public void Add(Set key, AutomataState mapTo)
{
Set set = null;
if (base.Contains(key))
{
set = (Set)base[key];
}
else
{
set = new Set();
}
set.addElement(mapTo);
base[key] = set;
}
/*** add the transition between the start state "this" and the end state "endState", using 'trans_char', to the list of outgoing transition of this ***/
public void addOutgoingTransition(string trans_char, AutomataState endState)
{
Tuple<string, AutomataState> trans = new Tuple<string, AutomataState>(trans_char, endState);
transitions.Add(trans);
}
/*** Replace the endstate (with "newState") of which transitions s.t. endstate is equal to "oldState" ***/
public int replaceEndstateForTransitions(AutomataState oldState, AutomataState newState)
{
int count = 0;
for (int i = 0; i < transitions.Count; i++)
{
if (transitions[i].Item2 == oldState)
{
transitions[i] = new Tuple<string, AutomataState>(transitions[i].Item1, newState);
count++;
}
}
return count;
}
/*** Build states and transions of DFA starting from the start state of NFA, using subset construction algorithm. Return the start state of DFA.***/
private AutomataState NFAtoDFA(AutomataState Szero_NFA)
{
// 1) fill the 2nd and 3rd arguments
Set setAllSym = new Set();
Set setAllState = new Set();
FillStatesAndSymbols(setAllState, setAllSym, Szero_NFA);
setAllSym.removeElFromSet(RExpr_Parser.Tokens.EPSILON);
Set epsClos = getEpsClosureFromState(Szero_NFA);
AutomataState Szero_DFA = new AutomataState();
if (ExistFinalStateInSet(epsClos))
{
// set the start state as also final state
Szero_DFA.IsFinalState = true;
}
CreateNewDFAState(epsClos, Szero_DFA);
// 2) Compute "subset construction" algorithm
string transChar = "";
AutomataState T = null, U = null;
Set epsClosureT = null, mvs = null;
// main loop (breakable with null checking)
while (true)
{
// until exists an unmarked state T
T = getUnmarkedState();
if (T == null)
break;
// "Mark" this state
markState(T);
// get the EpsClosure of T
epsClosureT = getEpsClosure(T);
// for each symbol in the set of all symbols (inner for of the "construction set" algorithm)
foreach (object obj in setAllSym)
{
transChar = obj.ToString();
mvs = getMoves(transChar, epsClosureT);
if (mvs.NumOfElement != 0)
{
// U = E-clos(move(T,inputSym))
epsClos = getEpsClosureFromStateSet(mvs);
U = FindDfaStateByEclosure(epsClos);
// if in this set of NFA's states exists a final state, the set is a final state of DFA
if (U == null)
{
U = new AutomataState();
if (ExistFinalStateInSet(epsClos))
{
U.IsFinalState = true;
}
// add a new (unmarked) state
CreateNewDFAState(epsClos, U);
}
// add to DFA transitions (T,transChar) -> U
T.addOutgoingTransition(transChar, U);
}
}
}
return Szero_DFA;
}
/*** Create a minimized version of the DFA (called DFAmin) ***/
private AutomataState MinimizeDFA(AutomataState Szero_DFA)
{
// 1) partition the DFS states (filling 2nd and 3rd arguments)
Set transSymbols = new Set();
Set DFAstates = new Set();
FillStatesAndSymbols(DFAstates, transSymbols, Szero_DFA);
ArrayList arr = createDFASets(DFAstates, transSymbols);
// 2) through all the groups and select a pivot for each group.
AutomataState stateStartReducedDfa = null;
foreach (object objGroup in arr)
{
Set setGroup = (Set)objGroup;
// check final states SzeroDFA in the group
bool finalStInGroup = ExistFinalStateInSet(setGroup);
bool startDFAinGroup = setGroup.Contains(Szero_DFA);
AutomataState pivotState = (AutomataState)setGroup[0];
if (startDFAinGroup)
{
stateStartReducedDfa = pivotState;
}
if (finalStInGroup)
{
pivotState.IsFinalState = true;
}
// if there are only once element, continue loop
if (setGroup.NumOfElement == 1)
{
continue;
}
// 3) [innerLoop] remove the pivot from its group and replace all the references of the remaining member of the group
setGroup.removeElFromSet(pivotState);
// state to be replaced with the group of pivot
AutomataState stateToBeReplaced = null;
int numOfReplace = 0;
foreach (object objStateToReplaced in setGroup)
{
stateToBeReplaced = (AutomataState)objStateToReplaced;
DFAstates.removeElFromSet(stateToBeReplaced);
foreach (object objState in DFAstates)
{
numOfReplace = numOfReplace + ((AutomataState)objState).replaceEndstateForTransitions(stateToBeReplaced, pivotState);
}
}
}
// 4) finally can remove all "close states"
for (int n = 0; n < DFAstates.Count; n++)
{
AutomataState state = (AutomataState)DFAstates[n];
if (state.isAClosedState())
{
DFAstates.RemoveAt(n);
continue;
}
}
return stateStartReducedDfa;
}
/*** Get all the states moves as above but starting from a single state ***/
private Set getMoves(string trans_chr, AutomataState state)
{
Set s = new Set();
List<AutomataState> lTrns = state.getAllDestStatesWithStringTransaction(trans_chr);
if (lTrns != null && lTrns.Count > 0)
{
s.addElementRange(lTrns.ToArray());
}
return s;
}
/*** Finds all states that are "toStates" by a startState via E-transition ***/
private Set getEpsClosureFromState(AutomataState startState)
{
// set for dividing states
Set processedStates = new Set();
Set unprocessedStates = new Set();
// add start state to unprocessed set
unprocessedStates.addElement(startState);
// until exists unprocessed states
while (unprocessedStates.Count > 0)
{
// get all "toState" of E-transitions from "state"
AutomataState state = (AutomataState)unprocessedStates[0];
List<AutomataState> l_trns = state.getAllDestStatesWithStringTransaction(RExpr_Parser.Tokens.EPSILON);
// process state
processedStates.addElement(state);
unprocessedStates.removeElFromSet(state);
if (l_trns != null && l_trns.Count > 0)
{
foreach (AutomataState Estate in l_trns)
{
if (!processedStates.Contains(Estate))
{
unprocessedStates.addElement(Estate);
}
}
}
}
return processedStates;
}
/*** Find in which set of the "arrayOfSet" the state "state" is contained. Return null if there are no set that contains "state". ***/
private Set findInWhichSet(ArrayList arrayOfSet, AutomataState state)
{
foreach (object objSet in arrayOfSet)
{
Set set = (Set)objSet;
if (set.Contains(state))
{
return set;
}
}
return null;
}
/*** Fill the sets "allStates" and "allSym" (respectivly) with all the states and the symbols of the automata (discriminate NFA-DFA-DFAmin from starting state) ***/
private static void FillStatesAndSymbols(Set allStates, Set allSym, AutomataState stateStart)
{
Set unprocessedStates = new Set();
// add first state to unprocessed
unprocessedStates.addElement(stateStart);
// untile the are unprocessed states
while (unprocessedStates.Count > 0)
{
AutomataState state = (AutomataState)unprocessedStates[0];
allStates.addElement(state);
unprocessedStates.removeElFromSet(state);
// for each transition char of transitions of "state"
foreach (string s in state.getAllTransitionsChars())
{
allSym.addElement(s);
// get all "Tostate"s from state by "s"
List<AutomataState> l_trns = state.getAllDestStatesWithStringTransaction(s);
if (l_trns != null && l_trns.Count > 0)
{
foreach (AutomataState EpsState in l_trns)
{
if (!allStates.Contains(EpsState))
{
unprocessedStates.addElement(EpsState);
}
}
}
}
}
}
/*** check if the transition from "currState" is caused by "." ***/
private static bool checkSomeChar(AutomataState currState)
{
return currState.getExactTransition(RExpr_Parser.Tokens.TOK_SOMECHAR_TRANS) != null;
}
/*** Given a string contains a regular expression, perform the parse of it. If the parse is positive, produces a Minimum DFA model. Otherwise throw SyntaxException. ***/
public StringBuilder ParseRegexAndCreateAutomata(Stopwatch timer, string regex)
{
StringBuilder statistics_s = new StringBuilder();
this.isCompiled = false;
// set the global start id for states to 0
AutomataState.resetStatesGlobalCounter();
// reset hashtable for DFA
DFAStatesTable.Clear();
// start timing for parsing
timer.Reset();
timer.Start();
// invoke the parser (it can generate SyntaxException) and set the parsed string as Text of "label_formatted_regex" in Main form
string parsed_regex = RExpr_parser.ParseRExpr(regex);
// arrange parsed regex string applying postfixing tecnique
string arranged_regex = ArrangeRegex(parsed_regex);
/*** 1) Create a NFA starting from re-arranged parsed regex ***/
AutomataState Szero_NFA = BuildNFA(arranged_regex);
/*** 2) Create a DFA starting from NFA start state ***/
AutomataState.resetStatesGlobalCounter();
AutomataState Szero_DFA = NFAtoDFA(Szero_NFA);
/*** 3) Create min DFA from DFA start state ***/
AutomataState SzeroDFAmin = MinimizeDFA(Szero_DFA);
Sz_DFAmin = SzeroDFAmin;
// stop timing for parsing
timer.Stop();
return statistics_s;
}
/*** Mark the passed state of the hashtable ***/
public void markState(AutomataState s)
{
((AutomataDFAState)DFAStatesTable[s]).isMark = true;
}
/*** Given an input state, get it E-closure. ***/
public Set getEpsClosure(AutomataState state)
{
AutomataDFAState s = (AutomataDFAState)DFAStatesTable[state];
return (s == null) ? null : s.EpsClos;
}
/*** Add a new DFA state to the hashtable ***/
public void CreateNewDFAState(Set Eclos, AutomataState DFAstate)
{
AutomataDFAState stateRecord = new AutomataDFAState();
stateRecord.EpsClos = Eclos;
DFAStatesTable[DFAstate] = stateRecord;
}
