it.unimi.dsi.fastutil

Class IndirectPriorityQueues.EmptyIndirectPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.IndirectPriorityQueues.EmptyIndirectPriorityQueue

All Implemented Interfaces:

IndirectPriorityQueue

Enclosing class:

IndirectPriorityQueues

public static class IndirectPriorityQueues.EmptyIndirectPriorityQueue
extends Object
implements IndirectPriorityQueue

An immutable class representing the empty indirect priority queue.

This class may be useful to implement your own in case you subclass IndirectPriorityQueue.

Method Summary

Modifier and Type	Method and Description
void	allChanged() Notifies this queue that the all elements have changed (optional operation).
void	changed() Notifies this queue that the first element has changed (optional operation).
void	changed(int i) Notifies this queue that the specified element has changed (optional operation).
void	clear() Removes all elements from this queue.
Comparator<?>	comparator() Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.
boolean	contains(int index) Checks whether a given index belongs to this queue (optional operation).
int	dequeue() Dequeues the first element from this queue.
void	enqueue(int i) Enqueues a new element.
int	first() Returns the first element of this queue.
int	front(int[] a) Retrieves the front of this queue in a given array (optional operation).
boolean	isEmpty() Checks whether this queue is empty.
int	last() Returns the last element of this queue, that is, the element the would be dequeued last (optional operation).
boolean	remove(int i) Removes the specified element from this queue (optional operation).
int	size() Returns the number of elements in this queue.

Methods inherited from class java.lang.Object

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

Method Detail

enqueue

public void enqueue(int i)

Description copied from interface: IndirectPriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface IndirectPriorityQueue

Parameters:

i - the element to enqueue.

dequeue

public int dequeue()

Description copied from interface: IndirectPriorityQueue

Dequeues the first element from this queue.

Specified by:

dequeue in interface IndirectPriorityQueue

Returns:

the dequeued element.

isEmpty

public boolean isEmpty()

Description copied from interface: IndirectPriorityQueue

Checks whether this queue is empty.

This default implementation checks whether IndirectPriorityQueue.size() is zero.

Specified by:

isEmpty in interface IndirectPriorityQueue

Returns:

true if this queue is empty.

size

public int size()

Description copied from interface: IndirectPriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface IndirectPriorityQueue

Returns:

the number of elements in this queue.

contains

public boolean contains(int index)

Description copied from interface: IndirectPriorityQueue

Checks whether a given index belongs to this queue (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

contains in interface IndirectPriorityQueue

Parameters:

index - an index possibly in the queue.

Returns:

true if the specified index belongs to this queue.

clear

public void clear()

Description copied from interface: IndirectPriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface IndirectPriorityQueue

first

public int first()

Description copied from interface: IndirectPriorityQueue

Returns the first element of this queue.

Specified by:

first in interface IndirectPriorityQueue

Returns:

the first element.

last

public int last()

Description copied from interface: IndirectPriorityQueue

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

This default implementation just throws an UnsupportedOperationException.

Specified by:

last in interface IndirectPriorityQueue

Returns:

the last element.

changed

public void changed()

Description copied from interface: IndirectPriorityQueue

Notifies this queue that the first element has changed (optional operation).

This default implementation just calls IndirectPriorityQueue.changed(int) with argument IndirectPriorityQueue.first().

Specified by:

changed in interface IndirectPriorityQueue

allChanged

public void allChanged()

Description copied from interface: IndirectPriorityQueue

Notifies this queue that the all elements have changed (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

allChanged in interface IndirectPriorityQueue

comparator

public Comparator<?> comparator()

Description copied from interface: IndirectPriorityQueue

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

Specified by:

comparator in interface IndirectPriorityQueue

Returns:

the comparator associated with this sorted set, or null if it uses its elements' natural ordering.

changed

public void changed(int i)

Description copied from interface: IndirectPriorityQueue

Notifies this queue that the specified element has changed (optional operation).

Note that the specified element must belong to this queue.

This default implementation just throws an UnsupportedOperationException.

Specified by:

changed in interface IndirectPriorityQueue

Parameters:

i - the element that has changed.

remove

public boolean remove(int i)

Description copied from interface: IndirectPriorityQueue

Removes the specified element from this queue (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

remove in interface IndirectPriorityQueue

Parameters:

i - the element to be removed.

Returns:

true if the index was in the queue.

front

public int front(int[] a)

Description copied from interface: IndirectPriorityQueue

Retrieves the front of this queue in a given array (optional operation).

The front of an indirect queue is the set of indices whose associated elements in the reference array are equal to the element associated to the first index. These indices can be always obtain by dequeueing, but this method should retrieve efficiently such indices in the given array without modifying the state of this queue.

This default implementation just throws an UnsupportedOperationException.

Specified by:

front in interface IndirectPriorityQueue

Parameters:

a - an array large enough to hold the front (e.g., at least long as the reference array).

Returns:

the number of elements actually written (starting from the first position of a).