burlap.behavior.singleagent.auxiliary

Class StateEnumerator

java.lang.Object

burlap.behavior.singleagent.auxiliary.StateEnumerator

public class StateEnumerator
extends java.lang.Object

For some algorithms, it is useful to have an explicit unique state identifier for each possible state and the hashcode of a state cannot reliably give a unique number. This class is used to take hashable states and assign them a unique number. States can be enumerated iteratively on an as needed basis or all reachable states from a source state can be queried to seed the list of states. This class can also go in the reverse direction by returning the state associated with an enumeration id, as long as that id has already been assigned to a state.

Author:

James MacGlashan

Field Summary

Fields

Modifier and Type	Field and Description
protected Domain	domain The domain whose states will be enumerated
protected java.util.Map<StateHashTuple,java.lang.Integer>	enumeration The forward state enumeration map
protected StateHashFactory	hashingFactory The hashing factory used to hash states and perform equality tests
protected int	nextEnumeratedID The id to use for the next unique state that is added
protected java.util.Map<java.lang.Integer,State>	reverseEnumerate The reverse enumeration id to state map

Constructor Summary

Constructors

Constructor and Description
StateEnumerator(Domain domain, StateHashFactory hashingFactory) Constructs

Method Summary

Methods

Modifier and Type	Method and Description
void	findReachableStatesAndEnumerate(State from) Finds all states that are reachable from an input state and enumerates them
void	findReachableStatesAndEnumerate(State from, TerminalFunction tf) Finds all states that are reachable from an input state and enumerates them.
int	getEnumeratedID(State s) Get or create and get the enumeration id for a state
protected int	getEnumeratedID(StateHashTuple sh) Get or create and get the enumeration id for a hashed state
State	getStateForEnumertionId(int id) Returns the state associated with the given enumeration id.
int	numStatesEnumerated() Returns the number of states that have been enumerated

Methods inherited from class java.lang.Object

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

Field Detail

domain

protected Domain domain

The domain whose states will be enumerated

hashingFactory

protected StateHashFactory hashingFactory

The hashing factory used to hash states and perform equality tests

enumeration

protected java.util.Map<StateHashTuple,java.lang.Integer> enumeration

The forward state enumeration map

reverseEnumerate

protected java.util.Map<java.lang.Integer,State> reverseEnumerate

The reverse enumeration id to state map

nextEnumeratedID

protected int nextEnumeratedID

The id to use for the next unique state that is added

Constructor Detail

StateEnumerator

public StateEnumerator(Domain domain,
               StateHashFactory hashingFactory)

Constructs

Parameters:

domain - the domain of the states to be enumerated

hashingFactory - the hashing factory to use

Method Detail

findReachableStatesAndEnumerate

public void findReachableStatesAndEnumerate(State from)

Finds all states that are reachable from an input state and enumerates them

Parameters:

from - the state from which all reachable states should be searched

findReachableStatesAndEnumerate

public void findReachableStatesAndEnumerate(State from,
                                   TerminalFunction tf)

Finds all states that are reachable from an input state and enumerates them. Will not search from states that are marked as terminal states.

Parameters:

from - the state from which all reachable states should be searched

tf - the terminal function that prevents expanding from terminal states

getEnumeratedID

public int getEnumeratedID(State s)

Get or create and get the enumeration id for a state

Parameters:

s - the state to get the enumeration id

Returns:

the enumeration id

getStateForEnumertionId

public State getStateForEnumertionId(int id)

Returns the state associated with the given enumeration id. A state must have previously be associated with the input enumeration id, or a runtime exception is thrown.

Parameters:

id - the enumeration id

Returns:

the state associated with the given enumeration id.

numStatesEnumerated

public int numStatesEnumerated()

Returns the number of states that have been enumerated

Returns:

the number of states that have been enumerated

getEnumeratedID

protected int getEnumeratedID(StateHashTuple sh)

Get or create and get the enumeration id for a hashed state

Parameters:

sh - the hased state to get the enumeration id

Returns:

the enumeration id