// To minimize the amount of implementation needed, and simplify inversion of control,
// we provide instantiation routines that fit most types of elements in the right order and
// we provide implemented defaults for interfaces that the element could implement.
// Normally, an element shouldn't have to override instantiate or uninstantiate directly.
public virtual void Instantiate(GraphReference instance)
{
// Create the data for this graph, non-recursively, that is
// required for the nest instantiation, so we do it first.
if (this is IGraphElementWithData withData)
{
instance.data.CreateElementData(withData);
}
// Nest instantiation is a recursive operation that will
// call Instantiate on descendant graphs and elements.
// Because event listening will descend graph data recursively,
// we need to create it before.
if (this is IGraphNesterElement nester && nester.nest.graph != null)
{
GraphInstances.Instantiate(instance.ChildReference(nester, true));
}
// StartListening is a recursive operation that will
// descend graphs recursively. It must be called after
// instantiation of all child graphs because it will require
// their data. The drawback with this approach is that it will be
// called at each step bubbling up, whereas it will only
// effectively trigger once we reach the top level.
// Traversal is currently O(n!) where n is the number of descendants,
// ideally it would be O(n) if only triggered from the root.
// => Listening has to be implemented by Bolt classes, because Graphs isn't aware of the event system
}
public virtual void Uninstantiate(GraphReference instance)
{
// See above comments, in reverse order.
if (this is IGraphNesterElement nester && nester.nest.graph != null)
{
GraphInstances.Uninstantiate(instance.ChildReference(nester, true));
}
if (this is IGraphElementWithData withData)
{
instance.data.FreeElementData(withData);
}
}
public static void TriggerEventHandler <TArgs>(this GraphReference reference, Func <EventHook, bool> predicate, TArgs args, Func <IGraphParentElement, bool> recurse, bool force)
{
Ensure.That(nameof(reference)).IsNotNull(reference);
foreach (var element in reference.graph.elements)
{
if (element is IGraphEventHandler <TArgs> handler && (predicate?.Invoke(handler.GetHook(reference)) ?? true))
{
if (force || handler.IsListening(reference))
{
handler.Trigger(reference, args);
}
}
if (element is IGraphParentElement parentElement && recurse(parentElement))
{
reference.ChildReference(parentElement, false, 0)?.TriggerEventHandler(predicate, args, recurse, force);
}
}
}