public Regular_Expression GetExpression()
{
Regular_Expression expression = null;
string token = listNotation.First();
switch (token)
{
case "|":
expression = new Choice();
listNotation.Remove(token);
expression.Left_Expression = GetExpression();
expression.Right_Expression = GetExpression();
break;
case ".":
expression = new Concatenation();
listNotation.Remove(token);
expression.Left_Expression = GetExpression();
expression.Right_Expression = GetExpression();
break;
case "_":
expression = new Epsilon();
listNotation.Remove(token);
break;
case "*":
expression = new Repetition();
listNotation.Remove(token);
expression.Left_Expression = GetExpression();
break;
default:
expression = new Alphabet(token);
listNotation.Remove(token);
break;
}
return(expression);
}
public void ParsingFile(string fileName)
{
listStates = new List <State>();
listAlphabets = new List <Alphabet>();
listTransitions = new List <Transition>();
listWords = new List <Word>();
listStacks = new List <Stack>();
FileStream fs = null;
StreamReader sr = null;
try
{
fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
sr = new StreamReader(fs);
string line = sr.ReadLine();
int count_line = 1;
while (line != null)
{
string s = line.Replace(" ", "");
if (s != "" && s[0] != '#')
{
string first_word = s.Substring(0, s.IndexOf(':'));
if (first_word == "alphabet")
{
string the_rest = s.Substring(s.IndexOf(':') + 1);
if (the_rest == "")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
foreach (char character in the_rest)
{
Alphabet alphabet = CheckExistAlphabet(character.ToString(), listAlphabets);
if (alphabet == null)
{
alphabet = new Alphabet(character.ToString());
listAlphabets.Add(alphabet);
}
}
}
if (first_word == "stack")
{
string the_rest = s.Substring(s.IndexOf(':') + 1);
if (the_rest == "")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
foreach (char character in the_rest)
{
Stack stack = CheckExistStack(character.ToString(), listStacks);
if (stack == null)
{
stack = new Stack(character.ToString());
listStacks.Add(stack);
}
}
}
if (first_word == "states")
{
string the_rest = s.Substring(s.LastIndexOf(':') + 1);
if (the_rest == "")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
string[] state_names = the_rest.Split(',');
foreach (string name in state_names)
{
State state = CheckExistState(name, listStates);
if (state == null)
{
state = new State(name);
listStates.Add(state);
}
}
listStates[0].IsInitial = true;
}
if (first_word == "final")
{
string the_rest = s.Substring(s.LastIndexOf(':') + 1);
if (the_rest == "")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
string[] state_names = the_rest.Split(',');
foreach (string name in state_names)
{
foreach (State state in listStates)
{
if (state.State_Name == name)
{
state.IsFinal = true;
}
}
}
}
if (first_word == "transitions")
{
line = sr.ReadLine();
count_line++;
while (line != "end.")
{
s = line.Replace(" ", "");
string state_and_symbol = s.Substring(0, s.IndexOf('-'));
string left_state = state_and_symbol.Substring(0, state_and_symbol.IndexOf(','));
string symbol = state_and_symbol.Substring(state_and_symbol.IndexOf(',') + 1);
string right_state = s.Substring(s.IndexOf('>') + 1);
if (left_state == "" || symbol == "" || right_state == "")
{
throw new InvalidValueInFileException($"Invalid transition at line {count_line}");
}
if (IsIncorrectCharacterInLabeledTransition(symbol, listAlphabets, listStacks))
{
throw new InvalidValueInFileException($"Invalid transition at line {count_line}");
}
Transition transition = new Transition(symbol, listStacks);
State Left = CheckExistState(left_state, listStates);
State Right = CheckExistState(right_state, listStates);
if (Left != null && Right != null)
{
transition.SetLeftState(Left);
transition.SetRightState(Right);
}
listTransitions.Add(transition);
line = sr.ReadLine();
count_line++;
}
}
if (first_word == "dfa")
{
string the_rest = s.Substring(s.LastIndexOf(':') + 1);
if (the_rest != "n" && the_rest != "y")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
}
if (first_word == "finite")
{
string the_rest = s.Substring(s.LastIndexOf(':') + 1);
if (the_rest != "n" && the_rest != "y")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
}
if (first_word == "words")
{
line = sr.ReadLine();
count_line++;
while (line != "end.")
{
s = line.Replace(" ", "");
string[] data = s.Split(',');
string words = data[0];
string indication = data[1];
if (DoesWordContainIncorrectCharacter(words, listAlphabets))
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
Word word = new Word(words);
if (indication != "y" && indication != "n")
{
throw new InvalidValueInFileException($"Invalid value at line {count_line}");
}
listWords.Add(word);
line = sr.ReadLine();
count_line++;
}
}
}
else if (s != "" && s[0] == '#')
{
comment = s.Substring(1);
}
line = sr.ReadLine();
count_line++;
}
Automaton = new Automaton(listAlphabets, listStates, listTransitions, listWords, listStacks);
Automaton.Comment = comment;
}
catch (IOException)
{
throw new IOException();
}
finally
{
if (sr != null)
{
sr.Close();
}
if (fs != null)
{
fs.Close();
}
}
}