public Tokenizer(string input)
{
RootToken = currentToken = new Token(TokenType.Root, "", null);
StringReader reader = new StringReader(input);
while (true)
{
int nextCharNum = reader.Read();
if (nextCharNum == -1) //end of expression
{
RootToken.AddChild(new Token(TokenType.EOF, "", null));
break;
}
char nextChar = (char)nextCharNum;
if (Char.IsWhiteSpace(nextChar))
{
continue;
}
if (Char.IsNumber(nextChar) || (nextChar == '-' && Char.IsNumber((char)reader.Peek()))) //number, or minus sign before number
{
string fullNum = nextChar.ToString();
while (Char.IsNumber((char)reader.Peek()) || (char)reader.Peek() == '.')
{
fullNum += (char)reader.Read(); //get the full number
}
double temp;
if (!double.TryParse(fullNum, out temp))
{
throw new ExpressionParseException(fullNum + " is not a valid number");
}
Token t = new Token(TokenType.Number, fullNum, currentToken);
currentToken.AddChild(t);
}
else if (Parser.Operators.ContainsKey(nextChar)) //operator
{
Token t = new Token(TokenType.Operator, nextChar.ToString(), currentToken);
currentToken.AddChild(t);
}
else if (nextChar == ')') //end of function or group
{
currentToken = currentToken.Parent;
}
else if (nextChar == '(') //open of group
{
Token t = new Token(TokenType.Group, "", currentToken);
currentToken.AddChild(t);
currentToken = t;
}
else if (nextChar == ',')
{
if (currentToken.Type == TokenType.Root)
{
throw new ExpressionParseException("Argument seperator while not in function");
}
Token t = new Token(TokenType.ArgSep, "", currentToken);
currentToken.AddChild(t);
}
else
{
string functionName = nextChar.ToString();
while (true)
{
int c = reader.Peek();
if (c == -1)
{
throw new ExpressionParseException("End of string present before function end");
}
if ((char)c == '(') // function name end, start of args
{
break;
}
functionName += (char)reader.Read();
}
if (!Parser.Functions.ContainsKey(functionName))
{
throw new ExpressionParseException("Unknown function '" + functionName + "'");
}
Token t = new Token(TokenType.Function, functionName, currentToken);
currentToken.AddChild(t);
currentToken = t;
}
}
}
