it.unimi.dsi.fastutil.chars
Class CharLinkedOpenCustomHashSet

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

public class CharLinkedOpenCustomHashSet
extends AbstractCharSortedSet
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 created by this map 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.

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 set are very expensive, as they usually require scanning the list until the element to be removed and the elements shifted because of the removal are found.

Warning: The implementation of this class has significantly changed in fastutil 6.1.0. Please read the comments about this issue in the section “Faster Hash Tables” of the overview.

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
protected  float f
          The acceptable load factor.
protected  int first
          The index of the first entry in iteration order.
protected  char[] key
          The array of keys.
protected  int last
          The index of the last entry in iteration order.
protected  int[] link
          For each entry, the next and the previous entry in iteration order exclusive-or'd together.
protected  int mask
          The mask for wrapping a position counter.
protected  int maxFill
          Threshold after which we rehash.
protected  int n
          The current table size.
static long serialVersionUID
           
protected  int size
          Number of entries in the set.
protected  CharHash.Strategy strategy
          The hash strategy of this custom set.
protected  boolean[] used
          The array telling whether a position is used.
 
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
CharLinkedOpenCustomHashSet(char[] a, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
CharLinkedOpenCustomHashSet(char[] a, float f, CharHash.Strategy strategy)
          Creates a new hash set copying the elements of an array.
CharLinkedOpenCustomHashSet(char[] a, int offset, int length, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
CharLinkedOpenCustomHashSet(char[] a, int offset, int length, float f, CharHash.Strategy strategy)
          Creates a new hash set and fills it with the elements of a given array.
CharLinkedOpenCustomHashSet(CharCollection c, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
CharLinkedOpenCustomHashSet(CharCollection c, float f, CharHash.Strategy strategy)
          Creates a new hash set copying a given type-specific collection.
CharLinkedOpenCustomHashSet(CharHash.Strategy strategy)
          Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
CharLinkedOpenCustomHashSet(CharIterator i, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
CharLinkedOpenCustomHashSet(CharIterator i, float f, CharHash.Strategy strategy)
          Creates a new hash set using elements provided by a type-specific iterator.
CharLinkedOpenCustomHashSet(Collection<? extends Character> c, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
CharLinkedOpenCustomHashSet(Collection<? extends Character> c, float f, CharHash.Strategy strategy)
          Creates a new hash set copying a given collection.
CharLinkedOpenCustomHashSet(int expected, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
CharLinkedOpenCustomHashSet(int expected, float f, CharHash.Strategy strategy)
          Creates a new hash set.
CharLinkedOpenCustomHashSet(Iterator<?> i, CharHash.Strategy strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator.
CharLinkedOpenCustomHashSet(Iterator<?> i, float f, CharHash.Strategy strategy)
          Creates a new hash set using elements provided by an iterator.
 
Method Summary
 boolean add(char k)
           
 void clear()
           
 CharLinkedOpenCustomHashSet clone()
          Returns a deep copy of this set.
 CharComparator comparator()
          Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering.
 boolean contains(char k)
           
 char firstChar()
          Returns the first element of this set in iteration order.
protected  void fixPointers(int i)
          Modifies the link vector so that the given entry is removed.
protected  void fixPointers(int s, int d)
          Modifies the link vector for a shift from s to d.
 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.
 CharSortedSet headSet(char to)
           
 boolean isEmpty()
           
 CharBidirectionalIterator iterator()
          Returns a type-specific iterator on the elements of this collection.
 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()
          Deprecated. A no-op.
protected  void rehash(int newN)
          Resizes the set.
 boolean remove(char k)
          Removes an element from this set.
protected  void shiftKeys(int pos)
          Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
 int size()
           
 CharHash.Strategy strategy()
          Returns the hashing strategy.
 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
charIterator, 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, rem, removeAll, removeAll, retainAll, retainAll, toArray, toArray, toArray, toCharArray, toCharArray, toString
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.chars.CharCollection
addAll, containsAll, rem, removeAll, retainAll, toArray, toArray, toCharArray, toCharArray
 
Methods inherited from interface java.util.Set
add, addAll, contains, containsAll, equals, remove, removeAll, retainAll, toArray, toArray
 

Field Detail

serialVersionUID

public static final long serialVersionUID
See Also:
Constant Field Values

key

protected transient char[] key
The array of keys.


used

protected transient boolean[] used
The array telling whether a position is used.


f

protected final float f
The acceptable load factor.


n

protected transient int n
The current table size.


maxFill

protected transient int maxFill
Threshold after which we rehash. It must be the table size times f.


mask

protected transient int mask
The mask for wrapping a position counter.


size

protected int size
Number of entries in the set.


first

protected transient int first
The index of the first entry in iteration order. It is valid iff size is nonzero; otherwise, it contains -1.


last

protected transient int last
The index of the last entry in iteration order. It is valid iff size is nonzero; otherwise, it contains -1.


link

protected transient int[] link
For each entry, the next and the previous entry in iteration order exclusive-or'd together. It is valid only on Hash.OCCUPIED entries. The first and the last entry contain the actual successor and predecessor, respectively, exclusived-or'd with -1.


strategy

protected CharHash.Strategy strategy
The hash strategy of this custom set.

Constructor Detail

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(int expected,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(int expected,
                                   CharHash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.

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

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(CharHash.Strategy strategy)
Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(Collection<? extends Character> c,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(Collection<? extends Character> c,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(CharCollection c,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(CharCollection c,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(CharIterator i,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(CharIterator i,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(Iterator<?> i,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(Iterator<?> i,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(char[] a,
                                   int offset,
                                   int length,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(char[] a,
                                   int offset,
                                   int length,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(char[] a,
                                   float f,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.

CharLinkedOpenCustomHashSet

public CharLinkedOpenCustomHashSet(char[] a,
                                   CharHash.Strategy strategy)
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.
strategy - the strategy.
Method Detail

strategy

public CharHash.Strategy strategy()
Returns the hashing strategy.

Returns:
the hashing strategy of this custom hash set.

add

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

shiftKeys

protected final void shiftKeys(int pos)
Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.

Parameters:
pos - a starting position.

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
Overrides:
contains in class AbstractCharCollection
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 AbstractCollection<Character>

size

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

isEmpty

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

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)

fixPointers

protected void fixPointers(int i)
Modifies the link vector so that the given entry is removed.

If the given entry is the first or the last one, this method will complete in constant time; otherwise, it will have to search for the given entry.

Parameters:
i - the index of an entry.

fixPointers

protected void fixPointers(int s,
                           int d)
Modifies the link vector for a shift from s to d.

If the given entry is the first or the last one, this method will complete in constant time; otherwise, it will have to search for the given entry.

Parameters:
s - the source position.
d - the destination position.

firstChar

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

headSet

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

subSet

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

comparator

public CharComparator comparator()
Description copied from interface: CharSortedSet
Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering.

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

Specified by:
comparator in interface CharSortedSet
Specified by:
comparator in interface SortedSet<Character>
See Also:
SortedSet.comparator()

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
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 CharBidirectionalIterator 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 CharSortedSet
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 AbstractCharSortedSet
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()

rehash

protected void rehash(int newN)
Resizes the set.

This method implements the basic rehashing strategy, and may be overriden by subclasses implementing different rehashing strategies (e.g., disk-based rehashing). However, you should not override this method unless you understand the internal workings of this class.

Parameters:
newN - the new size

clone

public CharLinkedOpenCustomHashSet 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.


Copyright © 2011. All Rights Reserved.