// Creates and returns a new node.
public static StateSpaceNode CreateNode(Planner planner, Domain domain, Problem problem, Plan plan, State state)
{
// Create a node for the current state.
StateSpaceNode root = new StateSpaceNode();
// Record that a node was created.
StateSpaceMediator.NodeCount++;
// Check if the node is a leaf.
if (StateSpaceSearchTools.CheckLeaf(plan, state, root))
{
return(root);
}
// Set the node's domain.
root.domain = domain;
// Set the node's problem.
root.problem = problem;
// Set the node's plan.
root.plan = plan;
// Set the node's state.
root.state = state;
// Find out what the player knows.
root.problem.Initial = RobertsonMicrotheory.Annotate(problem.Initial, problem.Player);
// Find all outgoing user actions from this state.
root.outgoing = StateSpaceTools.GetAllPossibleActions(domain, problem, plan, state);
// Record the number of outgoing edges.
StateSpaceMediator.OutgoingEdgesCount = StateSpaceMediator.OutgoingEdgesCount + root.outgoing.Count;
// Return the current node.
return(root);
}
// Build the mediation tree using a depth-first strategy.
public static StateSpaceNode BuildTree(Planner planner, Domain domain, Problem problem, Plan plan, State state, int depth)
{
// Create a node for the current state.
StateSpaceNode root = new StateSpaceNode();
// Record that a node was created.
NodeCount++;
// Return any empty plans.
if (plan.Steps.Count == 0)
{
// If the goal is satisfied...
if (state.Satisfies(plan.GoalStep.Preconditions))
{
// Differentiate a satisfied goal.
root.satisfiesGoal = true;
// Record that a goal state was reached.
GoalStateCount++;
}
else
{
// Record that a dead end state was reached.
DeadEndCount++;
}
// Return the leaf node.
return(root);
}
// Set the node's domain.
root.domain = domain;
// Set the node's problem.
root.problem = problem;
// Set the node's plan.
root.plan = plan;
// Set the node's state.
root.state = state;
// Find out what the player knows.
root.problem.Initial = RobertsonMicrotheory.Annotate(problem.Initial, problem.Player);
// Find all outgoing user actions from this state.
root.outgoing = StateSpaceTools.GetAllPossibleActions(domain, problem, plan, state);
// Return the node if the depth limit has been reached.
if (depth <= 0)
{
return(root);
}
// Loop through the possible actions.
foreach (StateSpaceEdge edge in root.outgoing)
{
StateSpaceNode child = ExpandTree(planner, domain, problem, plan.Clone() as Plan, state.Clone() as State, edge, depth);
// Set the child's parent to this node.
child.parent = root;
// Add the child to the parent's collection of children, by way of the current action.
root.children[edge] = child;
}
// Return the current node.
return(root);
}
