Package it.unimi.dsi.fastutil.ints

Class IntLinkedOpenHashSet

java.lang.Object

java.util.AbstractCollection<Integer>

it.unimi.dsi.fastutil.ints.AbstractIntCollection

it.unimi.dsi.fastutil.ints.AbstractIntSet

it.unimi.dsi.fastutil.ints.AbstractIntSortedSet

it.unimi.dsi.fastutil.ints.IntLinkedOpenHashSet

All Implemented Interfaces:

Hash, IntBidirectionalIterable, IntCollection, IntIterable, IntSet, IntSortedSet, Serializable, Cloneable, Iterable<Integer>, Collection<Integer>, Set<Integer>, SortedSet<Integer>

public class IntLinkedOpenHashSet
extends AbstractIntSortedSet
implements Serializable, Cloneable, Hash

A type-specific linked 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.

Iterators generated by this set will enumerate elements in the same order in which they have been added to the set (addition of elements already present in the set does not change the iteration order). Note that this order has nothing in common with the natural order of the keys. The order is kept by means of a doubly linked list, represented via an array of longs parallel to the table.

This class implements the interface of a sorted set, so to allow easy access of the iteration order: for instance, you can get the first element in iteration order with first() without having to create an iterator; however, this class partially violates the SortedSet contract because all subset methods throw an exception and comparator() returns always null.

Additional methods, such as addAndMoveToFirst(), make it easy to use instances of this class as a cache (e.g., with LRU policy).

The iterators provided by this class are type-specific list iterators, and can be started at any element which is in the set (if the provided element is not in the set, a NoSuchElementException exception will be thrown). If, however, the provided element is not the first or last element in the set, the first access to the list index will require linear time, as in the worst case the entire set must be scanned in iteration order to retrieve the positional index of the starting element. If you use just the methods of a type-specific BidirectionalIterator, however, all operations will be performed in constant time.

See Also:

• Hash
• HashCommon
• Serialized Form

Nested Class Summary

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

Hash.Strategy<K>

Field Summary

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

Method Summary

Modifier and Type	Method	Description
boolean	add(int k)	Ensures that this collection contains the specified element (optional operation).
boolean	addAll(IntCollection c)	Adds all elements of the given type-specific collection to this collection.
boolean	addAll(Collection<? extends Integer> c)
boolean	addAndMoveToFirst(int k)	Adds a key to the set; if the key is already present, it is moved to the first position of the iteration order.
boolean	addAndMoveToLast(int k)	Adds a key to the set; if the key is already present, it is moved to the last position of the iteration order.
void	clear()
IntLinkedOpenHashSet	clone()	Returns a deep copy of this set.
IntComparator	comparator()
boolean	contains(int k)	Returns true if this collection contains the specified element.
void	ensureCapacity(int capacity)	Ensures that this set can hold a certain number of elements without rehashing.
int	firstInt()	Returns the first element of this set in iteration order.
void	forEach(IntConsumer action)	Performs the given action for each element of this type-specific Iterable until all elements have been processed or the action throws an exception.
int	hashCode()	Returns a hash code for this set.
IntSortedSet	headSet(int to)	Returns a view of the portion of this sorted set whose elements are strictly less than toElement.
boolean	isEmpty()
IntListIterator	iterator()	Returns a type-specific list iterator on the elements in this set, starting from the first element.
IntListIterator	iterator(int from)	Returns a type-specific list iterator on the elements in this set, starting from a given element of the set.
int	lastInt()	Returns the last element of this set in iteration order.
static IntLinkedOpenHashSet	of()	Creates a new empty hash set.
static IntLinkedOpenHashSet	of(int e)	Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the given element.
static IntLinkedOpenHashSet	of(int... a)	Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using a list of elements.
static IntLinkedOpenHashSet	of(int e0, int e1)	Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements given.
static IntLinkedOpenHashSet	of(int e0, int e1, int e2)	Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements given.
boolean	remove(int k)	Removes an element from this set.
int	removeFirstInt()	Removes the first key in iteration order.
int	removeLastInt()	Removes the the last key in iteration order.
int	size()
IntSpliterator	spliterator()	Returns a type-specific spliterator on the elements of this sorted-set.
IntSortedSet	subSet(int from, int to)	Returns a view of the portion of this sorted set whose elements range from fromElement, inclusive, to toElement, exclusive.
IntSortedSet	tailSet(int from)	Returns a view of the portion of this sorted set whose elements are greater than or equal to fromElement.
static IntLinkedOpenHashSet	toSet(IntStream stream)	Collects the result of a primitive Stream into a new hash set.
static IntLinkedOpenHashSet	toSetWithExpectedSize(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

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

toArray

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 it.unimi.dsi.fastutil.ints.IntSet

add, contains, rem, remove

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

first, headSet, last, subSet, tailSet

Methods inherited from interface java.util.Set

add, contains, containsAll, equals, remove, removeAll, retainAll, toArray, toArray

Constructor Details

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet()

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

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(Collection<? extends 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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(Collection<? extends 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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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.

IntLinkedOpenHashSet

public IntLinkedOpenHashSet(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 Details

of

public static IntLinkedOpenHashSet of()

Creates a new empty hash set.

Returns:

a new empty hash set.

of

public static IntLinkedOpenHashSet of(int e)

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

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 IntLinkedOpenHashSet of(int e0,
 int e1)

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

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:

IllegalArgumentException - if there were duplicate entries.

of

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

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

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:

IllegalArgumentException - if there were duplicate entries.

of

public static IntLinkedOpenHashSet of(int... a)

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

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:

IllegalArgumentException - if a duplicate entry was encountered.

toSet

public static IntLinkedOpenHashSet toSet(IntStream stream)

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

This method performs a terminal operation on the given Stream

API Notes:

Taking a primitive stream instead of returning something like a Collector is necessary because there is no primitive Collector equivalent in the Java API.

toSetWithExpectedSize

public static IntLinkedOpenHashSet toSetWithExpectedSize(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

API Notes:

Taking a primitive stream instead returning something like a Collector is necessary because there is no primitive Collector equivalent in the Java API.

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(IntCollection c)

Description copied from interface: IntCollection

Adds all elements of the given type-specific collection to this collection.

Specified by:

addAll in interface IntCollection

Overrides:

addAll in class AbstractIntCollection

Parameters:

c - a type-specific collection.

Returns:

true if this collection changed as a result of the call.

See Also:

• Collection.addAll(Collection)

addAll

public boolean addAll(Collection<? extends Integer> c)

Description copied from class: AbstractIntCollection

Specified by:

addAll in interface Collection<Integer>

Specified by:

addAll in interface Set<Integer>

Overrides:

addAll in class AbstractIntCollection

add

public boolean add(int k)

Description copied from class: AbstractIntCollection

Ensures that this collection contains the specified element (optional operation).

Specified by:

add in interface IntCollection

Overrides:

add in class AbstractIntCollection

See Also:

• Collection.add(Object)

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)

Description copied from class: AbstractIntCollection

Returns true if this collection contains the specified element.

Specified by:

contains in interface IntCollection

Overrides:

contains in class AbstractIntCollection

See Also:

• Collection.contains(Object)

removeFirstInt

public int removeFirstInt()

Removes the first key in iteration order.

Returns:

the first key.

Throws:

NoSuchElementException - is this set is empty.

removeLastInt

public int removeLastInt()

Removes the the last key in iteration order.

Returns:

the last key.

Throws:

NoSuchElementException - is this set is empty.

addAndMoveToFirst

public boolean addAndMoveToFirst(int k)

Adds a key to the set; if the key is already present, it is moved to the first position of the iteration order.

Parameters:

k - the key.

Returns:

true if the key was not present.

addAndMoveToLast

public boolean addAndMoveToLast(int k)

Adds a key to the set; if the key is already present, it is moved to the last position of the iteration order.

Parameters:

k - the key.

Returns:

true if the key was not present.

clear

public void clear()

Specified by:

clear in interface Collection<Integer>

Specified by:

clear in interface Set<Integer>

Overrides:

clear in class AbstractCollection<Integer>

size

public int size()

Specified by:

size in interface Collection<Integer>

Specified by:

size in interface Set<Integer>

Specified by:

size in class AbstractCollection<Integer>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<Integer>

Specified by:

isEmpty in interface Set<Integer>

Overrides:

isEmpty in class AbstractCollection<Integer>

firstInt

public int firstInt()

Returns the first element of this set in iteration order.

Specified by:

firstInt in interface IntSortedSet

Returns:

the first element in iteration order.

See Also:

• SortedSet.first()

lastInt

public int lastInt()

Returns the last element of this set in iteration order.

Specified by:

lastInt in interface IntSortedSet

Returns:

the last element in iteration order.

See Also:

• SortedSet.last()

tailSet

public IntSortedSet tailSet(int from)

Returns a view of the portion of this sorted set whose elements are greater than or equal to fromElement.

Specified by:

tailSet in interface IntSortedSet

See Also:

• SortedSet.tailSet(Object)

Implementation Specification:

This implementation just throws an UnsupportedOperationException.

headSet

public IntSortedSet headSet(int to)

Returns a view of the portion of this sorted set whose elements are strictly less than toElement.

Specified by:

headSet in interface IntSortedSet

See Also:

• SortedSet.headSet(Object)

Implementation Specification:

This implementation just throws an UnsupportedOperationException.

subSet

public IntSortedSet subSet(int from,
 int to)

Returns a view of the portion of this sorted set whose elements range from fromElement, inclusive, to toElement, exclusive.

Specified by:

subSet in interface IntSortedSet

See Also:

• SortedSet.subSet(Object,Object)

Implementation Specification:

This implementation just throws an UnsupportedOperationException.

comparator

public IntComparator comparator()

Specified by:

comparator in interface IntSortedSet

Specified by:

comparator in interface SortedSet<Integer>

Implementation Specification:

This implementation just returns null.

iterator

public IntListIterator iterator(int from)

Returns a type-specific list iterator on the elements in this set, starting from a given element of the set. Please see the class documentation for implementation details.

Specified by:

iterator in interface IntSortedSet

Parameters:

from - an element to start from.

Returns:

a type-specific list iterator starting at the given element.

Throws:

IllegalArgumentException - if from does not belong to the set.

iterator

public IntListIterator iterator()

Returns a type-specific list iterator on the elements in this set, starting from the first element. Please see the class documentation for implementation details.

Specified by:

iterator in interface Collection<Integer>

Specified by:

iterator in interface IntBidirectionalIterable

Specified by:

iterator in interface IntCollection

Specified by:

iterator in interface IntIterable

Specified by:

iterator in interface IntSet

Specified by:

iterator in interface IntSortedSet

Specified by:

iterator in interface Iterable<Integer>

Specified by:

iterator in interface Set<Integer>

Specified by:

iterator in class AbstractIntSortedSet

Returns:

a type-specific list iterator starting at the first element.

See Also:

• Iterable.iterator()

spliterator

public IntSpliterator spliterator()

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

SortedSet spliterators must report at least Spliterator.DISTINCT, Spliterator.ORDERED, and Spliterator.SORTED. The returned spliterator's getComparator() must be the same (or at the very least, consistent with) this instance's IntSortedSet.comparator().

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

There isn't a way to split efficiently while still preserving order for a linked data structure, so this implementation is just backed by the iterator. Thus, this spliterator is not well optimized for parallel streams.

Note, contrary to the specification of SortedSet, this spliterator does not, report Spliterator.SORTED. This is because iteration order is based on insertion order, not natural ordering.

Specified by:

spliterator in interface Collection<Integer>

Specified by:

spliterator in interface IntCollection

Specified by:

spliterator in interface IntIterable

Specified by:

spliterator in interface IntSet

Specified by:

spliterator in interface IntSortedSet

Specified by:

spliterator in interface Iterable<Integer>

Specified by:

spliterator in interface Set<Integer>

Specified by:

spliterator in interface SortedSet<Integer>

Returns:

a type-specific spliterator on the elements of this collection.

forEach

public void forEach(IntConsumer action)

Description copied from interface: IntIterable

Performs the given action for each element of this type-specific Iterable until all elements have been processed or the action throws an exception.

Specified by:

forEach in interface IntIterable

Parameters:

action - the action to be performed for each element.

See Also:

• Iterable.forEach(java.util.function.Consumer)

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()

clone

public IntLinkedOpenHashSet 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.

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 Collection<Integer>

Specified by:

hashCode in interface Set<Integer>

Overrides:

hashCode in class AbstractIntSet

Returns:

a hash code for this set.