it.unimi.dsi.fastutil.objects

Class ObjectArrayFIFOQueue<K>

java.lang.Object

it.unimi.dsi.fastutil.AbstractPriorityQueue<K>

it.unimi.dsi.fastutil.objects.ObjectArrayFIFOQueue<K>

All Implemented Interfaces:

PriorityQueue<K>

public class ObjectArrayFIFOQueue<K>
extends AbstractPriorityQueue<K>

A type-specific array-based FIFO queue, supporting also deque operations.

Instances of this class represent a FIFO queue using a backing array in a circular way. The array is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

This class provides additional methods that implement a deque (double-ended queue).

Field Summary

Fields

Modifier and Type	Field and Description
protected K[]	array The backing array.
protected int	end The end position in array.
static int	INITIAL_CAPACITY The standard initial capacity of a queue.
protected int	length The current (cached) length of array.
protected int	start The start position in array.

Constructor Summary

Constructors

Constructor and Description
ObjectArrayFIFOQueue() Creates a new empty queue with standard initial capacity.
ObjectArrayFIFOQueue(int capacity) Creates a new empty queue with given capacity.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Removes all elements from this queue.
Comparator<? super K>	comparator() Returns null (FIFO queues have no comparator).
K	dequeue() Dequeues the first element from the queue.
K	dequeueLast() Dequeues the last element from the queue.
void	enqueue(K x) Enqueues a new element.
void	enqueueFirst(K x) Enqueues a new element as the first element (in dequeuing order) of the queue.
K	first() Returns the first element of the queue.
K	last() Returns the last element of the queue.
int	size() Returns the number of elements in this queue.
void	trim() Trims the queue to the smallest possible size.

Methods inherited from class it.unimi.dsi.fastutil.AbstractPriorityQueue

changed, isEmpty

Methods inherited from class java.lang.Object

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

Field Detail

INITIAL_CAPACITY

public static final int INITIAL_CAPACITY

The standard initial capacity of a queue.

See Also:

Constant Field Values

array

protected K[] array

The backing array.

length

protected int length

The current (cached) length of array.

start

protected int start

The start position in array. It is always strictly smaller than length.

end

protected int end

The end position in array. It is always strictly smaller than length. Might be actually smaller than start because array is used cyclically.

Constructor Detail

ObjectArrayFIFOQueue

public ObjectArrayFIFOQueue(int capacity)

Creates a new empty queue with given capacity.

Parameters:

capacity - the initial capacity of this queue.

ObjectArrayFIFOQueue

public ObjectArrayFIFOQueue()

Creates a new empty queue with standard initial capacity.

Method Detail

comparator

public Comparator<? super K> comparator()

Returns null (FIFO queues have no comparator).

Returns:

null.

dequeue

public K dequeue()

Description copied from interface: PriorityQueue

Dequeues the first element from the queue.

Returns:

the dequeued element.

dequeueLast

public K dequeueLast()

Dequeues the last element from the queue.

Returns:

the dequeued element.

Throws:

NoSuchElementException - if the queue is empty.

enqueue

public void enqueue(K x)

Description copied from interface: PriorityQueue

Enqueues a new element.

Parameters:

x - the element to enqueue..

enqueueFirst

public void enqueueFirst(K x)

Enqueues a new element as the first element (in dequeuing order) of the queue.

first

public K first()

Returns the first element of the queue.

Returns:

the first element of the queue.

last

public K last()

Returns the last element of the queue.

Specified by:

last in interface PriorityQueue<K>

Overrides:

last in class AbstractPriorityQueue<K>

Returns:

the last element of the queue.

clear

public void clear()

Description copied from interface: PriorityQueue

Removes all elements from this queue.

trim

public void trim()

Trims the queue to the smallest possible size.

size

public int size()

Description copied from interface: PriorityQueue

Returns the number of elements in this queue.

Returns:

the number of elements in this queue.