/**
* Returns whether an abstract action is defined by some PC-rule, i.e. whether the abstract action
* matches with the head of some PC-rule.
*
* @param a the abstract action
* @return true if the action is defined by some rule, false otherwise
*/
public boolean defines(AbstractAction a) {
APLFunction plan = a.getPlan();
for (PCrule r : rules) {
APLFunction head = r.getHead();
if (head.getName().equals(plan.getName())
&& head.getParams().size() == plan.getParams().size()) return true;
}
return false;
}
/**
* Selects an applicable PC-rule. A PC-rule is applicable if the head matches the
* event/message/abstract action <code>a</code> and the guard is satisfied by the beliefs of the
* module. Returns a copy of the rule with fresh (unique) variables such that is does not
* interfere with the variables that already occur in the plan from which the abstract action is
* called.
*
* @param beliefbase the beliefs
* @param a the event/message/abstract action
* @param unfreshVars the list variables that cannot be used anymore
* @param theta the substitution for applying the rule
* @return the selected PC-rule
* @throws NoRuleException thrown if no rule is specified for <code>a</code>
*/
public PCrule selectRule(
Beliefbase beliefbase, APLFunction a, ArrayList<String> unfreshVars, SubstList<Term> theta)
throws NoRuleException {
boolean norulefound = true;
for (PCrule pcrule : rules) {
SubstList<Term> theta2 = new SubstList<Term>();
PCrule variant = pcrule.getVariant(unfreshVars);
Query guard = variant.getGuard().clone();
APLFunction head = variant.getHead();
if (a == null) continue; // TODO why???
if (Unifier.unify(head, a.clone(), theta2)) {
norulefound = false;
guard.applySubstitution(theta2);
if (beliefbase.doQuery(guard, theta2)) {
theta.putAll(theta2);
return variant;
}
}
}
if (norulefound) throw new NoRuleException();
return null;
}
/**
* Executes this action.
*
* @param module the module to execute this action for.
* @return true if the action succeeds, false otherwise.
*/
public PlanResult execute(APLModule module) {
Beliefbase beliefs = module.getBeliefbase();
PCrulebase pcrules = module.getPCrulebase();
plan.evaluateArguments();
SubstList<Term> theta = new SubstList<Term>();
PCrule rule;
try {
rule = pcrules.selectRule(beliefs, plan, getTopParent().getVariables(), theta, module);
} catch (NoRuleException e) {
return new PlanResult(this, PlanResult.FAILED);
}
if (rule != null) {
PlanSeq p = rule.getBody().clone();
p.applySubstitution(theta);
parent.removeFirst();
parent.addFirst(p);
return new PlanResult(this, PlanResult.SUCCEEDED);
} else return new PlanResult(this, PlanResult.FAILED);
}
