Class LongBigArrayBitVector
- java.lang.Object
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- java.util.AbstractCollection<java.lang.Boolean>
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- it.unimi.dsi.fastutil.booleans.AbstractBooleanCollection
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- it.unimi.dsi.fastutil.booleans.AbstractBooleanBigList
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- it.unimi.dsi.bits.AbstractBitVector
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- it.unimi.dsi.bits.LongBigArrayBitVector
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- All Implemented Interfaces:
BitVector
,it.unimi.dsi.fastutil.BigList<java.lang.Boolean>
,it.unimi.dsi.fastutil.booleans.BooleanBigList
,it.unimi.dsi.fastutil.booleans.BooleanCollection
,it.unimi.dsi.fastutil.booleans.BooleanIterable
,it.unimi.dsi.fastutil.booleans.BooleanStack
,it.unimi.dsi.fastutil.Size64
,it.unimi.dsi.fastutil.Stack<java.lang.Boolean>
,java.io.Serializable
,java.lang.Cloneable
,java.lang.Comparable<it.unimi.dsi.fastutil.BigList<? extends java.lang.Boolean>>
,java.lang.Iterable<java.lang.Boolean>
,java.util.Collection<java.lang.Boolean>
,java.util.RandomAccess
public class LongBigArrayBitVector extends AbstractBitVector implements java.lang.Cloneable, java.io.Serializable
A bit vector implementation based on a big arrays of longs.The main goal of this class is to be able to accommodate very large bit vectors. With respect to
LongArrayBitVector
, many optimized methods are missing and rely on the generic implementations inAbstractBitVector
. Instances of this class represent a bit vector using a big array of longs that is enlarged as needed when new entries are created (usingLongBigArrays.grow(long[][], long, long)
), but is never made smaller (even on aclear()
). Usetrim()
for that purpose.Besides usual methods for setting and getting bits, this class provides views that make it possible to access comfortably the bit vector in different ways: for instance,
asLongBigList(int)
provide access as a list of longs, whereasAbstractBitVector.asLongSet()
provides access in setwise form.When enlarging the underlying array (e.g., for
append(long, int)
operations or add operations on the big list view), or when invokingensureCapacity(long)
, this class callsLongBigArrays.grow(long[][], long, long)
, which could enlarge the array more than expected. On the contrary,length(long)
(and the corresponding method in the big list view) sizes the underlying array in an exact manner.Bit numbering follows the right-to-left convention: bit k (counted from the right) of word w is bit 64w + k of the overall bit vector.
If
CHECKS
is true at compile time, boundary checks for all bit operations will be compiled in. For maximum speed, you may want to recompile this class withCHECKS
set to false.CHECKS
is public, so you can check from your code whether you're being provided a version with checks or not. In any case, many checks happen when you enable assertions.Warning: Several optional methods have still to be implemented (e.g., adding an element at an arbitrary position using the
BooleanBigList
methods).Warning: The
AbstractBitVector.bits()
method uses theAbstractBitVector
implementation, which will fail for bit vectors that cannot be stored in a single long array (i.e., more thanArrays.MAX_ARRAY_SIZE
) *Long.SIZE
).- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class Description protected static class
LongBigArrayBitVector.LongBigListView
A list-of-integers view of a bit vector.-
Nested classes/interfaces inherited from class it.unimi.dsi.bits.AbstractBitVector
AbstractBitVector.LongSetView, AbstractBitVector.SubBitVector
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Constructor Summary
Constructors Modifier Constructor Description protected
LongBigArrayBitVector(long capacity)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
add(boolean value)
LongBigArrayBitVector
append(long value, int width)
Appends the less significant bits of a long integer to this bit vector.it.unimi.dsi.fastutil.longs.LongBigList
asLongBigList(int width)
Returns a view of this bit vector as a list of nonnegative integers of specified width.long[][]
bigBits()
Returns the underlying big array.static long
bits(long word)
Returns the number of bits in the given number of words.void
clear()
Sets the size of this bit vector to 0.void
clear(long index)
Clears a bit in this bit vector (optional operation).LongBigArrayBitVector
clone()
Returns a cloned copy of this bit vector.LongBigArrayBitVector
copy()
Returns a copy of this bit vector.static LongBigArrayBitVector
copy(BitVector bv)
Returns a copy of the given bit vector.LongBigArrayBitVector
ensureCapacity(long numBits)
Ensures that this bit vector can hold the specified number of bits.boolean
equals(LongBigArrayBitVector v)
boolean
equals(java.lang.Object o)
LongBigArrayBitVector
fast()
Returns this bit vector.void
fill(boolean value)
Sets all bits this bit vector to the given boolean value (optional operation).boolean
getBoolean(long index)
static LongBigArrayBitVector
getInstance()
Creates a new empty bit vector.static LongBigArrayBitVector
getInstance(long capacity)
Creates a new empty bit vector of given capacity.long
getLong(long from, long to)
Returns the specified bit range as a long.int
hashCode()
Returns a hash code for this bit vector.long
length()
Returns the number of bits in this bit vector.LongBigArrayBitVector
length(long newLength)
Sets the number of bits in this bit vector.static LongBigArrayBitVector
of(int... bit)
Creates a new bit vector with given bits.static LongBigArrayBitVector
ofLength(long length)
Creates a new empty bit vector of given length.void
set(long index)
Sets a bit in this bit vector (optional operation).boolean
set(long index, boolean value)
boolean
trim()
Reduces as must as possible the size of the backing array.static long
word(long index)
Return the index of the word that holds a bit of specified index.static long
words(long size)
Returns the number of words that are necessary to hold the given number of bits.static LongBigArrayBitVector
wrap(long[][] array)
Wraps the given array of longs in a bit vector.static LongBigArrayBitVector
wrap(long[][] array, long size)
Wraps the given big array of longs in a bit vector for the given number of bits.-
Methods inherited from class it.unimi.dsi.bits.AbstractBitVector
add, add, add, add, and, append, asLongSet, bits, clear, compareTo, compareTo, copy, count, ensureIndex, ensureRestrictedIndex, equals, fill, fill, fill, firstOne, firstZero, flip, flip, flip, flip, getBoolean, getInt, isPrefix, isProperPrefix, lastOne, lastZero, longestCommonPrefixLength, nextOne, nextZero, or, previousOne, previousZero, removeBoolean, removeBoolean, replace, set, set, set, size, size, size64, subVector, subVector, toString, xor
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Methods inherited from class it.unimi.dsi.fastutil.booleans.AbstractBooleanBigList
add, addAll, addAll, addAll, addAll, addElements, addElements, contains, forEach, get, getElements, indexOf, indexOf, iterator, lastIndexOf, lastIndexOf, listIterator, listIterator, peek, peekBoolean, pop, popBoolean, push, push, rem, remove, removeElements, set, setElements, subList, top, topBoolean
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Methods inherited from class it.unimi.dsi.fastutil.booleans.AbstractBooleanCollection
add, contains, containsAll, containsAll, remove, removeAll, removeAll, retainAll, retainAll, toArray, toBooleanArray, toBooleanArray
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Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface it.unimi.dsi.fastutil.booleans.BooleanBigList
add, addAll, addAll, addAll, addAll, addAll, addElements, addElements, get, getElements, getElements, indexOf, indexOf, iterator, lastIndexOf, lastIndexOf, listIterator, listIterator, remove, removeElements, set, setElements, setElements, setElements, spliterator, subList
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Methods inherited from interface it.unimi.dsi.fastutil.booleans.BooleanCollection
add, addAll, contains, contains, containsAll, rem, remove, removeAll, removeIf, removeIf, retainAll, toArray, toBooleanArray, toBooleanArray
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Field Detail
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CHECKS
public static final boolean CHECKS
Whether this class has been compiled with index checks or not.- See Also:
- Constant Field Values
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length
protected long length
The number of bits in this vector.
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bits
protected transient long[][] bits
The backing big array of this vector. Bit 0 of the first element of the first array contains bit 0 of the bit vector, bit 0 of the second element contains bitLong.SIZE
of the bit vector and so on.
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Method Detail
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words
public static final long words(long size)
Returns the number of words that are necessary to hold the given number of bits.- Parameters:
size
- a number of bits.- Returns:
- the number of words that are necessary to hold the given number of bits.
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bits
public static final long bits(long word)
Returns the number of bits in the given number of words.- Parameters:
word
- a word position.- Returns:
Long.SIZE
*word
.
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word
public static final long word(long index)
Return the index of the word that holds a bit of specified index.- Parameters:
index
- the index of a bit, or -1.- Returns:
- the index of the word that holds the bit of given index, or -1 if
index
is -1.
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getInstance
public static LongBigArrayBitVector getInstance(long capacity)
Creates a new empty bit vector of given capacity. The resulting vector will be able to containcapacity
bits without reallocations of the backing array.Note that this constructor creates an empty bit vector. If you want a cleared bit vector of a specified size, please use the
ofLength(long)
factory method.- Parameters:
capacity
- the capacity (in bits) of the new bit vector.- Returns:
- a new bit vector of given capacity.
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getInstance
public static LongBigArrayBitVector getInstance()
Creates a new empty bit vector. No allocation is actually performed.- Returns:
- a new bit vector with no capacity.
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ofLength
public static LongBigArrayBitVector ofLength(long length)
Creates a new empty bit vector of given length.- Parameters:
length
- the size (in bits) of the new bit vector.
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of
public static LongBigArrayBitVector of(int... bit)
Creates a new bit vector with given bits.- Parameters:
bit
- a list of bits that will be set in the newly created bit vector.
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length
public long length()
Description copied from interface:BitVector
Returns the number of bits in this bit vector.If the number of bits in this bit vector is smaller than or equal to
Integer.MAX_VALUE
, this method is semantically equivalent toList.size()
. In any case, this method is semantically equivalent toSize64.size64()
, but it is prefererred.
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bigBits
public long[][] bigBits()
Returns the underlying big array.- Returns:
- the underlying big array.
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ensureCapacity
public LongBigArrayBitVector ensureCapacity(long numBits)
Ensures that this bit vector can hold the specified number of bits.This method uses
LongBigArrays.grow(long[][], long, long)
to ensure that there is enough space for the given number of bits. As a consequence, the actual length of the long array allocated might be larger than expected.- Parameters:
numBits
- the number of bits that this vector must be able to contain.- Returns:
- this bit vector.
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length
public LongBigArrayBitVector length(long newLength)
Description copied from interface:BitVector
Sets the number of bits in this bit vector.It is expected that this method will try to allocate exactly the necessary space.
If the argument fits an integer, this method has the same side effects of
BooleanList.size(int)
. In any case, this method has the same side effects ofBigList.size(long)
, but it is preferred, as it has the advantage of returning this bit vector, thus making it possible to chain methods.- Specified by:
length
in interfaceBitVector
- Overrides:
length
in classAbstractBitVector
- Parameters:
newLength
- the new length in bits for this bit vector.- Returns:
- this bit vector.
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fill
public void fill(boolean value)
Description copied from interface:BitVector
Sets all bits this bit vector to the given boolean value (optional operation).- Specified by:
fill
in interfaceBitVector
- Overrides:
fill
in classAbstractBitVector
- Parameters:
value
- the value (true or false).
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trim
public boolean trim()
Reduces as must as possible the size of the backing array.- Returns:
- true if some trimming was actually necessary.
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clear
public void clear()
Sets the size of this bit vector to 0.Note that this method does not try to reallocate that backing array. If you want to force that behaviour, call
trim()
afterwards.- Specified by:
clear
in interfacejava.util.Collection<java.lang.Boolean>
- Overrides:
clear
in classAbstractBitVector
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copy
public LongBigArrayBitVector copy()
Description copied from interface:BitVector
Returns a copy of this bit vector.- Specified by:
copy
in interfaceBitVector
- Overrides:
copy
in classAbstractBitVector
- Returns:
- a copy of this bit vector.
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fast
public LongBigArrayBitVector fast()
Returns this bit vector.- Specified by:
fast
in interfaceBitVector
- Overrides:
fast
in classAbstractBitVector
- Returns:
- this bit vector.
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copy
public static LongBigArrayBitVector copy(BitVector bv)
Returns a copy of the given bit vector.This method uses
BitVector.getLong(long, long)
onLong.SIZE
boundaries to copy at high speed.- Parameters:
bv
- a bit vector.- Returns:
- an instance of this class containing a copy of the given vector.
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getBoolean
public boolean getBoolean(long index)
- Specified by:
getBoolean
in interfaceit.unimi.dsi.fastutil.booleans.BooleanBigList
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set
public boolean set(long index, boolean value)
- Specified by:
set
in interfaceit.unimi.dsi.fastutil.booleans.BooleanBigList
- Overrides:
set
in classAbstractBitVector
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set
public void set(long index)
Description copied from interface:BitVector
Sets a bit in this bit vector (optional operation).- Specified by:
set
in interfaceBitVector
- Overrides:
set
in classAbstractBitVector
- Parameters:
index
- the index of a bit.
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clear
public void clear(long index)
Description copied from interface:BitVector
Clears a bit in this bit vector (optional operation).- Specified by:
clear
in interfaceBitVector
- Overrides:
clear
in classAbstractBitVector
- Parameters:
index
- the index of a bit.
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append
public LongBigArrayBitVector append(long value, int width)
Description copied from interface:BitVector
Appends the less significant bits of a long integer to this bit vector.- Specified by:
append
in interfaceBitVector
- Overrides:
append
in classAbstractBitVector
- Parameters:
value
- a value to be appendedwidth
- the number of less significant bits to be added to this bit vector.- Returns:
- this bit vector.
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add
public boolean add(boolean value)
- Specified by:
add
in interfaceit.unimi.dsi.fastutil.booleans.BooleanCollection
- Overrides:
add
in classAbstractBitVector
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getLong
public long getLong(long from, long to)
Description copied from interface:BitVector
Returns the specified bit range as a long.Note that bit 0 of the returned long will be bit
from
of this bit vector.Implementations are invited to provide high-speed implementations for the case in which
from
is a multiple ofLong.SIZE
andto
isfrom
+Long.SIZE
(or less, in case the vector length is exceeded). This behaviour make it possible to implement high-speed hashing, copies, etc.- Specified by:
getLong
in interfaceBitVector
- Overrides:
getLong
in classAbstractBitVector
- Parameters:
from
- the starting bit (inclusive).to
- the ending bit (exclusive).- Returns:
- the long value contained in the specified bits.
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wrap
public static LongBigArrayBitVector wrap(long[][] array, long size)
Wraps the given big array of longs in a bit vector for the given number of bits.Note that all bits in
array
beyond that of indexsize
must be unset, or an exception will be thrown.- Parameters:
array
- a big array of longs.size
- the number of bits of the newly created bit vector.- Returns:
- a bit vector of size
size
usingarray
as backing big array.
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wrap
public static LongBigArrayBitVector wrap(long[][] array)
Wraps the given array of longs in a bit vector.- Parameters:
array
- an array of longs.- Returns:
- a bit vector of size
Long.SIZE
times the length ofarray
usingarray
as backing array.
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clone
public LongBigArrayBitVector clone() throws java.lang.CloneNotSupportedException
Returns a cloned copy of this bit vector.This method is functionally equivalent to
copy()
, except thatcopy()
trims the backing array.- Overrides:
clone
in classjava.lang.Object
- Returns:
- a copy of this bit vector.
- Throws:
java.lang.CloneNotSupportedException
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hashCode
public int hashCode()
Description copied from interface:BitVector
Returns a hash code for this bit vector.Hash codes for bit vectors are defined as follows:
final long length = length(); long fullLength = length & -Long.SIZE; long h = 0x9e3779b97f4a7c13L ^ length; for(long i = 0; i < fullLength; i += Long.SIZE) h ^= (h << 5) + getLong(i, i + Long.SIZE) + (h >>> 2); if (length != fullLength) h ^= (h << 5) + getLong(fullLength, length) + (h >>> 2); (int)((h >>> 32) ^ h);
The last value is the hash code of the bit vector. This hashing is based on shift-add-xor hashing (M.V. Ramakrishna and Justin Zobel, “Performance in practice of string hashing functions”, Proc. of the Fifth International Conference on Database Systems for Advanced Applications, 1997, pages 215−223).
The returned value is not a high-quality hash such as Jenkins's, but it can be computed very quickly; in any case, 32 bits are too few for a high-quality hash to be used in large-scale applications.
Important: all bit vector implementations are required to return the value defined here. The simplest way to obtain this result is to subclass
AbstractBitVector
.- Specified by:
hashCode
in interfaceBitVector
- Specified by:
hashCode
in interfacejava.util.Collection<java.lang.Boolean>
- Overrides:
hashCode
in classAbstractBitVector
- Returns:
- a hash code for this bit vector.
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equals
public boolean equals(java.lang.Object o)
- Specified by:
equals
in interfacejava.util.Collection<java.lang.Boolean>
- Overrides:
equals
in classAbstractBitVector
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equals
public boolean equals(LongBigArrayBitVector v)
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asLongBigList
public it.unimi.dsi.fastutil.longs.LongBigList asLongBigList(int width)
Description copied from interface:BitVector
Returns a view of this bit vector as a list of nonnegative integers of specified width.More formally,
getLong(p)
will return the nonnegative integer defined by the bits starting atp * width
(bit 0, inclusive) and ending at(p + 1) * width
(bitwidth
− 1, exclusive).- Specified by:
asLongBigList
in interfaceBitVector
- Overrides:
asLongBigList
in classAbstractBitVector
- Parameters:
width
- a bit width.- Returns:
- a view of this bit vector as a list of nonnegative integers of specified width.
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