private void Scan(IO.TextReader input)
{
while (input.Peek() != -1)
{
char ch = (char)input.Peek();
// Scan individual tokens
if (char.IsWhiteSpace(ch))
{
// eat the current char and skip ahead!
input.Read();
}
else if (char.IsLetter(ch) || ch == '_')
{
// keyword or identifier
Text.StringBuilder accum = new Text.StringBuilder();
while (char.IsLetter(ch) || ch == '_')
{
accum.Append(ch);
input.Read();
if (input.Peek() == -1)
{
break;
}
else
{
ch = (char)input.Peek();
}
}
this.result.Add(accum.ToString());
}
else if (ch == '"')
{
// string literal
Text.StringBuilder accum = new Text.StringBuilder();
input.Read(); // skip the '"'
if (input.Peek() == -1)
{
throw new System.Exception("unterminated string literal");
}
while ((ch = (char)input.Peek()) != '"')
{
accum.Append(ch);
input.Read();
if (input.Peek() == -1)
{
throw new System.Exception("unterminated string literal");
}
}
// skip the terminating "
input.Read();
this.result.Add(accum);
}
else if (char.IsDigit(ch))
{
// numeric literal
Text.StringBuilder accum = new Text.StringBuilder();
while (char.IsDigit(ch))
{
accum.Append(ch);
input.Read();
if (input.Peek() == -1)
{
break;
}
else
{
ch = (char)input.Peek();
}
}
this.result.Add(int.Parse(accum.ToString()));
}
else switch (ch)
{
case '+':
input.Read();
this.result.Add(Scanner.Add);
break;
case '-':
input.Read();
this.result.Add(Scanner.Sub);
break;
case '*':
input.Read();
this.result.Add(Scanner.Mul);
break;
case '/':
input.Read();
this.result.Add(Scanner.Div);
break;
case '=':
input.Read();
this.result.Add(Scanner.Equal);
break;
case ';':
input.Read();
this.result.Add(Scanner.Semi);
break;
default:
throw new System.Exception("Scanner encountered unrecognized character '" + ch + "'");
}
}
}
private void Scan(IO.TextReader input)
{
while (input.Peek() != -1)
{
char caracter = (char)input.Peek();
// Scan individual tokens
if (char.IsWhiteSpace(caracter))
{
// eat the current char and skip ahead!
input.Read();
}
else if (char.IsLetter(caracter) || caracter == '_')
{
// keyword or identifier
Text.StringBuilder accum = new Text.StringBuilder();
while (char.IsLetter(caracter) || caracter == '_')
{
accum.Append(caracter);
input.Read();
if (input.Peek() == -1)
{
break;
}
else
{
caracter = (char)input.Peek();
}
}
this.resultado.Add(accum.ToString());
}
else if (caracter == '"')
{
// string literal
Text.StringBuilder accum = new Text.StringBuilder();
input.Read(); // skip the '"'
if (input.Peek() == -1)
{
throw new System.Exception("Cadena sin terminar");
}
while ((caracter = (char)input.Peek()) != '"')
{
accum.Append(caracter);
input.Read();
if (input.Peek() == -1)
{
throw new System.Exception("Cadena sin terminar");
}
}
// skip the terminating "
input.Read();
this.resultado.Add(accum);
}
else if (char.IsDigit(caracter))
{
// numeric literal
Text.StringBuilder accum = new Text.StringBuilder();
while (char.IsDigit(caracter))
{
accum.Append(caracter);
input.Read();
if (input.Peek() == -1)
{
break;
}
else
{
caracter = (char)input.Peek();
}
}
this.resultado.Add(int.Parse(accum.ToString()));
}
else switch (caracter)
{
case '+':
input.Read();
this.resultado.Add(Scanner.Sum);
break;
case '-':
input.Read();
this.resultado.Add(Scanner.Res);
break;
case '*':
input.Read();
this.resultado.Add(Scanner.Mul);
break;
case '/':
input.Read();
this.resultado.Add(Scanner.Div);
break;
case '=':
input.Read();
if (input.Peek() == '=')
{
input.Read();
this.resultado.Add(Scanner.Eq);
}
else
this.resultado.Add(Scanner.Igual);
break;
case ';':
input.Read();
this.resultado.Add(Scanner.PyC);
break;
case '>':
input.Read();
if (input.Peek() == '=')
{
input.Read();
this.resultado.Add(Scanner.Gte);
}
else
this.resultado.Add(Scanner.Gt);
break;
case '<':
input.Read();
if (input.Peek() == '=')
{
input.Read();
this.resultado.Add(Scanner.Lte);
}
else
this.resultado.Add(Scanner.Lt);
break;
case '!':
input.Read();
if (input.Peek() == '=')
{
input.Read();
this.resultado.Add(Scanner.Neq);
}
else
throw new System.Exception("No se reconoce el siguiente caracter: '" + caracter + "'");
break;
default:
throw new System.Exception("No se reconoce el siguiente caracter: '" + caracter + "'");
}
}
}
