protected virtual Expression VisitOuterJoined(OuterJoinedExpression outer)
{
Expression test = this.Visit(outer.Test);
Expression expression = this.Visit(outer.Expression);
if (test != outer.Test || expression != outer.Expression)
{
return(new OuterJoinedExpression(test, expression));
}
return(outer);
}
public static ProjectionExpression AddOuterJoinTest(this ProjectionExpression proj)
{
string colName = proj.Source.GetAvailableColumnName("Test");
SelectExpression newSource = proj.Source.AddColumn(new ColumnDeclaration(colName, Expression.Constant(1, typeof(int?))));
Expression newProjector =
new OuterJoinedExpression(
new ColumnExpression(typeof(int?), newSource.Alias, colName),
proj.Projector
);
return(new ProjectionExpression(newSource, newProjector, proj.Aggregator));
}
protected virtual Expression VisitOuterJoined(OuterJoinedExpression outer)
{
this.Write("Outer(");
this.WriteLine(Indentation.Inner);
this.Visit(outer.Test);
this.Write(", ");
this.WriteLine(Indentation.Same);
this.Visit(outer.Expression);
this.WriteLine(Indentation.Outer);
this.Write(")");
return(outer);
}
protected override Expression VisitOuterJoined(OuterJoinedExpression outer)
{
Expression expr = Visit(outer.Expression);
ColumnExpression column = (ColumnExpression)outer.Test;
ParameterExpression reader;
int iOrdinal;
if (scope.TryGetValue(column, out reader, out iOrdinal))
{
return(Expression.Condition(
Expression.Call(reader, "IsDbNull", null, Expression.Constant(iOrdinal)),
Expression.Constant(null, outer.Type),
expr
));
}
return(expr);
}