Package arc.struct

Class ObjectSet<T>

java.lang.Object

arc.struct.ObjectSet<T>

All Implemented Interfaces:

Eachable<T>, Iterable<T>

Direct Known Subclasses:

OrderedSet

public class ObjectSet<T>
extends Object
implements Iterable<T>, Eachable<T>

An unordered set where the keys are objects. This implementation uses cuckoo hashing using 3 hashes, random walking, and a small stash for problematic keys. Null keys are not allowed. No allocation is done except when growing the table size.

This set performs very fast contains and remove (typically O(1), worst case O(log(n))). Add may be a bit slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the set will have to rehash to the next higher POT size.

Iteration can be very slow for a set with a large capacity. clear(int) and shrink(int) can be used to reduce the capacity. OrderedSet provides much faster iteration.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	ObjectSet.ObjectSetIterator

Field Summary

Fields

Modifier and Type	Field	Description
int	size

Constructor Summary

Constructors

Constructor	Description
ObjectSet()	Creates a new set with an initial capacity of 51 and a load factor of 0.8.
ObjectSet(int initialCapacity)	Creates a new set with a load factor of 0.8.
ObjectSet(int initialCapacity, float loadFactor)	Creates a new set with the specified initial capacity and load factor.
ObjectSet(ObjectSet set)	Creates a new set identical to the specified set.

Method Summary

Modifier and Type	Method	Description
boolean	add(T key)	Returns true if the key was not already in the set.
void	addAll(ObjectSet<T> set)
void	addAll(Seq<? extends T> array)
void	addAll(Seq<? extends T> array, int offset, int length)
void	addAll(T... array)
void	addAll(T[] array, int offset, int length)
void	clear()	Clears the set, leaving the backing arrays at the current capacity.
void	clear(int maximumCapacity)	Clears the set and reduces the size of the backing arrays to be the specified capacity, if they are larger.
boolean	contains(T key)
void	each(Cons<? super T> cons)
void	ensureCapacity(int additionalCapacity)	Increases the size of the backing array to accommodate the specified number of additional items.
boolean	equals(Object obj)
T	first()
T	get(T key)
int	hashCode()
boolean	isEmpty()	Returns true if the set is empty.
ObjectSet<T>.ObjectSetIterator	iterator()	Returns an iterator for the keys in the set.
boolean	remove(T key)	Returns true if the key was removed.
void	removeAll(Seq<? extends T> array)
void	removeAll(T[] array)
void	removeAll(T[] array, int offset, int length)
ObjectSet<T>	select(Boolf<T> predicate)	Allocates a new set with all elements that match the predicate.
void	shrink(int maximumCapacity)	Reduces the size of the backing arrays to be the specified capacity or less.
Seq<T>	toSeq()
String	toString()
String	toString(String separator)
static <T> ObjectSet<T>	with(Seq<T> array)
static <T> ObjectSet<T>	with(T... array)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Details

size

public int size

Constructor Details

ObjectSet

public ObjectSet()

Creates a new set with an initial capacity of 51 and a load factor of 0.8.

ObjectSet

public ObjectSet(int initialCapacity)

Creates a new set with a load factor of 0.8.

Parameters:

initialCapacity - If not a power of two, it is increased to the next nearest power of two.

ObjectSet

public ObjectSet(int initialCapacity,
 float loadFactor)

Creates a new set with the specified initial capacity and load factor. This set will hold initialCapacity items before growing the backing table.

Parameters:

initialCapacity - If not a power of two, it is increased to the next nearest power of two.

ObjectSet

public ObjectSet(ObjectSet set)

Creates a new set identical to the specified set.

Method Details

with

public static <T> ObjectSet<T> with(T... array)

with

public static <T> ObjectSet<T> with(Seq<T> array)

select

public ObjectSet<T> select(Boolf<T> predicate)

Allocates a new set with all elements that match the predicate.

toSeq

public Seq<T> toSeq()

each

public void each(Cons<? super T> cons)

Specified by:

each in interface Eachable<T>

add

public boolean add(T key)

Returns true if the key was not already in the set. If this set already contains the key, the call leaves the set unchanged and returns false.

addAll

public void addAll(Seq<? extends T> array)

addAll

public void addAll(Seq<? extends T> array,
 int offset,
 int length)

addAll

public void addAll(T... array)

addAll

public void addAll(T[] array,
 int offset,
 int length)

addAll

public void addAll(ObjectSet<T> set)

removeAll

public void removeAll(T[] array,
 int offset,
 int length)

removeAll

public void removeAll(T[] array)

removeAll

public void removeAll(Seq<? extends T> array)

remove

public boolean remove(T key)

Returns true if the key was removed.

isEmpty

public boolean isEmpty()

Returns true if the set is empty.

shrink

public void shrink(int maximumCapacity)

Reduces the size of the backing arrays to be the specified capacity or less. If the capacity is already less, nothing is done. If the set contains more items than the specified capacity, the next highest power of two capacity is used instead.

clear

public void clear(int maximumCapacity)

Clears the set and reduces the size of the backing arrays to be the specified capacity, if they are larger. The reduction is done by allocating new arrays, though for large arrays this can be faster than clearing the existing array.

clear

public void clear()

Clears the set, leaving the backing arrays at the current capacity. When the capacity is high and the population is low, iteration can be unnecessarily slow. clear(int) can be used to reduce the capacity.

contains

public boolean contains(T key)

get

public T get(T key)

Returns:

May be null.

first

public T first()

ensureCapacity

public void ensureCapacity(int additionalCapacity)

Increases the size of the backing array to accommodate the specified number of additional items. Useful before adding many items to avoid multiple backing array resizes.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

toString

public String toString(String separator)

iterator

public ObjectSet<T>.ObjectSetIterator iterator()

Returns an iterator for the keys in the set. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use the ObjectSet<T>.ObjectSetIterator constructor for nested or multithreaded iteration.

Specified by:

iterator in interface Iterable<T>