/// <summary>
/// Moves the DFBnB algorithm forward one step.
/// </summary>
/// <returns>Returns the state the alorithm is in after the step, Searching or Ended.</returns>
internal override State Step()
{
// stop condition
if (openList.IsEmpty())
{
return(State.Ended);
}
// Check the next node in the queue and pop it
var currentNode = openList.Pop();
//do Prune if needed
if (candidateGoalNode != null && currentNode.f < candidateGoalNode.g)
{
AlgPruned++;
return(State.Searching);
}
//Expand what is not pruned
Expended++;
//store best candidate if we seeing it
if (GoalCheckMethod.ValidGoal(currentNode))
{
if (candidateGoalNode == null || currentNode.g > candidateGoalNode.g)
{
candidateGoalNode = currentNode;
#if DEBUG
Log.WriteLineIf("[AStarMax] Best Candidate:" + candidateGoalNode, TraceLevel.Verbose);
#endif
}
}
foreach (var child in currentNode.Children)
{
if (!PrunningMethod.ShouldPrune(child))
{
openList.Push(child);
Generated++;
}
else
{
ExternalPruned++;
}
}
return(State.Searching);
}
internal override State Step()
{
#if DEBUG
Log.WriteLineIf($"[StepStart] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned}", TraceLevel.Verbose);
#endif
// stop condition
if (openList.IsEmpty())
{
#if DEBUG
Log.WriteLineIf($"[StepEnd] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned} - return Ended-EmptyList", TraceLevel.Verbose);
#endif
return(State.Ended);
}
// Check the next best node in OPEN and set it to current
var currentNode = openList.Pop();
if (Generated % LogSearchStatusEveryXGenerated == 0)
{
#if DEBUG
Log.WriteLineIf($"[AStarMax] OpenListSize:{openList.Count}", TraceLevel.Verbose);
#endif
}
//store best candidate if we seeing it
if (GoalCheckMethod.ValidGoal(currentNode)) ///TODO: if this is a valid goal - dont try to expand id
{
if (candidateGoalNode == null || currentNode.g > candidateGoalNode.g)
{
candidateGoalNode = currentNode;
#if DEBUG
Log.WriteLineIf("[ValidCandidate] Best Candidate:" + candidateGoalNode, TraceLevel.Verbose);
#endif
}
}
if (candidateGoalNode != null && currentNode.f < candidateGoalNode.g)
{
#if DEBUG
Log.WriteLineIf($"[BestCandidate] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned} - return Ended-BestFound!!!", TraceLevel.Verbose);
#endif
return(State.Ended);
}
//Expand current node
Expended++;
#if DEBUG
Log.WriteLineIf("[StepExpanding...] ", TraceLevel.Verbose);
#endif
foreach (var child in currentNode.Children)
{
#if DEBUG
if (child.h > currentNode.h)
{
Log.WriteLineIf($"[HEURISTIC NOT CONSISTENT] Parent: {currentNode.h}, Child:{child.GetBitsString()}", TraceLevel.Error);
}
#endif
#if DEBUG
Log.WriteLineIf($"[GenerateChild...] {child.GetBitsString()}", TraceLevel.Info);
#endif
if (!PrunningMethod.ShouldPrune(child))
{
#if DEBUG
Log.WriteLineIf("[Prune] false", TraceLevel.Verbose);
#endif
openList.Add(child);
Generated++;
}
else
{
#if DEBUG
Log.WriteLineIf("[Prune] true", TraceLevel.Verbose);
#endif
ExternalPruned++;
}
}
#if DEBUG
Log.WriteLineIf($"[AStarMax.StepEnd] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned} - return Searching", TraceLevel.Verbose);
#endif
return(State.Searching);
}