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

java.lang.Object
  extended by java.util.AbstractCollection<K>
      extended by it.unimi.dsi.fastutil.objects.AbstractObjectCollection<K>
          extended by it.unimi.dsi.fastutil.objects.AbstractObjectSet<K>
              extended by it.unimi.dsi.fastutil.objects.AbstractObjectSortedSet<K>
                  extended by it.unimi.dsi.fastutil.objects.ObjectLinkedOpenCustomHashSet<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 ObjectLinkedOpenCustomHashSet<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
protected  float f
          The acceptable load factor.
protected  int first
          The index of the first entry in iteration order.
protected  K[] key
          The array of keys.
protected  int last
          The index of the last entry in iteration order.
protected  long[] link
          For each entry, the next and the previous entry in iteration order, stored as ((prev & 0xFFFFFFFFL) << 32) | (next & 0xFFFFFFFFL).
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  Hash.Strategy<K> 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
ObjectLinkedOpenCustomHashSet(Collection<? extends K> c, float f, Hash.Strategy<K> strategy)
          Creates a new hash set copying a given collection.
ObjectLinkedOpenCustomHashSet(Collection<? extends K> c, Hash.Strategy<K> strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
ObjectLinkedOpenCustomHashSet(Hash.Strategy<K> strategy)
          Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
ObjectLinkedOpenCustomHashSet(int expected, float f, Hash.Strategy<K> strategy)
          Creates a new hash set.
ObjectLinkedOpenCustomHashSet(int expected, Hash.Strategy<K> strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
ObjectLinkedOpenCustomHashSet(K[] a, float f, Hash.Strategy<K> strategy)
          Creates a new hash set copying the elements of an array.
ObjectLinkedOpenCustomHashSet(K[] a, Hash.Strategy<K> strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
ObjectLinkedOpenCustomHashSet(K[] a, int offset, int length, float f, Hash.Strategy<K> strategy)
          Creates a new hash set and fills it with the elements of a given array.
ObjectLinkedOpenCustomHashSet(K[] a, int offset, int length, Hash.Strategy<K> strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
ObjectLinkedOpenCustomHashSet(ObjectCollection<? extends K> c, float f, Hash.Strategy<K> strategy)
          Creates a new hash set copying a given type-specific collection.
ObjectLinkedOpenCustomHashSet(ObjectCollection<? extends K> c, Hash.Strategy<K> strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
ObjectLinkedOpenCustomHashSet(ObjectIterator<K> i, float f, Hash.Strategy<K> strategy)
          Creates a new hash set using elements provided by a type-specific iterator.
ObjectLinkedOpenCustomHashSet(ObjectIterator<K> i, Hash.Strategy<K> strategy)
          Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor 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()
           
 ObjectLinkedOpenCustomHashSet<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.
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.
 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.
protected  void rehash(int newN)
          Resizes the set.
 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.
protected  int shiftKeys(int pos)
          Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
 int size()
           
 Hash.Strategy<K> strategy()
          Returns the hashing strategy.
 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
finalize, 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

key

protected transient K[] 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 long[] link
For each entry, the next and the previous entry in iteration order, stored as ((prev & 0xFFFFFFFFL) << 32) | (next & 0xFFFFFFFFL). The first entry contains predecessor -1, and the last entry contains successor -1.


strategy

protected Hash.Strategy<K> strategy
The hash strategy of this custom set.

Constructor Detail

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(int expected,
                                     float f,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(int expected,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(Collection<? extends K> c,
                                     float f,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(Collection<? extends K> c,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(ObjectCollection<? extends K> c,
                                     float f,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(ObjectCollection<? extends K> c,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(ObjectIterator<K> i,
                                     float f,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(ObjectIterator<K> i,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(K[] a,
                                     int offset,
                                     int length,
                                     float f,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(K[] a,
                                     int offset,
                                     int length,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(K[] a,
                                     float f,
                                     Hash.Strategy<K> 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.

ObjectLinkedOpenCustomHashSet

public ObjectLinkedOpenCustomHashSet(K[] a,
                                     Hash.Strategy<K> 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 Hash.Strategy<K> strategy()
Returns the hashing strategy.

Returns:
the hashing strategy of this custom hash set.

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>

shiftKeys

protected final int 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.
Returns:
the position cleared by the shifting process.

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)

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.

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()

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 ObjectLinkedOpenCustomHashSet<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.


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