/*
* Returns true if the KC_PrologExpression on the unit has already been evaluated, false otherwise.
* Given a unit containing a KC_PrologExpression and a blackboard, returns true if there is a
* L_SelectedUnitLink to a Unit with a KC_EvaluatablePrologExpression matching the KC_PrologExpression.
*/
protected static bool HasLinkToEvaluatedExpression(Unit unit, IBlackboard blackboard)
{
ISet <(IUnit, string, LinkDirection)> links = blackboard.LookupLinks(unit);
foreach ((IUnit linkedIUnit, string type, LinkDirection dir) in links)
{
/*
* There should only be up to 1 outgoing L_SelectedUnit link, but since I'm not enforcing this on the blackboard,
* for now testing all L_SelectedUnit links until I find a matching KC_EvaluatablePrologExpression
*/
if (type.Equals(LinkTypes.L_SelectedUnit) && dir == LinkDirection.End)
{
Unit linkedUnit = linkedIUnit as Unit;
// If the linkedUnit contains a matching, evaluated, KC_EvaluatablePrologExpression, return true.
if (linkedUnit.HasComponent <KC_EvaluatablePrologExpression>())
{
KC_EvaluatablePrologExpression evaledPrologExp = linkedUnit.GetComponent <KC_EvaluatablePrologExpression>();
if (evaledPrologExp.PrologExpName.Equals(unit.GetPrologExpName <KC_PrologExpression>()) && evaledPrologExp.Evaluated)
{
Debug.Assert(evaledPrologExp.PrologExp.Equals(unit.GetPrologExp()));
return(true);
}
/* fixme
* Consider making this recursively search links if the linked Unit has an EvaluatablePrologExpression with a matching name but it has
* not been evaluated (though currently there's no KS in the system that does this) OR there's a PrologExpression with a matching name.
* The latter is a likely use case. If we downselected in a pool with prolog expressions first, then evaluated those, that would result
* in this case.
*/
}
}
}
return(false); // No linked, matching KC_EvaluatablePrologExpression was found.
}
/*
* Copy all the units bound by the precondition into the OutputPool adding a KC_EvaluatablePrologExpression and evaluate the expression.
*/
protected override void Execute(object[] boundVars)
{
// Get the units and the prolog KB from the precondition bindings.
var units = (IEnumerable <Unit>)boundVars[FilteredUnits];
Unit prologKB = (Unit)boundVars[PrologKB];
// Copy each of the units to the output pool, adding a KC_EvaluatablePrologExpression and evaluating it.
foreach (var unit in units)
{
Unit unitCopy = CopyUnitToOutputPool(unit);
// fixme: ignoring the name. When the Unit component infrastructure is updated to handle multiple named components, change the call here.
KC_PrologExpression expToEvaluate = unitCopy.GetComponent <KC_PrologExpression>();
// Remove the KC_PrologExpression
unitCopy.RemoveComponent(expToEvaluate);
// Create a KC_EvaluatablePrologExpression based on expToEvaluate.
KC_EvaluatablePrologExpression evaluatablePrologExp = new KC_EvaluatablePrologExpression(expToEvaluate);
// Add the KC_EvaluatablePrologExpression to the Unit
unitCopy.AddComponent(evaluatablePrologExp);
/*
* Evaluate the prolog expression.
* The original unit now being linked (via CopyUnitToOutputPool) to a unit with a matching and evaled KC_EvaluatablePrologExpression
* is what will keep this unit from repeatedly matching in the precondition. The precondition is testing !HasLinkToEvaluatedExpression
* as a filter condition.
*/
evaluatablePrologExp.Evaluate(prologKB.GetComponent <KC_PrologKB>());
}
}