Class ByteArrayIndirectPriorityQueue

java.lang.Object
it.unimi.dsi.fastutil.bytes.ByteArrayIndirectPriorityQueue
All Implemented Interfaces:
ByteIndirectPriorityQueue, IndirectPriorityQueue<Byte>

public class ByteArrayIndirectPriorityQueue
extends Object
implements ByteIndirectPriorityQueue
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

    Constructors 
    Constructor Description
    ByteArrayIndirectPriorityQueue​(byte[] refArray)
    Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, int capacity)
    Creates a new empty queue with given capacity and using the natural order.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, int[] a)
    Wraps a given array in a queue using the natural order.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, int[] a, int size)
    Wraps a given array in a queue using the natural order.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, int[] a, int size, ByteComparator c)
    Wraps a given array in a queue using a given comparator.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, int[] a, ByteComparator c)
    Wraps a given array in a queue using a given comparator.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, int capacity, ByteComparator c)
    Creates a new empty queue without elements with a given capacity and comparator.
    ByteArrayIndirectPriorityQueue​(byte[] refArray, ByteComparator c)
    Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.
  • Method Summary

    Modifier and Type Method Description
    void allChanged()
    Signals the queue that all elements have changed.
    void changed()
    Notifies this queue that the first element has changed (optional operation).
    void changed​(int index)
    Notifies this queue that the specified element has changed (optional operation).
    void clear()
    Removes all elements from this queue.
    ByteComparator comparator()
    Returns the type-specific comparator associated with this queue.
    int dequeue()
    Dequeues the first element from this queue.
    void enqueue​(int x)
    Enqueues a new element.
    int first()
    Returns the first element of this queue.
    int front​(int[] a)
    Writes in the provided array the front of the queue, that is, the set of indices whose elements have the same priority as the top.
    int last()
    Returns the last element of this queue, that is, the element the would be dequeued last (optional operation).
    boolean remove​(int index)
    Removes the specified element from this 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 java.lang.Object

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

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

    contains, isEmpty
  • Constructor Details

    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] refArray, int capacity, ByteComparator 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] refArray, ByteComparator 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] refArray, int[] a, int size, ByteComparator 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] refArray, int[] a, ByteComparator 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] 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.
    • ByteArrayIndirectPriorityQueue

      public ByteArrayIndirectPriorityQueue​(byte[] 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 Details