private bool Logic(OperatorNode obj)
{
bool lhs = ScriptTypeUtil.EvalToBoolean(obj.Lhs.Accept(this));
//Note: Short cut Rhs
if (lhs && obj.Token.TokenValue == "||")
{
return(true);
}
if (!lhs && obj.Token.TokenValue == "&&")
{
return(false);
}
//Note: Eval Rhs
bool rhs = ScriptTypeUtil.EvalToBoolean(obj.Rhs.Accept(this));
if (obj.Token.TokenValue == "||")
{
return(lhs || rhs);
}
if (obj.Token.TokenValue == "&&")
{
return(lhs && rhs);
}
ExceptionHelper.ThrowBinaryOperatorInvalid(obj.Token.TokenValue, lhs, rhs);
return(false);
}
public override object Visit(OperatorNode obj)
{
switch (obj.Token.TokenType)
{
case TokenType.LogicalOperator:
return(Logic(obj));
case TokenType.CompareOperator:
return(Compare(obj));
case TokenType.ArithmeticOperator:
return(Arithmetic(obj));
}
ExceptionHelper.ThrowBinaryOperatorInvalid(obj.Token.TokenValue, obj.Lhs.GetType(), obj.Rhs.GetType());
return(null);
}
private bool Compare(OperatorNode obj)
{
object lhs = obj.Lhs.Accept(this);
object rhs = obj.Rhs.Accept(this);
if (ScriptTypeUtil.IsNumber(lhs) && ScriptTypeUtil.IsNumber(rhs))
{
decimal lNumber = ScriptTypeUtil.ConvertToDecimal(lhs);
decimal rNumber = ScriptTypeUtil.ConvertToDecimal(rhs);
switch (obj.Token.TokenValue)
{
case ">":
return(lNumber > rNumber);
case "<":
return(lNumber < rNumber);
case ">=":
return(lNumber >= rNumber);
case "<=":
return(lNumber <= rNumber);
case "==":
return(lNumber == rNumber);
case "<>":
case "!=":
return(lNumber != rNumber);
}
}
//Note: If compare equality, null is OK.
switch (obj.Token.TokenValue)
{
case "==":
if (lhs == null)
{
return(rhs == null);
}
else
{
return(lhs.Equals(rhs));
}
case "<>":
case "!=":
if (lhs == null)
{
return(rhs != null);
}
else
{
return(!(lhs.Equals(rhs)));
}
}
ExceptionHelper.ThrowBinaryOperatorInvalid(obj.Token.TokenValue, lhs, rhs);
return(false);
}
private object Arithmetic(OperatorNode obj)
{
object lhs = obj.Lhs.Accept(this);
object rhs = obj.Rhs.Accept(this);
//Note:string concat
if (obj.Token.TokenValue == "+" && (lhs is string || rhs is string))
{
string result = string.Empty;
if (lhs != null)
{
result += lhs.ToString();
}
if (rhs != null)
{
result += rhs.ToString();
}
return(result);
}
//Note:string multiple
if (obj.Token.TokenValue == "*" && lhs is string && ScriptTypeUtil.IsLong(rhs))
{
StringBuilder result = new StringBuilder();
for (int i = 0; i < (long)rhs; i++)
{
result.Append(lhs);
}
return(result.ToString());
}
//Note:Only number is valid currently, everything will convert to decimal
decimal lNumber = ScriptTypeUtil.ConvertToDecimal(lhs);
decimal rNumber = ScriptTypeUtil.ConvertToDecimal(rhs);
switch (obj.Token.TokenValue)
{
case "+":
return(lNumber + rNumber);
case "-":
return(lNumber - rNumber);
case "*":
return(lNumber * rNumber);
case "/":
return(lNumber / rNumber);
case "%":
return(lNumber % rNumber);
case "^":
double b = double.Parse(lNumber.ToString());
double x = double.Parse(rNumber.ToString());
return((decimal)Math.Pow(b, x));
}
ExceptionHelper.ThrowBinaryOperatorInvalid(obj.Token.TokenValue, lhs, rhs);
return(null);
}