Package org.h2.dev.hash

Class IntPerfectHash

java.lang.Object
org.h2.dev.hash.IntPerfectHash
public class IntPerfectHash extends Object
A minimum perfect hash function tool. It needs about 2.2 bits per key.

  • Nested Class Summary

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

  • Constructor Summary

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

  • Method Summary

    Modifier and Type
    Method
    Description
    static byte[]
    generate(ArrayList<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 Details

    • IntPerfectHash

      public IntPerfectHash(byte[] data)
      Create a hash object to convert keys to hashes.
      Parameters:
      data - the data returned by the generate method

  • Method Details

    • 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(ArrayList<Integer> list)
      Generate the minimal perfect hash function data from the given list.
      Parameters:
      list - the data
      Returns:
      the hash function description