public IReservationsProgram <int?> TryAccept(Reservation reservation)
{
return(ReservationsProgram
.IsReservationInFuture(reservation)
.SelectMany(isInFuture =>
{
if (!isInFuture)
{
return new Pure <int?>(null);
}
return ReservationsProgram
.ReadReservations(reservation.Date)
.SelectMany(reservations =>
{
var reservedSeats = reservations.Sum(r => r.Quantity);
if (Capacity < reservedSeats + reservation.Quantity)
{
return new Pure <int?>(null);
}
reservation.IsAccepted = true;
return ReservationsProgram
.Create(reservation)
.Select(x => new int?(x));
});
}));
}
public static async Task <TResult> Run <TResult>(this ReservationsProgram <TResult> prg, IReservationsInstrHandler handler)
{
var result = default(TResult);
var done = false;
while (!done)
{
switch (prg)
{
case Return <TResult> ret:
result = ret.Result;
done = true;
break;
case Delay <TResult> delay:
prg = delay.Func();
break;
case Await <TResult> _await:
prg = await _await.Accept(handler);
break;
default:
throw new NotSupportedException($"{prg.GetType().Name}");
}
}
return(result);
}
public void Start <TStateMachine>(ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
{
var state = stateMachine;
this.cont = () =>
{
state.MoveNext();
return(this.prg);
};
this.prg = new Delay <TResult>(cont);
}
public IReservationsProgram <IMaybe <int> > TryAccept(Reservation reservation)
{
return
(from isInFuture in ReservationsProgram.IsReservationInFuture(reservation)
from _ in ReservationsProgram.Guard(isInFuture)
from reservations in ReservationsProgram.ReadReservations(reservation.Date)
let reservedSeats = reservations.Sum(r => r.Quantity)
from __ in ReservationsProgram.Guard(reservedSeats + reservation.Quantity <= Capacity)
from ___ in ReservationsProgram.Do(() => { reservation.IsAccepted = true; })
from id in ReservationsProgram.Create(reservation)
select id);
}
public void AwaitUnsafeOnCompleted <TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine)
where TAwaiter : ReservationsInstr
where TStateMachine : IAsyncStateMachine
{
this.prg = awaiter.Await(this.cont);
}
public void SetResult(TResult result)
{
this.prg = new Return <TResult>(result);
}