Idiomatic way to write a range that tracks how much it consumes

[drug]

27.04.2020 06:38, Jon Degenhardt пишет:
> 
> Is there a better way to write this?
> 
> --Jon

I don't know a better way, I think you enlist all possible ways - get a 
value using either `front` or special range member. I prefer the second 
variant, I don't think it is less consistent with range paradigms. 
Considering you need amount of consumed bytes only when range is empty 
the second way is more effective.