it.unimi.dsi.fastutil.doubles

Class DoubleArrayFIFOQueue

java.lang.Object

it.unimi.dsi.fastutil.doubles.DoubleArrayFIFOQueue

All Implemented Interfaces:

DoublePriorityQueue, PriorityQueue<java.lang.Double>, java.io.Serializable

public class DoubleArrayFIFOQueue
extends java.lang.Object
implements DoublePriorityQueue, java.io.Serializable

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 and shrunk as needed. You can use the trim() method to reduce its memory usage, if necessary.

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

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	INITIAL_CAPACITY The standard initial capacity of a queue.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all elements from this queue.
DoubleComparator	comparator() Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
double	dequeueDouble() Dequeues the first element from the queue.
double	dequeueLastDouble() Dequeues the last element from the queue.
void	enqueue(double x) Enqueues a new element.
void	enqueueFirst(double x) Enqueues a new element as the first element (in dequeuing order) of the queue.
double	firstDouble() Returns the first element of the queue.
double	lastDouble() Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).
int	size() Returns the number of elements in this queue.
void	trim() Trims the queue to the smallest possible size.

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.dsi.fastutil.doubles.DoublePriorityQueue

dequeue, enqueue, first, last

Methods inherited from interface it.unimi.dsi.fastutil.PriorityQueue

changed, isEmpty

Field Detail

INITIAL_CAPACITY

public static final int INITIAL_CAPACITY

The standard initial capacity of a queue.

See Also:

Constant Field Values

Constructor Detail

DoubleArrayFIFOQueue

public DoubleArrayFIFOQueue(int capacity)

Creates a new empty queue with given capacity.

Parameters:

capacity - the initial capacity of this queue.

DoubleArrayFIFOQueue

public DoubleArrayFIFOQueue()

Creates a new empty queue with standard initial capacity.

Method Detail

comparator

public DoubleComparator comparator()

Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.

Note that this specification strengthens the one given in PriorityQueue.comparator().

This implementation returns null (FIFO queues have no comparator).

Specified by:

comparator in interface DoublePriorityQueue

Specified by:

comparator in interface PriorityQueue<java.lang.Double>

Returns:

the comparator associated with this priority queue.

See Also:

PriorityQueue.comparator()

dequeueDouble

public double dequeueDouble()

Description copied from interface: DoublePriorityQueue

Dequeues the first element from the queue.

Specified by:

dequeueDouble in interface DoublePriorityQueue

Returns:

the dequeued element.

See Also:

DoublePriorityQueue.dequeue()

dequeueLastDouble

public double dequeueLastDouble()

Dequeues the last element from the queue.

Returns:

the dequeued element.

Throws:

java.util.NoSuchElementException - if the queue is empty.

enqueue

public void enqueue(double x)

Description copied from interface: DoublePriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface DoublePriorityQueue

Parameters:

x - the element to enqueue.

See Also:

PriorityQueue.enqueue(Object)

enqueueFirst

public void enqueueFirst(double x)

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

Parameters:

x - the element to enqueue.

firstDouble

public double firstDouble()

Description copied from interface: DoublePriorityQueue

Returns the first element of the queue.

Specified by:

firstDouble in interface DoublePriorityQueue

Returns:

the first element.

See Also:

DoublePriorityQueue.first()

lastDouble

public double lastDouble()

Description copied from interface: DoublePriorityQueue

Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

lastDouble in interface DoublePriorityQueue

Returns:

the last element.

See Also:

DoublePriorityQueue.last()

clear

public void clear()

Description copied from interface: PriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface PriorityQueue<java.lang.Double>

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.

Specified by:

size in interface PriorityQueue<java.lang.Double>

Returns:

the number of elements in this queue.