//handle numbers, reserved workds, and identifiers
private void defaultScannerFallback()
{
if (!checkDigit())
{
if (!checkWord())
{
clrVal();
token = Globals.Token.unknownT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
}
}
//check for integers and floating point numbers
private bool checkDigit()
{
string digits = "0123456789";
clrVal();
if (digits.Contains(input[inputIndex]))
{
int i = 0;
int j = 1;
while (inputIndex + i + 1 < input.Length && digits.Contains(input[inputIndex + i]))
{
i++;
}
token = Globals.Token.numT;
if (inputIndex + i < input.Length && input[inputIndex + i] == '.')
{
while (inputIndex + i + j + 1 < input.Length && digits.Contains(input[inputIndex + i + j]))
{
j++;
}
}
if (j > 1)
{
sb.Clear();
for (int k = 0; k < i + j; k++)
{
sb.Append(input[inputIndex + k]);
}
ValueR = float.Parse(sb.ToString());
inputIndex += i + j;
}
else
{
sb.Clear();
for (int k = 0; k < i; k++)
{
sb.Append(input[inputIndex + k]);
}
Value = int.Parse(sb.ToString());
inputIndex += i;
}
return(true);
}
else
{
return(false);
}
}
//check for reserved words and identifiers
private bool checkWord()
{
clrVal();
if (char.IsLetter(input[inputIndex]))
{
int i = 1;
while (inputIndex + i + 1 < input.Length && (char.IsLetterOrDigit(input[inputIndex + i]) || input[inputIndex + i] == '_') && i < 31)
{
i++;
}
sb.Clear();
for (int j = 0; j < i; j++)
{
sb.Append(input[inputIndex + j]);
}
token = Globals.Token.idT;
Lexeme = sb.ToString();
i = 1;
while (inputIndex + i + 1 < input.Length && (char.IsLetterOrDigit(input[inputIndex + i]) || input[inputIndex + i] == '.') && i < 256)
{
i++;
}
sb.Clear();
for (int j = 0; j < i; j++)
{
sb.Append(input[inputIndex + j]);
}
if (lookupTable.TryGetValue(sb.ToString(), out Globals.Token myTok))
{
clrVal();
token = myTok;
Lexeme = sb.ToString();
}
inputIndex += Lexeme.Length;
return(true);
}
return(false);
}
//try to scan the next token and update the scanner state.
public void GetNextToken()
{
//handle eof
if (inputIndex >= input.Length)
{
clrVal();
token = Globals.Token.eofT;
return;
}
switch (input[inputIndex])
{
//handle simple symbol lexems
case '(':
clrVal();
token = Globals.Token.oParenT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case ')':
clrVal();
token = Globals.Token.cParenT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '{':
clrVal();
token = Globals.Token.oBraceT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '}':
clrVal();
token = Globals.Token.cBraceT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '[':
clrVal();
token = Globals.Token.oBrackT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case ']':
clrVal();
token = Globals.Token.cBrackT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case ';':
clrVal();
token = Globals.Token.semicolonT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '.':
clrVal();
token = Globals.Token.dotT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case ',':
clrVal();
token = Globals.Token.commaT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '+':
clrVal();
token = Globals.Token.addOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '-':
clrVal();
token = Globals.Token.addOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
case '*':
clrVal();
token = Globals.Token.mulOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
break;
//handle compound 2 char lexemes
case '=':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '=')
{
token = Globals.Token.relOpT;
Lexeme = "" + input[inputIndex] + input[inputIndex + 1];
inputIndex += 2;
}
else
{
token = Globals.Token.assignOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
case '>':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '=')
{
token = Globals.Token.relOpT;
Lexeme = "" + input[inputIndex] + input[inputIndex + 1];
inputIndex += 2;
}
else
{
token = Globals.Token.relOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
case '<':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '=')
{
token = Globals.Token.relOpT;
Lexeme = "" + input[inputIndex] + input[inputIndex + 1];
inputIndex += 2;
}
else
{
token = Globals.Token.relOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
case '!':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '=')
{
token = Globals.Token.relOpT;
Lexeme = "" + input[inputIndex] + input[inputIndex + 1];
inputIndex += 2;
}
else
{
token = Globals.Token.unknownT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
case '|':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '|')
{
token = Globals.Token.addOpT;
Lexeme = "" + input[inputIndex] + input[inputIndex + 1];
inputIndex += 2;
}
else
{
token = Globals.Token.unknownT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
case '&':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '&')
{
token = Globals.Token.mulOpT;
Lexeme = "" + input[inputIndex] + input[inputIndex + 1];
inputIndex += 2;
}
else
{
token = Globals.Token.unknownT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
//handle whitespace
case ' ':
inputIndex++;
GetNextToken();
break;
case '\n':
inputIndex++;
GetNextToken();
break;
case '\t':
inputIndex++;
GetNextToken();
break;
case '\r':
inputIndex++;
GetNextToken();
break;
//handle variable length lexemes
case '/':
clrVal();
if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '/')
{
int cIndex = 0;
while (inputIndex + cIndex < input.Length && input[inputIndex + cIndex] != '\n')
{
cIndex++;
}
inputIndex += cIndex;
GetNextToken();
}
else if (inputIndex + 1 < input.Length && input[inputIndex + 1] == '*')
{
int cIndex = 2;
while (inputIndex + cIndex + 1 < input.Length && !(input[inputIndex + cIndex] == '*' && input[inputIndex + cIndex + 1] == '/'))
{
cIndex++;
}
cIndex++;
if (inputIndex + cIndex >= input.Length)
{
Printer.WarnLine("Scanner Warning: Unmatched parenthesis, was expecting '*/' but found 'eof'");
}
inputIndex += cIndex;
GetNextToken();
}
else
{
token = Globals.Token.mulOpT;
Lexeme = "" + input[inputIndex];
inputIndex++;
}
break;
case '"':
clrVal();
token = Globals.Token.dQuoteT;
{
sb.Clear();
int i = 1;
while (inputIndex + i + 1 < input.Length && input[inputIndex + i] != '\"' && input[inputIndex + i] != '\n')
{
if (input[inputIndex + i] == '\\' && input[inputIndex + i] == '\"')
{
i++;
}
i++;
}
if (inputIndex + i < input.Length && input[inputIndex + i] != '\"')
{
Printer.WarnLine("Scanner Warning: Unmatched parenthesis, was expecting '\"' but found '" + input[inputIndex + i] + "'");
}
else if (inputIndex + i >= input.Length)
{
Printer.WarnLine("Scanner Warning: Unmatched parenthesis, was expecting '\"' but found 'eof'");
}
for (int j = 1; j < i; j++)
{
sb.Append(input[inputIndex + i]);
}
hasLiteral = true;
Literal = sb.ToString();
Lexeme = "\"" + Literal + "\"";
inputIndex += i;
if (inputIndex + i < input.Length && input[inputIndex + i] == '\"')
{
inputIndex++;
}
}
break;
default:
defaultScannerFallback();
break;
}
}
