// Lexical scanner
private void Scan()
{
int k;
while (Cradle.Look == Cradle.CR)
{
Cradle.Fin();
}
if (Cradle.IsAlpha(Cradle.Look))
{
GetName();
}
else if (Cradle.IsDigit(Cradle.Look))
{
GetNum();
}
else if (IsOp(Cradle.Look))
{
GetOp();
}
else
{
Value = Cradle.Look.ToString();
Token = SymType.Operator;
Cradle.GetChar();
}
Cradle.SkipWhite();
}
// Skip over a comma
private void SkipComma()
{
Cradle.SkipWhite();
if (Cradle.Look == ',')
{
Cradle.GetChar();
Cradle.SkipWhite();
}
}
// Get a number
private void GetNum()
{
Value = "";
if (!Cradle.IsDigit(Cradle.Look))
{
Cradle.Expected("Integer");
}
while (Cradle.IsDigit(Cradle.Look))
{
Value += Cradle.Look;
Cradle.GetChar();
}
Token = SymType.Number;
}
// Get an operator
private void GetOp()
{
Value = "";
if (!IsOp(Cradle.Look))
{
Cradle.Expected("Operator");
}
while (IsOp(Cradle.Look))
{
Value += Cradle.Look;
Cradle.GetChar();
}
Token = SymType.Operator;
}
// Get an identifier
private void GetName()
{
Value = "";
if (!Cradle.IsAlpha(Cradle.Look))
{
Cradle.Expected("Name");
}
while (Cradle.IsAlNum(Cradle.Look))
{
Value += char.ToUpper(Cradle.Look);
Cradle.GetChar();
}
Token = KWCode[Lookup(Value) + 1];
}
// Parse and translate the first math factor
private void SignedFactor()
{
if (Cradle.Look == '+') Cradle.GetChar();
if (Cradle.Look == '-')
{
Cradle.GetChar();
if (Cradle.IsDigit(Cradle.Look))
Cradle.EmitLn("MOVE #-" + Cradle.GetNum() + ",D0");
else
{
Factor();
Cradle.EmitLn("NEG D0");
}
}
else
Factor();
}
// Get an operator
private void GetOp()
{
Value = "";
if (!IsOp(Cradle.Look))
{
Cradle.Expected("Operator");
}
while (IsOp(Cradle.Look))
{
Value += Cradle.Look;
Cradle.GetChar();
}
if (Value.Length == 1)
{
Token = Value[0];
}
else
{
Token = '?';
}
}
// Get an identifier
private void GetName()
{
int k;
Value = "";
if (!Cradle.IsAlpha(Cradle.Look))
{
Cradle.Expected("Name");
}
while (Cradle.IsAlNum(Cradle.Look))
{
Value += char.ToUpper(Cradle.Look);
Cradle.GetChar();
}
k = Lookup(Value);
if (k == -1)
{
Token = SymType.Ident;
}
else
{
Token = (SymType)k;
}
}