private void PopOperatorsToOutput(bool precedence, MathToken token)
{
while (OpStack.Count > 0 &&
OpStack[0].Operator != Operator.StartParen &&
!(precedence && token.Operator == Operator.Add && OpStack[0].Operator == Operator.Mul))
{
Output.Add(OpStack[0]);
OpStack.RemoveAt(0);
}
}
public List <MathToken> InfixToPostfix(bool precedence, List <MathToken> infix)
{
Output.Clear();
OpStack.Clear();
foreach (MathToken token in infix)
{
if (token.Type == TokenType.Operand)
{
Output.Add(token);
}
else if (token.Operator == Operator.StartParen)
{
OpStack.Insert(0, token);
}
else if (token.Operator == Operator.EndParen)
{
PopOperatorsToOutput(precedence, token);
if (OpStack[0].Operator == Operator.StartParen)
{
OpStack.RemoveAt(0);
}
else
{
throw new Exception("Mismatched parenthesis");
}
}
else
{
PopOperatorsToOutput(precedence, token);
OpStack.Insert(0, token);
}
}
MathToken end = new MathToken();
end.Type = TokenType.Operator;
end.Operator = Operator.EndParen;
PopOperatorsToOutput(precedence, end);
return(Output);
}
private List <MathToken> Tokenize(string input)
{
List <MathToken> tokens = new List <MathToken>();
Regex TokenRe = new Regex(@"\s*(\d+|\+|\*|\(|\))");
foreach (Match match in TokenRe.Matches(input))
{
MathToken token = new MathToken();
switch (match.Groups[1].Value)
{
case "(":
token.Type = TokenType.Operator;
token.Operator = Operator.StartParen;
break;
case ")":
token.Type = TokenType.Operator;
token.Operator = Operator.EndParen;
break;
case "+":
token.Type = TokenType.Operator;
token.Operator = Operator.Add;
break;
case "*":
token.Type = TokenType.Operator;
token.Operator = Operator.Mul;
break;
default:
token.Type = TokenType.Operand;
token.Operand = int.Parse(match.Groups[1].Value);
break;
}
tokens.Add(token);
}
return(tokens);
}
