protected virtual Expression VisitOuterJoined(OuterJoinedExpression outer)
{
Expression test = Visit(outer.Test);
Expression expression = Visit(outer.Expression);
return(UpdateOuterJoined(outer, test, expression));
}
public virtual ProjectionExpression AddOuterJoinTest(ProjectionExpression proj)
{
Expression test = GetOuterJoinTest(proj.Select);
SelectExpression select = proj.Select;
ColumnExpression testCol = null;
// look to see if test expression exists in columns already
foreach (ColumnDeclaration col in select.Columns)
{
if (test.Equals(col.Expression))
{
QueryType colType = TypeSystem.GetColumnType(test.Type);
testCol = new ColumnExpression(test.Type, colType, select.Alias, col.Name);
break;
}
}
if (testCol == null)
{
// add expression to projection
testCol = test as ColumnExpression;
string colName = (testCol != null) ? testCol.Name : "Test";
colName = proj.Select.Columns.GetAvailableColumnName(colName);
QueryType colType = TypeSystem.GetColumnType(test.Type);
select = select.AddColumn(new ColumnDeclaration(colName, test, colType));
testCol = new ColumnExpression(test.Type, colType, select.Alias, colName);
}
var newProjector = new OuterJoinedExpression(testCol, proj.Projector);
return(new ProjectionExpression(select, newProjector, proj.Aggregator));
}
protected OuterJoinedExpression UpdateOuterJoined(OuterJoinedExpression outer, Expression test, Expression expression)
{
if (test != outer.Test || expression != outer.Expression)
{
return(new OuterJoinedExpression(test, expression));
}
return(outer);
}
public static ProjectionExpression AddOuterJoinTest(this ProjectionExpression proj, QueryLanguage language, Expression expression)
{
string colName = proj.Select.Columns.GetAvailableColumnName("Test");
QueryType colType = language.TypeSystem.GetColumnType(expression.Type);
SelectExpression newSource = proj.Select.AddColumn(new ColumnDeclaration(colName, expression, colType));
Expression newProjector = new OuterJoinedExpression(new ColumnExpression(expression.Type, colType, newSource.Alias, colName), proj.Projector);
return(new ProjectionExpression(newSource, newProjector, proj.Aggregator));
}
protected virtual Expression VisitOuterJoined(OuterJoinedExpression outer)
{
Write("Outer(");
WriteLine(Indentation.Inner);
Visit(outer.Test);
Write(", ");
WriteLine(Indentation.Same);
Visit(outer.Expression);
WriteLine(Indentation.Outer);
Write(")");
return(outer);
}
protected override Expression VisitOuterJoined(OuterJoinedExpression outer)
{
Expression expr = Visit(outer.Expression);
var 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(TypeHelper.GetDefault(outer.Type), outer.Type), expr));
}
return(expr);
}
