/// <summary>
/// Creates a measure expression
/// </summary>
/// <param name="node">method call node</param>
/// <returns>a measure expression corresponding to the node</returns>
internal Expression CreateMeasureExpression(MethodCallExpression node)
{
_measureCounter++;
Expression c = _binder.Visit(node.Arguments[0]);
Type t = node.Method.ReturnType;
if (c is GroupingProjection)
{
GroupingProjection grp = ((GroupingProjection)c);
c = grp.SubQueryProjectionExpression.Projector;
t = grp.SubQueryProjectionExpression.Projector.Type;
}
if (c is ProjectionExpression)
{
c = ((ProjectionExpression)c).Projector;
}
var col = c as ColumnExpression;
if (col != null)
{
var table = col.TableName;
// TODO: Add a level of indirection here as well see XAggregations
string dbname = node.Method.Name.ToUpper() + "(" + col.DbName + ")";
string name = string.Format("[{0}Of{1}{2}]", node.Method.Name, col.Name, _measureCounter);
if (node.Arguments.Count() == 1)
{
return(new MeasureExpression(
t, //node.Method.ReturnType,
name,
dbname,
name,
table));
}
Expression filter;
switch (node.Arguments[1].NodeType)
{
case ExpressionType.Parameter:
filter = TableFactory.GetTableExpression(node.Arguments[1]);
break;
default:
filter = _binder.Visit(node.Arguments[1]);
break;
}
return(new MeasureExpression(t, (ExpressionType)DaxExpressionType.Measure, name, dbname, name, table,
filter));
}
throw new TabularException("could not create measure: the column reference was not found");
}
private Expression VisitGroupingProjection(GroupingProjection groupingProjection)
{
var key = (ProjectionExpression)Visit(groupingProjection.KeyProjection);
var subQuery = (ProjectionExpression)Visit(groupingProjection.SubQueryProjectionExpression);
if (key != groupingProjection.KeyProjection || subQuery != groupingProjection.SubQueryProjectionExpression)
{
return(new GroupingProjection(groupingProjection.Type, key, subQuery));
}
return(groupingProjection);
}
