it.unimi.dsi.fastutil.objects
Class ObjectLinkedOpenHashSet<K>

java.lang.Object
  java.util.AbstractCollection<K>
      it.unimi.dsi.fastutil.objects.AbstractObjectCollection<K>
          it.unimi.dsi.fastutil.objects.AbstractObjectSet<K>
              it.unimi.dsi.fastutil.objects.AbstractObjectSortedSet<K>
                  it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet<K>

All Implemented Interfaces:

Hash, ObjectCollection<K>, ObjectIterable<K>, ObjectSet<K>, ObjectSortedSet<K>, Serializable, Cloneable, Iterable<K>, Collection<K>, Set<K>, SortedSet<K>

public class ObjectLinkedOpenHashSet<K>
extends AbstractObjectSortedSet<K>
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 enlarged as needed by doubling its size when new entries are created, but it is never made smaller (even on a clear()). 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

static long

serialVersionUID

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

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

ObjectLinkedOpenHashSet(Collection<? extends K> c)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.

ObjectLinkedOpenHashSet(Collection<? extends K> c, float f)
Creates a new hash set copying a given collection.

ObjectLinkedOpenHashSet(int expected)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.

ObjectLinkedOpenHashSet(int expected, float f)
Creates a new hash set.

ObjectLinkedOpenHashSet(K[] a)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.

ObjectLinkedOpenHashSet(K[] a, float f)
Creates a new hash set copying the elements of an array.

ObjectLinkedOpenHashSet(K[] 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.

ObjectLinkedOpenHashSet(K[] a, int offset, int length, float f)
Creates a new hash set and fills it with the elements of a given array.

ObjectLinkedOpenHashSet(ObjectCollection<? extends K> c)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.

ObjectLinkedOpenHashSet(ObjectCollection<? extends K> c, float f)
Creates a new hash set copying a given type-specific collection.

ObjectLinkedOpenHashSet(ObjectIterator<K> i)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.

ObjectLinkedOpenHashSet(ObjectIterator<K> i, float f)
Creates a new hash set using elements provided by a type-specific iterator.

Method Summary

boolean	add(K k)
boolean	addAndMoveToFirst(K 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(K 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()
ObjectLinkedOpenHashSet<K>	clone() Returns a deep copy of this set.
Comparator<? super K>	comparator()
boolean	contains(Object k)
K	first() Returns the first element of this set in iteration order.
K	get(Object k) Returns the element of this set that is equal to the given key, or null.
int	growthFactor() Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
void	growthFactor(int growthFactor) Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
int	hashCode() Returns a hash code for this set.
ObjectSortedSet<K>	headSet(K to) Returns a view of the portion of this sorted set whose elements are strictly less than toElement.
boolean	isEmpty()
ObjectListIterator<K>	iterator() Returns a type-specific iterator on the elements of this collection.
ObjectListIterator<K>	iterator(K from) Returns a type-specific list iterator on the elements in this set, starting from a given element of the set.
K	last() Returns the last element of this set in iteration order.
boolean	rehash() Deprecated. A no-op.
boolean	remove(Object k) Removes an element from this set.
K	removeFirst() Removes the first key in iteration order.
K	removeLast() Removes the the last key in iteration order.
int	size()
ObjectSortedSet<K>	subSet(K from, K to) Returns a view of the portion of this sorted set whose elements range from fromElement, inclusive, to toElement, exclusive.
ObjectSortedSet<K>	tailSet(K from) Returns a view of the portion of this sorted set whose elements are greater than or equal to fromElement.
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.objects.AbstractObjectSortedSet

objectIterator

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectSet

equals

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectCollection

addAll, containsAll, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.objects.ObjectCollection

toArray

Methods inherited from interface java.util.Set

addAll, containsAll, equals, removeAll, retainAll, toArray, toArray

Field Detail

serialVersionUID

public static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet()

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

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(Collection<? extends K> 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(Collection<? extends K> 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(ObjectCollection<? extends K> 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(ObjectCollection<? extends K> 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(ObjectIterator<K> 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(ObjectIterator<K> 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(K[] 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(K[] 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(K[] 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.

ObjectLinkedOpenHashSet

public ObjectLinkedOpenHashSet(K[] 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

add

public boolean add(K k)

Specified by:

add in interface Collection<K>

Specified by:

add in interface Set<K>

Overrides:

add in class AbstractObjectCollection<K>

remove

public boolean remove(Object k)

Description copied from interface: ObjectSet

Removes an element from this set.

Note that the corresponding method of the type-specific collection is rem(). This unfortunate situation is caused by the clash with the similarly named index-based method in the List interface.

Specified by:

remove in interface ObjectSet<K>

Specified by:

remove in interface Collection<K>

Specified by:

remove in interface Set<K>

Overrides:

remove in class AbstractObjectSet<K>

See Also:

Collection.remove(Object)

contains

public boolean contains(Object k)

Specified by:

contains in interface Collection<K>

Specified by:

contains in interface Set<K>

Overrides:

contains in class AbstractCollection<K>

get

public K get(Object k)

Returns the element of this set that is equal to the given key, or null.

Returns:

the element of this set that is equal to the given key, or null.

removeFirst

public K removeFirst()

Removes the first key in iteration order.

Returns:

the first key.

Throws:

NoSuchElementException - is this set is empty.

removeLast

public K removeLast()

Removes the the last key in iteration order.

Returns:

the last key.

Throws:

NoSuchElementException - is this set is empty.

addAndMoveToFirst

public boolean addAndMoveToFirst(K 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(K 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<K>

Specified by:

clear in interface Set<K>

Overrides:

clear in class AbstractCollection<K>

size

public int size()

Specified by:

size in interface Collection<K>

Specified by:

size in interface Set<K>

Specified by:

size in class AbstractCollection<K>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<K>

Specified by:

isEmpty in interface Set<K>

Overrides:

isEmpty in class AbstractObjectCollection<K>

growthFactor

@Deprecated
public void growthFactor(int growthFactor)

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

A no-op for backward compatibility.

Parameters:

growthFactor - unused.

growthFactor

@Deprecated
public int growthFactor()

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

Gets the growth factor (2).

Returns:

the growth factor of this set, which is fixed (2).

See Also:

growthFactor(int)

first

public K first()

Returns the first element of this set in iteration order.

Specified by:

first in interface SortedSet<K>

Returns:

the first element in iteration order.

last

public K last()

Returns the last element of this set in iteration order.

Specified by:

last in interface SortedSet<K>

Returns:

the last element in iteration order.

tailSet

public ObjectSortedSet<K> tailSet(K from)

Description copied from interface: ObjectSortedSet

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

Note that this specification strengthens the one given in SortedSet.tailSet(Object).

Specified by:

tailSet in interface ObjectSortedSet<K>

Specified by:

tailSet in interface SortedSet<K>

See Also:

SortedSet.tailSet(Object)

headSet

public ObjectSortedSet<K> headSet(K to)

Description copied from interface: ObjectSortedSet

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

Note that this specification strengthens the one given in SortedSet.headSet(Object).

Specified by:

headSet in interface ObjectSortedSet<K>

Specified by:

headSet in interface SortedSet<K>

See Also:

SortedSet.headSet(Object)

subSet

public ObjectSortedSet<K> subSet(K from,
                                 K to)

Description copied from interface: ObjectSortedSet

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

Note that this specification strengthens the one given in SortedSet.subSet(Object,Object).

Specified by:

subSet in interface ObjectSortedSet<K>

Specified by:

subSet in interface SortedSet<K>

See Also:

SortedSet.subSet(Object,Object)

comparator

public Comparator<? super K> comparator()

Specified by:

comparator in interface SortedSet<K>

iterator

public ObjectListIterator<K> iterator(K 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 ObjectSortedSet<K>

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 ObjectListIterator<K> iterator()

Description copied from interface: ObjectCollection

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

Note that this specification strengthens the one given in Iterable.iterator(), which was already strengthened in the corresponding type-specific class, but was weakened by the fact that this interface extends Collection.

Specified by:

iterator in interface ObjectCollection<K>

Specified by:

iterator in interface ObjectIterable<K>

Specified by:

iterator in interface ObjectSet<K>

Specified by:

iterator in interface ObjectSortedSet<K>

Specified by:

iterator in interface Iterable<K>

Specified by:

iterator in interface Collection<K>

Specified by:

iterator in interface Set<K>

Specified by:

iterator in class AbstractObjectSortedSet<K>

Returns:

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

rehash

@Deprecated
public boolean rehash()

Deprecated. A no-op.

A no-op for backward compatibility. The kind of tables implemented by this class never need rehashing.

If you need to reduce the table size to fit exactly this set, use trim().

Returns:

true.

See Also:

trim()

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 ObjectLinkedOpenHashSet<K> 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 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 Collection<K>

Specified by:

hashCode in interface Set<K>

Overrides:

hashCode in class AbstractObjectSet<K>

Returns:

a hash code for this set.