/// <summary>
/// evaluate the expression and return the result
/// </summary>
/// <param name = "resType">is the expected type </param>
/// <param name = "length">of expected Alpha string </param>
/// <returns> evaluated value or null if value evaluated to null (by ExpressionEvaluator) </returns>
internal String evaluate(StorageAttribute resType, int length)
{
ExpressionEvaluator.ExpVal expVal = null;
String retVal = null;
if (computedByClient())
{
expVal = ExpressionEvaluator.eval(_expBytes, resType, _task);
ConvertExpValForDotNet(expVal);
if (expVal.IsNull)
{
// even if actual dotnet obj is null, we need to return blobPrefix
if (expVal.Attr == StorageAttribute.DOTNET)
{
retVal = expVal.ToMgVal();
}
else
{
retVal = null;
}
}
else if (resType == StorageAttribute.BLOB_VECTOR && expVal.Attr == StorageAttribute.BLOB)
{
if (VectorType.validateBlobContents(expVal.StrVal))
{
retVal = expVal.ToMgVal();
}
else
{
retVal = null;
}
}
else if (expVal.Attr == StorageAttribute.BLOB_VECTOR &&
resType != StorageAttribute.BLOB_VECTOR && resType != StorageAttribute.BLOB)
{
retVal = null;
}
else
{
retVal = expVal.ToMgVal();
}
}
else
{
RunTimeEvent rtEvt = ClientManager.Instance.EventsManager.getLastRtEvent();
Task mprgCreator = null;
if (rtEvt != null)
{
mprgCreator = rtEvt.getMainPrgCreator();
}
// create a new command object only when necessary
if (resType != _prevResType)
{
_cmdToServer = CommandFactory.CreateEvaluateCommand(_task.getTaskTag(), resType, _id, length, mprgCreator);
}
ClientManager.Instance.execRequestWithSubformRecordCycle(_cmdsToServer, _cmdToServer, this, _task);
if (resType != StorageAttribute.BLOB && resType != StorageAttribute.BLOB_VECTOR)
{
retVal = _resultValue;
}
else if (_resultValue != null && _resultValue.Equals(" "))
{
retVal = "";
}
else
{
retVal = RecordUtils.byteStreamToString(_resultValue);
}
}
_prevResType = resType;
return(retVal);
}