayList(final ObjectIterator<? extends K> i) {
this();
while (i.hasNext())
this.add(i.next());
}
/**
* Returns the backing array of this list.
*
* <P>
* If this array list was created by wrapping a given array, it is guaranteed that the type of the
* returned array will be the same. Otherwise, the returned array will be of type {@link Object
* Object[]} (in spite of the declared return type).
*
* <strong>Warning</strong>: This behaviour may cause (unfathomable) run-time errors if a method
* expects an array actually of type <code>K[]</code>, but this methods returns an array of type
* {@link Object Object[]}.
*
* @return the backing array.
*/
public K[] elements() {
return a;
}
/**
* Wraps a given array into an array list of given size.
*
* @param a an array to wrap.
* @param length the length of the resulting array list.
* @return a new array list of the given size, wrapping the given array.
*/
public static <K> IdentityArrayList<K> wrap(final K a[], final int length) {
if (length > a.length)
throw new IllegalArgumentException("The specified length (" + length
+ ") is greater than the array size (" + a.length + ")");
final IdentityArrayList<K> l = new IdentityArrayList<K>(a, false);
l.size = length;
return l;
}
/**
* Wraps a given array into an array list.
*
* @param a an array to wrap.
* @return a new array list wrapping the given array.
*/
public static <K> IdentityArrayList<K> wrap(final K a[]) {
return wrap(a, a.length);
}
/**
* Ensures that this array list can contain the given number of entries without resizing.
*
* @param capacity the new minimum capacity for this array list.
*/
@SuppressWarnings("unchecked")
public void ensureCapacity(final int capacity) {
if (wrapped)
a = ObjectArrays.ensureCapacity(a, capacity, size);
else {
if (capacity > a.length) {
final Object t[] = new Object[capacity];
System.arraycopy(a, 0, t, 0, size);
a = (K[]) t;
}
}
if (ASSERTS)
assert size <= a.length;
}
/**
* Grows this array list, ensuring that it can contain the given number of entries without
* resizing, and in case enlarging it at least by a factor of two.
*
* @param capacity the new minimum capacity for this array list.
*/
@SuppressWarnings("unchecked")
private void grow(final int capacity) {
if (wrapped)
a = ObjectArrays.grow(a, capacity, size);
else {
if (capacity > a.length) {
final int newLength = (int) Math
.max(Math.min(2L * a.length, it.unimi.dsi.fastutil.Arrays.MAX_ARRAY_SIZE), capacity);
final Object t[] = new Object[newLength];
System.arraycopy(a, 0, t, 0, size);
a = (K[]) t;
}
}
if (ASSERTS)
assert size <= a.length;
}
public void add(final int index, final K k) {
ensureIndex(index);
grow(size + 1);
if (index != size)
System.arraycopy(a, index, a, index + 1, size - index);
a[index] = k;
size++;
if (ASSERTS)
assert size <= a.length;
}
public boolean add(final K k) {
grow(size + 1);
a[size++] = k;
if (ASSERTS)
assert size <= a.length;
return true;
}
public K get(final int index) {
if (index >= size)
throw new IndexOutOfBoundsException(
"Index (" + index + ") is greater than or equal to list size (" + size + ")");
return a[index];
}
public int indexOf(final Object k) {
for (int i = 0; i < size; i++)
if (((k) == null ? (a[i]) == null : (k) == (a[i])))
return i;
return -1;
}
public int lastIndexOf(final Object k) {
for (int i = size; i-- != 0;)
if (((k) == null ? (a[i]) == null : (k) == (a[i])))
return i;
return -1;
}
public K remove(final int index) {
if (index >= size)
throw new IndexOutOfBoundsException(
"Index (" + index + ") is greater than or equal to list size (" + size + ")");
final K old = a[index];
size--;
if (index != size)
System.arraycopy(a, index + 1, a, index, size - index);
a[size] = null;
if (ASSERTS)
assert size <= a.length;
return old;
}
public boolean rem(final Object k) {
int index = indexOf(k);
if (index == -1)
return false;
remove(index);
if (ASSERTS)
assert size <= a.length;
return true;
}
public boolean remove(final Object o) {
return rem(o);
}
public K set(final int index, final K k) {
if (index >= size)
throw new IndexOutOfBoundsException(
"Index (" + index + ") is greater than or equal to list size (" + size + ")");
K old = a[index];
a[index] = k;
return old;
}
public void clear() {
Arrays.fill(a, 0, size, null);
size = 0;
if (ASSERTS)
assert size <= a.length;
}
public int size() {
return size;
}
public void size(final int size) {
if (size > a.length)
ensureCapacity(size);
if (size > this.size)
Arrays.fill(a, this.size, size, (null));
else
Arrays.fill(a, size, this.size, (null));
this.size = size;
}
public boolean isEmpty() {
return size == 0;
}
/**
* Trims this array list so that the capacity is equal to the size.
*
* @see java.util.ArrayList#trimToSize()
*/
public void trim() {
trim(0);
}
/**
* Trims the backing array if it is too large.
*
* If the current array length is smaller than or equal to <code>n</code>, this method does
* nothing. Otherwise, it trims the array length to the maximum between <code>n</code> and
* {@link #size()}.
*
* <P>
* This method is useful when reusing lists. {@linkplain #clear() Clearing a list} leaves the
* array length untouched. If you are reusing a list many times, you can call this method with a
* typical size to avoid keeping around a very large array just because of a few large transient
* lists.
*
* @param n the threshold for the trimming.
*/
@SuppressWarnings("unchecked")
public void trim(final int n) {
// TODO: use Arrays.trim() and preserve type only if necessary
if (n >= a.length || size == a.length)
return;
final K t[] = (K[]) new Object[Math.max(n, size)];
System.arraycopy(a, 0, t, 0, size);
a = t;
if (ASSERTS)
assert size <= a.length;
}
/**
* Copies element of this type-specific list into the given array using optimized system calls.
*
* @param from the start index (inclusive).
* @param a the destination array.
* @param offset the offset into the destination array where to store the first element copied.
* @param length the number of elements to be copied.
*/
public void getElements(final int from, final Object[] a, final int offset, final int length) {
ObjectArrays.ensureOffsetLength(a, offset, length);
System.arraycopy(this.a, from, a, offset, length);
}
/**
* Removes elements of this type-specific list using optimized system calls.
*
* @param from the start index (inclusive).
* @param to the end index (exclusive).
*/
public void removeElements(final int from, final int to) {
it.unimi.dsi.fastutil.Arrays.ensureFromTo(size, from, to);
System.arraycopy(a, to, a, from, size - to);
size -= (to - from);
int i = to - from;
while (i-- != 0)
a[size + i] = null;
}
/**
* Adds elements to this type-specific list using optimized system calls.
*
* @param index the index at which to add elements.
* @param a the array containing the elements.
* @param offset the offset of the first element to add.
* @param length the number of elements to add.
*/
public void addElements(final int index, final K a[], final int offset, final int length) {
ensureIndex(index);
ObjectArrays.ensureOffsetLength(a, offset, length);
grow(size + length);
System.arraycopy(this.a, index, this.a, index + length, size - index);
System.arraycopy(a, offset, this.a, index, length);
size += length;
}
public ObjectListIterator<K> listIterator(final int index) {
ensureIndex(index);
return new AbstractObjectListIterator<K>() {
int pos = index, last = -1;
public boolean hasNext() {
return pos < size;
}
public boolean hasPrevious() {
return pos > 0;
}
public K next() {
if (!hasNext())
throw new NoSuchElementException();
return a[last = pos++];
}
public K previous() {
if (!hasPrevious())
throw new NoSuchElementException();
return a[last = --pos];
}
public int nextIndex() {
return pos;
}
public int previousIndex() {
return pos - 1;
}
public void add(K k) {
if (last == -1)
throw new IllegalStateException();
IdentityArrayList.this.add(pos++, k);
last = -1;
}
public void set(K k) {
if (last == -1)
throw new IllegalStateException();
IdentityArrayList.this.set(last, k);
}
public void remove() {
if (last == -1)
throw new IllegalStateException();
IdentityArrayList.this.remove(last);
/*
* If the last operation was a next(), we are removing an element *before* us, and we must
* decrease pos correspondingly.
*/
if (last < pos)
pos--;
last = -1;
}
};
}
@SuppressWarnings("unchecked")
public IdentityArrayList<K> clone() {
IdentityArrayList<K> c = new IdentityArrayList<K>(size);
System.arraycopy(a, 0, c.a, 0, size);
c.size = size;
return c;
}
private boolean valEquals(final K a, final K b) {
return a == b;
}
/**
* Compares this type-specific array list to another one.
*
* <P>
* This method exists only for sake of efficiency. The implementation inherited from the abstract
* implementation would already work.
*
* @param l a type-specific array list.
* @return true if the argument contains the same elements of this type-specific array list.
*/
public boolean equals(final IdentityArrayList<K> l) {
if (l == this)
return true;
int s = size();
if (s != l.size())
return false;
final K[] a1 = a;
final K[] a2 = l.a;
while (s-- != 0)
if (!valEquals(a1[s], a2[s]))
return false;
return true;
}
/**
* Compares this array list to another array list.
*
* <P>
* This method exists only for sake of efficiency. The implementation inherited from the abstract
* implementation would already work.
*
* @param l an array list.
* @return a negative integer, zero, or a positive integer as this list is lexicographically less
* than, equal to, or greater than the argument.
*/
@SuppressWarnings("unchecked")
public int compareTo(final IdentityArrayList<? extends K> l) {
final int s1 = size(), s2 = l.size();
final K a1[] = a, a2[] = l.a;
K e1, e2;
int r, i;
for (i = 0; i < s1 && i < s2; i++) {
e1 = a1[i];
e2 = a2[i];
if ((r = (((Comparable<K>) (e1)).compareTo(e2))) != 0)
return r;
}
return i < s2 ? -1 : (i < s1 ? 1 : 0);
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
s.defaultWriteObject();
for (int i = 0; i < size; i++)
s.writeObject(a[i]);
}
@SuppressWarnings("unchecked")
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
a = (K[]) new Object[size];
for (int i = 0; i < size; i++)
a[i] = (K) s.readObject();
}
/**
* For highest performance we sometimes must iterate over the actual Object array. This should
* only be used in carefully controlled circumstances.
*/
public Object[] getArrayRef() {
return a;
}
}