com.googlecode.javaewah.datastructure

Class ImmutableBitSet

java.lang.Object

com.googlecode.javaewah.datastructure.ImmutableBitSet

All Implemented Interfaces:

Cloneable, Iterable<Integer>

public class ImmutableBitSet
extends Object
implements Cloneable, Iterable<Integer>

This is an immutable version of the BitSet class in this same package. It is meant to be used with memory-file mapping.

final FileOutputStream fos = new FileOutputStream(tmpfile);
        BitSet Bitmap = BitSet.bitmapOf(0, 2, 55, 64, 512);
        Bitmap.serialize(new DataOutputStream(fos));
                RandomAccessFile memoryMappedFile = new RandomAccessFile(tmpfile, "r");
                ByteBuffer bb = memoryMappedFile.getChannel().map(
                                FileChannel.MapMode.READ_ONLY, 0, totalcount);
                ImmutableBitSet mapped = new ImmutableBitSet(bb.asLongBuffer());

Constructor Summary

Constructors

Constructor and Description
ImmutableBitSet(LongBuffer bs) Construct a ImmutableBitSet from the content of the LongBuffer which should have been initialized with BitSet.serialize (from the BitSet in this same package).

Method Summary

Modifier and Type	Method and Description
BitSet	asBitSet() Get a copy of this ImmutableBitSet as a mutable BitSet.
int	cardinality() Compute the number of bits set to 1
ImmutableBitSet	clone()
boolean	empty() Check whether a bitset contains a set bit.
boolean	equals(Object o)
boolean	get(int i)
int	getNumberOfWords() Get the total number of words contained in this data structure.
long	getWord(int index) Get the word at the given index
int	hashCode()
boolean	intersects(BitSet bs) Checks whether two bitsets intersect.
IntIterator	intIterator() Iterate over the set bits
Iterator<Integer>	iterator()
int	nextSetBit(int i) Usage: for(int i=bs.nextSetBit(0); i>=0; i=bs.nextSetBit(i+1)) { operate on index i here }
int	nextUnsetBit(int i) Usage: for(int i=bs.nextUnsetBit(0); i>=0; i=bs.nextUnsetBit(i+1)) { operate on index i here }
int	size() Query the size
String	toString()
IntIterator	unsetIntIterator() Iterate over the unset bits

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

ImmutableBitSet

public ImmutableBitSet(LongBuffer bs)

Construct a ImmutableBitSet from the content of the LongBuffer which should have been initialized with BitSet.serialize (from the BitSet in this same package). The input is not modified.

Parameters:

bs - the data source

Method Detail

asBitSet

public BitSet asBitSet()

Get a copy of this ImmutableBitSet as a mutable BitSet.

Returns:

a copy

cardinality

public int cardinality()

Compute the number of bits set to 1

Returns:

the number of bits

clone

public ImmutableBitSet clone()

Overrides:

clone in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

empty

public boolean empty()

Check whether a bitset contains a set bit.

Returns:

true if no set bit is found

get

public boolean get(int i)

Parameters:

i - index

Returns:

value of the bit

hashCode

public int hashCode()

Overrides:

hashCode in class Object

intIterator

public IntIterator intIterator()

Iterate over the set bits

Returns:

an iterator

iterator

public Iterator<Integer> iterator()

Specified by:

iterator in interface Iterable<Integer>

intersects

public boolean intersects(BitSet bs)

Checks whether two bitsets intersect.

Parameters:

bs - other bitset

Returns:

true if they have a non-empty intersection (result of AND)

nextSetBit

public int nextSetBit(int i)

Usage: for(int i=bs.nextSetBit(0); i>=0; i=bs.nextSetBit(i+1)) { operate on index i here }

Parameters:

i - current set bit

Returns:

next set bit or -1

nextUnsetBit

public int nextUnsetBit(int i)

Usage: for(int i=bs.nextUnsetBit(0); i>=0; i=bs.nextUnsetBit(i+1)) { operate on index i here }

Parameters:

i - current unset bit

Returns:

next unset bit or -1

size

public int size()

Query the size

Returns:

the size in bits.

unsetIntIterator

public IntIterator unsetIntIterator()

Iterate over the unset bits

Returns:

an iterator

getNumberOfWords

public int getNumberOfWords()

Get the total number of words contained in this data structure.

Returns:

the number

getWord

public long getWord(int index)

Get the word at the given index

Parameters:

index - the index

Returns:

the word

toString

public String toString()

Overrides:

toString in class Object