public async Task <List <HSPNode> > PerformPlan(List <HSPPredicate> _init, List <HSPPredicate> _goal, List <HSPAction> _actions)
{
return(await Task.Run(() => solve()));
List <HSPNode> solve()
{
List <HSPNode> plan = new List <HSPNode>();
HashSet <string> explored = new HashSet <string>();
Dictionary <string, int> g_cost = new Dictionary <string, int>();
HashSet <string> goal = groundPredicates(_goal);
HSPNode start = new HSPNode(groundPredicates(_init), null, null, 0, 0);
Enqueue(start, start.getStateString());
while (frontierQ.Count() > 0)
{
HSPNode node = frontierQ.Dequeue();
HashSet <string> state = node.GetState();
explored.Add(node.getStateString());
if (ArrivedAtGoal(goal, state))
{
plan = node.getPath();
plan.Reverse();
return(plan);
}
foreach (HSPAction action in _actions)
{
if (action.isApplicableIn(state))
{
HashSet <string> newState = DeriveNewStateFromAction(action, state);
//#if node already explored, don't bother
string stateString = createStateString(newState);
if (!explored.Contains(stateString))
{
HSPNode new_node = new HSPNode(newState, action, node, (node.GetG() + 1), 0);
if (!g_cost.ContainsKey(stateString))
{
g_cost.Add(stateString, new_node.GetG());
}
if (!enQueued.Contains(stateString) || new_node.GetG() < g_cost[stateString])
{
Enqueue(new_node, stateString);
}
}
}
}
}
return(null);
}
}
private void Enqueue(HSPNode node, string stateString)
{
frontierQ.Enqueue(node);
enQueued.Add(stateString);
}
