/// <summary>
/// Gets the expression resulting value.
/// </summary>
/// <returns></returns>
public object GetValue()
{
switch (_type)
{
case ExpressionType.Value:
return(_data);
case ExpressionType.DatabaseColumn:
try
{
return(tFilter.oCurrentData[iColumn]);
}
catch
{
throw Trace.Error(Trace.COLUMN_NOT_FOUND, sColumn);
}
case ExpressionType.Function:
return(fFunction.GetValue());
case ExpressionType.Query:
return(sSelect.GetValue(_columnType));
case ExpressionType.Negate:
return(Column.Negate(eArg.GetValue(_columnType), _columnType));
case ExpressionType.Count:
// count(*): sum(1); count(col): sum(col<>null)
if (eArg.Type == ExpressionType.Asterix || eArg.GetValue() != null)
{
return(1);
}
return(0);
case ExpressionType.Maximum:
case ExpressionType.Minimum:
case ExpressionType.Sum:
case ExpressionType.Average:
return(eArg.GetValue());
case ExpressionType.Exists:
return(Test());
case ExpressionType.Convert:
return(eArg.GetValue(_columnType));
case ExpressionType.CaseWhen:
if (eArg.Test())
{
return(eArg2.eArg.GetValue());
}
else
{
return(eArg2.eArg2.GetValue());
}
case ExpressionType.Variable:
return(eArg.GetValue());
}
// todo: simplify this
object a = null, b = null;
if (eArg != null)
{
a = eArg.GetValue(_columnType);
}
if (eArg2 != null)
{
b = eArg2.GetValue(_columnType);
}
switch (_type)
{
case ExpressionType.Add:
return(Column.Add(a, b, _columnType));
case ExpressionType.Subtract:
return(Column.Subtract(a, b, _columnType));
case ExpressionType.Multiply:
return(Column.Multiply(a, b, _columnType));
case ExpressionType.Divide:
return(Column.Divide(a, b, _columnType));
case ExpressionType.Concat:
return(Column.Concat(a, b, _columnType));
case ExpressionType.IfNull:
return(a == null ? b : a);
case ExpressionType.Equal:
if (eArg.Type == ExpressionType.Variable)
{
Trace.Check(eArg2 != null, Trace.GENERAL_ERROR);
return(eArg2.GetValue(eArg._columnType));
}
else
{
return(Test());
}
default:
// must be comparisation
// todo: make sure it is
return(Test());
}
}