/// <summary>
/// Format a calculate table expression
/// </summary>
/// <param name="calculateTable">expression to be formatted</param>
/// <returns>the original expression</returns>
protected override Expression VisitCalculateTableExpression(CalculateTableExpression calculateTable)
{
if (calculateTable.Filters == null)
{
return(this.Visit(calculateTable.MainTable));
}
this.Builder.Append("\tCALCULATETABLE(");
this.Visit(calculateTable.MainTable);
this.Builder.Append(",");
this.Visit(calculateTable.Filters);
this.Builder.Append(")");
return(calculateTable);
}
internal Expression Rewrite()
{
var keys = Grouping.KeyProjection;
var keyColumns = new ColumnProjector(TabularExpressionHelper.CanBeColumn).ProjectColumns(keys);
var keyFilters = keyColumns.Columns.Select(c => Expression.Equal(c.Expression, c.Expression)).Aggregate((x, y) => Expression.And(x, y));
var subQueryBase =
new CalculateTableExpression(Grouping.SubQueryProjectionExpression.Type,
Grouping.SubQueryProjectionExpression.Source, keyFilters);
var subQuery = new SubQueryProjection(Grouping.SubQueryProjectionExpression.Type, new ProjectionExpression(subQueryBase, Grouping.SubQueryProjectionExpression.Projector));
Type groupType =
typeof(TabularGrouping <,>).MakeGenericType(new Type[]
{ Grouping.KeyProjection.Type, Grouping.SubQueryProjectionExpression.Type });
return(new ProjectionExpression(new SummarizeExpression(groupType, new List <ColumnDeclaration>().AsReadOnly(), Grouping.SubQueryProjectionExpression.Source), subQuery));
}
