sun.rmi.rmic.iiop

Class StaticStringsHash

java.lang.Object

sun.rmi.rmic.iiop.StaticStringsHash

public class StaticStringsHash
extends java.lang.Object

StaticStringsHash takes an array of constant strings and uses several different hash methods to try to find the 'best' one for that set. The set of methods is currently fixed, but with a little work could be made extensible thru subclassing.

The current set of methods is:

1. length() - works well when all strings are different length.
2. charAt(n) - works well when one offset into all strings is different.
3. hashCode() - works well with larger arrays.

After constructing an instance over the set of strings, the getKey(String) method can be used to use the selected hash method to produce a key. The method string will contain "length()", "charAt(n)", or "hashCode()", and is intended for use by code generators.

The keys array will contain the full set of unique keys.

The buckets array will contain a set of arrays, one for each key in the keys, where buckets[x][y] is an index into the strings array.

Author:

Bryan Atsatt

Field Summary

Fields

Modifier and Type	Field and Description
int[][]	buckets Buckets for each key, where buckets[x][y] is an index into the strings[] array.
int[]	keys Unique hash keys
java.lang.String	method The method to invoke on String to produce the hash key
java.lang.String[]	strings The set of strings upon which the hash info is created

Constructor Summary

Constructors

Constructor and Description
StaticStringsHash(java.lang.String[] strings) Constructor

Method Summary

Methods

Modifier and Type	Method and Description
int	getKey(java.lang.String str) Get a key for the given string using the selected hash method.
static void	main(java.lang.String[] args) Print an optimized 'contains' method for the argument strings

Methods inherited from class java.lang.Object

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

Field Detail

strings

public java.lang.String[] strings

The set of strings upon which the hash info is created

keys

public int[] keys

Unique hash keys

buckets

public int[][] buckets

Buckets for each key, where buckets[x][y] is an index into the strings[] array.

method

public java.lang.String method

The method to invoke on String to produce the hash key

Constructor Detail

StaticStringsHash

public StaticStringsHash(java.lang.String[] strings)

Constructor

Parameters:

strings - the set of strings upon which to find an optimal hash method. Must not contain duplicates.

Method Detail

getKey

public int getKey(java.lang.String str)

Get a key for the given string using the selected hash method.

Parameters:

str - the string to return a key for.

Returns:

the key.

main

public static void main(java.lang.String[] args)

Print an optimized 'contains' method for the argument strings