burlap.statehashing.simple

Class SimpleHashableStateFactory

java.lang.Object

burlap.statehashing.simple.SimpleHashableStateFactory

All Implemented Interfaces:

HashableStateFactory

Direct Known Subclasses:

DiscretizingHashableStateFactory, DiscretizingMaskedHashableStateFactory, MaskedHashableStateFactory

public class SimpleHashableStateFactory
extends java.lang.Object
implements HashableStateFactory

A straightforward factory for creating HashableState objects from State instances. It produces either a IISimpleHashableState or a IDSimpleHashableState. The general approach is that hash values are computed by iterating through each variable key in the order returned by State.variableKeys() and the has code for values returned by State.get(Object) are combined. Similarly, two states are evaluated as equal when the values returned by State.get(Object) satisfy their implemented Object.equals(Object) method.

This class also automatically provides special treatment for OO-MDP states (states that implement OOState) by being object identifier independent (the names of objects don't affect the state identity). However, you may disable identifier independence by using the constructor SimpleHashableStateFactory(boolean). If your domain is relational, it may be important to be identifier *dependent* (that is, set the parameter in the constructor to false).

Author:

James MacGlashan.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	identifierIndependent Whether state evaluations of OO-MDPs are object identifier independent (the names of objects don't matter).

Constructor Summary

Constructors

Constructor and Description
SimpleHashableStateFactory() Default constructor: object identifier independent and no hash code caching.
SimpleHashableStateFactory(boolean identifierIndependent) Initializes with no hash code caching.

Method Summary

Modifier and Type	Method and Description
HashableState	hashState(State s) Turns State s into a HashableState
boolean	objectIdentifierIndependent()

Methods inherited from class java.lang.Object

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

Field Detail

identifierIndependent

protected boolean identifierIndependent

Whether state evaluations of OO-MDPs are object identifier independent (the names of objects don't matter). By default it is independent.

Constructor Detail

SimpleHashableStateFactory

public SimpleHashableStateFactory()

Default constructor: object identifier independent and no hash code caching.

SimpleHashableStateFactory

public SimpleHashableStateFactory(boolean identifierIndependent)

Initializes with no hash code caching.

Parameters:

identifierIndependent - if true then state evaluations for OOStates are object identifier independent; if false then dependent.

Method Detail

hashState

public HashableState hashState(State s)

Description copied from interface: HashableStateFactory

Turns State s into a HashableState

Specified by:

hashState in interface HashableStateFactory

Parameters:

s - the input State to transform.

Returns:

a HashableState.

objectIdentifierIndependent

public boolean objectIdentifierIndependent()