protected override Expression VisitSelect(SelectExpression select)
{
select = (SelectExpression)base.VisitSelect(select);
// look for redundant field declarations
List<FieldDeclaration> cols = select.Fields.OrderBy(c => c.Name).ToList();
BitArray removed = new BitArray(select.Fields.Count);
bool anyRemoved = false;
for (int i = 0, n = cols.Count; i < n - 1; i++)
{
FieldDeclaration ci = cols[i];
FieldExpression cix = ci.Expression as FieldExpression;
StorageType qt = cix != null ? cix.QueryType : ci.QueryType;
FieldExpression cxi = new FieldExpression(ci.Expression.Type, qt, select.Alias, ci.Name);
for (int j = i + 1; j < n; j++)
{
if (!removed.Get(j))
{
FieldDeclaration cj = cols[j];
if (SameExpression(ci.Expression, cj.Expression))
{
// any reference to 'j' should now just be a reference to 'i'
FieldExpression cxj = new FieldExpression(cj.Expression.Type, qt, select.Alias, cj.Name);
this.map.Add(cxj, cxi);
removed.Set(j, true);
anyRemoved = true;
}
}
}
}
if (anyRemoved)
{
List<FieldDeclaration> newDecls = new List<FieldDeclaration>();
for (int i = 0, n = cols.Count; i < n; i++)
{
if (!removed.Get(i))
{
newDecls.Add(cols[i]);
}
}
select = select.SetFields(newDecls);
}
return select;
}
