Hello,
I’m trying to make a NIF that splits binary once using a delimiter (like :binary.split(bin, separator, parts: 2)
) but in Rust I don’t quite understand how to use rustler::Binary
, rustler::OwnedBinary
and rustler::NewBinary
.
Here’s the code I currently have, it’s working but it could be improved (I think):
#[rustler::nif]
fn next<'a>(env: Env<'a>, raw: Binary<'a>) -> (Option<Binary<'a>>, Binary<'a>) {
match do_next(raw.as_slice()) {
Some((packet, remaining)) => {
let mut pb = NewBinary::new(env, packet.len());
pb.as_mut_slice().copy_from_slice(packet);
let mut rb = NewBinary::new(env, remaining.len());
rb.as_mut_slice().copy_from_slice(remaining);
(Some(pb.into()), rb.into())
}
None => (None, raw)
}
}
fn do_next(raw: &[u8]) -> Option<(&[u8], &[u8])> {
let index = raw.iter().position(|&r| r == SEPARATOR);
match index {
Some(i) => Some((&raw[0..i], &raw[i + 1..])),
_ => None,
}
}
I’ve few questions:
- Why is it possible to return an
OwnedBinary
but not if it’s in a tuple ?
Example:
// This works
#[rustler::nif]
fn encrypt(raw: String) -> OwnedBinary {
let enc: Vec<u8> = do_encrypt(raw.as_bytes());
let mut binary: OwnedBinary = OwnedBinary::new(enc.len()).unwrap();
binary.as_mut_slice().copy_from_slice(&enc);
binary
}
// But this don't
// The error is: the trait bound `OwnedBinary: Encoder` is not satisfied
#[rustler::nif]
fn encrypt(raw: String) -> (OwnedBinary , OwnedBinary) {
let enc: Vec<u8> = do_encrypt(raw.as_bytes());
let mut binary: OwnedBinary = OwnedBinary::new(enc.len()).unwrap();
binary.as_mut_slice().copy_from_slice(&enc);
(binary, binary)
}
- It is possible to return a binary inside a tuple but without to manually allocate it using the
env
?
Thanks in advance