using System;
using System.IO;
using Ilog.Language.IO;
using Ilog.Language.Parsing;

public class CalculatorTokenizer : Tokenizer
{
  TextReader reader;
  StreamTokenizer input;
  string file = "stdin";

  public CalculatorTokenizer ()
    {
      SetReader(Console.In);
      interactive = true;
      Banner();
      Prompt();
    }

  public CalculatorTokenizer (string stream, bool isFileName)
    {
      if (isFileName)
        {
	  SetReader(new StreamReader(file = stream));
	  interactive = false;
	  Banner();
	  Console.WriteLine("*** Parsing file: "+stream);
	}
      else
        {
	  SetReader(new StringReader(stream));
	  interactive = false;
	}
    }

  public int LineNumber
    {
      get { return input.GetLineNumber(); }
    }

  public TextReader GetReader ()
    {
      return reader;
    }

  public void SetReader (TextReader rd)
    {
      input = new StreamTokenizer(reader = rd);
      input.OrdinaryChars("+-/");
      input.WordChars('_','_');
    }

  private bool interactive;
  public bool IsInteractive
    {
      get { return interactive; }
    }

  private static string promptString = ">";

  public static void Prompt  ()
    {
      Console.Write(promptString+" ");
    }

  static public void SetPrompt (string p)
    {
      promptString = p;
    }
  
  private static string banner
  = "*** Welcome to the number calculator! [C# version]\n"
  + "*** Generated on " + DateTime.Now.ToLongDateString()
  + ", at " + DateTime.Now.ToLongTimeString();

  public static void Banner ()
    {
      Console.WriteLine(banner);
    }

  private ParseNode Locate (ParseNode node)
    {
      return ((ParseNode)node.SetStart(input.TokenStart()).SetEnd(input.TokenEnd()))
	.SetFile(file);
    }

  public ParseNode NextToken()
    {
      ParseNode t = null;
      int token = input.NextToken();
      switch (token)
        {
        case StreamTokenizer.TT_EOF:
          reader.Close();
          t = GenericParser.E_O_I;
          break;
        case StreamTokenizer.TT_WORD:
	  if (input.SValue == "exit")
	    t = GenericParser.LiteralToken("exit");
	  else
	    t = GenericParser.SymbolToken("IDENTIFIER",input.SValue);
          break;
        case StreamTokenizer.TT_NUMBER:
          t = GenericParser.NumberToken("NUMBER",input.NValue);
          break;
        default:
          char c = (char)token;       
          t = GenericParser.LiteralToken(c.ToString());
          break;
        }
      return Locate(t);
    }
}