/**
* Executes the provided function `f` and tracks which observables are being accessed.
* The tracking information is stored on the `derivation` object and the derivation is registered
* as observer of any of the accessed observables.
*/
public static T TrackedDerivedFunction <T>(this IDerivation derivation, Func <T> func, object context)
{
// pre allocate array allocation + room for variation in deps
// array will be trimmed by bindDependencies
derivation.ChangeDependenciesStateTo0();
derivation.NewObservings = new List <IObservable>(derivation.Observings.Count + 100);
derivation.UnboundDepsCount = 0;
derivation.RunId = States.NextRunId;
var previous = States.UntrackedStart(derivation);
T result = default(T);
if (States.State.DisableErrorBoundaries)
{
result = func();
}
else
{
try
{
result = func();
}
catch (Exception ex)
{
throw new CaughtException(ex);
}
}
States.UntrackedEnd(previous);
derivation.BindDependencies();
return(result);
}
public static bool ShouldCompute(this IDerivation derivation)
{
switch (derivation.DependenciesState)
{
case DerivationState.UP_TO_DATE:
return(false);
case DerivationState.NOT_TRACKING:
case DerivationState.STALE:
return(true);
case DerivationState.POSSIBLY_STALE:
{
var prevUntracked = States.UntrackedStart(); // no need for those computeds to be reported, they will be picked up in trackDerivedFunction.
foreach (var observer in derivation.Observings)
{
if (observer is IComputedValue computed)
{
if (States.State.DisableErrorBoundaries)
{
var x = computed.Value;
}
else
{
try
{
var y = computed.Value;
}
catch
{
// we are not interested in the value *or* exception at this moment, but if there is one, notify all
States.UntrackedEnd(prevUntracked);
return(true);
}
}
// if ComputedValue `obj` actually changed it will be computed and propagated to its observers.
// and `derivation` is an observer of `obj`
// invariantShouldCompute(derivation)
if (derivation.DependenciesState == DerivationState.STALE)
{
States.UntrackedEnd(prevUntracked);
return(true);
}
}
}
derivation.ChangeDependenciesStateTo0();
States.UntrackedEnd(prevUntracked);
return(false);
}
default:
return(false);
}
}
