Function get_expr_references

crates/compile/src/graph.rs:137–175

(
  expr: &'a Expr,
  cache: &mut FxHashMap<&'a Expr, NameSet>,
)

fn merge_ref_maps(l: RefMap, r: RefMap) -> RefMap {
  let (smaller, mut bigger) = if l.len() < r.len() { (l, r) } else { (r, l) };
  for (name, set) in smaller {
    match bigger.entry(name) {
      Entry::Vacant(entry) => {
        entry.insert(set);
      },
      Entry::Occupied(mut entry) => {
        entry.get_mut().extend(set);
      },
    }
  }
  bigger
}

pub fn build_ref_graph(env: &Env) -> RefGraph {
  let mk_in_refs = |name: &Name, deps: &NameSet| -> RefMap {
    let mut in_refs = RefMap::from_iter([(name.clone(), NameSet::default())]);
    for dep in deps {
      match in_refs.entry(dep.clone()) {
        Entry::Vacant(entry) => {
          entry.insert(NameSet::from_iter([name.clone()]));
        },
        Entry::Occupied(mut entry) => {
          entry.get_mut().insert(name.clone());
        },
      }
    }
    in_refs
  };

  let merge = |l: RefMap, r: RefMap| -> RefMap {
    let (smaller, mut bigger) = if l.len() < r.len() { (l, r) } else { (r, l) };
    for (name, set) in smaller {
      match bigger.entry(name) {
        Entry::Vacant(entry) => {
          entry.insert(set);
        },
        Entry::Occupied(mut entry) => {
          entry.get_mut().extend(set);
        },
      }
    }
    bigger