public Machine Step()
{
if (State < 0)
{
return(this);
}
return
(TransitionTable
.Where(t => t.InitialState == State && t.Read == Head.Read())
.Select(t => new Machine(t.NextState, Head.Write(t.Write).Move(t.HeadDirection), TransitionTable))
.First());
}
public Machine Step()
{
if (State < 0)
{
return(this);
}
var machine = TransitionTable
.Where(t => t.InitialState == State && t.Read == Head.Read())
.DefaultIfEmpty(new Transition(0, Head.Blank, Head.Read(), HeadDirection.NoMove,
TuringMachine.State.Error))
.Select(
t => new Machine(t.NextState, Head.Write(t.Write).Move(t.HeadDirection), TransitionTable, Alphabet))
.First();
return(machine);
}
//Compute the Strip based on States Table.
private void TuringMachine()
{
int iterations = 0;
//Initialize States, Head, CurrentState.
List <State> StateList = InitializeStates();
//VALIDATION 0: Check if there are parameters to execute in state 0.
if (StateList[0].Parameters == null)
{
Interaction.MsgBox("There are no instructions to start computation.");
return;
}
Head Head = new Head(txbStrip.Text);
int CurrentState = 0;
//Run machine until state is HALT (-1).
while (CurrentState != -1)
{
//Update cycle counter.
updateIterations(iterations += 1);
try
{
//VALIDATION 1: Check if state has response for the current position.
if (StateList[CurrentState].Parameters.ContainsKey(Head.Read()))
{
//STEP 1: READ AND SAVE THE CURRENT SYMBOL.
char readSymbol = Head.Read();
//STEP 2: WRITE NEW SYMBOL IN HEAD.STRIP[POSITION].
Head.Write(StateList[CurrentState].Parameters[readSymbol].newSymbol);
//STEP 3: MOVE HEAD.POSITION.
Head.Move(StateList[CurrentState].Parameters[readSymbol].Direction);
//VISUAL: Update Visuals
updateVisuals(CurrentState, Head);
this.Update();
Thread.Sleep(Properties.Settings.Default.IterationDelay);
//VALIDATION 2: Check if HEAD has gone off right end of tape.
if (Head.Position >= Head.Strip.Length)
{
Interaction.MsgBox("Halt: Head has gone out of the right end of tape. Halting Problem?");
CurrentState = -1;
}
//VALIDATION 3: Check if HEAD has gone off left end of tape.
else if (Head.Position < 0)
{
Interaction.MsgBox("Halt: Head has gone out of the left end of tape. Halting Problem?");
CurrentState = -1;
}
//STEP 4: CHANGE STATE, UPDATE STRIP.
else
{
CurrentState = StateList[CurrentState].Parameters[readSymbol].newState;
}
}
else
{
Interaction.MsgBox("Halt: State " + CurrentState + " does not have rule for symbol " + Head.Read());
return;
}
}
catch (ArgumentOutOfRangeException e)
{
Interaction.MsgBox("Halt: State '" + CurrentState + "' does not have rule for symbol '" + Head.Read() + "'");
return;
}
}
//FINAL STEP: MACHINE HAS REACHED HALT STATE, PRINT STRIP AND SUCESS MESSAGE.
if (CurrentState == -1 && Head.Position >= 0)
{
Interaction.MsgBox("Turing Machine: Computation complete.");
}
}