protected override Expression VisitProjection(DbProjectionExpression proj)
{
if (isTopLevel)
{
isTopLevel = false;
this.currentSelect = proj.Select;
var projector = this.Visit(proj.Projector);
if (projector != proj.Projector || this.currentSelect != proj.Select)
{
return(new DbProjectionExpression(this.currentSelect, projector, proj.Aggregator));
}
return(proj);
}
if (proj.IsSingleton && this.CanJoinOnServer(this.currentSelect))
{
var newAlias = new TableAlias();
this.currentSelect = this.currentSelect.AddRedundantSelect(this.language, newAlias);
var source = DbColumnMapper.Map(proj.Select, newAlias, this.currentSelect.Alias) as DbSelectExpression;
var pex = this.language.AddOuterJoinTest(new DbProjectionExpression(source, proj.Projector));
var pc = DbColumnProjector.ProjectColumns(this.language, pex.Projector, this.currentSelect.Columns, this.currentSelect.Alias, newAlias, proj.Select.Alias);
var join = new DbJoinExpression(JoinType.OuterApply, this.currentSelect.From, pex.Select, null);
this.currentSelect = new DbSelectExpression(this.currentSelect.Alias, pc.Columns, join, null);
return(this.Visit(pc.Projector));
}
var saveTop = this.isTopLevel;
var saveSelect = this.currentSelect;
this.isTopLevel = true;
this.currentSelect = null;
var result = base.VisitProjection(proj);
this.isTopLevel = saveTop;
this.currentSelect = saveSelect;
return(result);
}
protected override Expression VisitProjection(DbProjectionExpression proj)
{
var save = this.currentSelect;
this.currentSelect = proj.Select;
try
{
if (this.isTopLevel == false)
{
if (this.CanJoinOnClient(this.currentSelect))
{
var newOuterSelect = DbQueryDuplicator.Duplicate(save) as DbSelectExpression;
var newInnerSelect = DbColumnMapper.Map(proj.Select, newOuterSelect.Alias, save.Alias) as DbSelectExpression;
var newInnerProjection = this.language.AddOuterJoinTest(new DbProjectionExpression(newInnerSelect, proj.Projector));
if (newInnerProjection != null)
{
newInnerSelect = newInnerProjection.Select;
}
var newProjector = newInnerProjection.Projector;
var newAlias = new TableAlias();
var pc = DbColumnProjector.ProjectColumns(this.language, newProjector, null, newAlias, newOuterSelect.Alias, newInnerSelect.Alias);
var join = new DbJoinExpression(JoinType.OuterApply, newOuterSelect, newInnerSelect, null);
var joinedSelect = new DbSelectExpression(newAlias, pc.Columns, join, null, null, null, proj.IsSingleton, null, null, false);
this.currentSelect = joinedSelect;
if (pc != null)
{
newProjector = this.Visit(pc.Projector);
}
var outerKeys = new List <Expression>();
var innerKeys = new List <Expression>();
if (this.GetEquiJoinKeyExpressions(newInnerSelect.Where, newOuterSelect.Alias, outerKeys, innerKeys))
{
var outerKey = outerKeys.Select(k => DbColumnMapper.Map(k, save.Alias, newOuterSelect.Alias));
var innerKey = innerKeys.Select(k => DbColumnMapper.Map(k, joinedSelect.Alias, ((DbColumnExpression)k).Alias));
var newProjection = new DbProjectionExpression(joinedSelect, newProjector, proj.Aggregator);
return(new DbClientJoinExpression(newProjection, outerKey, innerKey));
}
}
else
{
var 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;
}
}
