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/*
* Copyright (C) 2012 United States Government as represented by the Administrator of the
* National Aeronautics and Space Administration.
* All Rights Reserved.
*/
package gov.nasa.worldwind.util;
/**
* A collection of 32-bit integer primitives that contains no duplicate elements. IntSet provides the minimal operations
* for working with on a set of integers: add, remove, contains, and clear. Additionally, IntSet provides methods for
* determining the number of integers in the set, and for retrieving the integers as an array.
*
* IntSet
*
* @author dcollins
* @version $Id: IntSet.java 1171 2013-02-11 21:45:02Z dcollins $
*/
public class IntSet
{
protected static final int DEFAULT_NUM_BUCKETS = 128;
protected static final int DEFAULT_BUCKET_CAPACITY = 8;
protected static class Bucket
{
public int[] values;
public int length;
public Bucket(int initialCapacity)
{
if (initialCapacity < 1)
{
String msg = Logging.getMessage("generic.SizeOutOfRange", initialCapacity);
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
this.values = new int[initialCapacity];
this.length = 0;
}
}
protected Bucket[] buckets;
protected int numBuckets;
protected int bucketInitialCapacity;
protected int size;
/** Creates an empty IntSet with the default number of buckets and initial bucket capacity. */
public IntSet()
{
this(DEFAULT_NUM_BUCKETS, DEFAULT_BUCKET_CAPACITY);
}
/**
* Creates an empty IntSet with the specified number of buckets and initial bucket capacity. Both the number of
* buckets and the initial bucket capacity must be greater than zero. For optimal performance with more than a few
* unique values, the number of buckets should be configured to a large value such as 128. The bucket initial
* capacity does not significantly affect performance, as each bucket eventually grows to fit its entries.
*
* @param numBuckets the number of buckets this IntSet uses to
* @param bucketInitialCapacity the initial capacity for each bucket.
*
* @throws IllegalArgumentException if either numBuckets or bucketInitialCapacity is less than 1.
*/
public IntSet(int numBuckets, int bucketInitialCapacity)
{
if (numBuckets < 1)
{
String msg = Logging.getMessage("generic.SizeOutOfRange", numBuckets);
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
if (bucketInitialCapacity < 1)
{
String msg = Logging.getMessage("generic.SizeOutOfRange", bucketInitialCapacity);
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
this.buckets = new Bucket[numBuckets];
this.numBuckets = numBuckets;
this.bucketInitialCapacity = bucketInitialCapacity;
}
/**
* Returns the number of unique integers in this set.
*
* @return the set's size.
*/
public int size()
{
return this.size;
}
/**
* Adds the specified value to this set. If this set does not contain the value, it is added to this set and this
* returns true. Otherwise this does nothing and returns false.
*
* @param value the value to add.
*
* @return true if the value is added to this set, otherwise false.
*/
public boolean add(int value)
{
int index = value % this.numBuckets;
Bucket bucket = this.buckets[index];
if (bucket == null)
{
bucket = this.buckets[index] = new Bucket(this.bucketInitialCapacity);
}
else
{
for (int i = 0; i < bucket.length; i++)
{
if (bucket.values[i] == value)
return false;
}
}
if (bucket.values.length <= bucket.length)
{
int[] tmp = new int[2 * bucket.values.length];
System.arraycopy(bucket.values, 0, tmp, 0, bucket.values.length);
bucket.values = tmp;
}
bucket.values[bucket.length++] = value;
this.size++;
return true;
}
/**
* Removes the specified value from this set. If this set does not contain the value, this does nothing and returns
* false. Otherwise this removes the value and returns true.
*
* @param value the value to remove.
*
* @return true of the value is removed from this set, otherwise false.
*/
public boolean remove(int value)
{
int index = value % this.numBuckets;
Bucket bucket = this.buckets[index];
if (bucket == null || bucket.length == 0)
return false;
int i;
for (i = 0; i < bucket.length; i++)
{
if (bucket.values[i] == value)
break;
}
if (i == bucket.length)
return false;
if (i < bucket.length - 1)
{
System.arraycopy(bucket.values, i + 1, bucket.values, i, bucket.length - i - 1);
}
bucket.length--;
this.size--;
return true;
}
/**
* Indicates whether this set contains the specified value.
*
* @param value the value to test.
*
* @return true if this set contains the value, otherwise false.
*/
public boolean contains(int value)
{
int index = value % this.numBuckets;
Bucket bucket = this.buckets[index];
if (bucket == null)
return false;
for (int i = 0; i < bucket.length; i++)
{
if (bucket.values[i] == value)
return true;
}
return false;
}
/** Removes all of the values from this set. This set is empty after this call returns. */
public void clear()
{
for (int i = 0; i < this.numBuckets; i++)
{
if (this.buckets[i] != null)
this.buckets[i].length = 0;
}
this.size = 0;
}
/**
* Returns the values in this set as a 32-bit integer array. The values are stored in the specified array if it has
* enough room. If the array is null or is not large enough, this allocates and returns a new array
* with length equal to this set's size.
*
* @param array the array into which the values are stored.
*
* @return the array of values in this set, or a new array if the specified array is null or not large
* enough.
*/
public int[] toArray(int[] array)
{
if (array == null || array.length < this.size)
array = new int[this.size];
int offset = 0;
for (int i = 0; i < this.numBuckets; i++)
{
Bucket bucket = this.buckets[i];
if (bucket != null)
{
System.arraycopy(bucket.values, 0, array, offset, bucket.length);
offset += bucket.length;
}
}
return array;
}
}
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