private static double ParseSimpleStatement()
{
// Get a token
Token token = ExpressionParser.ParseToken();
switch (token.tokenType)
{
case TokenType.START_BRACKET:
double val = ParseStatement();
ParseToken(")");
return(val);
case TokenType.IDENTIFIER:
return(ParseIdentifier(token));
case TokenType.OPERATOR:
switch (token.sval)
{
case "-":
return(-ParseSimpleStatement());
case "!":
return(ParseSimpleStatement() == 0.0 ? 1.0 : 0.0);
default:
throw new ArgumentException("Unexpected operator: " + token.sval);
}
case TokenType.VALUE:
return(token.dval);
default:
throw new ArgumentException("Unexpected value: " + token.sval);
}
}
private static double ParseStatement()
{
double lval = ParseSimpleStatement();
// End of statement
if (expression.Length == 0)
{
return(lval);
}
// Get next token
Token token = ExpressionParser.ParseToken();
while (token != null)
{
switch (token.tokenType)
{
case TokenType.START_BRACKET:
throw new ArgumentException("Unexpected value: " + token.sval);
case TokenType.END_BRACKET:
expression = ")" + expression;
return(lval);
case TokenType.IDENTIFIER:
case TokenType.VALUE:
throw new ArgumentException("Unexpected value: " + token.sval);
case TokenType.OPERATOR:
lval = ParseOperation(lval, token.sval);
break;
default:
throw new ArgumentException("Unexpected value: " + token.sval);
}
// Get next token
token = ExpressionParser.ParseToken();
}
return(lval);
}
private static double ParseOperation(double lval, string op)
{
double rval = ParseSimpleStatement();
// Get a token
Token token = ExpressionParser.ParseToken();
while (token != null)
{
switch (token.tokenType)
{
case TokenType.START_BRACKET:
case TokenType.IDENTIFIER:
case TokenType.VALUE:
throw new ArgumentException("Unexpected value: " + token.sval);
case TokenType.END_BRACKET:
expression = token.sval + expression;
return(ApplyOperator(lval, op, rval));
case TokenType.OPERATOR:
if (precedence[op] >= precedence[token.sval])
{
expression = token.sval + expression;
return(ApplyOperator(lval, op, rval));
}
else
{
rval = ParseOperation(rval, token.sval);
token = ExpressionParser.ParseToken();
}
break;
default:
throw new ArgumentException("Unexpected value: " + token.sval);
}
}
return(ApplyOperator(lval, op, rval));
}