/// <summary>
/// Applies a function to a series of Result arguments
/// </summary>
/// <typeparam name="TFailure">Type of Failure</typeparam>
/// <typeparam name="TResult">Type of Success</typeparam>
/// <typeparam name="T1">Type of the first argument</typeparam>
/// <typeparam name="T2">Type of the second argument</typeparam>
/// <typeparam name="T3">Type of the third argument</typeparam>
/// <param name="func">Function to call</param>
/// <param name="first">First argument for the function</param>
/// <param name="second">Second argument for the function</param>
/// <param name="third">Third argument for the function</param>
/// <returns>If all arguments are Success, then a Success is returned. Otherwise, all the Failures are concatentated into a Failure Result</returns>
/// <exception cref="ArgumentNullException"></exception>
public static IResult <IEnumerable <TFailure>, TResult> Apply <TResult, TFailure, T1, T2, T3>(Func <T1, T2, T3, TResult> func, IResult <TFailure, T1> first, IResult <TFailure, T2> second, IResult <TFailure, T3> third)
{
if (func == null)
{
throw new ArgumentNullException(nameof(func));
}
if (first == null)
{
throw new ArgumentNullException(nameof(first));
}
if (second == null)
{
throw new ArgumentNullException(nameof(second));
}
if (third == null)
{
throw new ArgumentNullException(nameof(third));
}
IResult <IEnumerable <TFailure>, TResult> doSuccess()
{
var firstValue = ((Success <TFailure, T1>)first).Value;
var secondValue = ((Success <TFailure, T2>)second).Value;
var thirdValue = ((Success <TFailure, T3>)third).Value;
return(Success <IEnumerable <TFailure>, TResult>(func(firstValue, secondValue, thirdValue)));
}
IResult <IEnumerable <TFailure>, TResult> doFailure()
{
var errors = new List <TFailure>();
void addError(TFailure error) => errors.Add(error);
first.Do(addError, _ => { });
second.Do(addError, _ => { });
third.Do(addError, _ => { });
return(Failure <IEnumerable <TFailure>, TResult>(errors));
}
var firstIsSuccess = first is Success <TFailure, T1>;
var secondIsSuccess = second is Success <TFailure, T2>;
var thirdIsSuccess = third is Success <TFailure, T3>;
return(firstIsSuccess && secondIsSuccess && thirdIsSuccess?doSuccess() : doFailure());
}