/// <summary>
/// Create aggregation functions
/// </summary>
public static Expression Aggregate(this Expression me, AggregationFunctionType aggregation)
{
var aggregateMethod = typeof(Enumerable).GetGenericMethod(aggregation.ToString(),
new Type[] { me.Type.GetTypeInfo().GenericTypeArguments[0] },
new Type[] { me.Type });
return(Expression.Call(aggregateMethod as MethodInfo, me));
}
public Aggregation Instantiate(ColumnType columnType, AggregationFunctionType function, IScalarResolver[] parameters, IAggregationStrategy[] strategies)
{
var missingValue = (IMissingValueStrategy)(strategies.SingleOrDefault(x => x is IMissingValueStrategy) ?? new DropStrategy(columnType));
var emptySeries = (IEmptySeriesStrategy)(strategies.SingleOrDefault(x => x is IEmptySeriesStrategy) ?? new ReturnDefaultStrategy(columnType));
var @namespace = $"{this.GetType().Namespace}.Function.";
var typeName = $"{Enum.GetName(typeof(AggregationFunctionType), function)}{Enum.GetName(typeof(ColumnType), columnType)}";
var type = GetType().Assembly.GetType($"{@namespace}{typeName}", false, true) ?? throw new ArgumentException($"No aggregation named '{typeName}' has been found in the namespace '{@namespace}'.");
if ((parameters?.Count() ?? 0) == 0)
{
return(new Aggregation((IAggregationFunction)(type.GetConstructor(Type.EmptyTypes).Invoke(Array.Empty <object>())), missingValue, emptySeries));
}
else
{
var ctor = type.GetConstructors().Where(x => x.IsPublic && (x.GetParameters().Count() == parameters.Count())).FirstOrDefault()
?? throw new ArgumentException($"No public constructor for the aggregation '{function}' expecting {parameters.Count()} parameters.");
return(new Aggregation((IAggregationFunction)ctor.Invoke(parameters), missingValue, emptySeries));
}
}
public AggregationArgs(AggregationFunctionType function, ColumnType columnType, IList <IScalarResolver> parameters) => (ColumnType, Function, Parameters) = (columnType, function, parameters ?? new List <IScalarResolver>());
public void Instantiate_ColumnTypeAndAggregationFunction_CorrectAggregation(ColumnType columnType, AggregationFunctionType function)
{
var factory = new AggregationFactory();
Assert.Throws <ArgumentException>(() => factory.Instantiate(columnType, function, Array.Empty <IScalarResolver>(), Array.Empty <IAggregationStrategy>()));
}
public void Instantiate_ColumnTypeandAggregationFunction_CorrectAggregation(ColumnType columnType, AggregationFunctionType function, Type expectedType)
{
var factory = new AggregationFactory();
var aggregation = factory.Instantiate(columnType, function, Array.Empty <IScalarResolver>(), Array.Empty <IAggregationStrategy>());
Assert.That(aggregation, Is.Not.Null);
Assert.That(aggregation.Function, Is.TypeOf(expectedType));
}
public ColumnAggregationArgs(IColumnIdentifier identifier, AggregationFunctionType function, ColumnType columnType, IList <IScalarResolver> parameters)
: base(function, columnType, parameters)
=> (Identifier) = (identifier);
public AggregationXml(AggregationFunctionType function) => Function = function;
