protected override Expression VisitSelect(SelectExpression select)
{
// visit column projection first
ReadOnlyCollection <ColumnDeclaration> columns = select.Columns;
List <ColumnDeclaration> alternate = null;
for (int i = 0, n = select.Columns.Count; i < n; i++)
{
ColumnDeclaration decl = select.Columns[i];
if (IsColumnUsed(select.Alias, decl.Name))
{
Expression expr = this.Visit(decl.Expression);
if (expr != decl.Expression)
{
decl = new ColumnDeclaration(decl.Name, expr);
}
}
else
{
decl = null; // null means it gets omitted
}
if (decl != select.Columns[i] && alternate == null)
{
alternate = new List <ColumnDeclaration>();
for (int j = 0; j < i; j++)
{
alternate.Add(select.Columns[j]);
}
}
if (decl != null && alternate != null)
{
alternate.Add(decl);
}
}
if (alternate != null)
{
columns = alternate.AsReadOnly();
}
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);
ClearColumnsUsed(select.Alias);
if (columns != select.Columns ||
orderbys != select.OrderBy ||
groupbys != select.GroupBy ||
where != select.Where ||
from != select.From)
{
select = new SelectExpression(select.Type, select.Alias, columns, from, where, orderbys, groupbys);
}
return(select);
}
protected override Expression VisitSelect(SelectExpression select)
{
select = (SelectExpression)base.VisitSelect(select);
if (lookup.Contains(select.Alias))
{
List <ColumnDeclaration> aggColumns = new List <ColumnDeclaration>(select.Columns);
foreach (AggregateSubqueryExpression ae in lookup[select.Alias])
{
string name = "agg" + aggColumns.Count;
ColumnDeclaration cd = new ColumnDeclaration(name, ae.AggregateInGroupSelect);
this.map.Add(ae, new ColumnExpression(ae.Type, ae.GroupByAlias, name));
aggColumns.Add(cd);
}
return(new SelectExpression(select.Type, select.Alias, aggColumns, select.From, select.Where, select.OrderBy, select.GroupBy));
}
return(select);
}
protected ReadOnlyCollection <ColumnDeclaration> VisitColumnDeclarations(ReadOnlyCollection <ColumnDeclaration> columns)
{
List <ColumnDeclaration> alternate = null;
for (int i = 0, n = columns.Count; i < n; i++)
{
ColumnDeclaration column = columns[i];
Expression e = this.Visit(column.Expression);
if (alternate == null && e != column.Expression)
{
alternate = columns.Take(i).ToList();
}
if (alternate != null)
{
alternate.Add(new ColumnDeclaration(column.Name, e));
}
}
if (alternate != null)
{
return(alternate.AsReadOnly());
}
return(columns);
}
protected override Expression VisitSelect(SelectExpression select)
{
sb.Append("SELECT ");
for (int i = 0, n = select.Columns.Count; i < n; i++)
{
ColumnDeclaration column = select.Columns[i];
if (i > 0)
{
sb.Append(", ");
}
ColumnExpression c = this.Visit(column.Expression) as ColumnExpression;
if (!string.IsNullOrEmpty(column.Name) && (c == null || c.Name != column.Name))
{
sb.Append(" AS ");
sb.Append(column.Name);
}
}
if (select.From != null)
{
this.AppendNewLine(Indentation.Same);
sb.Append("FROM ");
this.VisitSource(select.From);
}
if (select.Where != null)
{
this.AppendNewLine(Indentation.Same);
sb.Append("WHERE ");
this.Visit(select.Where);
}
if (select.OrderBy != null && select.OrderBy.Count > 0)
{
this.AppendNewLine(Indentation.Same);
sb.Append("ORDER BY ");
for (int i = 0, n = select.OrderBy.Count; i < n; i++)
{
OrderExpression exp = select.OrderBy[i];
if (i > 0)
{
sb.Append(", ");
}
this.Visit(exp.Expression);
if (exp.OrderType != OrderType.Ascending)
{
sb.Append(" DESC");
}
}
}
if (select.GroupBy != null && select.GroupBy.Count > 0)
{
this.AppendNewLine(Indentation.Same);
sb.Append("GROUP BY ");
for (int i = 0, n = select.GroupBy.Count; i < n; i++)
{
if (i > 0)
{
sb.Append(", ");
}
this.Visit(select.GroupBy[i]);
}
}
return(select);
}
