public Queue <Token> Parse()
{
while (tokenizer.Token != TokenType.End)
{
switch (tokenizer.Token)
{
case TokenType.Number:
ParseNumber();
break;
case TokenType.OpenParenthesis:
ParseOpenParenthesis();
break;
case TokenType.CloseParenthesis:
ParseCloseParenthesis();
break;
default:
ParseUnary();
ParseBinary();
break;
}
tokenizer.NextToken();
}
// We can't enqueue '(' so we get exception if it doesn't have a pair
try {
while (operators.Count != 0)
{
EnqueueOperator();
}
}
catch (KeyNotFoundException) {
throw new SyntaxException("Missing close parenthesis");
}
return(output);
}
Node ParseAddSubtract()
{
var lhs = ParseMultiplyDivide();
while (true)
{
Func <double, double, double> op = null;
if (_tokenizer.Token == Token.Add)
{
op = (a, b) => a + b;
}
else if (_tokenizer.Token == Token.Subtract)
{
op = (a, b) => a - b;
}
if (op == null)
{
return(lhs); // no
}
_tokenizer.NextToken();
var rhs = ParseMultiplyDivide();
lhs = new NodeBinary(lhs, rhs, op);
}
}
