private EntityComponent ValidateItem(int index, EntityComponent item)
{
if (item == null)
{
throw new ArgumentNullException(nameof(item), "Cannot add a null component");
}
var componentType = item.GetType();
var attributes = EntityComponentAttributes.Get(componentType);
var onlySingleComponent = !attributes.AllowMultipleComponents;
EntityComponent previousItem = null;
for (int i = 0; i < Count; i++)
{
var existingItem = this[i];
if (index == i)
{
previousItem = existingItem;
}
else
{
if (ReferenceEquals(existingItem, item))
{
throw new InvalidOperationException($"Cannot add a same component multiple times. Already set at index [{i}]");
}
if (onlySingleComponent && componentType == existingItem.GetType())
{
throw new InvalidOperationException($"Cannot add a component of type [{componentType}] multiple times");
}
}
}
if (!AllowReplaceForeignEntity && entity != null && item.Entity != null)
{
throw new InvalidOperationException($"This component is already attached to entity [{item.Entity}] and cannot be attached to [{entity}]");
}
if (entity != null)
{
var transform = item as TransformComponent;
if (transform != null)
{
entity.transform = transform;
}
else if (previousItem is TransformComponent)
{
// If previous item was a transform component but we are actually replacing it, we should
entity.transform = null;
}
item.Entity = entity;
}
return(previousItem);
}
private static EntityComponentAttributes GetInternal([NotNull] Type type)
{
EntityComponentAttributes attributes;
lock (ComponentAttributes)
{
if (!ComponentAttributes.TryGetValue(type, out attributes))
{
attributes = new EntityComponentAttributes(type.GetTypeInfo().GetCustomAttribute <AllowMultipleComponentsAttribute>() != null);
ComponentAttributes.Add(type, attributes);
}
}
return(attributes);
}
