protected override Expression VisitJoin(DbJoinExpression join)
{
if (join.Join == DbJoinType.SingletonLeftOuter)
{
// first visit right side w/o looking at condition
Expression right = this.Visit(join.Right);
DbAliasedExpression ax = right as DbAliasedExpression;
if (ax != null && !this.allColumnsUsed.ContainsKey(ax.Alias))
{
// if nothing references the alias on the right, then the join is redundant
return(this.Visit(join.Left));
}
// otherwise do it the right way
Expression cond = this.Visit(join.Condition);
Expression left = this.Visit(join.Left);
right = this.Visit(join.Right);
return(this.UpdateJoin(join, join.Join, left, right, cond));
}
else
{
// visit join in reverse order
Expression condition = this.Visit(join.Condition);
Expression right = this.VisitSource(join.Right);
Expression left = this.VisitSource(join.Left);
return(this.UpdateJoin(join, join.Join, left, right, condition));
}
}
protected override Expression VisitJoin(DbJoinExpression join)
{
Expression result = base.VisitJoin(join);
join = result as DbJoinExpression;
if (join != null)
{
DbAliasedExpression right = join.Right as DbAliasedExpression;
if (right != null)
{
DbAliasedExpression similarRight = (DbAliasedExpression)this.FindSimilarRight(join.Left as DbJoinExpression, join);
if (similarRight != null)
{
this.map.Add(right.Alias, similarRight.Alias);
return(join.Left);
}
}
}
return(result);
}