/// Wraps the SELECT part of a query using a format string provided in the argument.
///
/// If a subquery parts aggregator is open, redirects the call to it instead.
public void SetSelectPartAsScalar(string scalarPartFormat)
{
if (_visitingSubQueryExpression)
{
_subQueryExpressionPartsAggregator.SetSelectPartAsScalar(scalarPartFormat);
}
else
{
var renamingPartIndex = SelectPart.IndexOf("\" AS \"", StringComparison.Ordinal) + 1;
SelectPart = renamingPartIndex > 0 ? SelectPart.Substring(0, renamingPartIndex) : SelectPart;
SelectPart = string.Format(scalarPartFormat, SelectPart);
}
}
public override void VisitResultOperator(ResultOperatorBase resultOperator, QueryModel queryModel, int index)
{
var operatorType = resultOperator.GetType();
if (AggretatingOperators.ContainsKey(operatorType))
{
_queryParts.SetSelectPartAsScalar(AggretatingOperators[operatorType]);
base.VisitResultOperator(resultOperator, queryModel, index);
}
else if (SetOperators.ContainsKey(operatorType))
{
dynamic subQueryResultOperator = Convert.ChangeType(resultOperator, operatorType);
this.VisitSubQueryExpression(subQueryResultOperator.Source2); // Source2 is a SubQueryExpression.
_queryParts.AddSubQueryLinkAction(SetOperators[operatorType]);
base.VisitResultOperator(resultOperator, queryModel, index);
}
else if (resultOperator is TakeResultOperator || resultOperator is SkipResultOperator)
{
var limitter = resultOperator is TakeResultOperator ? "LIMIT" : "OFFSET";
var constExpression = resultOperator is TakeResultOperator ?
(resultOperator as TakeResultOperator).Count :
(resultOperator as SkipResultOperator).Count;
_queryParts.AddPagingPart(limitter, GetPsqlExpression(constExpression));
base.VisitResultOperator(resultOperator, queryModel, index);
}
else if (resultOperator is AnyResultOperator)
{
_queryParts.AddSubQueryLinkAction("EXISTS ({0})");
}
else if (resultOperator is AllResultOperator)
{
var subQuery = (resultOperator as AllResultOperator);
_queryParts.AddWherePart($"NOT ({GetPsqlExpression(subQuery.Predicate)})");
_queryParts.AddSubQueryLinkAction("NOT EXISTS ({0})");
}
else
{
throw new NotImplementedException(
$"This LINQ provider does not provide the {resultOperator} result operator.");
}
}
