private void ExtractFunctionName(PrefSQLParser.SkylinePreferenceUdfContext context, UdfModel model)
{
model.SchemaName = GetSchemaName(context.GetChild(0));
model.FunctionName = GetFunctionName(context.GetChild(0));
//model.FullFunctionName = $"{model.SchemaName}.{model.FunctionName}";
model.FullFunctionName = model.SchemaName + "." + model.FunctionName;
}
private void ExtractLevelingData(PrefSQLParser.SkylinePreferenceUdfContext context, UdfModel model)
{
// set defaults
model.IsLevelStepEqual = true;
model.LevelStep = string.Empty;
model.LevelAdd = string.Empty;
model.LevelMinus = string.Empty;
model.IsComparable = true;
model.HasIncomparableTuples = false;
model.ContainsOpenPreference = false;
// no STEP operator
if (context.ChildCount != 4)
{
return;
}
//If a third parameter is given, it is the Level Step (i.e. LOW price 1000 means prices divided through 1000)
//The user doesn't care about a price difference of 1000
//This results in a smaller skyline
model.LevelStep = " / " + context.GetChild(2).GetText();
model.LevelAdd = " + " + context.GetChild(2).GetText();
model.LevelMinus = " - " + context.GetChild(2).GetText();
//
if (context.GetChild(3).GetText().Equals("EQUAL"))
{
return;
}
model.IsLevelStepEqual = false;
model.IsComparable = false;
model.HasIncomparableTuples = true;
//Some algorithms cannot handle this incomparable preference --> It is like a categorical preference without explicit OTHERS
model.ContainsOpenPreference = true;
}
public override PrefSQLModel VisitSkylinePreferenceUdf(PrefSQLParser.SkylinePreferenceUdfContext context)
{
// extract data
var udfModel = new SqlUdfVisitor().VisitSkylinePreferenceUdf(context);
// set global flags
_hasIncomparableTuples = _hasIncomparableTuples || udfModel.HasIncomparableTuples;
_containsOpenPreference = _containsOpenPreference || udfModel.ContainsOpenPreference;
// create preference and add to list
var sub = new SqlUdfBuilder(udfModel, InnerTableSuffix);
return(AddSkyline(new AttributeModel(sub.CreateRankingExpr(), sub.CreateInnerExpr(), udfModel.FullFunctionName, "", udfModel.IsComparable, sub.CreateIncomporableAttribute(), false, "", 0, 0, sub.CreateExpression())));
}
public override UdfModel VisitSkylinePreferenceUdf(PrefSQLParser.SkylinePreferenceUdfContext context)
{
// extract schema and function
var model = new UdfModel();
ExtractFunctionName(context, model);
// extract parameter
ExtractParameterList(context.exprUdfParam(), model);
// extract leveling
ExtractLevelingData(context, model);
ExtractHighLowData(context, model);
return(model);
}
private void ExtractHighLowData(PrefSQLParser.SkylinePreferenceUdfContext context, UdfModel model)
{
// set defaults
model.OppositeOperator = string.Empty;
// operators not found
model.HasHighLowOperator = (context.op.Type == PrefSQLParser.K_LOW || context.op.Type == PrefSQLParser.K_HIGH);
if (!model.HasHighLowOperator)
{
return;
}
// mode HIGH
model.LevelAdditionaly = model.LevelAdd;
if (context.op.Type == PrefSQLParser.K_HIGH)
{
model.LevelAdditionaly = model.LevelMinus;
//Multiply with -1 (result: every value can be minimized!)
model.OppositeOperator = " * -1";
}
}
