/// <summary> /// Adds epsilon transitions to the given automaton. This method adds extra character interval /// transitions that are equivalent to the given set of epsilon transitions. /// </summary> /// <param name="a">The automaton.</param> /// <param name="pairs">A collection of <see cref="StatePair"/> objects representing pairs of /// source/destination states where epsilon transitions should be added.</param> internal static void AddEpsilons(Automaton a, ICollection <StatePair> pairs) { a.ExpandSingleton(); var forward = new Dictionary <State, HashSet <State> >(); var back = new Dictionary <State, HashSet <State> >(); foreach (StatePair p in pairs) { HashSet <State> to = forward[p.FirstState]; if (to == null) { to = new HashSet <State>(); forward.Add(p.FirstState, to); } to.Add(p.SecondState); HashSet <State> from = back[p.SecondState]; if (from == null) { from = new HashSet <State>(); back.Add(p.SecondState, from); } from.Add(p.FirstState); } var worklist = new LinkedList <StatePair>(pairs); var workset = new HashSet <StatePair>(pairs); while (worklist.Count != 0) { StatePair p = worklist.RemoveAndReturnFirst(); workset.Remove(p); HashSet <State> to = forward[p.SecondState]; HashSet <State> from = back[p.FirstState]; if (to != null) { foreach (State s in to) { var pp = new StatePair(p.FirstState, s); if (!pairs.Contains(pp)) { pairs.Add(pp); forward[p.FirstState].Add(s); back[s].Add(p.FirstState); worklist.AddLast(pp); workset.Add(pp); if (from != null) { foreach (State q in from) { var qq = new StatePair(q, p.FirstState); if (!workset.Contains(qq)) { worklist.AddLast(qq); workset.Add(qq); } } } } } } } // Add transitions. foreach (StatePair p in pairs) { p.FirstState.AddEpsilon(p.SecondState); } a.IsDeterministic = false; a.ClearHashCode(); a.CheckMinimizeAlways(); }
/// <summary> /// Returns an automaton that accepts the intersection of the languages of the given automata. /// Never modifies the input automata languages. /// </summary> /// <param name="a1">The a1.</param> /// <param name="a2">The a2.</param> /// <returns></returns> internal static Automaton Intersection(Automaton a1, Automaton a2) { if (a1.IsSingleton) { if (a2.Run(a1.Singleton)) { return(a1.CloneIfRequired()); } return(BasicAutomata.MakeEmpty()); } if (a2.IsSingleton) { if (a1.Run(a2.Singleton)) { return(a2.CloneIfRequired()); } return(BasicAutomata.MakeEmpty()); } if (a1 == a2) { return(a1.CloneIfRequired()); } Transition[][] transitions1 = Automaton.GetSortedTransitions(a1.GetStates()); Transition[][] transitions2 = Automaton.GetSortedTransitions(a2.GetStates()); var c = new Automaton(); var worklist = new LinkedList <StatePair>(); var newstates = new Dictionary <StatePair, StatePair>(); var p = new StatePair(c.Initial, a1.Initial, a2.Initial); worklist.AddLast(p); newstates.Add(p, p); while (worklist.Count > 0) { p = worklist.RemoveAndReturnFirst(); p.S.Accept = p.FirstState.Accept && p.SecondState.Accept; Transition[] t1 = transitions1[p.FirstState.Number]; Transition[] t2 = transitions2[p.SecondState.Number]; for (int n1 = 0, b2 = 0; n1 < t1.Length; n1++) { while (b2 < t2.Length && t2[b2].Max < t1[n1].Min) { b2++; } for (int n2 = b2; n2 < t2.Length && t1[n1].Max >= t2[n2].Min; n2++) { if (t2[n2].Max >= t1[n1].Min) { var q = new StatePair(t1[n1].To, t2[n2].To); StatePair r; newstates.TryGetValue(q, out r); if (r == null) { q.S = new State(); worklist.AddLast(q); newstates.Add(q, q); r = q; } char min = t1[n1].Min > t2[n2].Min ? t1[n1].Min : t2[n2].Min; char max = t1[n1].Max < t2[n2].Max ? t1[n1].Max : t2[n2].Max; p.S.Transitions.Add(new Transition(min, max, r.S)); } } } } c.IsDeterministic = a1.IsDeterministic && a2.IsDeterministic; c.RemoveDeadTransitions(); c.CheckMinimizeAlways(); return(c); }