public string Execute(string input, bool print_trace)
{
StringBuilder tape = new StringBuilder(input);
int pos = 0;
State current_state = this.start_state;
Console.WriteLine($"Initial Tape State : {tape.ToString()}");
// Turing machine iterator
while (true)
{
State prev_state = current_state;
char tape_symbol = tape[pos];
var key = transition_function.GetInput(current_state, tape_symbol);
if (key == null)
{
Console.WriteLine($"Machine was halted, trap state reached (Missing transition), Final contents : \'{tape.ToString()}\'");
return(tape.ToString());
}
TransitionOutput output = transition_function.Transitions[key];
tape[pos] = output.Symbol;
pos += (output.Direction == Directions.Left) ? -1 : 1;
string dir = (output.Direction == Directions.Left) ? "<-" : "->";
current_state = output.State;
if (pos < 0)
{
tape.Insert(0, this.blank);
pos = 0;
}
else if (pos >= tape.Length)
{
tape.Insert(tape.Length, this.blank);
}
//Console.WriteLine($"Current State is \'{prev_state.Name}\', Read a symbol \'{tape_symbol}\', Transitioned to state \'{current_state.Name}\', Wrote Symbol \'{output.Symbol}\', Moved Tape {dir}");
//Console.WriteLine($"Current State is \'{prev_state.Name}\', Read a symbol \'{tape_symbol}\', Transitioned to state \'{current_state.Name}\', Wrote Symbol \'{output.Symbol}\', Moved Tape {dir}");
Console.WriteLine($"({prev_state.Name},{tape_symbol}) = ({current_state.Name}, {output.Symbol}, {dir})");
//Console.WriteLine($"New State of tape : Pos is \'{pos}\', Content is : \'{tape.ToString()}\'");
Console.WriteLine($"{tape.ToString()}");
Console.WriteLine($"{new String(' ', pos)}^");
Console.WriteLine();
// String was accepted
if (current_state.Final)
{
Console.WriteLine($"String was accepted, Final contents : \'{tape.ToString()}\'");
return(tape.ToString());
}
}
}
public void AddTransition(TransitionInput input, TransitionOutput output)
{
transition_function.AddTransition(input, output);
}
public void AddTransition(TransitionInput input, TransitionOutput output)
{
transitions.Add(input, output);
transition_inputs.Add(new Tuple <State, char>(input.State, input.Symbol), input);
}
