it.unimi.dsi.fastutil.chars
Class CharLinkedOpenHashSet

java.lang.Object
  extended byit.unimi.dsi.fastutil.chars.AbstractCharCollection
      extended byit.unimi.dsi.fastutil.chars.AbstractCharSet
          extended byit.unimi.dsi.fastutil.chars.AbstractCharSortedSet
              extended byit.unimi.dsi.fastutil.chars.CharLinkedOpenHashSet
All Implemented Interfaces:
CharCollection, CharSet, CharSortedSet, Cloneable, Collection, Hash, Serializable, Set, SortedSet

public class CharLinkedOpenHashSet
extends AbstractCharSortedSet
implements Serializable, Cloneable, Hash, CharSortedSet

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 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).

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 AbstractCharSortedSet.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.

The iterators provided by this class are type-specific list iterators. However, creation of an iterator using a starting point is going to be very expensive, as the chosen starting point must be linearly searched for, unless it is AbstractCharSortedSet.last(), in which case the iterator is created in constant time.

Note that deletions in a linked table require scanning the list until the element to be removed is found. The only exceptions are the first element, the last element, and deletions performed using an iterator.

See Also:
Hash, HashCommon, Serialized Form

Nested Class Summary
 
Nested classes inherited from class it.unimi.dsi.fastutil.Hash
Hash.Strategy
 
Field Summary
static long serialVersionUID
           
 
Fields inherited from interface it.unimi.dsi.fastutil.Hash
DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED
 
Constructor Summary
CharLinkedOpenHashSet()
          Creates a new hash set with Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
CharLinkedOpenHashSet(char[] a)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
CharLinkedOpenHashSet(char[] a, float f)
          Creates a new set copying the elements of an array.
CharLinkedOpenHashSet(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.
CharLinkedOpenHashSet(char[] a, int offset, int length, float f)
          Creates a new hash set and fills it with the elements of a given array.
CharLinkedOpenHashSet(CharCollection c)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
CharLinkedOpenHashSet(CharCollection c, float f)
          Creates a new hash set copying a given type-specific collection.
CharLinkedOpenHashSet(CharIterator i)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
CharLinkedOpenHashSet(CharIterator i, float f)
          Creates a new hash set using elements provided by a type-specific iterator.
CharLinkedOpenHashSet(Collection c)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
CharLinkedOpenHashSet(Collection c, float f)
          Creates a new hash set copying a given collection.
CharLinkedOpenHashSet(int n)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
CharLinkedOpenHashSet(int n, float f)
          Creates a new hash set.
CharLinkedOpenHashSet(Iterator i)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator.
CharLinkedOpenHashSet(Iterator i, float f)
          Creates a new hash set using elements provided by an iterator.
 
Method Summary
 boolean add(char k)
           
 CharIterator charIterator()
          Returns a type-specific list iterator on the elements in this set, starting from the first element.
 void clear()
           
 Object clone()
          Returns a deep copy of this set.
 Comparator comparator()
           
 boolean contains(char k)
           
 char firstChar()
          Returns the first element of this set in iteration order.
 int growthFactor()
          Gets the growth factor.
 void growthFactor(int growthFactor)
          Sets the growth factor.
 int hashCode()
          Returns a hash code for this set.
 CharSortedSet headSet(char to)
           
 boolean isEmpty()
           
 CharBidirectionalIterator iterator(char from)
          Returns a type-specific list iterator on the elements in this set, starting from a given element of the set.
 char lastChar()
          Returns the last element of this set in iteration order.
 boolean rehash()
          Rehashes this set without changing the table size.
 boolean remove(char k)
          Note that the corresponding method of the type-specific collection is rem().
 int size()
           
 CharSortedSet subSet(char from, char to)
           
 CharSortedSet tailSet(char from)
           
 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.AbstractCharSortedSet
first, headSet, last, subSet, tailSet
 
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, contains, containsAll, containsAll, iterator, 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 java.util.Set
add, addAll, contains, containsAll, equals, iterator, remove, removeAll, retainAll, toArray, toArray
 
Methods inherited from interface it.unimi.dsi.fastutil.chars.CharCollection
addAll, containsAll, rem, removeAll, retainAll, toArray, toCharArray, toCharArray
 
Methods inherited from interface java.util.SortedSet
first, headSet, last, subSet, tailSet
 

Field Detail

serialVersionUID

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

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

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


CharLinkedOpenHashSet

public CharLinkedOpenHashSet(Collection 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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(Collection 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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(char[] a,
                             float f)
Creates a new set copying the elements of an array.

Parameters:
a - an array to be copied into the new hash set.
f - the load factor.

CharLinkedOpenHashSet

public CharLinkedOpenHashSet(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

remove

public boolean remove(char k)
Description copied from interface: CharSet
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

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 Set
Overrides:
clear in class AbstractCharCollection

firstChar

public final char firstChar()
Returns the first element of this set in iteration order.

Specified by:
firstChar in interface CharSortedSet
Returns:
the first element in iteration order.
See Also:
SortedSet.first()

lastChar

public final char lastChar()
Returns the last element of this set in iteration order.

Specified by:
lastChar in interface CharSortedSet
Returns:
the last element in iteration order.
See Also:
SortedSet.last()

tailSet

public final CharSortedSet tailSet(char from)
Specified by:
tailSet in interface CharSortedSet
See Also:
SortedSet.tailSet(Object)

headSet

public final CharSortedSet headSet(char to)
Specified by:
headSet in interface CharSortedSet
See Also:
SortedSet.headSet(Object)

subSet

public final CharSortedSet subSet(char from,
                                  char to)
Specified by:
subSet in interface CharSortedSet
See Also:
SortedSet.subSet(Object,Object)

comparator

public final Comparator comparator()
Specified by:
comparator in interface SortedSet

iterator

public CharBidirectionalIterator iterator(char from)
Returns a type-specific list iterator on the elements in this set, starting from a given element of the set.

This method provides an iterator positioned immediately after the given element. That is, the next call to previous() will return from, whereas the next call to next() will return the element immediately after from. This allows to call iterator(last()) and obtain an iterator starting from the end of the iteration order.

Because of the way linking is implemented, generating an iterator using this method requires constant time only if the argument is last(). In all other cases, a linear search for the given element will be necessary.

Note that this method returns a bidirectional iterator, which, however, can be safely cast to a type-specific list iterator.

Specified by:
iterator in interface CharSortedSet
Overrides:
iterator in class AbstractCharSet
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.

charIterator

public CharIterator charIterator()
Returns a type-specific list iterator on the elements in this set, starting from the first element.

Note that this method returns a bidirectional iterator, which, however, can be safely cast to a type-specific list iterator.

Specified by:
charIterator in interface CharCollection
Returns:
a type-specific list iterator.
See Also:
Collection.iterator()

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 optimise 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 n entries, still satisfying the load factor. If the current table size is smaller than or equal to N, or if the number of elements of this set is larger than 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 Set

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Set
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.

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 Set
Overrides:
hashCode in class AbstractCharSet
Returns:
a hash code for this set.