/**
* /// Trims an Fst, removing states and arcs that are not on successful paths.
* ///
* /// @param fst the fst to trim
*/
public static void Apply(Fst fst)
{
Semiring semiring = fst.Semiring;
if (semiring == null)
{
Logger.LogInfo <Connect>("Fst has no semiring.");
return;
}
HashSet <State> accessible = new HashSet <State>();
HashSet <State> coaccessible = new HashSet <State>();
List <Arc>[] exploredArcs = new List <Arc> [fst.GetNumStates()];
List <List <State> > paths = new List <List <State> >();
paths.Add(new List <State>());
DepthFirstSearch(fst, accessible, paths, exploredArcs, coaccessible);
HashSet <State> toDelete = new HashSet <State>();
for (int i = 0; i < fst.GetNumStates(); i++)
{
State s = fst.GetState(i);
if (!(accessible.Contains(s) || coaccessible.Contains(s)))
{
toDelete.Add(s);
}
}
fst.DeleteStates(toDelete);
}