public static AggregatedOutputColumn TryParse(string name)
{
// looks for aggregation expressions in the name string
// example: COUNT(someColumn), MIN(someColumn) etc...
AggregatedOutputColumn result = null;
bool isAggregated = false;
Match aggregationMatch = Regex.Match(name, @"(?<expression>\b(?<aggregationType>(COUNT|SUM|MAX|MIN))\s*\((?<baseColumn>(\w+|\*))\))\s+AS\s+(?<alias>\w+)", RegexOptions.IgnoreCase);
if (aggregationMatch.Success)
{
isAggregated = true;
result = new AggregatedOutputColumn();
result.Aggregation = (AggregationType)Enum.Parse(typeof(AggregationType), aggregationMatch.Groups["aggregationType"].ToString(), true);
result.BaseColumn = aggregationMatch.Groups["baseColumn"].ToString();
result.Expression = aggregationMatch.Groups["expression"].ToString();
result.Alias = aggregationMatch.Groups["alias"].ToString();
}
if (!isAggregated)
{
return(null);
}
return(result);
}
public AggregatedOutputColumn(OutputColumn col) : base()
{
Name = col.Name == null ? "" : col.Name;
Calculated = col.Calculated;
if (col is AggregatedOutputColumn)
{
AggregatedOutputColumn outCol = (AggregatedOutputColumn)col;
Aggregation = outCol.Aggregation;
Expression = outCol.Expression;
Alias = outCol.Alias;
BaseColumn = outCol.BaseColumn;
if (Name == "")
{
Name = Alias;
}
}
}
