SelectingAggregationHandler
constructor(selector: Selector<Value, Return>, indexOfResult: IndexOfResult<Value>, getReturnType: CalculateReturnType)
Parameters
selector
This function actually does the selection. Before it is called, nulls are filtered out. The type of the values is passed as KType to the selector.
indexOfResult
This function must be supplied to give the index of the result in the input values.
getReturnType
This function must be supplied to give the return type of selector given some input type and whether the input is empty. In practice the return type is always either typeOf<Value>() or typeOf<Value?>().