it.unimi.dsi.fastutil.bytes.ByteHeapPriorityQueue Maven / Gradle / Ivy
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/* Generic definitions */
/* Assertions (useful to generate conditional code) */
/* Current type and class (and size, if applicable) */
/* Value methods */
/* Interfaces (keys) */
/* Interfaces (values) */
/* Abstract implementations (keys) */
/* Abstract implementations (values) */
/* Static containers (keys) */
/* Static containers (values) */
/* Implementations */
/* Synchronized wrappers */
/* Unmodifiable wrappers */
/* Other wrappers */
/* Methods (keys) */
/* Methods (values) */
/* Methods (keys/values) */
/* Methods that have special names depending on keys (but the special names depend on values) */
/* Equality */
/* Object/Reference-only definitions (keys) */
/* Primitive-type-only definitions (keys) */
/* Object/Reference-only definitions (values) */
/*
* Copyright (C) 2003-2016 Paolo Boldi and Sebastiano Vigna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package it.unimi.dsi.fastutil.bytes;
import java.util.Iterator;
import java.util.Collection;
import java.util.NoSuchElementException;
/**
* A type-specific heap-based priority queue.
*
*
* Instances of this class represent a priority queue using a heap. The heap is
* enlarged as needed, but it is never shrunk. Use the {@link #trim()} method to
* reduce its size, if necessary.
*/
public class ByteHeapPriorityQueue extends AbstractBytePriorityQueue
implements
java.io.Serializable {
private static final long serialVersionUID = 1L;
/** The heap array. */
protected transient byte[] heap = ByteArrays.EMPTY_ARRAY;
/** The number of elements in this queue. */
protected int size;
/** The type-specific comparator used in this queue. */
protected ByteComparator c;
/**
* Creates a new empty queue with a given capacity and comparator.
*
* @param capacity
* the initial capacity of this queue.
* @param c
* the comparator used in this queue, or null for
* the natural order.
*/
public ByteHeapPriorityQueue(int capacity, ByteComparator c) {
if (capacity > 0)
this.heap = new byte[capacity];
this.c = c;
}
/**
* Creates a new empty queue with a given capacity and using the natural
* order.
*
* @param capacity
* the initial capacity of this queue.
*/
public ByteHeapPriorityQueue(int capacity) {
this(capacity, null);
}
/**
* Creates a new empty queue with a given comparator.
*
* @param c
* the comparator used in this queue, or null for
* the natural order.
*/
public ByteHeapPriorityQueue(ByteComparator c) {
this(0, c);
}
/**
* Creates a new empty queue using the natural order.
*/
public ByteHeapPriorityQueue() {
this(0, null);
}
/**
* Wraps a given array in a queue using a given comparator.
*
*
* The queue returned by this method will be backed by the given array. The
* first size element of the array will be rearranged so to
* form a heap (this is more efficient than enqueing the elements of
* a one by one).
*
* @param a
* an array.
* @param size
* the number of elements to be included in the queue.
* @param c
* the comparator used in this queue, or null for
* the natural order.
*/
public ByteHeapPriorityQueue(final byte[] a, int size,
final ByteComparator c) {
this(c);
this.heap = a;
this.size = size;
ByteHeaps.makeHeap(a, size, 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. The
* elements of the array will be rearranged so to form a heap (this is more
* efficient than enqueing the elements of a one by one).
*
* @param a
* an array.
* @param c
* the comparator used in this queue, or null for
* the natural order.
*/
public ByteHeapPriorityQueue(final byte[] a, final ByteComparator c) {
this(a, a.length, c);
}
/**
* Wraps a given array in a queue using the natural order.
*
*
* The queue returned by this method will be backed by the given array. The
* first size element of the array will be rearranged so to
* form a heap (this is more efficient than enqueing the elements of
* a one by one).
*
* @param a
* an array.
* @param size
* the number of elements to be included in the queue.
*/
public ByteHeapPriorityQueue(final byte[] a, int size) {
this(a, size, null);
}
/**
* Wraps a given array in a queue using the natural order.
*
*
* The queue returned by this method will be backed by the given array. The
* elements of the array will be rearranged so to form a heap (this is more
* efficient than enqueing the elements of a one by one).
*
* @param a
* an array.
*/
public ByteHeapPriorityQueue(final byte[] a) {
this(a, a.length);
}
/**
* Creates a queue using the elements in a type-specific collection using a
* given comparator.
*
*
* This constructor is more efficient than enqueing the elements of
* collection one by one.
*
* @param collection
* a collection; its elements will be used to initialize the
* queue.
* @param c
* the comparator used in this queue, or null for
* the natural order.
*/
public ByteHeapPriorityQueue(final ByteCollection collection,
final ByteComparator c) {
this(collection.toByteArray(), c);
}
/**
* Creates a queue using the elements in a type-specific collection using
* the natural order.
*
*
* This constructor is more efficient than enqueing the elements of
* collection one by one.
*
* @param collection
* a collection; its elements will be used to initialize the
* queue.
*/
public ByteHeapPriorityQueue(final ByteCollection collection) {
this(collection, null);
}
/**
* Creates a queue using the elements in a collection using a given
* comparator.
*
*
* This constructor is more efficient than enqueing the elements of
* collection one by one.
*
* @param collection
* a collection; its elements will be used to initialize the
* queue.
* @param c
* the comparator used in this queue, or null for
* the natural order.
*/
public ByteHeapPriorityQueue(final Collection collection,
final ByteComparator c) {
this(collection.size(), c);
final Iterator iterator = collection.iterator();
final int size = collection.size();
for (int i = 0; i < size; i++)
heap[i] = ((((Byte) (iterator.next())).byteValue()));
}
/**
* Creates a queue using the elements in a collection using the natural
* order.
*
*
* This constructor is more efficient than enqueing the elements of
* collection one by one.
*
* @param collection
* a collection; its elements will be used to initialize the
* queue.
*/
public ByteHeapPriorityQueue(final Collection collection) {
this(collection, null);
}
public void enqueue(byte x) {
if (size == heap.length)
heap = ByteArrays.grow(heap, size + 1);
heap[size++] = x;
ByteHeaps.upHeap(heap, size, size - 1, c);
}
public byte dequeueByte() {
if (size == 0)
throw new NoSuchElementException();
final byte result = heap[0];
heap[0] = heap[--size];
if (size != 0)
ByteHeaps.downHeap(heap, size, 0, c);
return result;
}
public byte firstByte() {
if (size == 0)
throw new NoSuchElementException();
return heap[0];
}
public void changed() {
ByteHeaps.downHeap(heap, size, 0, c);
}
public int size() {
return size;
}
public void clear() {
size = 0;
}
/**
* Trims the underlying heap array so that it has exactly {@link #size()}
* elements.
*/
public void trim() {
heap = ByteArrays.trim(heap, size);
}
public ByteComparator comparator() {
return c;
}
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
s.defaultWriteObject();
s.writeInt(heap.length);
for (int i = 0; i < size; i++)
s.writeByte(heap[i]);
}
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
heap = new byte[s.readInt()];
for (int i = 0; i < size; i++)
heap[i] = s.readByte();
}
}