public QsiDerivedTableNode VisitQueryParenthesisExpression(QueryParenthesisExpression queryParenthesisExpression)
{
return(TreeHelper.Create <QsiDerivedTableNode>(n =>
{
// Ignored ForClause, OffsetClause, OrderByClause
n.Columns.SetValue(TreeHelper.CreateAllColumnsDeclaration());
n.Source.SetValue(VisitQueryExpression(queryParenthesisExpression.QueryExpression));
SqlServerTree.PutFragmentSpan(n, queryParenthesisExpression);
}));
}
public override void Visit(QueryParenthesisExpression node) { this.action(node); }
public static EngineResult Evaluate(QueryExpression queryExpr, Scope scope)
{
var result = queryExpr switch
{
QuerySpecification querySpec => Evaluate(querySpec, scope),
QueryParenthesisExpression paren => Evaluate(paren.QueryExpression, scope),
BinaryQueryExpression binaryExpr => Evaluate(
binaryExpr.BinaryQueryExpressionType,
binaryExpr.All,
Evaluate(binaryExpr.FirstQueryExpression, scope).ResultSet,
Evaluate(binaryExpr.SecondQueryExpression, scope).ResultSet,
scope.Env),
_ => throw FeatureNotSupportedException.Subtype(queryExpr)
};
if (result.ResultSet == null)
{
return(result);
}
var projection = result.ResultSet;
// ORDER BY
if (queryExpr.OrderByClause != null)
{
var elements = queryExpr.OrderByClause.OrderByElements;
var firstElement = elements.First();
var restElements = elements.Skip(1);
var temp = projection.CopyLayout();
foreach (var row in restElements.Aggregate(
Order(projection.Rows, firstElement, scope),
(orderedRows, element) => Order(orderedRows, element, scope)))
{
CopyOnto(row, temp, scope.Env);
}
projection.Rows.Clear();
CopyOnto(temp, projection, scope.Env);
}
// OFFSET
if (queryExpr.OffsetClause != null)
{
var offset = Evaluate <int>(queryExpr.OffsetClause.OffsetExpression, NullArgument.It, scope);
for (var i = 0; i < offset; ++i)
{
projection.Rows.RemoveAt(0);
}
if (queryExpr.OffsetClause.FetchExpression != null)
{
var fetch = Evaluate <int>(queryExpr.OffsetClause.FetchExpression, NullArgument.It, scope);
while (projection.Rows.Count > fetch)
{
projection.Rows.RemoveAt(projection.Rows.Count - 1);
}
}
}
return(new EngineResult(projection));
}
}
public override void ExplicitVisit(QueryParenthesisExpression fragment)
{
_fragments.Add(fragment);
}
public override void ExplicitVisit(QueryParenthesisExpression node)
{
base.ExplicitVisit(node);
}
