private static TThis BuildSubautomaton(IReadOnlyList <State> states, IReadOnlyList <State> topologicalOrder, int group, HashSet <int> subgraph)
{
var weightsFromRoot = ComputeWeightsFromRoot(states.Count, topologicalOrder, group);
var weightsToEnd = ComputeWeightsToEnd(states.Count, topologicalOrder, group);
var subautomaton = new TThis();
var stateMapping = subgraph.ToDictionary(x => x, _ => subautomaton.AddState());
var hasNoIncomingTransitions = new HashSet <int>(subgraph);
// copy the automaton and find states without incoming transitions.
foreach (var stateIndex in subgraph)
{
var newSourceState = stateMapping[stateIndex];
for (int i = 0; i < states[stateIndex].TransitionCount; i++)
{
var transition = states[stateIndex].GetTransition(i);
if (transition.Group != group)
{
continue;
}
hasNoIncomingTransitions.Remove(transition.DestinationStateIndex);
newSourceState.AddTransition(
transition.ElementDistribution,
transition.Weight,
stateMapping[transition.DestinationStateIndex]);
}
}
var correctionFactor = Weight.Zero;
// mark start and end states, modulo paths bypassing the automaton.
foreach (var stateIndex in subgraph)
{
var newSourceState = stateMapping[stateIndex];
// consider start states
var weightFromRoot = newSourceState.TransitionCount > 0 ? weightsFromRoot[stateIndex] : Weight.Zero;
if (!weightFromRoot.IsZero)
{
subautomaton.Start.AddEpsilonTransition(weightFromRoot, newSourceState);
}
// consider end states
var weightToEnd = !hasNoIncomingTransitions.Contains(stateIndex) ? weightsToEnd[stateIndex] : Weight.Zero;
if (!weightToEnd.IsZero)
{
newSourceState.SetEndWeight(weightToEnd);
}
correctionFactor = Weight.Sum(correctionFactor, Weight.Product(weightFromRoot, weightToEnd));
}
if (!correctionFactor.IsZero)
{
throw new Exception("Write a unit test for this case. Code should be fine.");
}
var epsilonWeight = Weight.AbsoluteDifference(weightsToEnd[topologicalOrder[0].Index], correctionFactor);
subautomaton.Start.SetEndWeight(epsilonWeight);
return(subautomaton);
}
public MyServiceInterface(TThis service, string name, Type[] dependencies)
{
m_service = service;
this.Name = name;
m_dependencies = dependencies;
}