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

java.lang.Object
  extended by java.util.AbstractCollection<K>
      extended by it.unimi.dsi.fastutil.objects.AbstractReferenceCollection<K>
          extended by it.unimi.dsi.fastutil.objects.AbstractReferenceSet<K>
              extended by it.unimi.dsi.fastutil.objects.ReferenceOpenHashBigSet<K>
All Implemented Interfaces:
Hash, ObjectIterable<K>, ReferenceCollection<K>, ReferenceSet<K>, Size64, java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<K>, java.util.Collection<K>, java.util.Set<K>

public class ReferenceOpenHashBigSet<K>
extends AbstractReferenceSet<K>
implements java.io.Serializable, java.lang.Cloneable, Hash, Size64

A type-specific hash big set with with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a big set: the number of elements in the set is limited only by the amount of core memory. The table is backed by a big array and 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 method lets you control the size of the table; this is particularly useful if you reuse instances of this class.

The methods of this class are about 30% slower than those of the corresponding non-big set.

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
 
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
ReferenceOpenHashBigSet()
          Creates a new hash big set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
ReferenceOpenHashBigSet(java.util.Collection<? extends K> c)
          Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
ReferenceOpenHashBigSet(java.util.Collection<? extends K> c, float f)
          Creates a new hash big set copying a given collection.
ReferenceOpenHashBigSet(K[] a)
          Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
ReferenceOpenHashBigSet(K[] a, float f)
          Creates a new hash big set copying the elements of an array.
ReferenceOpenHashBigSet(K[] a, int offset, int length)
          Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
ReferenceOpenHashBigSet(K[] a, int offset, int length, float f)
          Creates a new hash big set and fills it with the elements of a given array.
ReferenceOpenHashBigSet(long expected)
          Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor.
ReferenceOpenHashBigSet(long expected, float f)
          Creates a new hash big set.
ReferenceOpenHashBigSet(ObjectIterator<K> i)
          Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
ReferenceOpenHashBigSet(ObjectIterator<K> i, float f)
          Creates a new hash big set using elements provided by a type-specific iterator.
ReferenceOpenHashBigSet(ReferenceCollection<? extends K> c)
          Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
ReferenceOpenHashBigSet(ReferenceCollection<? extends K> c, float f)
          Creates a new hash big set copying a given type-specific collection.
 
Method Summary
 boolean add(K k)
           
 void clear()
           
 ReferenceOpenHashBigSet<K> clone()
          Returns a deep copy of this big set.
 boolean contains(java.lang.Object k)
           
 int hashCode()
          Returns a hash code for this set.
 boolean isEmpty()
           
 ObjectIterator<K> iterator()
          Returns a type-specific iterator on the elements of this collection.
 boolean rehash()
          Deprecated. A no-op.
 boolean remove(java.lang.Object k)
          Removes an element from this set.
 int size()
          Deprecated. 
 long size64()
          Returns the size of this data structure as a long.
 boolean trim()
          Rehashes this set, making the table as small as possible.
 boolean trim(long n)
          Rehashes this set if the table is too large.
 
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractReferenceSet
equals
 
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractReferenceCollection
addAll, containsAll, objectIterator, removeAll, retainAll, toArray, toArray, toString
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.objects.ReferenceCollection
objectIterator, toArray
 
Methods inherited from interface java.util.Set
addAll, containsAll, removeAll, retainAll, toArray, toArray
 

Constructor Detail

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(long expected,
                               float f)
Creates a new hash big 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 set.
f - the load factor.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(long expected)
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor.

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

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet()
Creates a new hash big set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.


ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(java.util.Collection<? extends K> c,
                               float f)
Creates a new hash big set copying a given collection.

Parameters:
c - a Collection to be copied into the new hash big set.
f - the load factor.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(java.util.Collection<? extends K> c)
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.

Parameters:
c - a Collection to be copied into the new hash big set.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(ReferenceCollection<? extends K> c,
                               float f)
Creates a new hash big set copying a given type-specific collection.

Parameters:
c - a type-specific collection to be copied into the new hash big set.
f - the load factor.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(ReferenceCollection<? extends K> c)
Creates a new hash big 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 big set.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(ObjectIterator<K> i,
                               float f)
Creates a new hash big set using elements provided by a type-specific iterator.

Parameters:
i - a type-specific iterator whose elements will fill the new hash big set.
f - the load factor.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(ObjectIterator<K> i)
Creates a new hash big 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 new hash big set.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(K[] a,
                               int offset,
                               int length,
                               float f)
Creates a new hash big set and fills it with the elements of a given array.

Parameters:
a - an array whose elements will be used to fill the new hash big set.
offset - the first element to use.
length - the number of elements to use.
f - the load factor.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(K[] a,
                               int offset,
                               int length)
Creates a new hash big 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 new hash big set.
offset - the first element to use.
length - the number of elements to use.

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(K[] a,
                               float f)
Creates a new hash big set copying the elements of an array.

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

ReferenceOpenHashBigSet

public ReferenceOpenHashBigSet(K[] a)
Creates a new hash big 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 big set.
Method Detail

add

public boolean add(K k)
Specified by:
add in interface java.util.Collection<K>
Specified by:
add in interface java.util.Set<K>
Overrides:
add in class AbstractReferenceCollection<K>

remove

public boolean remove(java.lang.Object k)
Description copied from interface: ReferenceSet
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 ReferenceSet<K>
Specified by:
remove in interface java.util.Collection<K>
Specified by:
remove in interface java.util.Set<K>
Overrides:
remove in class AbstractReferenceSet<K>
See Also:
Collection.remove(Object)

contains

public boolean contains(java.lang.Object k)
Specified by:
contains in interface java.util.Collection<K>
Specified by:
contains in interface java.util.Set<K>
Overrides:
contains in class java.util.AbstractCollection<K>

clear

public void clear()
Specified by:
clear in interface java.util.Collection<K>
Specified by:
clear in interface java.util.Set<K>
Overrides:
clear in class java.util.AbstractCollection<K>

iterator

public ObjectIterator<K> iterator()
Description copied from interface: ReferenceCollection
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 ObjectIterable<K>
Specified by:
iterator in interface ReferenceCollection<K>
Specified by:
iterator in interface ReferenceSet<K>
Specified by:
iterator in interface java.lang.Iterable<K>
Specified by:
iterator in interface java.util.Collection<K>
Specified by:
iterator in interface java.util.Set<K>
Specified by:
iterator in class AbstractReferenceSet<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(long)

trim

public boolean trim(long n)
Rehashes this set if the table is too large.

Let N be the smallest table size that can hold max(n,size64()) 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()

size

@Deprecated
public int size()
Deprecated. 

Description copied from interface: Size64
Returns the size of this data structure, minimized with Integer.MAX_VALUE.

Specified by:
size in interface Size64
Specified by:
size in interface java.util.Collection<K>
Specified by:
size in interface java.util.Set<K>
Specified by:
size in class java.util.AbstractCollection<K>
Returns:
the size of this data structure, minimized with Integer.MAX_VALUE.
See Also:
Collection.size()

size64

public long size64()
Description copied from interface: Size64
Returns the size of this data structure as a long.

Specified by:
size64 in interface Size64
Returns:
the size of this data structure.

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface java.util.Collection<K>
Specified by:
isEmpty in interface java.util.Set<K>
Overrides:
isEmpty in class AbstractReferenceCollection<K>

clone

public ReferenceOpenHashBigSet<K> clone()
Returns a deep copy of this big set.

This method performs a deep copy of this big 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 java.lang.Object
Returns:
a deep copy of this big 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 java.util.Collection<K>
Specified by:
hashCode in interface java.util.Set<K>
Overrides:
hashCode in class AbstractReferenceSet<K>
Returns:
a hash code for this set.