Function implement_neu

src/lib.rs:1018–1127

@TODO

(
    name: &str,
    scope: &mut S,
    context: &mut I,
)

/// @TODO
pub fn implement_neu<T, I, S>(
    name: &str,
    scope: &mut S,
    context: &mut I,
) -> Result<
    (
        HashMap<String, Collection<S, Vec<Value>, isize>>,
        ShutdownHandle,
    ),
    Error,
>
where
    T: Timestamp + Lattice + Default,
    I: ImplContext<T>,
    S: Scope<Timestamp = T>,
{
    scope.iterative::<u64, _, _>(move |nested| {
        let publish = vec![name];
        let mut rules = collect_dependencies(&*context, &publish[..])?;

        let mut local_arrangements = VariableMap::new();
        let mut result_map = HashMap::new();

        // Step 0: Canonicalize, check uniqueness of bindings.
        if rules.is_empty() {
            return Err(Error::not_found(format!(
                "Couldn't find any rules for name {}.",
                name
            )));
        }

        rules.sort_by(|x, y| x.name.cmp(&y.name));
        for index in 1..rules.len() - 1 {
            if rules[index].name == rules[index - 1].name {
                return Err(Error::conflict(format!(
                    "Duplicate rule definitions for rule {}",
                    rules[index].name
                )));
            }
        }

        // @TODO at this point we need to know about...
        // @TODO ... which rules require recursion (and thus need wrapping in a Variable)
        // @TODO ... which rules are supposed to be re-used
        // @TODO ... which rules are supposed to be re-synthesized
        //
        // but based entirely on control data written to the server by something external
        // (for the old implement it could just be a decision based on whether the rule has a namespace)

        // Step 1: Create new recursive variables for each rule.
        for name in publish.iter() {
            if context.is_underconstrained(name) {
                local_arrangements.insert(
                    name.to_string(),
                    Variable::new(nested, Product::new(Default::default(), 1)),
                );
            }
        }