public Matcher(FST fst) { _FST = fst; }
public void Concatenate(FST rhs) { List <int> previouslyFinalStates = GetFinalStates(); if (previouslyFinalStates.Count == 0) { throw new Exception("Automaton does not have any final states"); } if (!StateExists(_StartState)) { throw new Exception("Automaton does not have a start state"); } if (!rhs.StateExists(rhs._StartState)) { throw new Exception("RHS Automaton does not have a start state"); } bool lhsStartWasFinal = IsFinal(_StartState); bool rhsStartWasFinal = rhs.IsFinal(rhs._StartState); // the mapping from the state IDs of the RHS automaton. Key is the // original RHS state ID, Value is the new state ID in the source automaton Dictionary <int, int> stateMapping = new Dictionary <int, int>(); // all previously final states become non-final unless the RHS start state is final if (!rhsStartWasFinal) { foreach (int pf in previouslyFinalStates) { SetFinal(pf, false); } } // copy over the states foreach (KeyValuePair <int, State> rhsState in rhs._States) { int newState = AddState(); stateMapping.Add(rhsState.Value.Id, newState); // final states in the RHS automaton remain final if (rhsState.Value.IsFinal) { SetFinal(newState, true); } } // now that all states exist, copy over the RHS transitions foreach (KeyValuePair <int, State> rhsState in rhs._States) { foreach (FSTTransition t in rhsState.Value.Transitions) { AddTransition(stateMapping[t.Source], stateMapping[t.Target], new Label(t.Input), new Label(t.Output)); } } // next, link the two automatons. // first, each transition which ends in a previously final state is // copied into a transition to the previous start state of RHS int newRhsStart = stateMapping[rhs._StartState]; foreach (KeyValuePair <int, State> lhsState in _States) { State testState = lhsState.Value; List <FSTTransition> transitions = testState.Transitions; // Take care with this iteration as the loop adds to the state's transitions for (int transition = transitions.Count - 1; transition >= 0; --transition) { FSTTransition link = transitions[transition]; if (previouslyFinalStates.Contains(link.Target)) { testState.AddTransition(newRhsStart, new Label(link.Input), new Label(link.Output)); } } } if (lhsStartWasFinal) { // need to introduce an eps transition to the rhs start state AddTransition(_StartState, newRhsStart, new Label(Label.SpecialSymbolEpsilon), new Label(Label.SpecialSymbolEpsilon)); } Clean(); }