public static Expression Split(string expressionString)
{
List <Token> tokens = new List <Token>();
//read the input-expression letter-by-letter and build tokens
string alphaNumericString = string.Empty;
Token lastOp = CalcUtilities.CreateOperatorToken('X');
for (int index = 0; index < expressionString.Length; index++)
{
char currentChar = expressionString[index];
if (AllOperators.Find("" + currentChar) != null) //if operator
{
if (alphaNumericString.Length > 0)
{
tokens.Add(Token.Resolve(alphaNumericString));
alphaNumericString = string.Empty;
}
if (lastOp != null && (((Operator)lastOp.TokenObject).PrecedenceLevel < 1 || ((Operator)lastOp.TokenObject).SymbolText != ")"))
{
if (currentChar == '-')
{
currentChar = '_';
}
}
Token op = CalcUtilities.CreateOperatorToken(currentChar);
lastOp = op;
tokens.Add(op);
}
else if (Char.IsLetterOrDigit(currentChar) || currentChar == '.') //if alphabet or digit or dot
{
alphaNumericString += currentChar;
lastOp = null;
}
}
//check if any token at last
if (alphaNumericString.Length > 0)
{
tokens.Add(Token.Resolve(alphaNumericString));
}
return(new Expression()
{
Tokens = tokens
});
}
