/// <summary>
///
/// </summary>
/// <returns></returns>
public NFAEditScript GetNFAOptimalEdit(Automaton <BDD> nfa2)
{
NFAEditScript editScript = new NFAEditScript();
//Start timer
sw.Start();
//Normalize NFAs
var normNfaPair = DFAUtilities.normalizeDFA(nfa2);
var normNfa2 = normNfaPair.First;
var stateNamesMapping = normNfaPair.Second;
NFAEditScript bestScript = new NFAEditScript();
bestScript.script = null;
// increase depth up to maxMoves
for (int depth = 1; true; depth++)
{
var editList = new List <NFAEdit>();
if (GetNFAEditScriptTimeout(
depth, -1, normNfa2,
editScript.script, editScript.GetCost(), bestScript))
{
// if hits timeout break and return null
break;
}
if (bestScript.script != null)
{
bestScript.script.Reverse();
sw.Stop();
var mappedEditList = new List <NFAEdit>();
//fix states name because of normalization
foreach (var edit in bestScript.script)
{
NFAEdit mappedEdit = null;
if (edit is NFAEditState)
{
var castEdit = edit as NFAEditState;
mappedEdit = new NFAEditState(stateNamesMapping[castEdit.state], castEdit.makeFinal);
}
if (edit is NFAEditMove)
{
var castEdit = edit as NFAEditMove;
mappedEdit = new NFAEditMove(
stateNamesMapping[castEdit.sourceState],
stateNamesMapping[castEdit.newTargetState],
castEdit.ch);
}
mappedEditList.Add(mappedEdit);
}
return(bestScript);
}
}
return(null);
}
// looks for an edit at depth "depth"
// returns false and null in bestScript if no edit is found at depth "depth"
// returns false and not null in bestScript if found
// returns true if timeout
internal bool GetNFAEditScriptTimeout(
int depth, long lastEditHash,
Automaton <BDD> currentNfa2,
List <NFAEdit> editList, int scriptCost,
NFAEditScript bestScript)
{
// if timeout return true
if (sw.ElapsedMilliseconds > timeout)
{
return(true);
}
//Stop if no more moves left
if (depth == 0)
{
if (DFAUtilities.ApproximateMNEquivalent(tests, nfa1density, currentNfa2, al, solver) && currentNfa2.IsEquivalentWith(nfa1, solver))
{
//check if totalCost < finalScript cost and replace if needed
if (bestScript.script == null || scriptCost < bestScript.GetCost())
{
bestScript.script = ObjectCopier.Clone <List <NFAEdit> >(editList);
}
}
return(false);
}
NFAEdit edit = null;
long thisEditHash = 0;
#region Flip one state from fin to non fin
foreach (var state in currentNfa2.States)
{
thisEditHash = state;
if (CanAdd(thisEditHash, lastEditHash))
{
//flip its final non final status
var newFinalStates = new HashSet <int>(currentNfa2.GetFinalStates());
Automaton <BDD> nfa2new = null;
if (currentNfa2.GetFinalStates().Contains(state))
{
edit = new NFAEditState(state, false);
editList.Insert(0, edit);
newFinalStates.Remove(state);
nfa2new = Automaton <BDD> .Create(currentNfa2.InitialState, newFinalStates, currentNfa2.GetMoves());
}
else
{
edit = new NFAEditState(state, true);
editList.Insert(0, edit);
newFinalStates.Add(state);
nfa2new = Automaton <BDD> .Create(currentNfa2.InitialState, newFinalStates, currentNfa2.GetMoves());
}
if (GetNFAEditScriptTimeout(depth - 1, thisEditHash, nfa2new, editList, scriptCost + edit.GetCost(), bestScript))
{
return(true);
}
editList.RemoveAt(0);
}
}
#endregion
#region Change transition from source state
currentNfa2 = NFAUtilities.normalizeMoves(currentNfa2, solver);
foreach (var sourceState in currentNfa2.States)
{
HashSet <int> unreachedStates = new HashSet <int>(currentNfa2.States);
foreach (var moveFromSource in currentNfa2.GetMovesFrom(sourceState))
{
// take all chars in alphabet
foreach (var c in al)
{
long moveHash = currentNfa2.StateCount + IntegerUtil.TripleToInt(sourceState, moveFromSource.TargetState, alphabetMap[c]);
thisEditHash = currentNfa2.StateCount + moveHash;
if (CanAdd(thisEditHash, lastEditHash))
{
BDD cCond = solver.False;
BDD newCond = solver.False;
//skip epsilon moves
if (moveFromSource.Label != null)
{
// if c in move, remove it and recursion
if (solver.Contains(moveFromSource.Label, c))
{
cCond = solver.MkNot(solver.MkCharConstraint(false, c));
newCond = solver.MkAnd(moveFromSource.Label, cCond);
}
else // if c not in move, add it and recursion
{
cCond = solver.MkCharConstraint(false, c);
newCond = solver.MkOr(moveFromSource.Label, cCond);
}
var newMoves = new List <Move <BDD> >(currentNfa2.GetMoves());
newMoves.Remove(moveFromSource);
newMoves.Add(new Move <BDD>(sourceState, moveFromSource.TargetState, newCond));
var nfa2new = Automaton <BDD> .Create(currentNfa2.InitialState, currentNfa2.GetFinalStates(), newMoves);
edit = new NFAEditMove(sourceState, moveFromSource.TargetState, c);
editList.Insert(0, edit);
if (GetNFAEditScriptTimeout(depth - 1, thisEditHash, nfa2new, editList, scriptCost + edit.GetCost(), bestScript))
{
return(true);
}
editList.RemoveAt(0);
}
}
}
unreachedStates.Remove(moveFromSource.TargetState);
}
foreach (var targetState in unreachedStates)
{
//try adding a symbol not in transition
foreach (var c in al)
{
long moveHash = IntegerUtil.TripleToInt(sourceState, targetState, alphabetMap[c]);
thisEditHash = currentNfa2.StateCount + moveHash;
var moveCond = solver.MkCharConstraint(false, c);
var newMoves = new List <Move <BDD> >(currentNfa2.GetMoves());
newMoves.Add(new Move <BDD>(sourceState, targetState, moveCond));
var nfa2new = Automaton <BDD> .Create(currentNfa2.InitialState, currentNfa2.GetFinalStates(), newMoves);
edit = new NFAEditMove(sourceState, targetState, c);
editList.Insert(0, edit);
//TODO put correct hash
if (GetNFAEditScriptTimeout(depth - 1, thisEditHash, nfa2new, editList, scriptCost + edit.GetCost(), bestScript))
{
return(true);
}
editList.RemoveAt(0);
}
}
}
#endregion
return(false);
}