/// <summary>
/// Update a shadow given current and next values.
/// </summary>
/// <typeparam name="TItem"></typeparam>
/// <param name="context"></param>
/// <param name="current"></param>
/// <param name="next"></param>
/// <param name="shadow"></param>
/// <param name="added"></param>
/// <param name="removed"></param>
public static void Update <TItem>(IShadowContext context, IPrimitive current,
IPrimitive next,
IShadow <TItem> shadow,
Action <IShadow <TItem> > added = default,
Action <IShadow <TItem> > removed = default)
{
// current == null and next != null implies -> new
// current != null && next != null implies -> update/change
// current != null && next == null, implies -> remove
try
{
// now, we do have a problem in that the shadow may not exist...//
// if so then its a create
if (shadow != null)
{
// the shadow could well change...
// in this case, we need to ...
var sameElementType = current.AreSameType(next);
if (!sameElementType)
{
if (current != null)
{
// this isn't right, since the layout hasn't been retained
context.MapperFactory.Remove(context, shadow, current);
// we could want to 'drop' the content view here, how would we do that ?
removed?.Invoke(shadow);
shadow = default;
}
}
else
{
context.MapperFactory.Update(context, shadow, current, next);
}
}
if (shadow == null)
{
var baseShadow = context.MapperFactory.Create(context, next);
shadow = (IShadow <TItem>)baseShadow;
added?.Invoke(shadow);
}
}
catch (Exception exception)
{
Logging.Instance.LogError(exception, "Shadow:Update Current:{current} Next:{next} ShadowType:{shadowType}", current, next, shadow?.GetType().FriendlyName());
throw;
}
}
