it.unimi.dsi.fastutil.objects
Class ObjectArrayIndirectPriorityQueue

java.lang.Object
  it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue
      it.unimi.dsi.fastutil.objects.ObjectArrayIndirectPriorityQueue

All Implemented Interfaces:

IndirectPriorityQueue

Direct Known Subclasses:

ObjectArrayIndirectDoublePriorityQueue

public class ObjectArrayIndirectPriorityQueue

extends AbstractIndirectPriorityQueue

A type-specific array-based semi-indirect priority queue.

Instances of this class use as reference list a reference array, which must be provided to each constructor, and represent a priority queue using a backing array of integer indices—all operations are performed directly on the array. The array is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

This implementation is extremely inefficient, but it is difficult to beat when the size of the queue is very small. Moreover, it allows to enqueue several time the same index, without limitations.

Constructor Summary

ObjectArrayIndirectPriorityQueue(Object[] refArray)
Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.

ObjectArrayIndirectPriorityQueue(Object[] refArray, Comparator c)
Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.

ObjectArrayIndirectPriorityQueue(Object[] refArray, int capacity)
Creates a new empty queue with given capacity and using the natural order.

ObjectArrayIndirectPriorityQueue(Object[] refArray, int[] a)
Wraps a given array in a queue using the natural order.

ObjectArrayIndirectPriorityQueue(Object[] refArray, int[] a, Comparator c)
Wraps a given array in a queue using a given comparator.

ObjectArrayIndirectPriorityQueue(Object[] refArray, int[] a, int size)
Wraps a given array in a queue using the natural order.

ObjectArrayIndirectPriorityQueue(Object[] refArray, int[] a, int size, Comparator c)
Wraps a given array in a queue using a given comparator.

ObjectArrayIndirectPriorityQueue(Object[] refArray, int capacity, Comparator c)
Creates a new empty queue without elements with a given capacity and comparator.

Method Summary

void	allChanged() Notifies the queue that the all elements have changed (optional operation).
void	changed() Notifies the queue that the first element has changed (optional operation).
void	changed(int index) Note that for efficiency reasons this method will not throw an exception when index is not in the queue.
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.
int	dequeue() Dequeues an element.
void	enqueue(int x) Enqueues a new element.
int	first() Returns the first element of the queue.
int	last() Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).
void	remove(int index) Removes the specified element from the queue (optional operation).
int	size() Returns the number of elements in this queue.
String	toString()
void	trim() Trims the backing array so that it has exactly size() elements.

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

isEmpty

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        int capacity,
                                        Comparator c)

Creates a new empty queue without elements with a given capacity and comparator.

Parameters:

refArray - the reference array.

capacity - the initial capacity of this queue.

c - the comparator used in this queue, or null for the natural order.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        int capacity)

Creates a new empty queue with given capacity and using the natural order.

Parameters:

refArray - the reference array.

capacity - the initial capacity of this queue.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        Comparator c)

Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.

Parameters:

refArray - the reference array.

c - the comparator used in this queue, or null for the natural order.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray)

Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.

Parameters:

refArray - the reference array.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        int[] a,
                                        int size,
                                        Comparator c)

Wraps a given array in a queue using a given comparator.

The queue returned by this method will be backed by the given array.

Parameters:

refArray - the reference array.

a - an array of indices into refArray.

size - the number of elements to be included in the queue.

c - the comparator used in this queue, or null for the natural order.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        int[] a,
                                        Comparator c)

Wraps a given array in a queue using a given comparator.

The queue returned by this method will be backed by the given array.

Parameters:

refArray - the reference array.

a - an array of indices into refArray.

c - the comparator used in this queue, or null for the natural order.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        int[] a,
                                        int size)

Wraps a given array in a queue using the natural order.

The queue returned by this method will be backed by the given array.

Parameters:

refArray - the reference array.

a - an array of indices into refArray.

size - the number of elements to be included in the queue.

ObjectArrayIndirectPriorityQueue

public ObjectArrayIndirectPriorityQueue(Object[] refArray,
                                        int[] a)

Wraps a given array in a queue using the natural order.

The queue returned by this method will be backed by the given array.

Parameters:

refArray - the reference array.

a - an array of indices into refArray.

Method Detail

enqueue

public void enqueue(int x)

Enqueues a new element.

Note that for efficiency reasons this method will not throw an exception when x is already in the queue. However, the queue state will become inconsistent and the following behaviour will not be predictable.

Parameters:

x - the element to enqueue..

dequeue

public int dequeue()

Dequeues an element.

Note that each call to this method requires a complete scan of the backing array. Please consider caching its result.

Returns:

the dequeued element.

first

public int first()

Description copied from interface: IndirectPriorityQueue

Returns the first element of the queue.

Returns:

the first element.

last

public int last()

Description copied from interface: IndirectPriorityQueue

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

Specified by:

last in interface IndirectPriorityQueue

Overrides:

last in class AbstractIndirectPriorityQueue

changed

public void changed()

Description copied from interface: IndirectPriorityQueue

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

Specified by:

changed in interface IndirectPriorityQueue

Overrides:

changed in class AbstractIndirectPriorityQueue

changed

public void changed(int index)

Note that for efficiency reasons this method will not throw an exception when index is not in the queue.

Specified by:

changed in interface IndirectPriorityQueue

Overrides:

changed in class AbstractIndirectPriorityQueue

allChanged

public void allChanged()

Description copied from interface: IndirectPriorityQueue

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

Specified by:

allChanged in interface IndirectPriorityQueue

Overrides:

allChanged in class AbstractIndirectPriorityQueue

remove

public void remove(int index)

Description copied from interface: IndirectPriorityQueue

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

Note that the specified element must belong to the queue.

Specified by:

remove in interface IndirectPriorityQueue

Overrides:

remove in class AbstractIndirectPriorityQueue

size

public int size()

Description copied from interface: IndirectPriorityQueue

Returns the number of elements in this queue.

Returns:

the number of elements in this queue.

clear

public void clear()

Description copied from interface: IndirectPriorityQueue

Removes all elements from this queue.

trim

public void trim()

Trims the backing array so that it has exactly size() elements.

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.

Returns:

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

toString

public String toString()