/// <summary>
/// Checks if this world state fulfills of the other.
/// Compare all symbols.
/// </summary>
/// <param name="other"></param>
/// <returns></returns>
public bool Satisfies(StratusWorldState other)
{
foreach (var symbol in other.symbols)
{
// Look for a matching symbol
var matchingSymbol = Find(symbol.key);
if (matchingSymbol != null)
{
// If the symbols were not equal...
if (!matchingSymbol.value.Compare(symbol.value))
{
//Trace.Script(Symbols[symbol.Key].Print() + " is not equal to " + symbol.Value.Print());
return(false);
}
}
// The symbol was not found
else
{
return(false);
}
}
// All symbols were a match
return(true);
}
public StratusWorldState Copy()
{
var newState = new StratusWorldState();
newState = this;
return(newState);
}
/// <summary>
/// Merges the symbols of the other world state with this one.
/// It will overwrite matching symbols, and add any not found in the current one.
/// </summary>
/// <param name="other"></param>
public void Merge(StratusWorldState other)
{
foreach (var otherSymbol in other.symbols)
{
Apply(otherSymbol);
}
}
public Node(Node parent, float cost, StratusWorldState state, StatefulAction action)
{
Parent = parent;
Cost = cost;
State = state;
Action = action;
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="startingState"></param>
/// <param name="goal"></param>
/// <param name="actions"></param>
public Search(StratusWorldState startingState, StratusWorldState goal, StatefulAction[] actions)
{
StartState = startingState.Copy();
EndState = goal;
Actions = actions;
}
/// <summary>
/// Given a goal, formulates a plan.
/// </summary>
/// <param name="goal"></param>
/// <returns></returns>
public static Plan Formulate(Planner planner, StatefulAction[] actions, StratusWorldState currentState, StratusGoal goal)
{
// Reset all actions
foreach (var action in actions)
{
action.Reset();
}
// Get all valid actions whose context preconditions are true
var usableActions = (from action
in actions
where action.contextPrecondition && !currentState.Satisfies(action.effects)
select action).ToArray();
if (planner.debug)
{
StratusDebug.Log("Making plan to satisfy the goal '" + goal.Name + "' with preconditions:" + goal.DesiredState.ToString(), planner.agent);
StratusDebug.Log("Actions available:", planner.agent);
foreach (var action in usableActions)
{
StratusDebug.Log("- " + action.description, planner.agent);
}
}
// The path of actions
Search.Path path;
if (Plan.UseAstar)
{
Search search = new Search(currentState, goal.DesiredState, usableActions);
search.Tracing = planner.debug;
search.Initialize();
path = search.FindSolution();
}
else
{
// Build up a tree of nodes
path = new Search.Path();
Search.Node starting = new Search.Node(null, 0f, goal.DesiredState, null);
// Look for a solution, backtracking from the goal's desired world state until
// we have fulfilled every precondition leading up to it!
var hasFoundPath = FindSolution(path, starting, usableActions, planner);
// If the path has not been found
if (!hasFoundPath)
{
if (planner.debug)
{
StratusDebug.Log("No plan could be formulated!", planner.agent);
}
return(new Plan());
}
}
// If no solution was found
if (path == null)
{
return(null);
}
// Make the plan
var plan = new Plan();
foreach (var action in path)
{
plan.Add(action);
}
return(plan);
}
