it.unimi.dsi.fastutil.chars
Class CharOpenHashSet

java.lang.Object
  extended by it.unimi.dsi.fastutil.chars.AbstractCharCollection
      extended by it.unimi.dsi.fastutil.chars.AbstractCharSet
          extended by it.unimi.dsi.fastutil.chars.CharOpenHashSet
All Implemented Interfaces:
CharCollection, CharIterable, CharSet, Hash, Serializable, Cloneable, Iterable<Character>, Collection<Character>, Set<Character>

public class CharOpenHashSet
extends AbstractCharSet
implements Serializable, Cloneable, 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 enlarged as needed 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.

The enlargement speed is controlled by the growth factor, a positive number. If the growth factor is p, then the table is enlarged each time roughly by a factor 2p/16. By default, p is Hash.DEFAULT_GROWTH_FACTOR, which means that the table is doubled at each enlargement, but one can easily set more or less aggressive policies by calling growthFactor(int) (note that the growth factor is not serialized: deserialized tables gets the default growth factor).

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
CharOpenHashSet()
          Creates a new hash set with Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
CharOpenHashSet(char[] a)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
CharOpenHashSet(char[] a, float f)
          Creates a new hash set copying the elements of an array.
CharOpenHashSet(char[] 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.
CharOpenHashSet(char[] a, int offset, int length, float f)
          Creates a new hash set and fills it with the elements of a given array.
CharOpenHashSet(CharCollection c)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
CharOpenHashSet(CharCollection c, float f)
          Creates a new hash set copying a given type-specific collection.
CharOpenHashSet(CharIterator i)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
CharOpenHashSet(CharIterator i, float f)
          Creates a new hash set using elements provided by a type-specific iterator.
CharOpenHashSet(Collection<? extends Character> c)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
CharOpenHashSet(Collection<? extends Character> c, float f)
          Creates a new hash set copying a given collection.
CharOpenHashSet(int n)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
CharOpenHashSet(int n, float f)
          Creates a new hash set.
CharOpenHashSet(Iterator<?> i)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator.
CharOpenHashSet(Iterator<?> i, float f)
          Creates a new hash set using elements provided by an iterator.
 
Method Summary
 boolean add(char k)
           
 void clear()
           
 Object clone()
          Returns a deep copy of this set.
 boolean contains(char k)
           
 int growthFactor()
          Gets the growth factor.
 void growthFactor(int growthFactor)
          Sets the growth factor.
 int hashCode()
          Returns a hash code for this set.
 boolean isEmpty()
           
 CharIterator iterator()
          Returns a type-specific iterator on the elements of this collection.
 boolean rehash()
          Rehashes this set without changing the table size.
 boolean remove(char k)
          Removes an element from this set.
 int 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.chars.AbstractCharSet
equals, rem, remove
 
Methods inherited from class it.unimi.dsi.fastutil.chars.AbstractCharCollection
add, addAll, addAll, charIterator, contains, containsAll, containsAll, rem, removeAll, removeAll, retainAll, retainAll, toArray, toArray, toArray, toCharArray, toCharArray, toString
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.chars.CharCollection
addAll, charIterator, containsAll, removeAll, retainAll, toArray, toArray, toCharArray, toCharArray
 
Methods inherited from interface java.util.Set
add, addAll, contains, containsAll, removeAll, retainAll, toArray, toArray
 

Field Detail

serialVersionUID

public static final long serialVersionUID
See Also:
Constant Field Values
Constructor Detail

CharOpenHashSet

public CharOpenHashSet(int n,
                       float f)
Creates a new hash set. The actual table size is the least available prime greater than n/f.

Parameters:
n - the expected number of elements in the hash set.
f - the load factor.
See Also:
Hash.PRIMES

CharOpenHashSet

public CharOpenHashSet(int n)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:
n - the expected number of elements in the hash set.

CharOpenHashSet

public CharOpenHashSet()
Creates a new hash set with Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.


CharOpenHashSet

public CharOpenHashSet(Collection<? extends Character> 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.

CharOpenHashSet

public CharOpenHashSet(Collection<? extends Character> 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.

CharOpenHashSet

public CharOpenHashSet(CharCollection 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.

CharOpenHashSet

public CharOpenHashSet(CharCollection 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.

CharOpenHashSet

public CharOpenHashSet(CharIterator 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.

CharOpenHashSet

public CharOpenHashSet(CharIterator 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.

CharOpenHashSet

public CharOpenHashSet(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.

CharOpenHashSet

public CharOpenHashSet(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.

CharOpenHashSet

public CharOpenHashSet(char[] 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.

CharOpenHashSet

public CharOpenHashSet(char[] 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.

CharOpenHashSet

public CharOpenHashSet(char[] 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.

CharOpenHashSet

public CharOpenHashSet(char[] 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

growthFactor

public void growthFactor(int growthFactor)
Sets the growth factor. Subsequent enlargements will increase the table size roughly by a multiplicative factor of 2p/16.

Parameters:
growthFactor - the new growth factor; it must be positive.

growthFactor

public int growthFactor()
Gets the growth factor.

Returns:
the growth factor of this set.
See Also:
growthFactor(int)

add

public boolean add(char k)
Specified by:
add in interface CharCollection
Overrides:
add in class AbstractCharCollection
See Also:
Collection.add(Object)

remove

public boolean remove(char k)
Description copied from interface: CharSet
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 CharSet
Overrides:
remove in class AbstractCharSet
See Also:
Collection.remove(Object)

contains

public boolean contains(char k)
Specified by:
contains in interface CharCollection
See Also:
Collection.contains(Object)

clear

public void clear()
Specified by:
clear in interface Collection<Character>
Specified by:
clear in interface Set<Character>
Overrides:
clear in class AbstractCharCollection

iterator

public CharIterator iterator()
Description copied from interface: CharCollection
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 CharCollection
Specified by:
iterator in interface CharIterable
Specified by:
iterator in interface CharSet
Specified by:
iterator in interface Iterable<Character>
Specified by:
iterator in interface Collection<Character>
Specified by:
iterator in interface Set<Character>
Specified by:
iterator in class AbstractCharSet
Returns:
a type-specific iterator on the elements of this collection.

rehash

public boolean rehash()
Rehashes this set without changing the table size.

This method should be called when the set underwent numerous deletions and insertions. In this case, free entries become rare, and unsuccessful searches require probing all entries. For reasonable load factors this method is linear in the number of entries. You will need as much additional free memory as that occupied by the table.

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

Returns:
true if there was enough memory to rehash the set, false otherwise.
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 (by collecting deleted entries) and size.

If the table size is already the minimum possible, this method does nothing. If you want to guarantee rehashing, use rehash().

Returns:
true if there was enough memory to trim the set.
See Also:
trim(int), rehash()

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()

size

public int size()
Specified by:
size in interface Collection<Character>
Specified by:
size in interface Set<Character>

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Collection<Character>
Specified by:
isEmpty in interface Set<Character>
Overrides:
isEmpty in class AbstractCharCollection

clone

public Object 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<Character>
Specified by:
hashCode in interface Set<Character>
Overrides:
hashCode in class AbstractCharSet
Returns:
a hash code for this set.