private List<Token> tokenize(string formula)
{
formula = formula.Replace(" ","");
List<Token> tokens = new List<Token>();
Token currentToken = new Token();
bool bypass = false;
int position = -1;
foreach (char c in formula)
{
position++;
if (bypass)
{
bypass = false;
continue;
}
if (isNumber(c))
{
if (!currentToken.isEmpty() && !currentToken.isNumber)
{
tokens.Add(currentToken);
currentToken = new Token();
}
currentToken.isNumber = true;
currentToken.numberValue += c;
}
else if (isOperator(c))
{
if (!currentToken.isEmpty())
{
tokens.Add(currentToken);
currentToken = new Token();
}
currentToken.isOperator = true;
currentToken.operatorValue = c;
}
else if (isParen(c))
{
if (!currentToken.isEmpty())
{
tokens.Add(currentToken);
currentToken = new Token();
}
currentToken.isParen = true;
currentToken.parenValue = c;
}
else if (c == 'E')
{
if (formula[position + 1] == '+')
{
bypass = true;
if (!currentToken.isEmpty())
{
tokens.Add(currentToken);
currentToken = new Token();
}
currentToken.isOperator = true;
currentToken.operatorValue = 'e';
}
else
{
throw new Exception("Scientific notation is E+ or e");
}
}
else
{
throw new Exception("I don't know how to handle '" + c + "'");
}
}
if (!currentToken.isEmpty()) { tokens.Add(currentToken); }
return tokens;
}
private void ProcessParens(ref List<Token> tokens)
{
int posLParen = -1;
do
{
posLParen = tokens.indexOfLParen();
if (posLParen != -1)
{
int posRParen = tokens.indexOfRParen(posLParen);
// remove this range from the array
List<Token> subExpression = new List<Token>();
for(int i = posLParen+1; i < posRParen; i++)
{
subExpression.Add(tokens[i]);
}
tokens.RemoveRange(posLParen, (posRParen - posLParen + 1));
double subExpressionValue = evaluateTokens(subExpression);
Token t = new Token();
t.isNumber = true;
t.numberValue = subExpressionValue.ToString();
tokens.Insert(posLParen, t);
}
}
while (posLParen != -1);
// shouldn't be any R parens left
}
private void ProcessUnaryMinus(ref List<Token> tokens)
{
int posOperator = 0;
do
{
posOperator = tokens.indexOfNextOperator('-', posOperator);
if (posOperator != -1)
{
Token left = null;
Token right = null;
if (posOperator - 1 != -1) { left = tokens[posOperator - 1]; }
if (posOperator + 1 < tokens.Count) { right = tokens[posOperator + 1]; }
// special case, unary minus. If there is nothing to the left of the minus, or there is a non token number, perform unary minus
if (left == null || (left != null && !left.isNumber && right.isNumber))
{
Token unt = new Token();
unt.isNumber = true;
unt.numberValue = (-1 * Convert.ToDouble(right.numberValue)).ToString();
// remove this range from the array
tokens.RemoveRange(posOperator, 2);
tokens.Insert(posOperator, unt);
}
posOperator++;
}
}
while (posOperator != -1);
}
private void ProcessOperator(ref List<Token> tokens, char op)
{
int posOperator = -1;
do
{
posOperator = tokens.indexOfOperator(op);
if (posOperator != -1)
{
Token left = null;
Token right = null;
if (posOperator - 1 != -1) { left = tokens[posOperator - 1]; }
if (posOperator + 1 < tokens.Count) { right = tokens[posOperator + 1]; }
if (right == null) { throw new Exception("Nothing to the right of the operator"); }
if (left == null) { throw new Exception("Nothing to the left of the operator"); }
if (!left.isNumber) { throw new Exception("Left side is not a number"); }
if (!right.isNumber) { throw new Exception("Right side is not a number"); }
Token t = new Token();
t.isNumber = true;
switch (tokens[posOperator].operatorValue)
{
case '^':
t.numberValue = Math.Pow(Convert.ToDouble(left.numberValue), Convert.ToDouble(right.numberValue)).ToString(); break;
case '/':
t.numberValue = (Convert.ToDouble(left.numberValue) / Convert.ToDouble(right.numberValue)).ToString(); break;
case '*':
t.numberValue = (Convert.ToDouble(left.numberValue) * Convert.ToDouble(right.numberValue)).ToString(); break;
case '%':
t.numberValue = (Convert.ToDouble(left.numberValue) % Convert.ToDouble(right.numberValue)).ToString(); break;
case '+':
t.numberValue = (Convert.ToDouble(left.numberValue) + Convert.ToDouble(right.numberValue)).ToString(); break;
case '-':
t.numberValue = (Convert.ToDouble(left.numberValue) - Convert.ToDouble(right.numberValue)).ToString(); break;
case 'e':
t.numberValue = (Convert.ToDouble(left.numberValue) * Math.Pow(10, Convert.ToDouble(right.numberValue))).ToString(); break;
}
// remove this range from the array
tokens.RemoveRange(posOperator - 1, 3);
tokens.Insert(posOperator - 1, t);
}
}
while (posOperator != -1);
}
