private void InsertColumns()
{
DataTable table;
foreach (var tuple in ResultSelector.GetSelectedColumns())
{
switch (tuple.Key)
{
case "outer":
table = OuterTable;
break;
case "inner":
table = InnerTable;
break;
default:
throw new ArgumentException("In result selector script were used different variables than outer and inner!");
}
var columnName = tuple.Value;
var column = table.Columns[columnName];
if (column == null)
{
throw new ArgumentNullException($"{table.TableName} ({tuple.Key}) does not have column {tuple.Value}!");
}
Result.Columns.Add(column.ColumnName, column.DataType);
}
}
/// <summary>
/// Monadically composes the <see cref="Result{TOk, TError}"/> with the next operation
/// by either processing the successful value with the continuation, or immediately
/// returning the failed value without process.
/// </summary>
/// <typeparam name="TOut">The type of the success value of the continuation</typeparam>
/// <typeparam name="TResult">
/// The success value after combining the initial value with the value of the continuation
/// </typeparam>
/// <param name="selector">
/// The function which processes the successful value and returns a new
/// <see cref="Result{TOut, TError}"/>
/// </param>
/// <param name="combine">
/// A function which combines the current successful value with the new successful value
/// of the continuation and combines them into a <typeparamref name="TResult"/>
/// </param>
/// <remarks>
/// This method is used to support multiple uses of the <c>from</c> keywords when using
/// LINQ syntax. The <paramref name="combine"/> parameter is used by the LINQ syntax
/// to allow multiple uses of the from clause while avoiding nested lambdas.
/// </remarks>
public Result <TResult, TError> SelectMany <TOut, TResult>(ResultSelector <TOk, TOut, TError> selector, Func <TOk, TOut, TResult> combine) =>
IsSuccess
? selector(_Ok).Select(new Combiner <TOut, TResult>(_Ok, combine).Combine)
: Result <TResult, TError> .Error(_Error)
;