Get the number of bytes parsed from `nom`


Hello all!

Is it possible to get the number of bytes parsed from nom? I am trying to use nom inside an implementation of tokio_io::codec::Decoder and I need to know how many bytes were parsed in order to remove them from a growing BytesMut.


Doesn’t nom return both what bytes we’re parsed and the remaining slice? You can just call .len() on that no?


nom parsers return the parsed object which could be of any type. For example nom::be_u64 parses a big-endian u64 and returns a u64, not 8 bytes.


You know what? I think taking the len() of the original BytesMut and subtracting the len() of the unparsed slice might give me the length of the parsed slice.
Thanks @cbreeden :slight_smile: