public int Compare(T x, T y)
{
for (int i = 0; i < getters.Length; i++)
{
var getter = getters[i];
var xVal = getter(x);
var yVal = getter(y);
var cmp = CompareTypeUtils.CompareTo(xVal, yVal);
if (cmp != 0)
{
return(orderAsc[i] ? cmp : cmp * -1);
}
}
return(0);
}
public virtual int CompareTo(object a, object b)
{
return(CompareTypeUtils.CompareTo(a, b));
}
public virtual object SelectAggregate(IDataQuery q, string name, IEnumerable <string> args)
{
name = name?.ToUpper() ?? throw new ArgumentNullException(nameof(name));
if (name != "COUNT" && name != "MIN" && name != "MAX" && name != "AVG" && name != "SUM" &&
name != "FIRST" && name != "LAST")
{
return(null);
}
var query = (DataQuery <T>)q;
var argsArray = args.ToArray();
var firstArg = argsArray.FirstOrDefault();
string modifier = null;
if (firstArg != null && firstArg.StartsWithIgnoreCase("DISTINCT "))
{
modifier = "DISTINCT";
firstArg = firstArg.Substring(modifier.Length + 1);
}
if (name == "COUNT" && (firstArg == null || firstArg == "*"))
{
return(Count(q));
}
var firstGetter = TypeProperties <T> .Instance.GetPublicGetter(firstArg);
if (firstGetter == null)
{
return(null);
}
var data = ApplyConditions(GetDataSource(q), query.Conditions);
if (name == "FIRST" || name == "LAST")
{
data = ApplySorting(data, q.OrderBy);
}
var source = data.ToArray();
switch (name)
{
case "COUNT":
if (modifier == "DISTINCT")
{
var results = new HashSet <object>();
foreach (var item in source)
{
results.Add(firstGetter(item));
}
return(results.Count);
}
return(CompareTypeUtils.Aggregate(source,
(acc, next) => CompareTypeUtils.Add(acc, firstGetter(next)), 0));
case "MIN":
return(CompareTypeUtils.Aggregate(source,
(acc, next) => CompareTypeUtils.Min(acc, firstGetter(next))));
case "MAX":
return(CompareTypeUtils.Aggregate(source,
(acc, next) => CompareTypeUtils.Max(acc, firstGetter(next))));
case "SUM":
return(CompareTypeUtils.Sum(source.Map(x => firstGetter(x))));
case "AVG":
object sum = CompareTypeUtils.Sum(source.Map(x => firstGetter(x)));
var sumDouble = (double)Convert.ChangeType(sum, typeof(double));
return(sumDouble / source.Length);
case "FIRST":
return(source.Length > 0 ? firstGetter(source[0]) : null);
case "LAST":
return(source.Length > 0 ? firstGetter(source[source.Length - 1]) : null);
}
return(null);
}
