protected override Expression VisitSelect(SelectExpression select)
{
select = (SelectExpression)base.VisitSelect(select);
if (lookup.Contains(select.Alias))
{
List<FieldDeclaration> aggFields = new List<FieldDeclaration>(select.Fields);
foreach (AggregateSubqueryExpression ae in lookup[select.Alias])
{
string name = "agg" + aggFields.Count;
var colType = this.language.TypeSystem.GetStorageType(ae.Type);
FieldDeclaration cd = new FieldDeclaration(name, ae.AggregateInGroupSelect, colType);
this.map.Add(ae, new FieldExpression(ae.Type, colType, ae.GroupByAlias, name));
aggFields.Add(cd);
}
return new SelectExpression(select.Alias, aggFields, select.From, select.Where, select.OrderBy, select.GroupBy, select.IsDistinct, select.Skip, select.Take, select.IsReverse);
}
return select;
}
protected virtual bool CompareFieldDeclaration(FieldDeclaration a, FieldDeclaration b)
{
return a.Name == b.Name && this.Compare(a.Expression, b.Expression);
}
protected override Expression VisitSelect(SelectExpression select)
{
// visit field projection first
ReadOnlyCollection<FieldDeclaration> fields = select.Fields;
var wasRetained = this.retainAllFields;
this.retainAllFields = false;
List<FieldDeclaration> alternate = null;
for (int i = 0, n = select.Fields.Count; i < n; i++)
{
FieldDeclaration decl = select.Fields[i];
if (wasRetained || select.IsDistinct || IsFieldUsed(select.Alias, decl.Name))
{
Expression expr = this.Visit(decl.Expression);
if (expr != decl.Expression)
{
decl = new FieldDeclaration(decl.Name, expr, decl.QueryType);
}
}
else
{
decl = null; // null means it gets omitted
}
if (decl != select.Fields[i] && alternate == null)
{
alternate = new List<FieldDeclaration>();
for (int j = 0; j < i; j++)
{
alternate.Add(select.Fields[j]);
}
}
if (decl != null && alternate != null)
{
alternate.Add(decl);
}
}
if (alternate != null)
{
fields = alternate.AsReadOnly();
}
Expression take = this.Visit(select.Take);
Expression skip = this.Visit(select.Skip);
ReadOnlyCollection<Expression> groupbys = this.VisitExpressionList(select.GroupBy);
ReadOnlyCollection<OrderExpression> orderbys = this.VisitOrderBy(select.OrderBy);
Expression where = this.Visit(select.Where);
Expression from = this.Visit(select.From);
ClearFieldsUsed(select.Alias);
if (fields != select.Fields
|| take != select.Take
|| skip != select.Skip
|| orderbys != select.OrderBy
|| groupbys != select.GroupBy
|| where != select.Where
|| from != select.From)
{
select = new SelectExpression(select.Alias, fields, from, where, orderbys, groupbys, select.IsDistinct, skip, take, select.IsReverse);
}
this.retainAllFields = wasRetained;
return select;
}
public static SelectExpression RemoveField(this SelectExpression select, FieldDeclaration field)
{
List<FieldDeclaration> fields = new List<FieldDeclaration>(select.Fields);
fields.Remove(field);
return select.SetFields(fields);
}
