Package it.unimi.dsi.big.util

Class ShiftAddXorSignedStringMap

java.lang.Object

it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction<CharSequence>

it.unimi.dsi.big.util.ShiftAddXorSignedStringMap

All Implemented Interfaces:

StringMap<CharSequence>, Function<CharSequence,Long>, Object2LongFunction<CharSequence>, Size64, Serializable, Function<CharSequence,Long>, ToLongFunction<CharSequence>

@Deprecated
public class ShiftAddXorSignedStringMap
extends AbstractObject2LongFunction<CharSequence>
implements StringMap<CharSequence>, Serializable

Deprecated.

There are much better and faster hash functions.

A string map based on a function signed using Shift-Add-Xor hashes.

A minimal perfect hash function maps a set of string to an initial segment of the natural numbers, but will actually map any string to that segment. By signing each output value with a hash of the string, we get a dictionary-like functionality with a rate error that can be balanced with space occupancy (signatures can go from 1 to Long.SIZE bits).

For the kind of hash we use, see “Performance in practice of string hashing functions”, by M.V. Ramakrishna and Justin Zobel, Proc. of the Fifth International Conference on Database Systems for Advanced Applications, 1997, pages 215−223.

Since:

2.0

Author:

Sebastiano Vigna

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected Object2LongFunction<? extends CharSequence>	function	Deprecated. The underlying map.
protected long	mask	Deprecated. The mask to get only width nonzero bits.
protected int	shift	Deprecated. The left shift to get only width nonzero bits.
protected LongBigList	signatures	Deprecated. Signatures.
protected int	width	Deprecated. The width in bits of each signature.

Fields inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction

defRetValue

Constructor Summary

Constructors

Constructor	Description
ShiftAddXorSignedStringMap(Iterator<? extends CharSequence> iterator, Object2LongFunction<? extends CharSequence> map)	Deprecated. Creates a new shift-add-xor signed string map using a given hash map and 32-bit signatures.
ShiftAddXorSignedStringMap(Iterator<? extends CharSequence> iterator, Object2LongFunction<? extends CharSequence> map, int signatureWidth)	Deprecated. Creates a new shift-add-xor signed string map using a given hash map.

Method Summary

Modifier and Type	Method	Description
boolean	containsKey(Object o)	Deprecated.
Long	get(Object o)	Deprecated.
long	getLong(Object o)	Deprecated.
ObjectBigList<CharSequence>	list()	Deprecated. Returns a list view of the domain of this string map (optional operation).
static void	main(String[] arg)	Deprecated.
int	size()	Deprecated.
long	size64()	Deprecated. Returns the intended number of keys in this function, or -1 if no such number exists.

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction

defaultReturnValue, defaultReturnValue

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.dsi.fastutil.Function

apply, clear

Methods inherited from interface java.util.function.Function

andThen, compose

Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2LongFunction

applyAsLong, defaultReturnValue, defaultReturnValue, put, put, remove, removeLong

Field Detail

function

protected final Object2LongFunction<? extends CharSequence> function

Deprecated.

The underlying map.

signatures

protected final LongBigList signatures

Deprecated.

Signatures.

width

protected final int width

Deprecated.

The width in bits of each signature.

shift

protected final int shift

Deprecated.

The left shift to get only width nonzero bits.

mask

protected final long mask

Deprecated.

The mask to get only width nonzero bits.

Constructor Detail

ShiftAddXorSignedStringMap

public ShiftAddXorSignedStringMap(Iterator<? extends CharSequence> iterator,
                                  Object2LongFunction<? extends CharSequence> map)

Deprecated.

Creates a new shift-add-xor signed string map using a given hash map and 32-bit signatures.

Parameters:

iterator - an iterator enumerating a set of strings.

map - a minimal perfect hash for the strings enumerated by iterator; it must support size() and have default return value -1.

ShiftAddXorSignedStringMap

public ShiftAddXorSignedStringMap(Iterator<? extends CharSequence> iterator,
                                  Object2LongFunction<? extends CharSequence> map,
                                  int signatureWidth)

Deprecated.

Creates a new shift-add-xor signed string map using a given hash map.

Parameters:

iterator - an iterator enumerating a set of strings.

map - a minimal perfect hash for the strings enumerated by iterator; it must support size() and have default return value -1.

signatureWidth - the width, in bits, of the signature of each string.

Method Detail

getLong

public long getLong(Object o)

Deprecated.

Specified by:

getLong in interface Object2LongFunction<CharSequence>

get

public Long get(Object o)

Deprecated.

Specified by:

get in interface Function<CharSequence,Long>

Specified by:

get in interface Object2LongFunction<CharSequence>

containsKey

public boolean containsKey(Object o)

Deprecated.

Specified by:

containsKey in interface Function<CharSequence,Long>

size

@Deprecated
public int size()

Deprecated.

Description copied from interface: StringMap

Specified by:

size in interface Function<CharSequence,Long>

Specified by:

size in interface Size64

Specified by:

size in interface StringMap<CharSequence>

size64

public long size64()

Deprecated.

Description copied from interface: StringMap

Returns the intended number of keys in this function, or -1 if no such number exists.

Most function implementations will have some knowledge of the intended number of keys in their domain. In some cases, however, this might not be possible. This default implementation, in particular, returns -1.

Specified by:

size64 in interface Size64

Specified by:

size64 in interface StringMap<CharSequence>

Returns:

the intended number of keys in this function, or -1 if that number is not available.

list

public ObjectBigList<CharSequence> list()

Deprecated.

Description copied from interface: StringMap

Returns a list view of the domain of this string map (optional operation).

Note that the list view acts as an inverse of the mapping implemented by this map.

Specified by:

list in interface StringMap<CharSequence>

Returns:

a list view of the domain of this string map, or null if this map does not support this operation.

main

public static void main(String[] arg)
                 throws NoSuchMethodException,
                        IOException,
                        JSAPException,
                        ClassNotFoundException

Deprecated.

Throws:

NoSuchMethodException

IOException

JSAPException

ClassNotFoundException