Package it.unimi.dsi.bits

Class BitVectors

java.lang.Object

it.unimi.dsi.bits.BitVectors

public class BitVectors
extends Object

A class providing static methods and objects that do useful things with bit vectors.

See Also:

• BitVector

Field Summary

Fields

Modifier and Type	Field	Description
static final BitVector	EMPTY_VECTOR	An immutable, singleton empty bit vector.
static it.unimi.dsi.bits.BitVectors.BitVectorOfflineSerializer	OFFLINE_SERIALIZER	A serializer for LongArrayBitVector instances that can be used with OfflineIterable.
static final BitVector	ONE	An immutable bit vector of length one containing a one.
static final BitVector	ZERO	An immutable bit vector of length one containing a zero.

Method Summary

Modifier and Type	Method	Description
static void	ensureFromTo(long bitVectorLength, long from, long to)
static <T extends BitVector> TransformationStrategy<T>	identity()	Deprecated.
static LongArrayBitVector	readFast(DataInput dis)	Reads quickly a bit vector from a DataInputStream.
static LongArrayBitVector	readFast(DataInput dis, LongArrayBitVector bv)	Reads quickly a bit vector from a DataInputStream.
static void	writeFast(BitVector v, DataOutput dos)	Writes quickly a bit vector to a DataOutputStream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

EMPTY_VECTOR

public static final BitVector EMPTY_VECTOR

An immutable, singleton empty bit vector.

ZERO

public static final BitVector ZERO

An immutable bit vector of length one containing a zero.

ONE

public static final BitVector ONE

An immutable bit vector of length one containing a one.

OFFLINE_SERIALIZER

public static it.unimi.dsi.bits.BitVectors.BitVectorOfflineSerializer OFFLINE_SERIALIZER

A serializer for LongArrayBitVector instances that can be used with OfflineIterable. It can serialize any implementation of BitVector, and requires at construction time an instance of LongArrayBitVector that will be used to return deserialized elements.

Method Details

identity

@Deprecated
public static <T extends BitVector>
TransformationStrategy<T> identity()

Deprecated.

ensureFromTo

public static void ensureFromTo(long bitVectorLength,
 long from,
 long to)

writeFast

public static void writeFast(BitVector v,
 DataOutput dos)
                      throws IOException

Writes quickly a bit vector to a DataOutputStream.

This method writes a bit vector in a simple format: first, a long representing the length. Then, as many longs as necessary to write the bits in the bit vectors (i.e., LongArrayBitVector.words(long) of the bit vector length), obtained via BitVector.getLong(long, long).

The main purpose of this function is to support OfflineIterable (see OFFLINE_SERIALIZER).

Parameters:

v - a bit vector.

dos - a data output stream.

Throws:

IOException

readFast

public static LongArrayBitVector readFast(DataInput dis)
                                   throws IOException

Reads quickly a bit vector from a DataInputStream.

This method is the dual of writeFast(BitVector, DataOutput). If you need to avoid creating a bit vector at each call, please have a look at readFast(DataInput, LongArrayBitVector).

Parameters:

dis - a data input stream.

Returns:

the next bit vector in the stream, as saved by writeFast(BitVector, DataOutput).

Throws:

IOException

See Also:

• writeFast(BitVector, DataOutput)
• readFast(DataInput, LongArrayBitVector)

readFast

public static LongArrayBitVector readFast(DataInput dis,
 LongArrayBitVector bv)
                                   throws IOException

Reads quickly a bit vector from a DataInputStream.

This method is similar in purpose to readFast(DataInput), but it allows reuse of the bit vector.

Parameters:

dis - a data input stream.

bv - a long-array bit vector.

Returns:

bv, filled with the next bit vector in the stream, as saved by writeFast(BitVector, DataOutput).

Throws:

IOException

See Also:

• writeFast(BitVector, DataOutput)
• readFast(DataInput)