override public object Eval(DataRow row)
{
object obj1 = expr1.Eval(row);
if (obj1 == DBNull.Value || obj1 == null)
{
return(obj1);
}
object obj2 = expr2.Eval(row);
if (obj2 == DBNull.Value || obj2 == null)
{
return(obj2);
}
if (op == Operation.ADD && (obj1 is string || obj2 is string))
{
return(obj1.ToString() + obj2.ToString());
}
IConvertible o1 = (IConvertible)obj1;
IConvertible o2 = (IConvertible)obj2;
switch (op)
{
case Operation.ADD:
return(Numeric.Add(o1, o2));
case Operation.SUB:
return(Numeric.Subtract(o1, o2));
case Operation.MUL:
return(Numeric.Multiply(o1, o2));
case Operation.DIV:
return(Numeric.Divide(o1, o2));
case Operation.MOD:
return(Numeric.Modulo(o1, o2));
default:
return(0);
}
}
private void Aggregate(IConvertible val)
{
switch (function)
{
case AggregationFunction.Min:
result = (result != null ? Numeric.Min(result, val) : val);
return;
case AggregationFunction.Max:
result = (result != null ? Numeric.Max(result, val) : val);
return;
case AggregationFunction.Sum:
case AggregationFunction.Avg:
case AggregationFunction.StDev:
case AggregationFunction.Var:
result = (result != null ? Numeric.Add(result, val) : val);
return;
}
}