//TODO: maybe move this to a subclass
protected virtual RecordTable ApplyOutputClause(RecordTable source, OutputClause clause)
{
var selectors = Visit <Func <Environment, Func <IResultTable, Selector[]> > >(clause)?.Invoke(Database.GlobalEnvironment)(source);
if (selectors != null)
{
return(new RecordTable(source.TableName, selectors, Filter.From(source.Records, (row) => true, null)));
}
return(null);
}
protected override object InternalVisit(OutputClause node)
{
return(new Func <Environment, Func <IResultTable, Selector[]> >(
(env) =>
{
return new Func <IResultTable, Selector[]>((table) =>
{
return node.SelectColumns.SelectMany(
(element) =>
{
return EvaluateExpression <Func <IResultTable, Selector[]> >(element, env)(table);
}).ToArray();
});
}));
}
public override void Visit(OutputClause node) { this.action(node); }
public override void ExplicitVisit(OutputClause fragment)
{
_fragments.Add(fragment);
}
