change iterator API

[rgerhards]

currently, the full iterator structure is returned. this is inefficient if it is larges as a pointer. We can alternatively change it so that the caller always needs to pass in a pointer. However, this means implementation details will not properly be abstracted. In any case, we need to find a good way to handle this. Maybe the right one is to keep things like they are...

[davidelang]

On Mon, 11 Apr 2016, Rainer Gerhards wrote: currently, the full iterator structure is returned. this is inefficient if it is larges as a pointer. We can alternatively change it so that the caller always needs to pass in a pointer. However, this means implementation details will not properly be abstracted. In any case, we need to find a good way to handle this. Maybe the right one is to keep things like they are...

Whatever is passed should be opaque to the caller, just a 'thing' that the internals use to keep track of there it is. As long as it can never be manipulated by the callers, we should be ok. So we can change it's type to a custom type and cast without changing the current implementation and get flagged if the caller tries to do anything else with it. David Lang