Package it.unimi.dsi.util

Class LiterallySignedStringMap

java.lang.Object

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

it.unimi.dsi.util.LiterallySignedStringMap

All Implemented Interfaces:

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

public class LiterallySignedStringMap
extends AbstractObject2LongFunction<CharSequence>
implements StringMap<MutableString>, Serializable

A string map based on a function signed using the original list of strings.

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. We can check that a string is part of the key set by hashing it to a value h, and checking that the h-th string of the original list does coincide. Since, moreover, this class implements StringMap, and thus exposes the original list, we have a two-way dictionary. In other words, this is a full StringMap implementation.

Note that some care must be exercised: CharSequence's contract does not prescribe equality by content, so if your function behaves badly on some implementations of CharSequence you might make the checks fail. To avoid difficulties, the constructor checks that every string in the list is hashed correctly.

For the same reason, this class implements StringMap<MutableString>, and requires that the list of strings provided at construction time is actually a list of mutable strings.

A typical usage of this class pairs a FrontCodedStringList with some kind of succinct structure from Sux4J.

Since:

1.0.8

Author:

Sebastiano Vigna

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected Object2LongFunction<? extends CharSequence>	function	The underlying map.
protected ObjectList<? extends MutableString>	list	The underlying list.
protected int	size	The size of list.

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

defRetValue

Constructor Summary

Constructors

Constructor	Description
LiterallySignedStringMap(Object2LongFunction<? extends CharSequence> function, ObjectList<? extends MutableString> list)	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)
Long	get(Object o)	Deprecated.
long	getLong(Object o)
ObjectList<? extends MutableString>	list()	Returns a list view of the domain of this string map (optional operation).
static void	main(String[] arg)
int	size()

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

The underlying map.

list

protected final ObjectList<? extends MutableString> list

The underlying list.

size

protected final int size

The size of list.

Constructor Detail

LiterallySignedStringMap

public LiterallySignedStringMap(Object2LongFunction<? extends CharSequence> function,
                                ObjectList<? extends MutableString> list)

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

Parameters:

function - a function mapping each string in list to its ordinal position.

list - a list of strings.

Method Detail

getLong

public long getLong(Object o)

Specified by:

getLong in interface Object2LongFunction<CharSequence>

get

@Deprecated
public Long get(Object o)

Deprecated.

Specified by:

get in interface Function<CharSequence,Long>

Specified by:

get in interface Object2LongFunction<CharSequence>

size

public int size()

Specified by:

size in interface Function<CharSequence,Long>

containsKey

public boolean containsKey(Object o)

Specified by:

containsKey in interface Function<CharSequence,Long>

list

public ObjectList<? extends MutableString> list()

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<MutableString>

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 IOException,
                        JSAPException,
                        ClassNotFoundException,
                        SecurityException,
                        NoSuchMethodException

Throws:

IOException

JSAPException

ClassNotFoundException

SecurityException

NoSuchMethodException