ix.util.lisp
Class ObjectHash

java.lang.Object
  ix.util.lisp.ObjectHash

public class ObjectHash
extends java.lang.Object

Provides re-readable (within a JVM) names for objects.

The names have the form "{" class-name "-" hash-value "}", where the hash-value is obtained by calling hash(Object). These names are used by Lisp.printToString(Object) and by Lisp.readFromString(String) and LispReaders in general, but they use a particular ObjectHash object that is private to the Lisp class.

Note that ordinary, strong references are used. Objects that have been given to hash(Object) will therefore not be garbage collected. This is to ensure that hash-names in strings will work even if no other reference to the object exists. Indeed, the only ref might be the user's memory of some output that contained a hash-name. The user can type in the same hash-name and get back the object.

The class-name part of hash-names is not checked. It is there only to make the names more meaningful.

Field Summary

protected java.util.List	hashToObject
protected EqMap	objectToHash

Constructor Summary

ObjectHash()

Method Summary

int	hash(java.lang.Object obj) Maps an object to an int that can be given to unhash(int) to get back the same (==) object.
java.lang.String	hashName(java.lang.Object obj) Returns a name of the form "{" class-name "-" hash-value "}", where the hash-value is obtained by calling hash(Object).
static void	main(java.lang.String[] argv) Test loop
java.lang.Object	parseHashName(java.lang.String name) The inverse of hashName(Object).
java.lang.Object	unhash(int h) The inverse of hash(Object).

Methods inherited from class java.lang.Object

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

Field Detail

objectToHash

protected EqMap objectToHash

hashToObject

protected java.util.List hashToObject

Constructor Detail

ObjectHash

public ObjectHash()

Method Detail

hash

public int hash(java.lang.Object obj)

Maps an object to an int that can be given to unhash(int) to get back the same (==) object.

unhash

public java.lang.Object unhash(int h)

The inverse of hash(Object).

hashName

public java.lang.String hashName(java.lang.Object obj)

Returns a name of the form "{" class-name "-" hash-value "}", where the hash-value is obtained by calling hash(Object).

parseHashName

public java.lang.Object parseHashName(java.lang.String name)

The inverse of hashName(Object).

Throws:

java.lang.IllegalArgumentException - if a valid object hash value cannot be found in the name.

main

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

Test loop