org.h2.dev.hash

Class IntPerfectHash

java.lang.Object

org.h2.dev.hash.IntPerfectHash

public class IntPerfectHash
extends java.lang.Object

A minimum perfect hash function tool. It needs about 2.2 bits per key.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	IntPerfectHash.BitArray A helper class for bit arrays.

Constructor Summary

Constructors

Constructor and Description
IntPerfectHash(byte[] data) Create a hash object to convert keys to hashes.

Method Summary

Modifier and Type	Method and Description
static byte[]	generate(java.util.ArrayList<java.lang.Integer> list) Generate the minimal perfect hash function data from the given list.
int	get(int x) Calculate the hash value for the given key.
byte[]	getData() Get the hash function description.

Methods inherited from class java.lang.Object

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

Constructor Detail

IntPerfectHash

public IntPerfectHash(byte[] data)

Create a hash object to convert keys to hashes.

Parameters:

data - the data returned by the generate method

Method Detail

getData

public byte[] getData()

Get the hash function description.

Returns:

the data

get

public int get(int x)

Calculate the hash value for the given key.

Parameters:

x - the key

Returns:

the hash value

generate

public static byte[] generate(java.util.ArrayList<java.lang.Integer> list)

Generate the minimal perfect hash function data from the given list.

Parameters:

list - the data

Returns:

the hash function description