//----------------------------------------------------------------------------
// Copyright (C) 2011 Ingrid Nunes
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
// To contact the authors:
// http://inf.ufrgs.br/prosoft/bdi4jade/
//
//----------------------------------------------------------------------------
package bdi4jade.belief;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import bdi4jade.core.Capability;
import bdi4jade.event.BeliefEvent;
import bdi4jade.event.BeliefEvent.Action;
import bdi4jade.event.BeliefListener;
import bdi4jade.exception.BeliefAlreadyExistsException;
/**
* This class represents a belief base of a capability. It aggregates its
* knowledge.
*
* @author Ingrid Nunes
*/
public final class BeliefBase implements Serializable {
private static final long serialVersionUID = -6411530721625492882L;
private final Set<BeliefListener> beliefListeners;
private final Map<String, Belief<?>> beliefs;
private Capability capability;
/**
* The default constructor. It should be only used if persistence frameworks
* are used.
*/
protected BeliefBase() {
this.beliefListeners = new HashSet<BeliefListener>();
this.beliefs = new HashMap<String, Belief<?>>();
}
/**
* Creates a belief base associated with a capability.
*
* @param capability
* the capability to which this belief base belongs.
*/
public BeliefBase(final Capability capability) {
this(capability, null);
}
/**
* Creates a belief base associated with a capability and adds the beliefs
* in the provided belief set as the initial beliefs of this belief base.
*
* @param capability
* the capability to which this belief base belongs.
* @param beliefs
* the initial beliefs.
*/
public BeliefBase(final Capability capability, Set<Belief<?>> beliefs) {
if (capability == null)
throw new NullPointerException("Capability must be not null.");
this.capability = capability;
this.beliefListeners = new HashSet<BeliefListener>();
this.beliefs = new HashMap<String, Belief<?>>();
if (beliefs != null) {
for (Belief<?> belief : beliefs) {
this.beliefs.put(belief.getName(), belief);
}
}
}
/**
* Adds a belief to the belief base.
*
* @param belief
* the belief to be added.
*/
public void addBelief(Belief<?> belief) {
if (!hasBelief(belief.getName())) {
belief.addBeliefBase(this);
this.beliefs.put(belief.getName(), belief);
notifyBeliefChanged(new BeliefEvent(belief, Action.BELIEF_ADDED));
} else {
throw new BeliefAlreadyExistsException(belief);
}
}
/**
* Adds a belief listener to be notified about changes in the belief base.
*
* @param beliefListener
* the listener to be added.
*/
public void addBeliefListener(BeliefListener beliefListener) {
this.beliefListeners.add(beliefListener);
}
/**
* Adds a belief to the belief base. It updates the belief value, if it
* already exists.
*
* @param belief
* the belief to be added or updated.
*/
public void addOrUpdateBelief(Belief<?> belief) {
if (hasBelief(belief.getName())) {
updateBelief(belief.getName(), belief.getValue());
} else {
addBelief(belief);
}
}
/**
* Gets all beliefs of this belief base and the belief bases of the
* whole-capabilities of the capability that this belief base belongs to.
*
* @return the beliefs of this capability and all of its whole-capabilities.
*/
public Collection<Belief<?>> getAllBeliefs() {
Collection<Belief<?>> beliefs = new LinkedList<Belief<?>>();
getAllBeliefs(beliefs);
return beliefs;
}
/**
* This is a recursive method to implement the {@link #getAllBeliefs()}
* method.
*
* @param beliefs
* the set to which beliefs are added.
*/
private void getAllBeliefs(final Collection<Belief<?>> beliefs) {
beliefs.addAll(this.beliefs.values());
if (capability.getWholeCapability() != null) {
capability.getWholeCapability().getBeliefBase()
.getAllBeliefs(beliefs);
}
}
/**
* Retrieves a belief from the belief base. If this belief base does not
* contain it, the method checks whole-capabilities' belief base
* recursively.
*
* @param name
* the name of the belief to be retrieved.
* @return the belief, or null if no belief is found.
*/
public Belief<?> getBelief(String name) {
Belief<?> belief = this.beliefs.get(name);
if (belief == null && capability.getWholeCapability() != null) {
belief = capability.getWholeCapability().getBeliefBase()
.getBelief(name);
}
return belief;
}
/**
* Returns all the current belief listeners of this belief base.
*
* @return the belief listeners.
*/
public Set<BeliefListener> getBeliefListeners() {
return new HashSet<BeliefListener>(beliefListeners);
}
/**
* Gets all beliefs of this specific belief base.
*
* @return the beliefs
*/
public Set<Belief<?>> getBeliefs() {
return new HashSet<Belief<?>>(beliefs.values());
}
/**
* Returns a list of all belief values from this belief base.
*
* @return the beliefValues
*/
public List<Object> getBeliefValues() {
List<Object> beliefValues = new ArrayList<Object>(beliefs.size());
for (Belief<?> belief : beliefs.values())
beliefValues.add(belief.getValue());
return beliefValues;
}
/**
* Returns the capability with which this belief base is associated.
*
* @return the capability.
*/
public Capability getCapability() {
return capability;
}
/**
* Checks whether a belief is part of the belief base. If this belief base
* does not contain it, the method checks whole-capabilities' belief base
* recursively.
*
* @param name
* the belief to be checked
* @return true if the belief base contains the belief.
*/
public boolean hasBelief(String name) {
boolean hasBelief = this.beliefs.containsKey(name);
if (!hasBelief && capability.getWholeCapability() != null) {
hasBelief = capability.getWholeCapability().getBeliefBase()
.hasBelief(name);
}
return hasBelief;
}
/**
* Notifies the capability associated with this belief base that a belief
* was modified. It also recursively notifies belief listeners of part
* capabilities.
*
* @param beliefChanged
* the belief that was changed
*/
protected void notifyBeliefChanged(BeliefEvent beliefChanged) {
for (BeliefListener beliefListener : beliefListeners) {
beliefListener.update(beliefChanged);
}
for (Capability part : capability.getPartCapabilities()) {
part.getBeliefBase().notifyBeliefChanged(beliefChanged);
}
}
/**
* Removes a belief from the belief base. If this belief base does not
* contain it, the method checks whole-capabilities' belief base recursively
* to remove this belief..
*
* @param name
* the name of the belief to be removed.
* @return the belief was removed, null if it is not part of the belief
* base.
*/
public Belief<?> removeBelief(String name) {
Belief<?> belief = this.beliefs.remove(name);
if (belief != null) {
belief.removeBeliefBase(this);
notifyBeliefChanged(new BeliefEvent(belief, Action.BELIEF_REMOVED));
} else {
if (capability.getWholeCapability() != null) {
belief = capability.getWholeCapability().getBeliefBase()
.removeBelief(name);
}
}
return belief;
}
/**
* Removes a belief listener.
*
* @param beliefListener
* the listener to be removed.
*/
public void removeBeliefListener(BeliefListener beliefListener) {
this.beliefListeners.remove(beliefListener);
}
/**
* Associates a capability with this belief base. Ideally, the capability
* should be final and initialized in the constructor. This method should be
* only used if persistence frameworks are used.
*
* @param capability
* the capability to set.
*/
protected void setCapability(Capability capability) {
this.capability = capability;
}
/**
* Gets the size of this specific belief base (the number of beliefs).
*
* @return the size of this belief base.
*/
public int size() {
return this.beliefs.size();
}
/**
* Returns this belief base as a string in the form:
* "Belief base of Capability ID = [ BELIEFS ]".
*
* @return the string representation of this belief base.
*
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
StringBuffer sb = new StringBuffer("Belief base of Capability ");
if (capability == null)
sb.append(" NO ID");
else
sb.append(capability.getId());
sb.append(" = ").append(beliefs);
return sb.toString();
}
/**
* Updates the value of a belief in the belief base. In case the belief is
* not present in the belief base (of in its whole-capabilities' belief
* bases), nothing is performed and the method returns false. If the type of
* the new value being provided does not match the current type, the method
* still subscribes the previous value.
*
* @param name
* the belief to be updated.
* @param value
* the new value to the belief.
* @return true if the belief was updated.
*/
@SuppressWarnings("unchecked")
public boolean updateBelief(String name, Object value) {
Belief belief = this.beliefs.get(name);
if (belief != null) {
belief.setValue(value);
return true;
} else if (capability.getWholeCapability() != null) {
return capability.getWholeCapability().getBeliefBase()
.updateBelief(name, value);
}
return false;
}
}