org.exist.util
Class Heap

java.lang.Object
  org.exist.util.Heap

public class Heap
extends Object

A heap-based priority queue, without any concurrency control (i.e., no blocking on empty/full states). This class provides the data structure mechanics for BoundedPriorityQueue.

The class currently uses a standard array-based heap, as described in, for example, Sedgewick's Algorithms text. All methods are fully synchronized. In the future, it may instead use structures permitting finer-grained locking.

[ Introduction to this package. ]

Constructor Summary

Heap(int capacity)
Create a Heap with the given capacity, and relying on natural ordering.

Heap(int capacity, Comparator cmp)
Create a Heap with the given initial capacity and comparator

Method Summary

void	clear() remove all elements
Object	extract() Return and remove least element, or null if empty
void	insert(Object x) insert an element, resize if necessary
Object	peek() Return least element without removing it, or null if empty
int	size() Return number of elements

Methods inherited from class java.lang.Object

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

Constructor Detail

Heap

public Heap(int capacity,
            Comparator cmp)
     throws IllegalArgumentException

Create a Heap with the given initial capacity and comparator

Throws:

IllegalArgumentException - if capacity less or equal to zero

Heap

public Heap(int capacity)

Create a Heap with the given capacity, and relying on natural ordering.

Method Detail

insert

public void insert(Object x)

insert an element, resize if necessary

extract

public Object extract()

Return and remove least element, or null if empty

peek

public Object peek()

Return least element without removing it, or null if empty

size

public int size()

Return number of elements

clear

public void clear()

remove all elements