org.apache.lucene.util
Class FixedBitSet

java.lang.Object
  org.apache.lucene.search.DocIdSet
      org.apache.lucene.util.FixedBitSet

All Implemented Interfaces:

Bits

public final class FixedBitSet
extends DocIdSet
implements Bits

BitSet of fixed length (numBits), backed by accessible (getBits()) long[], accessed with an int index, implementing Bits and DocIdSet. Unlike OpenBitSet this bit set does not auto-expand, cannot handle long index, and does not have fastXX/XX variants (just X).

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.lucene.util.Bits

Bits.MatchAllBits, Bits.MatchNoBits

Field Summary

Fields inherited from class org.apache.lucene.search.DocIdSet

EMPTY_DOCIDSET

Fields inherited from interface org.apache.lucene.util.Bits

EMPTY_ARRAY

Constructor Summary

FixedBitSet(FixedBitSet other)
Makes full copy.

FixedBitSet(int numBits)

FixedBitSet(long[] storedBits, int numBits)

Method Summary

void	and(DocIdSetIterator iter) Does in-place AND of the bits provided by the iterator.
void	and(FixedBitSet other) this = this AND other
void	andNot(DocIdSetIterator iter) Does in-place AND NOT of the bits provided by the iterator.
void	andNot(FixedBitSet other) this = this AND NOT other
Bits	bits() Optionally provides a Bits interface for random access to matching documents.
static int	bits2words(int numBits) returns the number of 64 bit words it would take to hold numBits
int	cardinality() Returns number of set bits.
void	clear(int index)
void	clear(int startIndex, int endIndex) Clears a range of bits.
FixedBitSet	clone()
boolean	equals(Object o) returns true if both sets have the same bits set
void	flip(int startIndex, int endIndex) Flips a range of bits
boolean	get(int index) Returns the value of the bit with the specified index.
boolean	getAndClear(int index)
boolean	getAndSet(int index)
long[]	getBits() Expert.
int	hashCode()
boolean	isCacheable() This DocIdSet implementation is cacheable.
DocIdSetIterator	iterator() Provides a DocIdSetIterator to access the set.
int	length() Returns the number of bits in this set
int	nextSetBit(int index) Returns the index of the first set bit starting at the index specified.
void	or(DocIdSetIterator iter) Does in-place OR of the bits provided by the iterator.
void	or(FixedBitSet other) this = this OR other
int	prevSetBit(int index) Returns the index of the last set bit before or on the index specified.
void	set(int index)
void	set(int startIndex, int endIndex) Sets a range of bits

Methods inherited from class java.lang.Object

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

Constructor Detail

FixedBitSet

public FixedBitSet(int numBits)

FixedBitSet

public FixedBitSet(long[] storedBits,
                   int numBits)

FixedBitSet

public FixedBitSet(FixedBitSet other)

Makes full copy.

Method Detail

bits2words

public static int bits2words(int numBits)

returns the number of 64 bit words it would take to hold numBits

iterator

public DocIdSetIterator iterator()

Description copied from class: DocIdSet

Provides a DocIdSetIterator to access the set. This implementation can return null or DocIdSet.EMPTY_DOCIDSET.iterator() if there are no docs that match.

Specified by:

iterator in class DocIdSet

bits

public Bits bits()

Description copied from class: DocIdSet

Optionally provides a Bits interface for random access to matching documents.

Overrides:

bits in class DocIdSet

Returns:

null, if this DocIdSet does not support random access. In contrast to DocIdSet.iterator(), a return value of null does not imply that no documents match the filter! The default implementation does not provide random access, so you only need to implement this method if your DocIdSet can guarantee random access to every docid in O(1) time without external disk access (as Bits interface cannot throw IOException). This is generally true for bit sets like FixedBitSet, which return itself if they are used as DocIdSet.

length

public int length()

Description copied from interface: Bits

Returns the number of bits in this set

Specified by:

length in interface Bits

isCacheable

public boolean isCacheable()

This DocIdSet implementation is cacheable.

Overrides:

isCacheable in class DocIdSet

getBits

public long[] getBits()

Expert.

cardinality

public int cardinality()

Returns number of set bits. NOTE: this visits every long in the backing bits array, and the result is not internally cached!

get

public boolean get(int index)

Description copied from interface: Bits

Returns the value of the bit with the specified index.

Specified by:

get in interface Bits

Parameters:

index - index, should be non-negative and < Bits.length(). The result of passing negative or out of bounds values is undefined by this interface, just don't do it!

Returns:

true if the bit is set, false otherwise.

set

public void set(int index)

getAndSet

public boolean getAndSet(int index)

clear

public void clear(int index)

getAndClear

public boolean getAndClear(int index)

nextSetBit

public int nextSetBit(int index)

Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.

prevSetBit

public int prevSetBit(int index)

Returns the index of the last set bit before or on the index specified. -1 is returned if there are no more set bits.

or

public void or(DocIdSetIterator iter)
        throws IOException

Does in-place OR of the bits provided by the iterator.

Throws:

IOException

or

public void or(FixedBitSet other)

this = this OR other

and

public void and(DocIdSetIterator iter)
         throws IOException

Does in-place AND of the bits provided by the iterator.

Throws:

IOException

and

public void and(FixedBitSet other)

this = this AND other

andNot

public void andNot(DocIdSetIterator iter)
            throws IOException

Does in-place AND NOT of the bits provided by the iterator.

Throws:

IOException

andNot

public void andNot(FixedBitSet other)

this = this AND NOT other

flip

public void flip(int startIndex,
                 int endIndex)

Flips a range of bits

Parameters:

startIndex - lower index

endIndex - one-past the last bit to flip

set

public void set(int startIndex,
                int endIndex)

Sets a range of bits

Parameters:

startIndex - lower index

endIndex - one-past the last bit to set

clear

public void clear(int startIndex,
                  int endIndex)

Clears a range of bits.

Parameters:

startIndex - lower index

endIndex - one-past the last bit to clear

clone

public FixedBitSet clone()

Overrides:

clone in class Object

equals

public boolean equals(Object o)

returns true if both sets have the same bits set

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object