Function manifest_apply_order

atomic-cli/src/commands/clone/helpers.rs:408–437

Order manifests so every parent is applied before its children. A manifest is ready when its declared parent is `None` (a root view), already applied locally (`already_applied`), or emitted earlier in the order. Repeatedly emits ready manifests until no progress can be made. # Returns `(ordered, stuck)` — indices into `manifests`. `ordered` is a valid root→leaf apply order; `stuck` holds manife

(
    manifests: &[ViewManifest],
    already_applied: &HashSet<String>,
)

/// (their parent chain has a cycle or references a view that is neither
/// in the set nor already applied).
pub fn manifest_apply_order(
    manifests: &[ViewManifest],
    already_applied: &HashSet<String>,
) -> (Vec<usize>, Vec<usize>) {
    let mut ordered: Vec<usize> = Vec::with_capacity(manifests.len());
    let mut emitted: HashSet<&str> = HashSet::with_capacity(manifests.len());
    let mut remaining: Vec<usize> = (0..manifests.len()).collect();

    loop {
        let before = ordered.len();
        remaining.retain(|&i| {
            let ready = match manifests[i].parent.as_deref() {
                None => true,
                Some(p) => already_applied.contains(p) || emitted.contains(p),
            };
            if ready {
                emitted.insert(manifests[i].name.as_str());
                ordered.push(i);
                false
            } else {
                true
            }
        });
        if ordered.len() == before {
            break;
        }
    }

    (ordered, remaining)
}

/// The union of change hashes across a set of manifests.
///