it.unimi.dsi.fastutil.longs

Class LongArrayFIFOQueue

java.lang.Object

it.unimi.dsi.fastutil.longs.LongArrayFIFOQueue

All Implemented Interfaces:

LongPriorityQueue, PriorityQueue<Long>, Serializable

public class LongArrayFIFOQueue
extends Object
implements LongPriorityQueue, 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
protected long[]	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
LongArrayFIFOQueue() Creates a new empty queue with standard initial capacity.
LongArrayFIFOQueue(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.
LongComparator	comparator() Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
long	dequeueLastLong() Dequeues the last element from the queue.
long	dequeueLong() Dequeues the first element from the queue.
void	enqueue(long x) Enqueues a new element.
void	enqueueFirst(long x) Enqueues a new element as the first element (in dequeuing order) of the queue.
long	firstLong() Returns the first element of the queue.
long	lastLong() 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

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

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongPriorityQueue

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

array

protected transient long[] array

The backing array.

length

protected transient int length

The current (cached) length of array.

start

protected transient int start

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

end

protected transient 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

LongArrayFIFOQueue

public LongArrayFIFOQueue(int capacity)

Creates a new empty queue with given capacity.

Parameters:

capacity - the initial capacity of this queue.

LongArrayFIFOQueue

public LongArrayFIFOQueue()

Creates a new empty queue with standard initial capacity.

Method Detail

comparator

public LongComparator 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 LongPriorityQueue

Specified by:

comparator in interface PriorityQueue<Long>

Returns:

the comparator associated with this priority queue.

See Also:

PriorityQueue.comparator()

dequeueLong

public long dequeueLong()

Description copied from interface: LongPriorityQueue

Dequeues the first element from the queue.

Specified by:

dequeueLong in interface LongPriorityQueue

Returns:

the dequeued element.

See Also:

LongPriorityQueue.dequeue()

dequeueLastLong

public long dequeueLastLong()

Dequeues the last element from the queue.

Returns:

the dequeued element.

Throws:

NoSuchElementException - if the queue is empty.

enqueue

public void enqueue(long x)

Description copied from interface: LongPriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface LongPriorityQueue

Parameters:

x - the element to enqueue.

See Also:

PriorityQueue.enqueue(Object)

enqueueFirst

public void enqueueFirst(long x)

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

Parameters:

x - the element to enqueue.

firstLong

public long firstLong()

Description copied from interface: LongPriorityQueue

Returns the first element of the queue.

Specified by:

firstLong in interface LongPriorityQueue

Returns:

the first element.

See Also:

LongPriorityQueue.first()

lastLong

public long lastLong()

Description copied from interface: LongPriorityQueue

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:

lastLong in interface LongPriorityQueue

Returns:

the last element.

See Also:

LongPriorityQueue.last()

clear

public void clear()

Description copied from interface: PriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface PriorityQueue<Long>

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<Long>

Returns:

the number of elements in this queue.