Function split_by_leaf_ids

crates/vm/src/exceptions.rs:2960–2996

Recursively split an exception (group) by leaf IDs. Returns the projection containing only matching leaves with preserved structure.

(
    exc: &PyObjectRef,
    leaf_ids: &HashSet<usize>,
    vm: &VirtualMachine,
)

/// Recursively split an exception (group) by leaf IDs.
/// Returns the projection containing only matching leaves with preserved structure.
fn split_by_leaf_ids(
    exc: &PyObjectRef,
    leaf_ids: &HashSet<usize>,
    vm: &VirtualMachine,
) -> PyResult {
    if vm.is_none(exc) {
        return Ok(vm.ctx.none());
    }

    // If not an exception group, check if it's in our set
    if !exc.fast_isinstance(vm.ctx.exceptions.base_exception_group) {
        if leaf_ids.contains(&exc.get_id()) {
            return Ok(exc.clone());
        }
        return Ok(vm.ctx.none());
    }

    // Exception group - recurse and reconstruct
    let excs_attr = exc.get_attr("exceptions", vm)?;
    let tuple: PyTupleRef = excs_attr.try_into_value(vm)?;

    let mut matched = Vec::new();
    for e in tuple.iter() {
        let m = split_by_leaf_ids(e, leaf_ids, vm)?;
        if !vm.is_none(&m) {
            matched.push(m);
        }
    }

    if matched.is_empty() {
        return Ok(vm.ctx.none());
    }

    // Reconstruct using derive() to preserve the structure (not necessarily the subclass type)
    let matched_tuple = vm.ctx.new_tuple(matched);
    vm.call_method(exc, "derive", (matched_tuple,))
}