/// <summary>
/// Generates all possible SAS+ relative states meeting conditions specified by the given conditions. Lazy generated via yield return.
/// </summary>
/// <param name="conditions">Reference conditions.</param>
/// <param name="variables">Variables of the planning problem.</param>
/// <returns>All possible SAS+ relative states meeting the conditions.</returns>
public static IEnumerable <IRelativeState> EnumerateRelativeStates(IConditions conditions, Variables variables)
{
foreach (var simpleCondition in conditions.GetSimpleConditions())
{
yield return(GetCorrespondingRelativeState(simpleCondition, variables));
}
}
/// <summary>
/// Gets a collection of all relevant predecessors (backwards transitions) from the specified conditions. Lazy generated via yield return.
/// </summary>
/// <param name="treeRoot">Root of the operator decision tree to be traversed.</param>
/// <param name="conditions">Original conditions.</param>
/// <returns>Lazy generated collection of relevant predecessors.</returns>
public IEnumerable <IPredecessor> GetPredecessors(IOperatorDecisionTreeNode treeRoot, IConditions conditions)
{
foreach (var simpleConditions in conditions.GetSimpleConditions())
{
foreach (var predecessor in treeRoot.Accept(this, conditions, simpleConditions))
{
yield return(predecessor);
}
}
}
/// <summary>
/// Generates all possible SAS+ states meeting conditions specified by the given conditions. Lazy generated via yield return.
/// </summary>
/// <param name="conditions">Reference conditions.</param>
/// <param name="variables">Variables of the planning problem.</param>
/// <returns>All possible SAS+ states meeting the conditions.</returns>
public static IEnumerable <IState> EnumerateStates(IConditions conditions, Variables variables)
{
foreach (var simpleCondition in conditions.GetSimpleConditions())
{
foreach (var state in EnumerateStates(simpleCondition, variables))
{
yield return(state);
}
}
}
/// <summary>
/// Computes the distances to the goals for the specified pattern.
/// </summary>
/// <param name="pattern">Pattern (i.e. variables of the pattern) to process.</param>
private PatternValuesDistances ComputePatternDistances(int[] pattern)
{
IHeap <double, ISimpleConditions> fringe = new LeftistHeap <ISimpleConditions>();
InsertPatternConditions(fringe, (Conditions)Problem.GoalConditions, 0, pattern);
PatternValuesDistances patternValuesDistances = new PatternValuesDistances();
while (fringe.GetSize() > 0)
{
double distance = fringe.GetMinKey();
ISimpleConditions conditions = fringe.RemoveMin();
int[] patternValues = conditions.GetAssignedValues();
Debug.Assert(pattern.Length == conditions.GetSize());
Debug.Assert(pattern.Length == patternValues.Length);
if (patternValuesDistances.ContainsKey(patternValues))
{
// already processed with a lower cost
continue;
}
patternValuesDistances.Add(patternValues, distance);
foreach (var predecessor in Problem.GetPredecessors(conditions))
{
IConditions predecessorConditions = (IConditions)predecessor.GetPredecessorConditions();
IOperator predecessorOperator = (IOperator)predecessor.GetAppliedOperator();
foreach (var predecessorSimpleConditions in predecessorConditions.GetSimpleConditions())
{
double cost = distance + predecessorOperator.GetCost();
InsertPatternConditions(fringe, predecessorSimpleConditions, cost, pattern);
}
}
}
return(patternValuesDistances);
}
