org.chocosolver.util.objects.queues

Class CircularQueue<E>

java.lang.Object

org.chocosolver.util.objects.queues.CircularQueue<E>

public class CircularQueue<E>
extends Object

A fixed sized circular queue optimized for removing first and last elements. Some few (essential regarding the usage) methods are implemented.
Be aware of the size computation: the modulo operation is not efficient in java. On the other hand, the modulo of powers of 2 can alternatively be expressed as a bitwise AND operation:
x % 2n == x & (2n - 1)
That is why the size of the data is automatically set to the closest greater powers of 2 value.

Since:

29 sept. 2010

Author:

Charles Prud'homme

Constructor Summary

Constructors

Constructor and Description
CircularQueue(int size)

Method Summary

Modifier and Type	Method and Description
boolean	addFirst(E e) Put a new element at the head of the queue.
boolean	addLast(E e) Put a new element at the tail of the queue.
void	clear() Removes all the content of the queue
E	get(int index) Get the index element of the queue, 0 being the last element
int	indexOf(E elem) Search an element equal to the parameter in the CircularQueue, and return its index (0 is the last element)
boolean	isEmpty()
E	pollFirst() Removes the first element of the queue and returns it This method is the main reason we re-wrote the class.
E	pollLast() Removes the last element of the queue and returns it This method is the main reason we re-wrote the class.
E	remove() This method is the main reason we re-wrote the class.
boolean	remove(E e) Remove the first element equal to the value given as parameter
E	remove(int index) Removes the index element of the queue and removes the resulting gap This method is the main reason we re-wrote the class.
int	size() Get the current number of elements

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CircularQueue

public CircularQueue(int size)

Method Detail

isEmpty

public boolean isEmpty()

Returns:

if the queue has no element (size == 0)

clear

public void clear()

Removes all the content of the queue

size

public int size()

Get the current number of elements

Returns:

current number of inserted elements in the queue

get

public E get(int index)

Get the index element of the queue, 0 being the last element

Parameters:

index - index of the element to retrieve

Returns:

the element itself, or null if it does not exist

See Also:

indexOf(Object)

addFirst

public boolean addFirst(E e)

Put a new element at the head of the queue. The CircularQueue grows by itself if it reaches its max capacity

Parameters:

e - element to add

Returns:

if the element has been added or not

addLast

public boolean addLast(E e)

Put a new element at the tail of the queue. The CircularQueue grows by itself if it reaches its max capacity

Parameters:

e - element to add

Returns:

if the element has been added or not

indexOf

public int indexOf(E elem)

Search an element equal to the parameter in the CircularQueue, and return its index (0 is the last element)

Parameters:

elem - element to query in the CircularQueue

Returns:

index of the element starting from the last of the CircularQueue, -1 if the element does not exists

pollFirst

public E pollFirst()

Removes the first element of the queue and returns it
This method is the main reason we re-wrote the class. It is optimized for removing first and last elements but also allows you to remove in the middle of the list.

Returns:

first element of the queue

pollLast

public E pollLast()

Removes the last element of the queue and returns it
This method is the main reason we re-wrote the class. It is optimized for removing first and last elements but also allows you to remove in the middle of the list.

Returns:

last element of the queue

remove

public E remove()

This method is the main reason we re-wrote the class. It is optimized for removing first and last elements but also allows you to remove in the middle of the list.

remove

public E remove(int index)

Removes the index element of the queue and removes the resulting gap
This method is the main reason we re-wrote the class. It is optimized for removing first and last elements but also allows you to remove in the middle of the list.

Parameters:

index -

Returns:

removed element

See Also:

indexOf(Object)

remove

public boolean remove(E e)

Remove the first element equal to the value given as parameter

Parameters:

e - value to remove from the CircularQueue

Returns:

if the value has been removed