internal static HashSet <string> Gather(Expression source, TextWriter logger)
{
AliasesProduced produced = new AliasesProduced(logger);
produced.Visit(source);
return(produced.aliases);
}
protected override Expression VisitSelect(SelectExpression select)
{
bool saveIsOuterMostSelect = this.isOuterMostSelect;
try {
this.isOuterMostSelect = false;
select = (SelectExpression)base.VisitSelect(select);
bool hasOrderBy = select.OrderBy != null && select.OrderBy.Count > 0;
if (hasOrderBy)
{
this.PrependOrderings(select.OrderBy);
}
bool canHaveOrderBy = saveIsOuterMostSelect;
bool canPassOnOrderings = !saveIsOuterMostSelect && (select.GroupBy == null || select.GroupBy.Count == 0);
IEnumerable <OrderExpression> orderings = (canHaveOrderBy) ? this.gatheredOrderings : null;
ReadOnlyCollection <ColumnDeclaration> columns = select.Columns;
if (this.gatheredOrderings != null)
{
if (canPassOnOrderings)
{
HashSet <string> producedAliases = AliasesProduced.Gather(select.From, Logger);
// reproject order expressions using this select's alias so the outer select will have properly formed expressions
BindResult project = this.RebindOrderings(this.gatheredOrderings, select.Alias, producedAliases, select.Columns);
this.gatheredOrderings = project.Orderings;
columns = project.Columns;
}
else
{
this.gatheredOrderings = null;
}
}
if (orderings != select.OrderBy || columns != select.Columns)
{
select = new SelectExpression(select.Type, select.Alias, columns, select.From, select.Where, orderings, select.GroupBy);
}
return(select);
}
finally {
this.isOuterMostSelect = saveIsOuterMostSelect;
}
}