public static SimulationPath <A, S> RunSimulation(PDA <A, S> pda, A[] word)
{
var acceptanceResult = pda.AcceptsWord(word);
if (!acceptanceResult.Accepts())
{
throw new NoAcceptanceException("the pda does not accept the word, therefore, a simulation is not possible");
}
var initialNode = SimulationNode <A, S> .InitialNode(
new Configuration <A, S>(pda.InitialState, new Word <A>(word), CurrentStack <S> .WithSingleSymbol(pda.FirstStackSymbol)),
pda.AcceptanceCondition);
var frontChain = new List <SimulationNode <A, S> > {
initialNode
};
while (frontChain.Count() > 0)
{
var nodesAcceptedWord = frontChain.Where(node => node.HasAcceptedWord).ToList();
if (nodesAcceptedWord.Count() > 0)
{
return(SimulationPathFromFinalNode(nodesAcceptedWord.First()));
}
foreach (var node in frontChain)
{
node.DoStep();
}
frontChain = frontChain.SelectMany(node => node.Children).ToList();
}
throw new InvalidOperationException("the given pda does not accept the word, therefore a simulation is not possible");
}
internal static SimulationPath <A, S> SimulationPathFromFinalNode(SimulationNode <A, S> finalNode)
{
var path = new List <SimulationNode <A, S> >()
{
finalNode
};
var currentNode = finalNode;
while (currentNode.Parent != null)
{
currentNode = currentNode.Parent;
path.Insert(0, currentNode);
}
return(new SimulationPath <A, S>(path));
}
internal static SimulationNode <A, S> ApplyTransitionToParentSimulationNode(Transition <A, S> transitionToHere, SimulationNode <A, S> nodeBefore)
{
return(new SimulationNode <A, S>(Configuration <A, S> .ApplyTransitionToConfiguration(transitionToHere, nodeBefore.Config), transitionToHere, nodeBefore, nodeBefore.acceptanceCondition));
}
public SimulationNode(Configuration <A, S> config, Transition <A, S> transitionToHere, SimulationNode <A, S> parent, AcceptanceCondition acceptanceCondition) : base(config, transitionToHere)
{
Parent = parent;
this.acceptanceCondition = acceptanceCondition;
CheckIfWordIsAccepted();
}
