it.unimi.dsi.fastutil.ints

Class IntOpenHashSet

java.lang.Object

java.util.AbstractCollection<java.lang.Integer>

it.unimi.dsi.fastutil.ints.AbstractIntCollection

it.unimi.dsi.fastutil.ints.AbstractIntSet

it.unimi.dsi.fastutil.ints.IntOpenHashSet

All Implemented Interfaces:

it.unimi.dsi.fastutil.Hash, it.unimi.dsi.fastutil.ints.IntCollection, it.unimi.dsi.fastutil.ints.IntIterable, IntSet, java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<java.lang.Integer>, java.util.Collection<java.lang.Integer>, java.util.Set<java.lang.Integer>

public class IntOpenHashSet
extends AbstractIntSet
implements java.io.Serializable, java.lang.Cloneable, it.unimi.dsi.fastutil.Hash

A type-specific hash set with with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a set. The table is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size; however, the table is never reduced to a size smaller than that at creation time: this approach makes it possible to create sets with a large capacity in which insertions and deletions do not cause immediately rehashing. Moreover, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.

Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash

it.unimi.dsi.fastutil.Hash.Strategy<K>

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	containsNull Whether this set contains the null key.
protected float	f The acceptable load factor.
protected int[]	key The array of keys.
protected int	mask The mask for wrapping a position counter.
protected int	maxFill Threshold after which we rehash.
protected int	minN We never resize below this threshold, which is the construction-time {#n}.
protected int	n The current table size.
protected int	size Number of entries in the set (including the null key, if present).

Fields inherited from interface it.unimi.dsi.fastutil.Hash

DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR

Constructor Summary

Constructors

Constructor and Description
IntOpenHashSet() Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
IntOpenHashSet(java.util.Collection<? extends java.lang.Integer> c) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
IntOpenHashSet(java.util.Collection<? extends java.lang.Integer> c, float f) Creates a new hash set copying a given collection.
IntOpenHashSet(int expected) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
IntOpenHashSet(int[] a) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
IntOpenHashSet(int[] a, float f) Creates a new hash set copying the elements of an array.
IntOpenHashSet(int[] a, int offset, int length) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
IntOpenHashSet(int[] a, int offset, int length, float f) Creates a new hash set and fills it with the elements of a given array.
IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntCollection c) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntCollection c, float f) Creates a new hash set copying a given type-specific collection.
IntOpenHashSet(int expected, float f) Creates a new hash set.
IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntIterator i) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntIterator i, float f) Creates a new hash set using elements provided by a type-specific iterator.
IntOpenHashSet(java.util.Iterator<?> i) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator.
IntOpenHashSet(java.util.Iterator<?> i, float f) Creates a new hash set using elements provided by an iterator.

Method Summary

Modifier and Type	Method and Description
boolean	add(int k)
boolean	addAll(java.util.Collection<? extends java.lang.Integer> c)
boolean	addAll(it.unimi.dsi.fastutil.ints.IntCollection c)
void	clear()
IntOpenHashSet	clone() Returns a deep copy of this set.
boolean	contains(int k)
void	ensureCapacity(int capacity) Ensures that this set can hold a certain number of elements without rehashing.
void	forEach(java.util.function.IntConsumer action)
int	hashCode() Returns a hash code for this set.
boolean	isEmpty()
it.unimi.dsi.fastutil.ints.IntIterator	iterator() Returns a type-specific iterator on the elements of this set.
static IntOpenHashSet	of() Creates a new empty hash set.
static IntOpenHashSet	of(int... a) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using a list of elements.
static IntOpenHashSet	of(int e) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the given element.
static IntOpenHashSet	of(int e0, int e1) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements given.
static IntOpenHashSet	of(int e0, int e1, int e2) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements given.
protected void	rehash(int newN) Rehashes the set.
boolean	remove(int k) Removes an element from this set.
protected void	shiftKeys(int pos) Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
int	size()
it.unimi.dsi.fastutil.ints.IntSpliterator	spliterator() Returns a type-specific spliterator on the elements of this set.
static IntOpenHashSet	toSet(java.util.stream.IntStream stream) Collects the result of a primitive Stream into a new hash set.
static IntOpenHashSet	toSetWithExpectedSize(java.util.stream.IntStream stream, int expectedSize) Collects the result of a primitive Stream into a new hash set, potentially pre-allocated to handle the given size.
boolean	trim() Rehashes this set, making the table as small as possible.
boolean	trim(int n) Rehashes this set if the table is too large.

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntSet

equals, rem

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntCollection

add, contains, containsAll, containsAll, forEach, remove, removeAll, removeAll, removeIf, retainAll, retainAll, toArray, toIntArray, toIntArray, toString

Methods inherited from class java.util.AbstractCollection

toArray, toArray

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntSet

add, contains, remove

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntCollection

containsAll, intIterator, intParallelStream, intSpliterator, intStream, parallelStream, removeAll, removeIf, removeIf, removeIf, retainAll, stream, toArray, toIntArray, toIntArray

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntIterable

forEach, forEach

Methods inherited from interface java.util.Set

containsAll, removeAll, retainAll, toArray, toArray

Field Detail

key

protected transient int[] key

The array of keys.

mask

protected transient int mask

The mask for wrapping a position counter.

containsNull

protected transient boolean containsNull

Whether this set contains the null key.

n

protected transient int n

The current table size. Note that an additional element is allocated for storing the null key.

maxFill

protected transient int maxFill

Threshold after which we rehash. It must be the table size times f.

minN

protected final transient int minN

We never resize below this threshold, which is the construction-time {#n}.

size

protected int size

Number of entries in the set (including the null key, if present).

f

protected final float f

The acceptable load factor.

Constructor Detail

IntOpenHashSet

public IntOpenHashSet(int expected,
                      float f)

Creates a new hash set.

The actual table size will be the least power of two greater than expected/f.

Parameters:

expected - the expected number of elements in the hash set.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(int expected)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

expected - the expected number of elements in the hash set.

IntOpenHashSet

public IntOpenHashSet()

Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.

IntOpenHashSet

public IntOpenHashSet(java.util.Collection<? extends java.lang.Integer> c,
                      float f)

Creates a new hash set copying a given collection.

Parameters:

c - a Collection to be copied into the new hash set.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(java.util.Collection<? extends java.lang.Integer> c)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.

Parameters:

c - a Collection to be copied into the new hash set.

IntOpenHashSet

public IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntCollection c,
                      float f)

Creates a new hash set copying a given type-specific collection.

Parameters:

c - a type-specific collection to be copied into the new hash set.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntCollection c)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.

Parameters:

c - a type-specific collection to be copied into the new hash set.

IntOpenHashSet

public IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntIterator i,
                      float f)

Creates a new hash set using elements provided by a type-specific iterator.

Parameters:

i - a type-specific iterator whose elements will fill the set.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(it.unimi.dsi.fastutil.ints.IntIterator i)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.

Parameters:

i - a type-specific iterator whose elements will fill the set.

IntOpenHashSet

public IntOpenHashSet(java.util.Iterator<?> i,
                      float f)

Creates a new hash set using elements provided by an iterator.

Parameters:

i - an iterator whose elements will fill the set.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(java.util.Iterator<?> i)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator.

Parameters:

i - an iterator whose elements will fill the set.

IntOpenHashSet

public IntOpenHashSet(int[] a,
                      int offset,
                      int length,
                      float f)

Creates a new hash set and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the set.

offset - the first element to use.

length - the number of elements to use.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(int[] a,
                      int offset,
                      int length)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the set.

offset - the first element to use.

length - the number of elements to use.

IntOpenHashSet

public IntOpenHashSet(int[] a,
                      float f)

Creates a new hash set copying the elements of an array.

Parameters:

a - an array to be copied into the new hash set.

f - the load factor.

IntOpenHashSet

public IntOpenHashSet(int[] a)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.

Parameters:

a - an array to be copied into the new hash set.

Method Detail

of

public static IntOpenHashSet of()

Creates a new empty hash set.

Specified by:

of in interface IntSet

Returns:

a new empty hash set.

of

public static IntOpenHashSet of(int e)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the given element.

Specified by:

of in interface IntSet

Parameters:

e - the element that the returned set will contain.

Returns:

a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor containing e.

of

public static IntOpenHashSet of(int e0,
                                int e1)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements given.

Specified by:

of in interface IntSet

Parameters:

e0 - the first element.

e1 - the second element.

Returns:

a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor containing e0 and e1.

Throws:

java.lang.IllegalArgumentException - if there were duplicate entries.

of

public static IntOpenHashSet of(int e0,
                                int e1,
                                int e2)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements given.

Specified by:

of in interface IntSet

Parameters:

e0 - the first element.

e1 - the second element.

e2 - the third element.

Returns:

a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor containing e0, e1, and e2.

Throws:

java.lang.IllegalArgumentException - if there were duplicate entries.

of

public static IntOpenHashSet of(int... a)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using a list of elements.

Specified by:

of in interface IntSet

Parameters:

a - a list of elements that will be used to initialize the new hash set.

Returns:

a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor containing the elements of a.

Throws:

java.lang.IllegalArgumentException - if a duplicate entry was encountered.

toSet

public static IntOpenHashSet toSet(java.util.stream.IntStream stream)

Collects the result of a primitive Stream into a new hash set.

This method performs a terminal operation on the given Stream

toSetWithExpectedSize

public static IntOpenHashSet toSetWithExpectedSize(java.util.stream.IntStream stream,
                                                   int expectedSize)

Collects the result of a primitive Stream into a new hash set, potentially pre-allocated to handle the given size.

This method performs a terminal operation on the given Stream

ensureCapacity

public void ensureCapacity(int capacity)

Ensures that this set can hold a certain number of elements without rehashing.

Parameters:

capacity - a number of elements; there will be no rehashing unless the set size exceeds this number.

addAll

public boolean addAll(it.unimi.dsi.fastutil.ints.IntCollection c)

Specified by:

addAll in interface it.unimi.dsi.fastutil.ints.IntCollection

Overrides:

addAll in class it.unimi.dsi.fastutil.ints.AbstractIntCollection

addAll

public boolean addAll(java.util.Collection<? extends java.lang.Integer> c)

Specified by:

addAll in interface java.util.Collection<java.lang.Integer>

Specified by:

addAll in interface java.util.Set<java.lang.Integer>

Overrides:

addAll in class it.unimi.dsi.fastutil.ints.AbstractIntCollection

add

public boolean add(int k)

Specified by:

add in interface it.unimi.dsi.fastutil.ints.IntCollection

Overrides:

add in class it.unimi.dsi.fastutil.ints.AbstractIntCollection

shiftKeys

protected final void shiftKeys(int pos)

Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.

Parameters:

pos - a starting position.

remove

public boolean remove(int k)

Description copied from class: AbstractIntSet

Removes an element from this set. Delegates to the type-specific rem() method implemented by type-specific abstract Collection superclass.

Specified by:

remove in interface IntSet

Overrides:

remove in class AbstractIntSet

See Also:

Collection.remove(Object)

contains

public boolean contains(int k)

Specified by:

contains in interface it.unimi.dsi.fastutil.ints.IntCollection

Overrides:

contains in class it.unimi.dsi.fastutil.ints.AbstractIntCollection

clear

public void clear()

Specified by:

clear in interface java.util.Collection<java.lang.Integer>

Specified by:

clear in interface java.util.Set<java.lang.Integer>

Overrides:

clear in class java.util.AbstractCollection<java.lang.Integer>

size

public int size()

Specified by:

size in interface java.util.Collection<java.lang.Integer>

Specified by:

size in interface java.util.Set<java.lang.Integer>

Specified by:

size in class java.util.AbstractCollection<java.lang.Integer>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Collection<java.lang.Integer>

Specified by:

isEmpty in interface java.util.Set<java.lang.Integer>

Overrides:

isEmpty in class java.util.AbstractCollection<java.lang.Integer>

iterator

public it.unimi.dsi.fastutil.ints.IntIterator iterator()

Description copied from interface: IntSet

Returns a type-specific iterator on the elements of this set.

Specified by:

iterator in interface it.unimi.dsi.fastutil.ints.IntCollection

Specified by:

iterator in interface it.unimi.dsi.fastutil.ints.IntIterable

Specified by:

iterator in interface IntSet

Specified by:

iterator in interface java.lang.Iterable<java.lang.Integer>

Specified by:

iterator in interface java.util.Collection<java.lang.Integer>

Specified by:

iterator in interface java.util.Set<java.lang.Integer>

Specified by:

iterator in class AbstractIntSet

Returns:

a type-specific iterator on the elements of this set.

spliterator

public it.unimi.dsi.fastutil.ints.IntSpliterator spliterator()

Description copied from interface: IntSet

Returns a type-specific spliterator on the elements of this set.

Set spliterators must report at least Spliterator.DISTINCT.

See Set.spliterator() for more documentation on the requirements of the returned spliterator.

Specified by:

spliterator in interface it.unimi.dsi.fastutil.ints.IntCollection

Specified by:

spliterator in interface it.unimi.dsi.fastutil.ints.IntIterable

Specified by:

spliterator in interface IntSet

Specified by:

spliterator in interface java.lang.Iterable<java.lang.Integer>

Specified by:

spliterator in interface java.util.Collection<java.lang.Integer>

Specified by:

spliterator in interface java.util.Set<java.lang.Integer>

Returns:

forEach

public void forEach(java.util.function.IntConsumer action)

Specified by:

forEach in interface it.unimi.dsi.fastutil.ints.IntIterable

trim

public boolean trim()

Rehashes this set, making the table as small as possible.

This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

If the table size is already the minimum possible, this method does nothing.

Returns:

true if there was enough memory to trim the set.

See Also:

trim(int)

trim

public boolean trim(int n)

Rehashes this set if the table is too large.

Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this set in a table of size N.

This method is useful when reusing sets. Clearing a set leaves the table size untouched. If you are reusing a set many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient sets.

Parameters:

n - the threshold for the trimming.

Returns:

true if there was enough memory to trim the set.

See Also:

trim()

rehash

protected void rehash(int newN)

Rehashes the set.

This method implements the basic rehashing strategy, and may be overriden by subclasses implementing different rehashing strategies (e.g., disk-based rehashing). However, you should not override this method unless you understand the internal workings of this class.

Parameters:

newN - the new size

clone

public IntOpenHashSet clone()

Returns a deep copy of this set.

This method performs a deep copy of this hash set; the data stored in the set, however, is not cloned. Note that this makes a difference only for object keys.

Overrides:

clone in class java.lang.Object

Returns:

a deep copy of this set.

hashCode

public int hashCode()

Returns a hash code for this set. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.

Specified by:

hashCode in interface java.util.Collection<java.lang.Integer>

Specified by:

hashCode in interface java.util.Set<java.lang.Integer>

Overrides:

hashCode in class AbstractIntSet

Returns:

a hash code for this set.