Get spns of a pgn?

[abalmos]

I am working on a tool that parses a can stream based on a dbc file in real time. I don't really have specific messages of interests (like the example), but rather, I want to parse all can frames that match to DBC.

Something like:

let lib = PgnLibrary::from_dbc_file("./j1939.dbc");

loop {
  let msg = s.recv()?;

  let Some(pgnDef) = lib.get_pgn(msg.pgn) {
    let d = pgnDef.spns.iter().map(|(s, def)| (s, def.parse_message(msg.data)?));
  }
  
  // Export `d` to database

}

Currently this does not compile because spns is a private member. Do you intend to support this? If so, I would be willing to offer a PR based on how you want to approach it.

[jmagnuson]

Hey, thanks for the interest and good idea! I eventually wanted to get to #17 to speed up SPN lookups, but that would probably entail breaking the internal PGN/SPN model. That said, do you see needing any other functionality beyond iterating the SPN map? Otherwise, I like the idea of exposing an API to do this, maybe something like:

impl PgnDefinition {
    ...
    pub fn spns() -> impl Iterator<Item = (&String, &SpnDefinition)> { ... }

which is basically just a proxy for pgnDef.spns.iter(), but should be pretty semver-resilient, I think.