Borrow Access in FilteredEntity(Ref|Mut) and Entity(Ref|Mut)Except

[chescock]

Objective

Improve the performance of FilteredEntity(Ref|Mut) and Entity(Ref|Mut)Except.

FilteredEntityRef needs an Access<ComponentId> to determine what components it can access. There is one stored in the query state, but query items cannot borrow from the state, so it has to clone() the access for each row. Cloning the access involves memory allocations and can be expensive.

Solution

Let query items borrow from their query state.

Have FilteredEntity(Ref|Mut) borrow the access from the query state to avoid cloning for each row.

Have Entity(Ref|Mut)Except look up the component ids on initialization and store them in an Access that can be borrowed by each row.