public void ReadFromFile(string filename)
{
string[] lines = System.IO.File.ReadAllLines("../../Input/" + filename);
Nonterminals = new HashSet <string>(lines[0].Split(' '));
Terminals = new HashSet <string>(lines[1].Split(' '));
StartSymbol = lines[2];
foreach (var line in lines.Skip(3))
{
string[] elements = line.Split('?');
string[] right = elements[1].Split(' ');
var produRule = new ProductionRule()
{
Left = elements[0], Right = right.ToList()
};
ProductionRules.Add(produRule, count++);
}
Console.WriteLine("Terminals:");
foreach (var t in Terminals)
{
Console.Write(t + " ");
}
Console.WriteLine("\nNonterminals");
foreach (var t in Nonterminals)
{
Console.Write(t + " ");
}
Console.WriteLine("\nProduction rules");
foreach (var rule in ProductionRules)
{
Console.Write(rule.Key.Left + " -> " + String.Join(" ", rule.Key.Right) + " (" + rule.Value + ")");
Console.WriteLine();
}
}
//Determine the first set for sym, where sym is the first element in the RHS of the rule
public static HashSet <string> FirstOf(string sym, Dictionary <string, HashSet <string> > firsts, ProductionRule rule)
{
var first = firsts[sym];
if (first.Count() == 0 || first.Any(x => x == EPSILON))
{
foreach (var rightElem in rule.Right.Where(x => x != sym))
{
first = new HashSet <string>(first.Union(firsts[rightElem]));
if (first.Count() == 0 || firsts[rightElem].Any(x => x == EPSILON))
{
continue;
}
else
{
first.Remove(EPSILON);
break;
}
}
}
return(first);
}