protected override Expression VisitSelect(SelectExpression select)
{
bool saveIsOuterMostSelect = this.isOuterMostSelect;
try
{
this.isOuterMostSelect = false;
var saveSuppressOrderBy = this.suppressOrderby;
this.suppressOrderby = false;
var saveGatheredOrderings = this.gatheredOrderings;
if (saveSuppressOrderBy)
{
this.gatheredOrderings = null;
this.isOuterMostSelect = true;
}
select = (SelectExpression)base.VisitSelect(select);
this.suppressOrderby = saveSuppressOrderBy;
if (saveSuppressOrderBy)
{
this.gatheredOrderings = saveGatheredOrderings;
}
bool hasOrderBy = select.OrderBy != null && select.OrderBy.Count > 0;
bool hasGroupBy = select.GroupBy != null && select.GroupBy.Count > 0;
bool canHaveOrderBy = saveIsOuterMostSelect || select.Take != null || select.Skip != null;
bool canReceiveOrderings = canHaveOrderBy && !hasGroupBy && !select.IsDistinct && !AggregateChecker.HasAggregates(select) && !suppressOrderby;
if (hasOrderBy)
{
this.PrependOrderings(select.OrderBy);
}
if (select.IsReverse)
{
if (this.gatheredOrderings == null || gatheredOrderings.Count == 0)
{
throw new NotSupportedException(string.Format(Res.OperationNotSupported, "", "Reverse", "if no 'OrderBy' expression."));
}
for (int i = 0, n = this.gatheredOrderings.Count; i < n; i++)
{
var ord = this.gatheredOrderings[i];
this.gatheredOrderings[i] =
new OrderExpression(
ord.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending,
ord.Expression
);
}
}
IEnumerable <OrderExpression> orderings = null;
if (canReceiveOrderings)
{
orderings = this.gatheredOrderings;
}
else if (canHaveOrderBy)
{
orderings = select.OrderBy;
}
bool canPassOnOrderings = !saveIsOuterMostSelect && !hasGroupBy && !select.IsDistinct && !suppressOrderby;
ReadOnlyCollection <ColumnDeclaration> columns = select.Columns;
if (this.gatheredOrderings != null)
{
if (canPassOnOrderings)
{
var producedAliases = TableAliasGatherer.Gather(select.From);
// 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 = null;
this.PrependOrderings(project.Orderings);
columns = project.Columns;
}
else
{
this.gatheredOrderings = null;
}
}
if (orderings != select.OrderBy || columns != select.Columns || select.IsReverse)
{
select = new SelectExpression(select.Alias, columns, select.From, select.Where, orderings, select.GroupBy, select.IsDistinct, select.Skip, select.Take, false);
}
return(select);
}
finally
{
this.isOuterMostSelect = saveIsOuterMostSelect;
}
}
public static SelectExpression SetColumns(this SelectExpression select, IEnumerable <ColumnDeclaration> columns)
{
return(new SelectExpression(select.Alias, columns.OrderBy(c => c.Name), select.From, select.Where, select.OrderBy, select.GroupBy, select.IsDistinct, select.Skip, select.Take, select.IsReverse));
}
protected override Expression VisitSelect(SelectExpression select)
{
// visit column projection first
ReadOnlyCollection <ColumnDeclaration> columns = select.Columns;
var wasRetained = this.retainAllColumns;
this.retainAllColumns = false;
List <ColumnDeclaration> alternate = null;
for (int i = 0, n = select.Columns.Count; i < n; i++)
{
ColumnDeclaration decl = select.Columns[i];
if (wasRetained || select.IsDistinct || IsColumnUsed(select.Alias, decl.Name))
{
Expression expr = this.Visit(decl.Expression);
if (expr != decl.Expression)
{
decl = new ColumnDeclaration(decl.Name, expr, decl.SqlType);
}
}
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();
}
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);
ClearColumnsUsed(select.Alias);
if (columns != select.Columns ||
take != select.Take ||
skip != select.Skip ||
orderbys != select.OrderBy ||
groupbys != select.GroupBy ||
where != select.Where ||
from != select.From)
{
select = new SelectExpression(select.Alias, columns, from, where, orderbys, groupbys, select.IsDistinct, skip, take, select.IsReverse);
}
this.retainAllColumns = wasRetained;
return(select);
}
public static SelectExpression SetGroupBy(this SelectExpression select, IEnumerable <Expression> groupBy)
{
return(new SelectExpression(select.Alias, select.Columns, select.From, select.Where, select.OrderBy, groupBy, select.IsDistinct, select.Skip, select.Take, select.IsReverse));
}
protected override Expression VisitProjection(ProjectionExpression proj)
{
SelectExpression save = this.currentSelect;
this.currentSelect = proj.Select;
try
{
if (!this.isTopLevel)
{
if (this.CanJoinOnClient(this.currentSelect))
{
// make a query that combines all the constraints from the outer queries into a single select
SelectExpression newOuterSelect = (SelectExpression)QueryDuplicator.Duplicate(save);
// remap any references to the outer select to the new alias;
SelectExpression newInnerSelect = (SelectExpression)ColumnMapper.Map(proj.Select, newOuterSelect.Alias, save.Alias);
// add outer-join test
ProjectionExpression newInnerProjection = this.dbExpressionBuilder.AddOuterJoinTest(new ProjectionExpression(newInnerSelect, proj.Projector));
newInnerSelect = newInnerProjection.Select;
Expression newProjector = newInnerProjection.Projector;
TableAlias newAlias = new TableAlias();
var pc = ColumnProjector.ProjectColumns(newProjector, null, newAlias, newOuterSelect.Alias, newInnerSelect.Alias);
JoinExpression join = new JoinExpression(JoinType.OuterApply, newOuterSelect, newInnerSelect, null);
SelectExpression joinedSelect = new SelectExpression(newAlias, pc.Columns, join, null, null, null, proj.IsSingleton, null, null, false);
// apply client-join treatment recursively
this.currentSelect = joinedSelect;
newProjector = this.Visit(pc.Projector);
// compute keys (this only works if join condition was a single column comparison)
List <Expression> outerKeys = new List <Expression>();
List <Expression> innerKeys = new List <Expression>();
if (this.GetEquiJoinKeyExpressions(newInnerSelect.Where, newOuterSelect.Alias, outerKeys, innerKeys))
{
// outerKey needs to refer to the outer-scope's alias
var outerKey = outerKeys.Select(k => ColumnMapper.Map(k, save.Alias, newOuterSelect.Alias));
// innerKey needs to refer to the new alias for the select with the new join
var innerKey = innerKeys.Select(k => ColumnMapper.Map(k, joinedSelect.Alias, ((ColumnExpression)k).Alias));
ProjectionExpression newProjection = new ProjectionExpression(joinedSelect, newProjector, proj.Aggregator);
return(new ClientJoinExpression(newProjection, outerKey, innerKey));
}
}
else
{
bool saveJoin = this.canJoinOnClient;
this.canJoinOnClient = false;
var result = base.VisitProjection(proj);
this.canJoinOnClient = saveJoin;
return(result);
}
}
else
{
this.isTopLevel = false;
}
return(base.VisitProjection(proj));
}
finally
{
this.currentSelect = save;
}
}
