org.batoo.common.collections.FastLinkedList Maven / Gradle / Ivy
/*
* Copyright (c) 2012 - Batoo Software ve Consultancy Ltd.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program 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 Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.batoo.common.collections;
import java.io.IOException;
import java.io.Serializable;
import java.util.AbstractSequentialList;
import java.util.Collection;
import java.util.Deque;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Queue;
/**
* Doubly-linked list implementation that avoids interfaces.
*
* Returns concrete interface classes from iterator() methods: {@link #iterator()} {@link #listIterator()}
* {@link #descendingIterator()}.
*
* Does not check list modifications during iterations.
*
* @param
* The type of the list
*
* @author hceylan
*/
public class FastLinkedList extends AbstractSequentialList implements List, Deque, Cloneable, Serializable {
static class FastLinkedListNode {
E item;
FastLinkedListNode next;
FastLinkedListNode prev;
FastLinkedListNode(FastLinkedListNode prev, E element, FastLinkedListNode next) {
super();
this.item = element;
this.next = next;
this.prev = prev;
}
}
transient final AbstractListListener listener;
transient int size = 0;
transient FastLinkedListNode first;
transient FastLinkedListNode last;
/**
* Constructs an empty list.
*
*/
public FastLinkedList() {
this((AbstractListListener) null);
}
/**
* Constructs an empty list with an optional addition removal listener.
*
* @param listener
* the listener to call on additions and removals
*
*/
public FastLinkedList(AbstractListListener listener) {
super();
this.listener = listener;
}
/**
* Constructs a list containing the elements of the specified collection, in the order they are returned by the collection's iterator.
* Additionally passes a list listener.
*
* Listener will be effective after initial creation of the list.
*
* @param listener
* the listener to call on additions and removals
* @param c
* the collection whose elements are to be placed into this list
* @throws NullPointerException
* if the specified collection is null
*
*/
public FastLinkedList(AbstractListListener listener, Collection c) {
super();
this.addAll(c);
this.listener = listener;
}
/**
* 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 FastLinkedList(Collection c) {
this(null, c);
this.addAll(c);
}
/**
* {@inheritDoc}
*
*/
@Override
public boolean add(E e) {
this.linkLast(e);
return true;
}
/**
* {@inheritDoc}
*
*/
@Override
public void add(int index, E element) {
this.checkPositionIndex(index);
if (index == this.size) {
this.linkLast(element);
}
else {
this.linkBefore(element, this.node(index));
}
}
/**
* {@inheritDoc}
*
*/
@Override
public boolean addAll(Collection c) {
return this.addAll(this.size, c);
}
/**
* {@inheritDoc}
*
*/
@Override
public boolean addAll(int index, Collection c) {
this.checkPositionIndex(index);
final Object[] a = c.toArray();
final int numNew = a.length;
if (numNew == 0) {
return false;
}
FastLinkedListNode pred, succ;
if (index == this.size) {
succ = null;
pred = this.last;
}
else {
succ = this.node(index);
pred = succ.prev;
}
for (final Object o : a) {
@SuppressWarnings("unchecked")
final E e = (E) o;
final FastLinkedListNode newNode = new FastLinkedListNode(pred, e, null);
if (pred == null) {
this.first = newNode;
}
else {
pred.next = newNode;
}
pred = newNode;
}
if (succ == null) {
this.last = pred;
}
else {
pred.next = succ;
succ.prev = pred;
}
this.size += numNew;
this.modCount++;
return true;
}
/**
* {@inheritDoc}
*
*/
@Override
public void addFirst(E e) {
this.linkFirst(e);
}
/**
* {@inheritDoc}
*
*/
@Override
public void addLast(E e) {
this.linkLast(e);
}
private void checkElementIndex(int index) {
if (!this.isElementIndex(index)) {
throw new IndexOutOfBoundsException(this.outOfBoundsMsg(index));
}
}
private void checkPositionIndex(int index) {
if (!this.isPositionIndex(index)) {
throw new IndexOutOfBoundsException(this.outOfBoundsMsg(index));
}
}
/**
* {@inheritDoc}
*
*/
@Override
public void clear() {
this.first = this.last = null;
this.size = 0;
this.modCount++;
}
/**
* {@inheritDoc}
*
*/
@Override
public Object clone() {
final FastLinkedList clone = this.superClone();
// Put clone into "virgin" state
clone.first = clone.last = null;
clone.size = 0;
clone.modCount = 0;
// Initialize clone with our elements
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
clone.add(x.item);
}
return clone;
}
/**
* {@inheritDoc}
*
*/
@Override
public boolean contains(Object o) {
return this.indexOf(o) != -1;
}
/**
* {@inheritDoc}
*
*/
@Override
public FastLinkedListIterator descendingIterator() {
return new FastLinkedListIterator(this, this.size, false);
}
/**
* {@inheritDoc}
*
*/
@Override
public E element() {
return this.getFirst();
}
/**
* {@inheritDoc}
*
*/
@Override
public E get(int index) {
this.checkElementIndex(index);
return this.node(index).item;
}
/**
* {@inheritDoc}
*
*/
@Override
public E getFirst() {
final FastLinkedListNode f = this.first;
if (f == null) {
throw new NoSuchElementException();
}
return f.item;
}
/**
* {@inheritDoc}
*
*/
@Override
public E getLast() {
final FastLinkedListNode l = this.last;
if (l == null) {
throw new NoSuchElementException();
}
return l.item;
}
/**
* {@inheritDoc}
*
*/
@Override
public int indexOf(Object o) {
int index = 0;
if (o == null) {
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
if (x.item == null) {
return index;
}
index++;
}
}
else {
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
if (o.equals(x.item)) {
return index;
}
index++;
}
}
return -1;
}
private boolean isElementIndex(int index) {
return (index >= 0) && (index < this.size);
}
private boolean isPositionIndex(int index) {
return (index >= 0) && (index <= this.size);
}
/**
* {@inheritDoc}
*
*/
@Override
public FastLinkedListIterator iterator() {
return this.listIterator();
}
/**
* {@inheritDoc}
*
*/
@Override
public int lastIndexOf(Object o) {
int index = this.size;
if (o == null) {
for (FastLinkedListNode x = this.last; x != null; x = x.prev) {
index--;
if (x.item == null) {
return index;
}
}
}
else {
for (FastLinkedListNode x = this.last; x != null; x = x.prev) {
index--;
if (o.equals(x.item)) {
return index;
}
}
}
return -1;
}
void linkBefore(E e, FastLinkedListNode succ) {
// assert succ != null;
final FastLinkedListNode pred = succ.prev;
final FastLinkedListNode newNode = new FastLinkedListNode(pred, e, succ);
succ.prev = newNode;
if (pred == null) {
this.first = newNode;
}
else {
pred.next = newNode;
}
this.size++;
this.modCount++;
final AbstractListListener listener = this.listener;
if (listener != null) {
listener.elementAdded(e);
}
}
private void linkFirst(E e) {
final FastLinkedListNode f = this.first;
final FastLinkedListNode newNode = new FastLinkedListNode(null, e, f);
this.first = newNode;
if (f == null) {
this.last = newNode;
}
else {
f.prev = newNode;
}
this.size++;
this.modCount++;
final AbstractListListener listener = this.listener;
if (listener != null) {
listener.elementAdded(e);
}
}
void linkLast(E e) {
final FastLinkedListNode l = this.last;
final FastLinkedListNode newNode = new FastLinkedListNode(l, e, null);
this.last = newNode;
if (l == null) {
this.first = newNode;
}
else {
l.next = newNode;
}
this.size++;
this.modCount++;
final AbstractListListener listener = this.listener;
if (listener != null) {
listener.elementAdded(e);
}
}
/**
* {@inheritDoc}
*
*/
@Override
public FastLinkedListIterator listIterator() {
return this.listIterator(0);
}
/**
* {@inheritDoc}
*
*/
@Override
public FastLinkedListIterator listIterator(int index) {
this.checkPositionIndex(index);
return new FastLinkedListIterator(this, index, true);
}
// Search Operations
/**
* Returns the (non-null) Node at the specified element index.
*/
FastLinkedListNode node(int index) {
// assert isElementIndex(index);
if (index < (this.size >> 1)) {
FastLinkedListNode x = this.first;
for (int i = 0; i < index; i++) {
x = x.next;
}
return x;
}
else {
FastLinkedListNode x = this.last;
for (int i = this.size - 1; i > index; i--) {
x = x.prev;
}
return x;
}
}
/**
* Adds the specified element as the tail (last element) of this list.
*
* @param e
* the element to add
* @return {@code true} (as specified by {@link Queue#offer})
* @since 1.5
*/
@Override
public boolean offer(E e) {
return this.add(e);
}
// Queue operations.
// Deque operations
/**
* Inserts the specified element at the front of this list.
*
* @param e
* the element to insert
* @return {@code true} (as specified by {@link Deque#offerFirst})
* @since 1.6
*/
@Override
public boolean offerFirst(E e) {
this.addFirst(e);
return true;
}
/**
* Inserts the specified element at the end of this list.
*
* @param e
* the element to insert
* @return {@code true} (as specified by {@link Deque#offerLast})
* @since 1.6
*/
@Override
public boolean offerLast(E e) {
this.addLast(e);
return true;
}
/**
* 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: " + this.size;
}
/**
* Retrieves, but does not remove, the head (first element) of this list.
*
* @return the head of this list, or {@code null} if this list is empty
* @since 1.5
*/
@Override
public E peek() {
final FastLinkedListNode f = this.first;
return (f == null) ? null : f.item;
}
/**
* Retrieves, but does not remove, the first element of this list, or returns {@code null} if this list is empty.
*
* @return the first element of this list, or {@code null} if this list is empty
* @since 1.6
*/
@Override
public E peekFirst() {
final FastLinkedListNode f = this.first;
return (f == null) ? null : f.item;
}
/**
* Retrieves, but does not remove, the last element of this list, or returns {@code null} if this list is empty.
*
* @return the last element of this list, or {@code null} if this list is empty
* @since 1.6
*/
@Override
public E peekLast() {
final FastLinkedListNode l = this.last;
return (l == null) ? null : l.item;
}
/**
* Retrieves and removes the head (first element) of this list.
*
* @return the head of this list, or {@code null} if this list is empty
* @since 1.5
*/
@Override
public E poll() {
final FastLinkedListNode f = this.first;
return (f == null) ? null : this.unlinkFirst(f);
}
/**
* Retrieves and removes the first element of this list, or returns {@code null} if this list is empty.
*
* @return the first element of this list, or {@code null} if this list is empty
* @since 1.6
*/
@Override
public E pollFirst() {
final FastLinkedListNode f = this.first;
return (f == null) ? null : this.unlinkFirst(f);
}
/**
* Retrieves and removes the last element of this list, or returns {@code null} if this list is empty.
*
* @return the last element of this list, or {@code null} if this list is empty
* @since 1.6
*/
@Override
public E pollLast() {
final FastLinkedListNode l = this.last;
return (l == null) ? null : this.unlinkLast(l);
}
/**
* Pops an element from the stack represented by this list. In other words, removes and returns the first element of this list.
*
*
* This method is equivalent to {@link #removeFirst()}.
*
* @return the element at the front of this list (which is the top of the stack represented by this list)
* @throws NoSuchElementException
* if this list is empty
* @since 1.6
*/
@Override
public E pop() {
return this.removeFirst();
}
/**
* Pushes an element onto the stack represented by this list. In other words, inserts the element at the front of this list.
*
*
* This method is equivalent to {@link #addFirst}.
*
* @param e
* the element to push
* @since 1.6
*/
@Override
public void push(E e) {
this.addFirst(e);
}
/**
* Reconstitutes this {@code ChildrenList} instance from a stream (that is, deserializes it).
*/
@SuppressWarnings("unchecked")
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
// Read in any hidden serialization magic
s.defaultReadObject();
// Read in size
final int size = s.readInt();
// Read in all elements in the proper order.
for (int i = 0; i < size; i++) {
this.linkLast((E) s.readObject());
}
}
/**
* Retrieves and removes the head (first element) of this list.
*
* @return the head of this list
* @throws NoSuchElementException
* if this list is empty
* @since 1.5
*/
@Override
public E remove() {
return this.removeFirst();
}
/**
* Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their
* indices). Returns the element that was removed from the list.
*
* @param index
* the index of the element to be removed
* @return the element previously at the specified position
* @throws IndexOutOfBoundsException
* {@inheritDoc}
*/
@Override
public E remove(int index) {
this.checkElementIndex(index);
return this.unlink(this.node(index));
}
/**
* Removes the first occurrence of the specified element from this list, if it is present. If this list does not contain the element, it
* is unchanged. More formally, removes the element with the lowest index {@code i} such that
* (o==null ? get(i)==null : o.equals(get(i))) (if such an element exists). Returns {@code true} 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 {@code true} if this list contained the specified element
*/
@Override
public boolean remove(Object o) {
if (o == null) {
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
if (x.item == null) {
this.unlink(x);
return true;
}
}
}
else {
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
if (o.equals(x.item)) {
this.unlink(x);
return true;
}
}
}
return false;
}
/**
* Removes and returns the first element from this list.
*
* @return the first element from this list
* @throws NoSuchElementException
* if this list is empty
*/
@Override
public E removeFirst() {
final FastLinkedListNode f = this.first;
if (f == null) {
throw new NoSuchElementException();
}
return this.unlinkFirst(f);
}
/**
* Removes the first occurrence of the specified element in this list (when traversing the list from head to tail). If the list does not
* contain the element, it is unchanged.
*
* @param o
* element to be removed from this list, if present
* @return {@code true} if the list contained the specified element
* @since 1.6
*/
@Override
public boolean removeFirstOccurrence(Object o) {
return this.remove(o);
}
/**
* Removes and returns the last element from this list.
*
* @return the last element from this list
* @throws NoSuchElementException
* if this list is empty
*/
@Override
public E removeLast() {
final FastLinkedListNode l = this.last;
if (l == null) {
throw new NoSuchElementException();
}
return this.unlinkLast(l);
}
/**
* Removes the last occurrence of the specified element in this list (when traversing the list from head to tail). If the list does not
* contain the element, it is unchanged.
*
* @param o
* element to be removed from this list, if present
* @return {@code true} if the list contained the specified element
* @since 1.6
*/
@Override
public boolean removeLastOccurrence(Object o) {
if (o == null) {
for (FastLinkedListNode x = this.last; x != null; x = x.prev) {
if (x.item == null) {
this.unlink(x);
return true;
}
}
}
else {
for (FastLinkedListNode x = this.last; x != null; x = x.prev) {
if (o.equals(x.item)) {
this.unlink(x);
return true;
}
}
}
return false;
}
/**
* 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}
*/
@Override
public E set(int index, E element) {
this.checkElementIndex(index);
final FastLinkedListNode x = this.node(index);
final E oldVal = x.item;
x.item = element;
return oldVal;
}
/**
* Returns the number of elements in this list.
*
* @return the number of elements in this list
*/
@Override
public int size() {
return this.size;
}
@SuppressWarnings("unchecked")
private FastLinkedList superClone() {
try {
return (FastLinkedList) super.clone();
}
catch (final CloneNotSupportedException e) {
throw new InternalError();
}
}
/**
* Returns an array containing all of the elements in this list in proper sequence (from first to last element).
*
*
* 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.
*
*
* 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
*/
@Override
public Object[] toArray() {
final Object[] result = new Object[this.size];
int i = 0;
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
result[i++] = x.item;
}
return result;
}
/**
* 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.
*
*
* 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 list is set to {@code null}. (This is useful in determining the length of the list
* only if the caller knows that the list does not contain any null elements.)
*
*
* Like the {@link #toArray()} method, this method acts as bridge between array-based and collection-based APIs. Further, this method
* allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation
* costs.
*
*
* Suppose {@code x} is a list known to contain only strings. The following code can be used to dump the list into a newly allocated
* array of {@code String}:
*
*
* String[] y = x.toArray(new String[0]);
*
*
* Note that {@code toArray(new Object[0])} is identical in function to {@code toArray()}.
*
* @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
*/
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
if (a.length < this.size) {
a = (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), this.size);
}
int i = 0;
final Object[] result = a;
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
result[i++] = x.item;
}
if (a.length > this.size) {
a[this.size] = null;
}
return a;
}
/**
* Unlinks non-null node x.
*/
E unlink(FastLinkedListNode x) {
final E element = x.item;
final FastLinkedListNode next = x.next;
final FastLinkedListNode prev = x.prev;
if (prev == null) {
this.first = next;
}
else {
prev.next = next;
x.prev = null;
}
if (next == null) {
this.last = prev;
}
else {
next.prev = prev;
x.next = null;
}
x.item = null;
this.size--;
this.modCount++;
final AbstractListListener listener = this.listener;
if (listener != null) {
listener.elementRemoved(element);
}
return element;
}
/**
* Unlinks non-null first node f.
*/
private E unlinkFirst(FastLinkedListNode f) {
final E element = f.item;
final FastLinkedListNode next = f.next;
f.item = null;
f.next = null; // help GC
this.first = next;
if (next == null) {
this.last = null;
}
else {
next.prev = null;
}
this.size--;
this.modCount++;
final AbstractListListener listener = this.listener;
if (listener != null) {
listener.elementRemoved(element);
}
return element;
}
/**
* Unlinks non-null last node l.
*/
private E unlinkLast(FastLinkedListNode l) {
final E element = l.item;
final FastLinkedListNode prev = l.prev;
l.item = null;
l.prev = null; // help GC
this.last = prev;
if (prev == null) {
this.first = null;
}
else {
prev.next = null;
}
this.size--;
this.modCount++;
final AbstractListListener listener = this.listener;
if (listener != null) {
listener.elementRemoved(element);
}
return element;
}
/**
* Saves the state of this {@code ChildrenList} instance to a stream (that is, serializes it).
*
* @serialData The size of the list (the number of elements it contains) is emitted (int), followed by all of its elements (each an
* Object) in the proper order.
*/
private void writeObject(java.io.ObjectOutputStream s) throws IOException {
// Write out any hidden serialization magic
s.defaultWriteObject();
// Write out size
s.writeInt(this.size);
// Write out all elements in the proper order.
for (FastLinkedListNode x = this.first; x != null; x = x.next) {
s.writeObject(x.item);
}
}
}