// Apply an operator's effects to the current state.
public List <IPredicate> ApplyAction(Operator action, List <IObject> objects)
{
// Create a new set of predicates.
List <IPredicate> newPredicates = new List <IPredicate>();
// Initialize the state to the previous state.
foreach (IPredicate pred in Predicates)
{
newPredicates.Add(pred.Clone() as Predicate);
}
// Store the conditional axioms that are true in the current state.
List <IAxiom> applicableEffects = ApplicableConditionals(action, objects);
action.Conditionals = applicableEffects;
List <IPredicate> effects = new List <IPredicate>();
foreach (IPredicate effect in action.Effects)
{
effects.Add(effect.Clone() as Predicate);
}
foreach (IAxiom conditional in applicableEffects)
{
foreach (IPredicate effect in conditional.Effects)
{
effects.Add(effect.Clone() as Predicate);
}
}
// Update the state using the current step effects.
foreach (IPredicate effect in effects)
{
// Bind the effect's terms for good.
//effect.BindTerms(action.Bindings);
// Add a positive effect that does not already exist.
if (effect.Sign)
{
if (!newPredicates.Contains(effect))
{
newPredicates.Add(effect);
}
}
// Hack because C# is silly... or maybe I am.
Predicate found = new Predicate();
// Find if a negative effect already exists.
if (!effect.Sign)
{
foreach (IPredicate pred in newPredicates)
{
if (pred.ToString().Equals(effect.ToStringPositive()))
{
found = pred as Predicate;
}
}
}
// Remove a negative effect.
if (!found.Name.Equals(""))
{
newPredicates.Remove(found);
}
}
// Return the new set of predicates.
return(newPredicates);
}
// Find applicable conditional effects.
public List <IAxiom> ApplicableConditionals(Operator action, List <IObject> objects)
{
// Store the conditional axioms that are true in the current state.
List <IAxiom> applicableEffects = new List <IAxiom>();
// Loop through the action's conditional effect axioms.
foreach (IAxiom conditional in action.Conditionals)
{
List <Hashtable> bindings = new List <Hashtable>();
Hashtable binding = new Hashtable();
if (conditional.Arity == 0)
{
Hashtable thisBind = action.Bindings.Clone() as Hashtable;
bindings.Add(thisBind);
}
else
{
for (int i = 0; i < conditional.Arity; i++)
{
List <Hashtable> lastBindings = new List <Hashtable>();
foreach (Hashtable lastBinding in bindings)
{
lastBindings.Add(lastBinding.Clone() as Hashtable);
}
List <Hashtable> newBindings = new List <Hashtable>();
foreach (IObject obj in objects)
{
List <Hashtable> theseBindings = new List <Hashtable>();
if (lastBindings.Count > 0)
{
foreach (Hashtable bind in lastBindings)
{
Hashtable thisBind = bind.Clone() as Hashtable;
thisBind.Add(conditional.TermAt(i), obj.Name);
theseBindings.Add(thisBind);
}
}
else
{
Hashtable thisBind = action.Bindings.Clone() as Hashtable;
thisBind.Add(conditional.TermAt(i), obj.Name);
theseBindings.Add(thisBind);
}
newBindings.AddRange(theseBindings);
}
bindings = newBindings;
}
}
foreach (Hashtable bind in bindings)
{
Axiom boundAxiom = conditional.Clone() as Axiom;
boundAxiom.Bindings = bind;
applicableEffects.Add(boundAxiom);
}
}
List <IAxiom> removeCond = new List <IAxiom>();
foreach (IAxiom conditional in applicableEffects)
{
conditional.BindTerms();
if (!Satisfies(conditional.Preconditions))
{
removeCond.Add(conditional);
}
}
foreach (Axiom remove in removeCond)
{
applicableEffects.Remove(remove);
}
return(applicableEffects);
}